abstract.pdf

The Comparison Study of PD Measurement with Conventional
Method and Unconventional Method
Prawit Petchphung, Monthon Leelajindakrairerk, Norasage Pattanadech, Pearawut
Yutthagowith,
Kraision Aunchaleevarapan
King Mongkut’s Institute of Technology, Ladkrabang Bangkok, Thailand
e-mail: petchphung@yahoo.com
Abstract--This paper represents the VHF/UHFpartialdischarge measurement technique compared with
conventionalpartial discharge measurement method, IEC 60270. The artificialpartial discharge objects which
represent corona discharge,internal discharge, and surface discharge, were set up and tested with the mention
techniques. The test results show that threekinds of partial discharge give obviously different frequencysignal
obtained from vertical and horizontal VHF/UHF antenna. Its amplitude also depends on electric field stress of the
test objects. Moreover the partial discharge activities of all kinds oftest object obtained from conventional method
are different.From the test results, it was found that unconventional partialdischarge measurement technique,
VHF/UHF method, can be aneffective choice for partial discharge measurement. It also can be improved for online
monitoring of insulation system in the future.Keywords:Partial discharge,Antenna, UHF,Couplingdevice
Advances in PD Measuring System
Techniques:
Parallel Synchronous Detection, Time
Domain and Frequency Domain Processing
for Improved Sensitivity
Abstract--The diagnostic examination of partial discharges (PD) for the condition assessment of insulating
systems of high voltage (HV) equipment, formerly carried out mostly in test bays to control new products after the
manufacturing process, has reached currently numerous on-site/on-line applications as well as being used for the
permanent monitoring of HV equipment with e.g. strategic importance.
Basic characteristics of modern PD measuring equipment should include the suppression of electromagnetic
interferences - which could be external noises from the measuring surroundings or internal noises from the HV test
circuit. These electromagnetic interferences have generally either sine-shaped (broadcast, television,
telecommunication) or pulse-shaped behaviour. The pulse-shaped disturbances could be subdivided into periodic
(e.g. switched inverters) and stochastic noise (e.g. external discharges, system switching).
Regarding the relevant suppression techniques frequency selective filtering, software or hardware windowing
and gating is used for the above mentioned disturbances. In the time domain modern digital filter design rely on

finite and infinite impulse response filters, while in the frequency domain center frequency tuning gives frequency
spectrum analyzer functionality and advantagous narrow-band measurements. Enhanced diagnostic approaches as
clustering, rejection of common-mode disturbances in 3-phase arrangements are enabled through parallel and
synchronous measurement at various channels which are interconnectable and synchronized in the nanoseconds
range.
Distinction of the partial discharge source in
oil by two frequency correlation method
Abstract--A method based on frequency characteristics to distinguish partial discharge (PD) source in oil filled
transformer is proposed. Frequency spectrum of electromagnetic wave from two typical PD sources, i.e., protrusion
of metal and air void in oil was investigated. It was found that metal protrusion gave PD signal with stronger
component in the frequency range above several hundreds MHz compared with air void. Since the acquisition of
frequency spectrum is difficult in practical transformer test condition, we tried to apply the two frequency correlation
method to distinguish the two PD sources. In the method, intensity of two frequency components of each PD signal
is plotted on the x-y plane, where the horizontal axis represents the intensity of low frequency band and vertical axis
represents that of high frequency band, which is a method to characterize a PD source on the x-y plane. The two PD
sources were plotted clearly on the different area of the two frequency correlation graph, that is, metal protrusion
yielded PD signal with higher frequency component than air void. We concluded that the method is effective to
identify the PD source in oil filled transformer.
Dependence of Partial Discharge Characteristics at Spacer
Surface on Particle Size
in SF6 Gas Insulated System
Abstract--A metallic particle appeared in a gas insulated switchgear (GIS) sometimes adheres on a solid spacer
surface. If the adhered metallic particle is exposed to a surge high voltage, a breakdown (BD) may be induced.
Therefore, it is eagerly demanded to diagnose its risk correctly under the service voltage by partial discharge (PD)
measurement. In this paper, particle-initiated surface PD characteristics were systematically studied in 0.4 MPa SF6
gas by changing the sizes of particles. PD inception voltage (PDIV), temporal change of PD current and the PD pulse
number were analyzed in detail. Furthermore, comparing with PD characteristics of particles in a gas gap, the
influence of the solid insulator on the PD characteristics was clarified. It was found out that PD characteristics
greatly changed with time owing to electric charges deposited on a spacer surface.
Application of Partial Discharge
Monitoring to Impulse Damaged Polymeric
Insulation

Abstract-- Impulse damage may occur to insulators within electrical systems due to lightning strikes, switching
operations or self-clearing flashovers. This damage may not result in immediate failure of the system; however,
progressive degradation can occur due to repeated events. If it is possible to develop economical systems to monitor
the effects of impulse degradation of solid insulation, it may be possible to prevent costly failures leading to
unplanned plant outage. The progression of the damage may become apparent through on-line partial discharge (PD)
monitoring using radio frequency (RF) techniques, which potentially allow non-contact on-line monitoring of
discharge activity occurring in electrical insulators. To determine the feasibility of correlating changes in PD activity
and phase-resolved patterns with material degradation on the basis of RF measurements, a laboratory study was
carried out using both the IEC 60270 conventional technique and RF methods to simultaneously measure PD activity
in samples of polymeric insulation that had been subjected to controlled impulse voltages. The IEC method was used
to provide a calibrated reference for pulses recorded using the RF technique. Model cylindrical insulators of
diameter 25 mm and height 13mm have been subjected to repeated impulse-driven surface flashovers created using a
Marx Generator. Following the impulses, the PD activity on the samples at electric field strengths equivalent to those
that would be experienced in service has been monitored. PD activity was observed in two of the five damaged
samples (Torlon and polypropylene – the two most heavily damaged samples in terms of appearance), regular RF
signals could be observed from the polypropylene sample, while the Torlon sample produced some RF data, but this
was insufficient for analysis. This shows that the RF technique is applicable to this situation but much work is still
needed before it becomes a reliable method.
PD Patterns in Oil-Impregnated
Insulation:
A Comparative Study
Abstract -- This paper presents results of PD test at elevated frequency of supply. Particular attention was given to
the discharges that occur in moist pressboard layers immersed in transformer oil. The effect of moisture content on
the PD activity was investigated based on the observation of the PD quantities and the characteristics of the PD
distributions. Data obtained from the PD test is presented in Phase-Resolved Analysis (PRA) and Voltage Different
Analysis (VDA). Index Terms -- Accelerated ageing, partial discharge, phase-resolved analysis, voltage different
analysis.
Diagnosis of Insulation Conditions :
Interpretation of Partial Discharges from
φ-q-n pattern, Pulse-Sequence and Pulse
Waveform

Abstract--Appearance of electrical discharges in high voltage apparatuses with reasonable magnitude and
frequency can be interpreted as abnormal condition. The discharge may take place in several types. Firstly, corona
discharges which represents abnormal electric stress on a conductor. Secondly, void discharge which represents
discharge take place in a gas filled void in solid or liquid insulation. Thirdly, treeing discharge which takes place in
tree channels inside a solid insulation. This paper reports experimental results on the three kinds of discharges. The
analysis was focused on the -q-n pattern, the time sequence between consecutive pulses and the waveform of a
discharge pulses. The difference among them maybe useful to diagnose of insulation condition. Index
Terms--diagnosis, discharge, pulse-sequence analysis, pulse waveform
Ultra-high Frequency Spectral Characteristics of Partial Discharge in Insulation Oil
Abstract--We have designed and manufactured four types oftypical defects found in power transformers to simulate
partialdischarge(PD) in oil insulated power transformers. Stable PDsignals were generated by applying AC voltages
on to the PDcells. We measured spectral response of PD signals from thesedefects using our Ultra-high
frequency(UHF) PD measuringsystem and apparent discharge using IEC60270 PD detectorsimultaneously. Partial
discharges from the defects in oilgenerated well detectable UHF signal up to about 2 GHz. UHFPD patterns were
recorded and analyzed for each defect types. The phase resolved partial discharge(PRPD) patterns of defectobtained
from UHF range were different from each other. Thepatterns of UHF PD signals were also different from
thoseobtained from that of conventional method. Type of defect couldbe identified by obtaining PRPD
patterns.Index Terms--Partial Discharge, UHF, Oil, PRPD
Partial Discharge Characteristics in
UHF-band of Composite Insulation System
Including Various Artificial Defects in
Transformer
Abstract--Experiments of partial discharge (PD) current pulse and phase resolved PD characteristics were performed
using various artificial defects in oil/pressboard composite insulation system in oil-filled transformer. As artificial
defects, we used barrier insulation model-in-oil, oil wedge model, air void model, floating electrode model, and oil
gap model. As a result, it was found that the rise time, fall time, and pulse width of each PD current pulse differed
depending on each model. Moreover, we confirmed the existence of PD-radiated electromagnetic wave with
frequency UHF band for the defects. It was shown from these results that UHF method is applicable for detecting PD
originating from the defects and identifying the defect types in oil-filled transformer.

Partial Discharge Modelling
Based on a Cylindrical Model in
Solid Dielectrics
Abstract--Partial discharges (PDs) are harmful to electrical insulation as they may degrade the
material. Consequently, a lot of efforts have been made to develop suitable systems for PD
measurements and monitoring. Due to the complexity of PDs and many factors that can influence
PD characteristics, the research on PDs is still very active and several models have been proposed
over the years to understand the behaviours of PDs. In the present paper, we have investigated the
frequency characteristics of a cylindrical void in solid dielectric based on the model proposed by
Forssen. Using similar program environments of MATLAB and COMSOL, our algorithm performs
better in computation time and gives the similar results compared with the experiments. More
importantly, a new interface has been developed so users are able to change parameters. This new
feature allows the user to examine effects of various factors such as conductivity of the cavity
surface, the applied voltage and statistical time lag on PD characteristics. Index Term--Partial
discharge, simulation, solid dielectrics, frequency effect.
Fundamental Differences of the PD
Measure-ment according to IEC 60270 and in
UHF range
Abstract--PD measurements in the UHF frequency range are an important tool for diagnostic at GIS. A general
correlation between the measurement according to IEC standard 60270 and measurements in the UHF range is not
possible. By the use of a "sensitivity check" the quality of the UHF measuring system is verified at GIS. In this
contribution the usual procedure is pointed out and the boundary conditions and simplifications are shown. The
knowledge of this is important for the interpretation of the result of the sensitivity check. Index Terms--partial
discharge, gas insulated switchgear (GIS), UHF measurement, IEC standard, IEC60270, verification of the
sensitivity
Fundamental Differences of the PD
Measure-ment according to IEC 60270 and in
UHF range

Abstract--PD measurements in the UHF frequency range are an important tool for diagnostic at GIS. A general
correlation between the measurement according to IEC standard 60270 and measurements in the UHF range is not
possible. By the use of a "sensitivity check" the quality of the UHF measuring system is verified at GIS. In this
contribution the usual procedure is pointed out and the boundary conditions and simplifications are shown. The
knowledge of this is important for the interpretation of the result of the sensitivity check. Index Terms--partial
discharge, gas insulated switchgear (GIS), UHF measurement, IEC standard, IEC60270, verification of the
sensitivity
Feature Extraction Methods for Time
Frequency Energy Distribution of PD Pulse
Abstract--Feature extraction methods for time-frequency energy distribution (TFED) using moment, marginal and
Renyi information are studied in this paper. They are developed by combination of TFED’s own characteristics with
mathematic statistic and information entropy. The Wigner-Ville Distribution (WVD) of a simulated PD pulse is
chosen as the subject investigated to illustrate those methods, which gives the result of time and frequency moments,
time and frequency marginals and Renyi information for the TFED. The results show that those methods can exactly
and easily make feature extraction for the TFED of PD pulse, which can be used to PD pattern recognition and
in-depth study of PD mechanism in the electrical insulation system. Index Terms-- PD pulse, time-frequency energy
distribution, feature extraction, moment and marginal, Renyi information.
On-line Insulation Diagnostic System and
Off-line PD Monitoring with HVAC
Testing
Abstract--The paper considers the relation between on-line monitoring and diagnostics on the one hand and
high-voltage (HV) withstand and partial discharge (PD) on-site testing on the other. HV testing supplies the basic
data (fingerprints) for diagnostics. In case of warnings by on-line diagnostic systems, off-line withstand and PD
testing delivers the best possible information about defects and enables the classification of the risk. Because
alternating voltage (AC) is the most important test voltage, the AC generation on site is considered. Frequency tuned
resonant (ACRF) test systems are best adapted to on-site conditions. They can be simply combined with PD
measuring equipment. The available ACRF test systems and their application to electric power equipment –from
cable systems to power transformers – is described. Index Terms--Cable, Frequency tuned resonant, High voltage
withstand, Off-line PD monitoring, On-line insulation diagnostic,
1Comparing IEC60270 and RF Partial

Discharge Patterns
Abstract--Defect classification using partial discharge (PD) measurement has historically been achieved by
representing the data in phase-resolved form. This paper presents phase-resolved PD patterns obtained using radio
frequency (RF) and conventional IEC60270 techniques for a number of different defects including free particles,
protrusions, floating electrodes and voids. Oil, SF6 and resin were used as insulating media. Each PD geometry was
placed inside an aluminium test chamber fitted with an internal UHF antenna. Around 2000 RF and IEC PD pulses
have been recorded simultaneously along with their phase position for each PD source configuration using a 3 GHz
digital oscilloscope. Results indicate that due to the responses of each system, clear differences exist in the
phase-resolved patterns, implying that more accurate defect classification should be achieved if a system is trained
exclusively using either IEC or RF data. In other words, if a classification algorithm has been trained using
measurements from a conventional IEC system, the accuracy of diagnosis will be reduced if RF sensors are then used
to measure on-line data without re-training the system. Index Terms--Epoxy resin insulation, fault diagnosis,
insulation, partial discharges, power system faults, power system monitoring, SF6, UHF couplers.
Investigation of PD Electromagnetic
Wave Characteristics in GIS
Abstract--For exploring the characteristics of PD (partial discharge) electromagnetic wave
(EM-wave) within gas insulated switchgear (GIS), the model for detecting PD electromagnetic
wave signals in GIS was built and simulated in this paper. The characteristics of PD EM-wave were
investigated in two aspects: excitation characteristic and propagation characteristic. The excitation
characteristics of PD EM-wave are analyzed by changing the parameters of PD sources. The results
show that the EM-wave signals which excited by PD sources are related with such factors as the
radial angle Ф, waveform of discharge pulse, radial position of PD source. The propagation
characteristics are calculated when PD EM-wave signal transited through the different component
of GIS. The simulation results show that the signal was attenuated obviously when it propagated
through insulator, L branch, and T branch. The attenuation of L branch is more serious than insulator
and the attenuation of plumb way of T branch is most serious. Index Terms--Electromagnetic wave
(EM-wave), high order mode, gas insulated switchgear (GIS), partial discharge, ultra high
frequency (UHF).
Classification of Defects and Evaluation of
Electrical Tree Degradation in Cable
Insulation Using Pattern Recognition
Method and Weibull Process of Partial
Discharge

Abstract--The purpose of this paper is to recognize partial discharge (PD) sources and evaluate of
electrical treeing degradation for cable insulation. To acquire PD data, three defective tree models
were made. And the data are shown by the phase-resolved partial discharge method (PRPD). As a
result of PRPD, tree discharge sources have their own characteristics. If other defects (void, metal
particle) exist at internal power cable, their characteristics are shown very differently. This result is
related to the time of breakdown and this is important point of cable diagnosis. To apply PD data
classification, methods of different type are selected. Those are, multi layer perceptions (MLP-BP),
adaptive neuro-fuzzy inference system (ANFIS) and principle component analysis-linear inference
system(PCA-LDA). As a result, ANFIS shows the highest rate which value is 100 %. Finally, we
performed classification of tree progress using ANFIS and that result is 99 %. To evaluate
degradation of electrical tree, weibull distribution was used. The time of each degradation stage
(initiation, middle, breakdown) was measured to classify electrical tree degradation with each
model by. Using the result, parameters are presumed by the each model and stage and it is possible
to calculate time difference of each degradation stage and estimate the lifetime. Index
Terms--classification, electrical tree, weibull process, partial discharge
Partial Discharge Characteristics of the
Ultra-High Voltage Cable Insulators
according to the Measuring Temperature
Abstract-- In this paper, it is investigated the effect of the cross linked polyethylene (XLPE)
insulators was examined according to the temperature into XLPE which was used as the insulation
of the electric power cable for the ultra-high voltage. In order to investigate the effect of changing
tree phenomenon according to the temperature on the electrical conduction mechanism, a partial
discharge experiment was conducted through the variation of temperature from 25[ ℃ ] to 80[ ℃ ],
and voltage applied to the electrodes from 1[kV] to 40[kV]. The activity of partial discharge
according to the temperature was examined using K-means distribution. As a result of experiments,
we found that the specimen with 80[ ℃ ] has the lowest inception and breakdown voltage, center
of
clusters move 0, 180 degree at each positive and negative region in the K-means. We obtained that
distribution of clusters concentrated on at inception condition, but the distribution spreads out
widely at breakdown. Index Terms--Cable insulator, Cluster, K-means, Partial discharge, XLPE,
Temperature
Change in Pattern of Void-Type PD with
Ageing
Abstract--The measurement and assessment of partial discharge (PD) activity is used both for

condition assessment of high voltage plant (by operators) and for quality control (by manufacturers).
Except for the online circumstances, the measurement usually lasts for a short period of time while
higher than working stress is applied. The resulting pattern of discharge data, when compared with a
knowledge base of PD patterns of different types of defects is a crucial factor in diagnosing the
condition of the insulation system in the plant. In this paper the characteristics of φ-q-n patterns for
a void-type defect is extensively investigated. The φ-q-n plots are obtained using an IEC60270 PD
measurement system, a fast digital oscilloscope and processing methods. Spherical void defects are
deliberately manufactured in epoxy resin samples in order to simulate natural defects as precisely as
possible. As one of the vital factors causing variation in PD patterns, different stress levels are
applied. Different sizes of void are also considered, to reveal the effect of void size on PD patterns.
Measures are taken to ensure that PD results only from the manufactured defects rather than any
other source. Several traditional criteria are calculated to characterize the different patterns. Based
on the observations and analysis, the mechanisms of PD patterns and their changes are discussed.
Index Terms--Partial discharge; Natural void in resin; φ-q-n patterns; Ageing; Mechanisms
Partial Discharge Pattern Analysis in
Cylindrical Insulators Model of Transformer
Abstract--This paper proposes a partial discharge analysis in cylindrical insulators model for finding
electrical parameters. There are three types of electric insulator, namely liquid, solid and gas
insulator. The capacitance, dielectric loss factor (tanδ) are found by measuring PD Pattern of each
insulator. The power dielectric loss (Pd) of each electric insulator also calculates by using the result
of partial discharge measurements. As we know that the partial discharge technique can show the
performance of electric insulator. The experimental results of partial discharge analysis show that
the performance of three insulators. It can be the primary data of high voltage equipments design in
electrical standard level. Index Terms-- cylindrical insulators model, PD, partial discharge.
Identification of Multiple Partial
Discharge
Abstract-- Partial discharge (PD) measurements are an important tool for assessing the health of
power equipment. Different PD may have different effects on the insulation performance of power
apparatus. Therefore, identification of PD sources is of great interest to both system utilities and
equipment manufacturers. This paper investigates the use of a wide bandwidth PD on-line
measurement system which consists of a wide bandwidth sensor, a sophisticated digital signal
oscilloscope and a high performance personal computer to facilitate automatic PD source
identification. Wavelet analysis was applied to the obtained raw measurement data. The
pre-processed data was then processed using correlation analysis. The obtained results have also

een processed by accepted approaches, such as phase resolved information. A machine learning
technique, namely the support vector machine (SVM) has been used to identify between the
different PD sources. Index Terms—Partial discharge (PD), on-line condition monitoring, power
transformer, radio frequency current transducer, wavelet analysis, support vector machine, pattern
recognition.
Status and Application Foreground of Ultraviolet Technology on Fault
Detection of Power Devices
Abstract--The safety of power grid depends on the reliable running of power devices and transmission circuits. At
present, the detection methods of electric device faults are often taken by infrared imaging system, ultrasonic
imagining system, etc.
However, these techniques have some inherited shortcomings.Thus it needs a more effective detection technology
for the safetyrunning of power system. As a new detection technology, UV hasits special advantages and wide
developing space. This paper states the UV mechanism, advantages, forms and diagnosingmethods, which also lists
its application examples in China andabroad. And it sums up the annual proceedings of TransmissionSpecialty
Council of CSEE on UV Detection Discussion in the year 2007. Finally, it points out some shortcomings of
UVtechnology and forecasts its developing trend. Index Terms—UV detection; Electric device; Insulation; On-line
monitoring
The Use of Conductivity Factors for Estimating the
Degradation State of Insulation Systems of
Medium-Power Electrical Machines
Abstract--The use of absorption/resorption currents tocharacterize the ageing state of electrical
equipments’ insulationsystems is well known. The maximal values and the slopes ofthese currents
give important information regarding the paperoilinsulations for power transformers and energy
cables, butthese are also used for insulation systems of medium and/or highpower machines. In
general, the values of the conductivity factorsare rarely used.In this paper, some results concerning
the estimation of theageing state of mica-based insulations for medium-powerelectrical machines
are presented. For experiments, plane platesof CALMICAGLAS tape (containing mica paper, glass
textureand epoxy resin) and samples from stator bars designed for 6MW (6 kV) generators were
used. The samples were thermallyaged at 210, 230 and 250 C. The absorption and
resorptioncurrents i1(t), respectively i2(t), were measured and thepolarization index kp and the
conductivity factors kc and kc1 fordifferent values of the ageing time τ were calculated.At the end, it
is shown that kp, kc and kc1 values change with τfor each ageing temperature and that these can
characterize theageing state for the samples and/or for the electrical machines’insulations.Index
Terms--

Intricate Aspects Of Turbogenerator Endwinding
Vibration Monitoring Based On Data Analysis
Abstract--End winding vibrations of large turbogenerators areassuming a greater role in the
reliability of the machines to avoidforced outages. So, on line monitoring during test run as
wellduring operations have been given utmost importance in recent times.
II. BRIEF TECHNICAL PARAMETERS
Electromagnetic forces, at double the operational frequency are responsible for overhang vibrations
besides other mechanical phenomena. These vibrations depend on factors like type of insulation,
slot fixing arrangement, overhang bracing and support system, dynamics of core with overhang and
natural frequency of the endwinding basket. This paper presents the comprehensive data generated
over a period of two decades on endwinding vibration on 200/210 MW turbogenerators and dwells
on the analysis there on. The data collected have been studied to examine the various intricate
aspects affecting these vibrations and the trends compared. In order to study the requirement of a
robust slot-wedge system to contain the overhang vibrations and validate the adequacy of the
adopted slot fixing system, the paper presents the experimentation done on a full-scale
turbogenerator Slot Model. Special treatment has been made on the natural frequency test on
overhang system and its significant bearing on the endwinding vibration touching upon some
corrective measures. Keyword-- endwinding vibration, natural frequency test, factory test-run
On-line Calculation Model of Thermal Stress of
Steam Turbine Rotor Based On Integrated
Modular Modeling Software
Abstract--The formula of two-dimensional temperature andthermal stress of steam turbine rotor is
derived by using energybalancmethod. The on-line calculation model of twodimensional
temperature and thermal stress of steam turbinerotor is built based on integrated modular modeling
software andengineering modularized method. A simulation experiment hasbeen given to compare
with the result computed by finite-elementmethod on the same condition. The result shows this
model has gained high accuracy and speed. The modularized structure of imulation model makes it
very convenient that modification of physical dimension of the turbine rotor and the grids, so this
model can be used for analyzing thermal state of other axissymmetry
object having similar boundary condition. Keywords--integrated modular modeling software;
turbine rotor; thermal stress; on-line; model
Development of Diagnosis Algorithm for
Induction Motor Using Flux Sensor

Abstract--The development of the diagnosis algorithm iscarried out for identifying health and
faulted conditions in threephaseinduction motors. The algorithm consists of featurecalculation,
feature extraction, and feature classificationprocedures in sequence. For that, the non-linear
featureextraction method with kernel function is used and the classifier
of k-nearest neighbors is introduced to decide motor conditionsamong normal motor, broken rotor
bar, short-turn stator windings, and bearing faults. Signal for this algorithm is acquired flux sensor.
It is to measure the change of magnetic flux at the air-gap. To get the effective features related with
faults, the peak ratio of some frequencies related with line frequency is introduced. This work
proposes the efficient diagnosis method for induction motors by developing the powerful algorithm.
The calculated features show a good linearity according to faults severities. Moreover, the final
results show a good classification rate on motor conditions. Index Terms— Bearing fault, Broken
rotor bars, Diagnosis algorithm, Flux sensor, Induction motor, Stator winding.
An Inverter-Embedded Stator Winding Insulation
Quality Assessment Technique for AC Machines
Abstract--The lifetime of the stator winding insulation isreduced when operated with PWM
inverters, since insulationdegradation is accelerated due to increased thermal and electrical stresses
on the motor. This paper focuses on a new approach for monitoring the condition of the stator
insulation for failure-prone inverter-fed machines. The main concept of the proposed technique is to
apply a variable frequency AC test voltage to the stator insulation using the inverter, to perform
standard off-line insulation tests whenever the motor is not operating. This allows the stator
insulation to be tested more frequently compared to off-line tests performed once every 3-6 yrs.
during periodic maintenance. A method for testing the insulation with minimal modifications to the
inverter circuit is proposed and verified experimentally. The results show that the proposed
technique provides a simple low cost solution for detecting stator insulation degradation at an early
stage for reliable operation of inverterfed machine systems, since the insulation condition can be
monitored frequently. This not only helps prevent forced outages and safety risks due to insulation
breakdown, but also helps perform maintenance in an efficient manner since individual motor
maintenance can be prioritized and scheduled based on its present condition. Index Terms--AC
Electric Machines, Capacitance Test, Condition Monitoring,Diagnostics, Dissipation
Factor,Insulation Resistance,Inverters,Predictive Maintenance,Stator Insulation.
A Practical Bearing Fault Diagnoser
Abstract-- Bearing is an important part of electric machines. In order to avoid unscheduled outputs,
it is important to detect an upcoming fault as soon as possible. Since fault in a great number of
bearings commences from a single point defect, research on this category of faults has shared a great
deal in predictive diagnosis literature. Single point defects will cause certain characteristic
frequencies to appear in machine vibration spectrum. Because of impulsive nature of fault strikes,
and complex modulations present in vibration signal, a simple spectrum analysis may result in

erroneous conclusions. When a shaft rotates at constant speed, strikes due to a single point defect
repeat at constant intervals. Each strike shows a high energy distribution around it. The time
intervals between successive impulses in auto-correlated vibration power signals are related to fault
frequency and therefore show the defective Part. According to the proposed method, an apparatus is
designed.Introducing the structure of this apparatus, the circuits, hardware, and software is the main
objective of this paper. The apparatus has shown its effectiveness in laboratory experiments and
field tests. Index Terms--Apparatus, Autocorrelation, Bearing, Diagnosis,Fault, Intelligent,
Vibration
Off-Line PD Diagnosis for Stator Winding of
Rotating Machines using UWB Sensors
Abstract--We studied the partial discharge detecting by sensing electromagnetic wave emitted from
the partial dischargesource in the HV Rotating Machine with UWB sensor. In this study, we design
new type of compact low frequency UWB sensor based on micro-strip technology and make many
experiments of offline and dismantled testing compare with the existing HFCT on stator winding of
HV generator in the laboratory. We mentioned detail design of new compact UWB sensor design
and
time domain and frequency domain results of partial discharge in stator winding of 6.6kV rotating
machine by offline testing in laboratory. Index Terms--HFCT, 6.6kV rotating machine, Off-line
PDdiagnosis, UWB sensors
Practical Implementation of a Remote and
Sensorless Stator Resistance-Based Thermal
Protection Method
Abstract-- A remote and sensorless stator winding resistance estimation method for thermal
monitoring has been proposed for soft-starter-connected induction motors by the authors. As an
continuation of the previous work, this paper specifically focuses on the practical implementation of
the proposed method. In this paper, a compensation method for the measurement offsets is
introduced to improve the performance of the resistance estimation. The design of a low pass analog
filter is discussed to reduce the requirements of data acquisition system. In addition, a cable
resistance compensation method is proposed to decrease the estimation error caused by the cable
resistance, and achieve remote monitoring. The proposed method is validated by the experimental
results. The stator resistance estimation error is within 1.5% without high requirements on the data
acquisition system. Index Terms—Analog filter, in-service testing, induction motor, signal injection,
soft-starter, and stator resistance.

A Case Study of Condition-Based Maintenance
of a 202-MVA Hydro-Generator
Abstract -- Over the last few decades, partial discharge (PD) measurement has proven to be one of
the most useful tools to identify degradation mechanisms of stator windings in air-cooled
generators. Under normal operating conditions, PD levels and, more importantly, PD trending can
indicate the presence of not only electrical but also mechanical, thermal or ambient (contamination)
degradation processes. Hydro-Qubec uses a 2D PDA (Partial Discharge Analysis) technique as its
first line of diagnostics during yearly measurements on more than 120 large
generators in its fleet. When a PDA measurement reveals a problem, such as high PD levels or
sudden increase in level, the Phase Resolved Partial Discharge (PRPD) technique is used to
improve the identification of the nature of the active PD sources. This paper presents results of
on-line PD measurements from both the PDA and the PRPD techniques on the case study of a
13.8-kV 202-MVA generator. Identification of slot discharge activity in the PRPD patterns in this
generator triggered a more detailed diagnostic. In-situ off-line measurement of the electrical contact
between individual bars and stator core was performed on selected bars in order to confir
Web-based PD monitoring of a Generator in
Loforsen Sweden
Abstract--In today’s energy market, operators want to minimize the costs for maintenance and outages.
Condition-based maintenance techniques using diagnostics and or monitoring systems are a prequisit in power grids
nowadays. At times where the need for such systems is increasing, the time and knowledge available for analysis and
interpretation is decreasing. Therefore, STRI, LDIC, VB Kraft and VB Elnt have decided to develop an on-line
web-based PD monitoring system to monitor one of the generators installed in a hydropower plant owned by VB
Kraft. The aim of this project is a) to get service experience with such a system b) to develop a system that is easy to
use and gives the user the information that is needed in a way that is understandable for them at times that they need
it. In this paper the complete system including, measuring system, generator, transmission system and website
together with the so-far obtained service experiences are presented. Index Terms--On-Line, Web-based, partial
discharge, monitoring, Generator, condition based maintenance.
A Subspace-Based Rejection Method for Detecting
Bearing Fault in Asynchronous Motor
Abstract-- Fault detection and diagnosis of asynchronous machine is became a central problem for
industrial domain since the past decade. A solution to tackle this problem is to use stator current for
a great condition monitoring, as referred to the “MCSA” (Motor Current Signal Analysis). Indeed, it
is known that due to the motor structure, mechanical spectral signature fault, as for example bearing
fault, is present in the stator current spectrum. However, a basic spectral analysis is not sufficient to
detect a bearing fault, because of the high dynamic of 50 Hz. So, we go further into the existing

methods, to introduce a new subspace algorithm. This new method, takes into account the a priori
knowledge of the electrical signal frequency (50 Hz) by totally canceling its influence on the desired
bearing fault signature. This algorithm is based on the MinNorm algorithm and therefore we name it
theWeighted Prior- MinNorm algorithm (WP-MinNorm). Accordingly, we improvethe detection
and we facilitate the diagnosis of an outer raceway fault. Finally, we illustrate for different load
conditions the ability of the method proposed to effectively detect with few collected data, the
bearing fault.
Research of Remote Condition Monitoring
System for Turbo-generator Unit Based on B/S
Model
Abstract--The turbo-generator unit is very important equipments for electric power production,
hich has a high rate of fault and causes a lot of harm because of the structural complexity and the
special circumstance. With the increasing of the capacity of the unit, the condition monitoring and
fault diagnosis plays an important role to ensure safe operation and guarantee the efficiency.
Therefore, the real-time monitoring to turbo-generator unit, and diagnosing accurately of the
abnormal condition, or eliminating it, have the vital significance to the safe operation. The rapid
development of computer, network communication and other related technologies makes the remote
monitoring and diagnosis become possible. The remote condition monitoring system for
turbo-generator unit based on embedded platform is designed in this paper. The system software
uses three-layer B/S structure which includes network communications, database management,
real-time monitoring, state analysis, system management and other functional modules. The
successfully development and research of the system provide a good technical scheme for on-line
monitoring application of large-scale generator units, which is very helpful to identify the status of
units for the manager, remote experts and operators. It will enhance production efficiency and the
economic efficiency of the generation enterprise. Index Terms--Turbo-generator unit, remote
monitoring, fault diagnosis, embedded system, B/S model.
Steam Turbine Rotor Thermal Stress On-line
Monitoring Based on XDPS
Abstract--This article discusses the rotor thermal stress online monitoring system on the XDPS
configuration platform. The finite element geometrical model of the rotors is built for some
domestic 200MW unit. The heat stress field and the temperature field are calculated for the typical
conditions by use of the largescale finite element software. And the most dangerous part of the rotor
could be decided and the trend of the largest stress value is obtained for different conditions. The
mathematical model of online monitoring rotor stress is built with high accuracy by emendation of
the stress simplified formula and the rotor temperature difference. This system combines the finite
element analysis method and one-dimensional analytical method to establish the model based on
the practical units parameters, so this model not only has a relatively higher accuracy but also meet
the demand of on-time monitoring. Key words--Steam turbine; Rotor; Thermal stress; On-line
monitoring; XDPS configuration platform

Stress and Fatigue Life Monitoring of High
Temperature Bearing Elements Based on the
Solution of Inverse Conduction Problem
Abstract--The stress and fatigue life monitoring of high temperature bearing elements is of great
significance for the safe and economic operation of thermal power plant. The calculation of
temperature distribution is the fundamental of the stress and fatigue life analysis. In order to
improve the precision of the temperature distribution, a method for stress and fatigue life analysis of
boiler drum, which is the biggest high temperature bearing elements of boiler, based on the solution
of inverse conduction problem is presented. On the basis of energy conservation and control volume
method, the general equations for calculating the boiler drum temperature distribution by the
inverse conduction problem were derived. The life expectancy of the boiler drum is then calculated
according to ASME Code. The cold start-up process of one 300MW boiler is analyzed by this
method. The results show that the temperature distribution i the drum cross section can be
determined based on the temperature measurements at several points on the drum outer surface,
which can avoid the errors caused by assumption of the boundary conditions on the inner surface of
the drum. This method can be used for the on-line analysis of the drum fatigue life Key Words--
Boilers, Fatigue, Stress, Inverse problems, Temperature, Monitoring
Non-invasive On-line Detection of Winding
Faults in Induction Motors –A Review
Abstract--This paper is a review and evaluation of different on-line methods for diagnosing winding
fault in induction motors presented in literature. Many methods can be found in literature in some
references, frequency analysis of motor signals such as current , speed, instantaneous power , Park’s
vector modulus and so on are introduced. Evaluation of negative sequence of current is also among
the proposed methods. Supply voltage unbalance and some other phenomena may be confused with
the winding fault. Therefore, the monitoring and fault detection of electrical machines have moved
in recent years from traditional techniques to artificial intelligence based techniques. There are
many other techniques that will be introduced and investigated in the detailed paper. A comparison
of Different methods introduced in literature is the main objective of this paper. Index Terms--
Condition monitoring, Fault diagnosis, Induction motor, Stator fault, Turn fault.
Online Performance Test Software and Its
Application for Large Capacity Combined-cycle

Units
Abstract--The paper introduces an online performance test software for Large Capacity
ombined-cycle Units. The software is composed of four parts, i.e. the integrated modular modeling
software (IMMS), real time database software, client browser software and communication
software. The results of the model are displayed in B/S mode on the user’s terminals. With IMMS,
on-line performance calculating model is developed by means of modular modeling method, which
follows the guidelines of “Performance Test Code on Overall Plant Performance” (PTC46-1996).
All the primary parameters used for model calculation are from DCS of the unit. The software has
been successfully applied to a 395MW combined-cycle power unit for a year. It runs stably and
reliably. It can provide the economic indicator on line, such as gross equipment power output and
gross equipment heat rate etc., so as to help operators monitoring and adjusting the operation of unit
more efficiently. Index Terms--power generation testing, condition monitoring, modeling,
programming, online, combined-cycle
A Survey of Testing and Monitoring Methods
for Stator Insulation Systems in Induction
Machines
Abstract--A breakdown of the electrical insulation system causes catastrophic failure of the
electrical machine and brings large process downtime losses. To determine the conditions of the
stator insulation system of motor drive systems, various testing and monitoring methods have been
developed. This paper presents an in-depth literature review of more than 20 existing methods,
including the most common methods to assess the phase-to-ground, phase-to-phase, and
turn-to-turn insulation conditions. The methods are categorized into as online and offline methods,
each of which are further grouped into specific areas according to their physical nature. The paper
focuses on turn-toturn insulation testing and monitoring of low-voltage machines, which is a rapidly
expanding area for both research and product development efforts. Finally, a new approach to online
monitoring of turn-to-turn insulation faults for low-voltage induction motors is recommended.
Comparison of On-line and Off-line PD
Measuring System for Hydro Generator Stator
Winding
Abstract--Partial discharge (PD) is one of the most promising phenomena to utilize in detecting
deterioration of high voltage rotating machine insulation. PD test can be performed either when the
machine is not operating (off-line) or during normal machine operation (on-line). Off-line PD test is
a well-known method to assess the stator winding insulation and on-line PD test has proven to be a
successful technique of monitoring stator insulation condition. This study carried out on-line and

the offlin PD tests on a hydro-generator using the same PD sensor and measuring instrument and
analyzed various PD characteristic parameters. We used the contact-type CC (Ceramic Coupler)
sensor for PD tests. To test reliability of this sensor, we analyzed the frequency response
characteristic test using S parameter and PD signal characteristic test for the simulated defect
winding. Also, we checked the similarity between the test results of diagnostic system (PDMS-HG)
was installed on the test hydro generator and of the on-line and off-line PD tests.
Fault Diagnosis Way Based on subsection Spectrum
zoom analysis by CZT for Squirrel Cage Induction
Motors
Abstract - Among the methods of fault diagnosis based on thecurrent analysis for Squirrel Cage
Induction Motors (SCIM), th efaults’ characteristic components are often submerged by
fundamental component and noises, especially for the broken rotor bars, and how to effectively
eliminate the influences of the fundamental component and noises is essential for the diagnosi
system. Fault Diagnosis Way Based on subsection Spectrum zoom analysis method by CZT for
Squirrel Cage Induction Motors is proposed in this paper. using subsection Spectrum zoom of CZT,
the fault current is analyzed to eliminate the effective of power and yawp and to highlight the fault
characteristic components. Key words-- quirrel cage induction motors; rotor; broken rotor bar;
eccentricity; fault diagnosis; CZT; quick frequency estimation
Experience With Continuous On-Line Partial
Discharge Monitoring Of Generators And Motors
Abstract--Partial discharge (PD) testing has been used for over 50 years to detect insulation
problems in motor and generator stator windings. By periodically measuring the on-line PD activity,
usually at least two years warning is given before the risk of stator winding failure is high – which is
sufficient time to plan corrective maintenance or a rewind. Such testing is now routinely applied to
more than 8000 machines around the world. To overcome the limitations of periodic PD testing, an
inexpensive continuous PD monitoring system was developed 15 years ago that removed the need
for visits to the plant, and which would automatically record the PD and collect operating data from
the plant computer. The monitors use all the noise separation methods that are incorporated into the
most common test instruments, to reduce the risk of false indications. The continuous PD monitors
also produces PD quantities that are the same as recorded by portable instruments, so that the results
can be interpreted in the same manner. In addition the monitorproduce an alarm if the PD activity is
very high or increasing rapidly. This paper describes how the system is implemented, as well as how
the PD monitor communicates with head office or plant maintenance staff. There is now over 14
years of operational experience with the continuous PD monitor on over 1000 machines. Some case
studies are presented.
The Application of Modal Analysis in Fault

Diagnosis of AC Motor
Abstract--Vibration is a basic phenomenon of AC motor. The vibration characteristics will change
when a fault occurs to motor. Experiment Modal Analysis an Finite Element Modal Analysis are
both effective methods for motor vibration analysis. This paper introduces these two methods, and
proposes a new conjoint method of motor fault diagnosis based on vibration situation of motor.
Through establishing motor vibration situation library and comparing practical vibration situation
with it, the corresponding type of motor faults can be estimated
The Application of Zoom FFT Technique to the
Extraction of Fault Character of Induction
Motor
Abstract-- Because the fault character signal frequency is very close to fundamental wave frequency
during the analysis of induction motor rotor winding fault based on the frequency of stator current,
though in practical application, there is only signal spectrum in very small frequency range need to
be taken into account, high resolution is demanded in the range, therefore the traditional base-band
FFT is difficult to analyze the fault character component of induction motor rotor winding
effectively. In this paper, the application of zoom FFT to identify the fault character signal of motor
is discussed, the fundamental principle of zoom FFT based on multiple modulations and its
application method is analyzed. Simulation calculation and practical engineering test have indicated
that zoom FFT technique based on multiple modulations can identify the nice frequency structure of
a certain band and extract the character signal in stator current under induction motor rotor winding
fault effectively. Index Terms-- Zoom FFT analysis, induction motor, character frequency signal,
fault diagnosis.
Design of Monitoring and Fault Diagnosis System
on-line for certain Gas Turbo-generator set
Abstract--Since its parameters can not been test about th certain gas turbo-generator set in local
rapidly after repairing, monitoring and fault diagnosis system based on IPC is designed in this
paper. The system adopts advanced measuring technology based on PCI bus, intelligent appearance
and VI technology and can check voltage, electric current, power and temperature of key parts
on-line about the set etc. Simultaneously it can give an alarm when the parameter is abnormal and
diagnose basic fault by FDES (Fault Diagnosis Expert System). Its results has characteristics of high
reliability, high speed and intuitive. So it can improve efficiency of test system maximum and save
repair expenditure. The system can helps to improve reliability of gas turbo-generator set and power
quality. Key words--gas turbo-generator set, monitor, fault diagnosis, IPC, VI
Methods for Thermal Protection of Medium
Voltage Induction Motors – A Review

Abstract--State-of-the-art overload relays for medium voltageinduction motors utilize a simple
thermal model and embedded emperature sensors for the thermal protection. However, this model is
too conservative and not robust to changes in the motor’s cooling capability. This paper reviews
thermal modelbased approaches and parameter-based approaches to estimate the motor temperature.
Each of these general approaches will be described along with their relative advantages and
disadvantages. Since most of the methods in the literature are applied to small to medium size
motors, this paper discusses their applicability to medium voltage motors, as well as issues that must
be addressed in order to apply them to the medium voltage induction motors. Index Terms--
Induction motors, Medium voltage, Parameter identification, Rotor resistance estimation, Stator
resistance estimation, Thermal model.
Investigation of Water Treeing – Electrical
Treeing Transition in Power Cables
Abstract--Water treeing is a phenomenon that is already known for more then 35 years and is one of
the reasons for cable failures (polymeric cables) in the medium-voltage network. The final stage of
water treeing is the formation of electrical trees on top of the water trees Due to the fact that the
moment of electrical tree initiation is crucial to determine the condition of the cable this paper will
focus on the investigation of the moment of transition from water trees to electrical trees. The
emphasis will be on the behaviour of the PDIV, PDEV and PD-level as function of time. It has been
observed that after the moment of first initiation the PDIV decreased with 40% to 50% and the PD
activity up to of hundreds of [pC] remained constant Index Terms--water treeing, partial discharges,
dielectri response, partial discharge, , cables, insulation, PD inception voltage, PD extinction
voltage, PD pattern
Charge Transport and Electroluminescence in
Insulating Polymers
Abstract--Polymers submitted to thermo/electrical stress suffer from ageing that can drastically
affect their functional behaviour. Understanding the physico/chemical processes at play during
ageing and defining transport regimes in which these mechanisms start to be critical is therefore a
prime goal to prevent degradation and to develop new formulation or new materials with improved
properties. It is thought that a way to define these critical regimes is to investigate under which
conditions (in terms of stress parameters) light is generated in the material by electroluminescence
(EL). This can happen through impact excitation/ionization involving hot carriers or upon bipolar
charge recombination (a definition that excludes light from partial discharges, which would sign an
advanced stage in the degradation process). After a brief review of the EL phenomenology under
DC, we introduce a numerical model of charge transport postulating a recombinationcontrolled
electroluminescence. The model output is critically evaluated with special emphasize on the
comparison between simulated and experimental light emission. Finally, we comment some open
questions and perspectives. Index Terms--Charge transport, Electrical stress, Electroluminescence,
Insulating polymer, Physico process, Thermo stress

Experimental Research on the Streaming
Electrification of Transformer Oil under Aging
Abstract--A series of accelerated aging tests of high voltage transformer oil from Karamay of China
were completed. All thoil samples were processed by dehydration and degasification firstly, and
added with different contents of oxygen and copper, then aged under 120 in different periods up to
675 hours, ℃ which is equal to 30 years on service of transformer oil. Improved mini-static
tester
was adopted to measure the electrostatic charging tendency (ECT), meanwhile, other traditional
parameters, such as dissipation factor, volume resistivity, acid number, were also measured
according to standard methods. The results indicate that ECT increases with aging time obviously,
addition of copper advances the process of accelerated aging and leads to saturated period occurred
in the late part of the aging (450h-675h). It can be found from mathematic analysis that correlation
between ECT and dissipation factor is positive and the highest. These results are valuable for the life
evaluation and condition monitoring of large power transformers. Index Terms--aging, copper,
correlation, electrostatic charging tendency, oxygen, transformer oil.
Experimental model of aging mechanisms
of on-load tap changer contacts
Abstract-- It is known that most failure of power transformers are related to aging effects of the
on-load tap changer contacts. To understand the aging mechanisms and to develop knowledge rules
to interpret different failure mechanisms a test model has been developed. In particular, the effect of
the several aging stages of tap changer change-over selector contacts on dynamic resistance
measurements (DRM) has been considered, by several measurements with aged tap changer
contacts. These aging phases include clean contacts, contacts with an oil film layer, contacts with
coking and contacts with pitting. Based on these experiments it is shown that the DRM method is
very sensitive to aged change-over selector contacts of an on-load tap changer. In addition to
laboratory experiments, the same measurements are performed on naturally aged change-over
selector contacts at a Dutch utility. Index Terms— aging, contact resistance, contacts, diagnostic
expert systems, dynamic response, power transformers, resistance measurement.
Analysis of Deterioration by Partial Discharge
of XLPE using GCMS and FTIR
Abstract--Deterioration of polymeric dielectrics by partial discharge (PD) might occur at defects in
an insulation layer. To elucidate the mechanism of deterioration by PD, measurement were
conducted of the gas components produced during deterioration and the substances created on the
surface of cross-linked polyethylene (XLPE) samples subjected to PD. Gas component
measurements were performed using an experimental apparatus including GC-MS. Results of gas
analyses showed that carbon dioxide (CO2) was produced when the XLPE sample is subjected to
the PD in a N2+O2 gas atmosphere. The amount of generated CO2 was confirmed to increase
concomitantly with the period of voltage application. The FTIR spectroscopic analysis of
substances on the surface of deteriorated XLPE revealed carbonyl compounds on the surface of the
deteriorated samples. The deterioration was suppressed when a phenolic antioxidant was added:

44-thiobis-3methyl-6tert butyl phenol. The process of deterioration by PD and the effect of the
antioxidant on the deterioration by PD were also discussed. Index Terms— absorbance, antioxidant,
carbonyl compound, deterioration, FTIR, GC-MS, partial discharge (PD), void, cross-linked
polyethylene (XLPE)
Retrofit with Hybrid Insulation System of a
Failed Power Transformer
Abstract--Retrofit of power transformers using high temperature aramid insulation materials in the
windings based on the hybrid insulation system has developed over the last two decades. By taking
advantage of the higher thermal withstand properties of such insulation materials, a failed unit could
be redesigned to increase its average winding rise to 95C. The windings can then be redesigned to
reduce the cooling space but replaced with more active material, thereby optimising the use of the
available space within the core window. This approach enhances the transformer retrofit scope and
flexibility which includes capacity expansion or loss reduction and improved reliability of the
retrofitted transformers. Index Terms--Aramid insulation, capacity expansion, hybrid insulation
system, improved reliability, loss reduction, retrofit transformers, winding temperature rise.
Research on Electrical Aging Lifetime Model of
Insulation Material under High Voltage Square
Impulses for Inverter-Fed Motors
Abstract--High voltage square impulses from converter can make stator insulation of inverter-fed
motors damaged much earlier. There are many differences in insulation aging mechanism etween
under continuous impulses and under sine waves. In order to test insulation properties under
continuous impulses, a new insulation aging test system is used to simulate the aging effect of
converter on the winding insulation in the inverter-fed motors. The influences of impulse amplitude,
frequency, on insulation lifetime are investigated by using polyimide film. Finally, an insulation
electrical aging lifetime model is developed based on the test results. Index Terms--inverter-fed
motors; ageing; insulation; mode
Phase-Resolved Measurement and Modelling
of
Electroluminescence Phenomenon in
Polyethylene Subjected to High Electrical Stress
Abstract--Electroluminescence (EL) has been widely used as ap robe to study early electrical ageing

in high voltage cable insulation systems since it can be associated with the energy dissipation of
mobile and trapped charges in the molecules of the dielectric medium. In addition to that, the study
of charge
injection and recombination mechanisms at the metal-polymer interface can also be deduced via EL
observations. This paper presents a series of measurements undertaken at Southampton to observe
the occurrence of EL with respect to the alternating electrical stress in order to gain a better
understanding on the processes responsible for light emission. Attempts have also been made to
simulate this phenomenon using a simple approach relating the charge injection and recombination
mechanisms
within a polymeric material. Index Terms--Aging, Charge injection, Electric variables measurement,
Electroluminescence, Modeling, Polyethylene insulation.
A practical investigation on the correlation
between aging and the dissipation factor value
of mica insulated generator windings
Abstract--The dissipation factor tan δ is a well know nparameter for the diagnosis of electrical high
voltage insulation. It is used according to standards for the evaluation of new mica insulated stator
bars of high voltage machines now for decades. It is also commonly used as parameter for the
estimation of aging conditions and operation reliability of power generators. While the methods for
the measurement of partial discharge have been in an evolutionary process over the last 30 years, the
principal method of tan δ measurements has not changed. So it is nowadays possible to observe the
tan δ value over a long period for certain machines. This work shows the experimental results
of an investigation which started more than 20 years ago. Tan δ values of several generators have
been collected over a period of about 20 years. The tan δ was measured from 0.2 of the nominal
voltage up to nominal voltage in steps of 10 % at power frequency of 50 Hz. Besides of the electrical
measurement, environmental parameters such as humidity and temperature were determined
because of their influence on the tan δ values. Unfortunately, the environmental conditions were not
constant at
on-site tests. Results of this investigation shows the dependence of tan δ on the operating time.
Depending on the type of the insulation system, different progression of the tan δ can be observed.
Index Terms--Dielectric measurements, Fault diagnosis Generators, Life estimation, Maintenance,
Power factor.
Analysis of Gasses Generated by Electrical
Discharges in Low Viscosity Silicone Oil
Abstract—Silicone oil has merits of less flammability and excellent environment-friendliness.
High-viscosity silicone oil of 50 cSt has been widely applied to power and distribution transformers.
Recently, application of low-viscosity silicone oil of 20 cSt to transformers has been considered for

its excellent cooling performance. Detection of incipient fault conditions in low-viscosity silicone
oil immersed transformers becomes more important when they are operated in electric power
systems. Detection of certain gases generated in a transformer is usually the useful indication of an
abnormal condition. To clarify its applicability to a low-viscosity silicone oil immersed transformer,
this paper described gas characteristics generated by electrical discharges in detail. It was clarified
that the identification of abnormal conditions are possible by considering the amounts and types of
generated gases. Finally, gas characteristics were compared with those in 50 cSt silicone oil and
mineral oil. Index Terms— Silicone oil, Transformer, Dissolved gas analysis (DGA), Diagnosis,
Discharge.
Study on the Interfacial Properties at the OTS
Treated SiO2 Film
Abstract--n-octadecyltrichlorosilane treated the SiO2 film was prepared by the mixed solution of
chloroform and hexane. The leakage current decreased by the treatment of organic dilutedsolutions,
but the leakage current of samples with various ratios was in proportion to increase the content of
noctadecyltrichlorosilane. The FTIR spectra of SiO2 film showed the various wave forms below
800 cm-1, and the FTIR spectra of 720 and 745 cm-1 did not disappear after organic treatment. The
FTIR spectra below 800 cm-1 became weak according to the increase of the content of of
n-octadecyltrichlorosilane. The FTIR spectra below 800 cm-1 between samples 6 and 7 varied
abruptly and the sample 6 showed the lowest leakage current.
Thermal Failure of Transformers
Abstract--The thermal failure in high voltage equipment is little heard and is generally known to
have the slow & deteriorating effect on the insulation system, which ultimately reduce the life of the
equipment. In a unique classical case, 9 units of 100 MVA 230/110/11 kV oil filled auto
transformers
supplied to one of the electrical utility in India failed in quick succession due to oil starvation in a
particular part of the winding leading to thermal failure of complete lot of 9 nos. transformers at
sites. In spite of oil starvation, the transformer withstood the voltage and passed all the dielectric
tests successfully, which concludes that the dielectric failure had not occurred. The failure due to
thermal failure was further confirmed by the different degrees of blackening of cellulose insulation
depending upon the time, it has put into service. In this paper, findings of the studies made and
corrective measures taken to avert such failures have been discussed & detailed.
New Diagnostic Method of Winding Insulation
Degradation in Power Transformers based on Partial
Discharge Characteristics
Abstract--A resolved gas analysis method has been one of the most important evaluation methods of

the degradation of insulation paper in power transformers. However the resolved gas analysis
method requires special care to sample the oil and takes time to get the result. Instead of resolved
gas analysis
method to estimate the degradation of the paper, it is found that a simple relationship between the
partial discharge magnitude and the decrease of polymerization, resulting from a lot of field
measurements of power transformers. It is also found that a certain partial discharge pattern strongly
correlates to the occurrence of acetylene in the insulation oil. This paper proposes a new evaluation
method based on the partial discharge magnitude and patterns. The new method may give the
maintenance staffs of power transformers a very effective and reliable diagnosis method of
insulation paper degradation Key Words--Insulation diagnosis, Partial discharges, Power
transformers,
Effects of temperature on Dielectric properties
of Rhicinnus Oils as insulating liquid
Abstract--Recently many researchers are attempting to find biodegradable liquid insulating
materials. This is because the conventionally used mineral oils are non renewable which isgoing run
out in the future and non biodegradable which may harmful to environment. Biodegradable liquid
insulating materials in general can be obtained from vegetables, flowers and seeds. Some of them
have been commercialized and being used as liquid insulation for high voltage power transformers.
We have investigated the rhicinnus oils with various grades and considered the oil as a candidate for
biodegradable liquid insulating material. This paper reports the experimental results on the effects
of heating/temperature on the dielectric properties of rhicinnus oils. The samples used including
crude rhicinnus oil, refined rhicinnus oil, refined rhicinnus oil with treatment and methyl ester
obtained from rhicinnus oil. The dielectric properties investigated in this experiment were
breakdown voltage, losses factor (tan δ), dielectric constant, viscosity, and neutralization number.
The effects of temperature on the dissolved gasses in oil were also investigated. Compariso between
the oil characteristics and those from mineral oils are also presented. The results indicated that
refined rhicinnus oil and methyl ester obtained from rhicinnus oil have good enough dielectric
properties to be used as liquid insulating materials. Index Terms--temperature, rhicinnus oil,
dielectric properties methyl ester
Thermal Instability on TR-XLPE 12/20 kV Ground
Cable : Non Adiabatic and Adiabatic Comparison
Method
Abstract - - Short circuit current constitutes one of the forms of disturbance on transmission system
of electric energy, including transmission system through underground cable. Effects of short circuit
current disturbance are, among other things: mechanical damage on cable due to electromagnetic
force from repulsion between conductors or between conductor and rapper; the sharp increased
temperature due to joule heat on the conductor and wrapper causing thermal instability on the cable.
This will further causes the occurrence of tree electric or the failure on insulation; the occurrence of
aging on the cable. This is certainly of disadvantage since the continuity of voltage distribution

may be disturbed and investment is of disadvantage. The calculation of capacity of thermally
permissible short circuit currents in cable is determined by the transfer of heat occurring in cable
parts into its surrounding This paper explains calculation/ determination of short circuit currents by
comparing two methods, namely adiabatic method and non-adiabatic method. The result of study
shows that non-adiabatic method better than adiabatic method in determining value of short circuit
capacity due to thermal instability on the use of underground TR-XLPE cable of 12/20kV especially
on thselection backfill type, cable burial depth, distance among cables,
Effect of Antioxidants on Thermal Degradation
of EPDM and XLPE
antioxidants on thermal degradation of EPDM and XLPE was carried out. We used “mapping
method” in our FTIR spectroscopy to evaluate the degree of thermal degradation. The obtained
absorbance data of FT-IR spectra were analyzed statistically. Thereby, we confirmed a clear
suppressive effect of sulfur-containing phenolic antioxidant, 4-4 thiobis (3methyl-6- tert-butyl
phenol), for thermal degradation of EPDM and XLPE. We confirmed also that a similar effect is
obtainable when a phenolic antioxidant is combined with a sulfur type antioxidant. In our
experiment, we discovered a great difference of antioxidant effects between EPDM and XLPE.
Based on the results of experiments, the scheme of suppressive effects of antioxidant on thermal
degradation was discussed. Index Terms--Antioxidant, EPDM, FT-IR, Gel fraction, Infrared
microscope, Synergy effect, Thermal degradation, XLPE
DMA Properties of Semiconductive Composites
in Power Cables by Dual Filler System
Abstract--This paper applied DMA to investigate the storage modulus, loss modulus, and Tanδ of
nano-composite materials using a dual filler system that is fabricated by using different contents of
CNT and CB for EEA. As a result, although the glass transition temperature of such nano-composite
materials did not show changes in the temperature according to the change in applied contents, the
storage modulus, loss modulus, and Tanδ increased according to the increase in applied contents. It
is considered that the polymer chains were aligned according to the application of CNT, which has a
large aspect ratio, as a reinforcing agent and there existed a certain crosslinking structure due to the
increase of mechanical interlocking in resin. Index Terms--DMA Properties, CNT, Semiconductive
Composites, Dual Filler System
The Effect of Thermal Ageing on the Electrical
Characteristics of Insulating Oil for Pole Transformers
Abstract--This paper describes the electrical characteristics of insulating oil employed in pole
transformers. In the experiment temperature and frequency were selected as variables, and dielectric
characteristic values such as the relative permittivity, the tanδ and the specific resistance of the
insulating oil were measured by a WinDETA system. As a result, the dielectric characteristics of the
testing objects were temperature and frequency-dependent, and especially, the relative permittivities
of each object showed considerable difference. In addition, the specific resistance acted as a key

factor determining the insulating performance, and it was rather frequency dependent than
temperature dependent. And, the dielectric values measured before ageing was slightly different
from those after ageing. Dielectric dispersion due to the space charge polarization was observed in
all testing objects.. Index Terms--ageing, dielectric dispersion, electrical characteristic, frequency,
insulating oil, relative permittivity, space charge polarization, specific resistance, tanδ, temperature,
variable
Failure of a Big Transformer in HPP –
Assessment of Damage, Repair and Tests
Abstract—The authors present the case of a big three phase generator step-up transformer with three
windings and five leg core, from its failure and diagnosis of damage up to repair on site and tests to
prove the quality of work, including first preventive tests after its return in operation.. Index
Terms—Power transformer, Fault diagnosis, Windings, Repair, Power transformer insulation testing,
Moisture measurement.
On-site Application and Improvement of WaterTree Deterioration
Diagnosis for XLPE Cableby Residual Charge Method
Abstract--"Residual charge method", which has been developed for detection of non-bridged water tree, is well
known as a high reliability water tree deterioration diagnosis technique for XLPE cable, and it has been applied for
on-site cable system diagnosis. Traditional residual charge method measures the amount of electrical charge, and the
information of cable length is required to evaluate the result. In this paper, we would like to introduce \ our
development of the new technique of residual charge method which does not need the information of cable length
to evaluate the deterioration degree. Index Terms--XLPE cable, water tree, deterioration diagnosis, residual charge
method
Analysis on Insulation Aging Failure of
Pulse Capacitor
Abstract--The pulse capacitor, as the important energy storage device, its stability will directly
influence the dependability of the pulse power system that capacitor located in. Life-span of the
capacitor has strong relationship with its working dependability, In this paper, by charging and
discharging to the pulse capacitor and testing direct current partial discharge to the capacitors at
different stage of life-span, the three curves of relation between life-span and maximal discharge
magnitude , mean discharge magnitude , mean discharge frequency were obtained. Observing the
surface topography of capacitor film at different stage of life-span by the scanning electron
microscopy, analyzing the influence of charge and discharge aging test to its surface topography.
Finally referring to the actual situation of capacitor breakdown and summarizing the factors that

caused the variation of pulse capacitor partial discharge performance, pointing out that some
insulating defect existed in the edge area of electrodes was the main reason that caused the capacitor
breakdown. Keyword--Pulse capacitor, direct current part discharges, aging, high-current pulse,
surface topography
Gaining Control on Anomalous Discharge as an
Effective Way to Increase Reliability of
Work of Outdoor HV Insulators
Abstract--The modern design of outdoor HV insulators is determined by rules which follow from
characteristics of flashover mechanisms, such as: 1). The leader-streamer mechanism of breakdown
of gaseous gaps close to dielectric surface under impulses of overvoltages, (determines necessary
height of insulator, and also the form and sizes of its electrode system); 2). The mechanism of
flashover of insulator on an AC by partial arcs with polluted and humidified surface, (determines
number of sheds, its profile and size). As a result of our research, [1-5], an alternative
flashovermechanism of HV insulation was discovered and researched. The mechanism was named -
anomalous discharge (AD). As it was discovered, AD-mechanism has essential practical value since
it’s capable to generate full flashovers on majority of modern insulators at much smaller voltages
than it was considered earlier, (lightning and switching overvoltages and also on an AC). This
research is devoted to efficiency of non-standard ways for control of AD with purpose to increase
reliability of work of power energetic objects as a whole, i.e. increase real BIL of their insulation.
Index Terms--anomalous surface discharges, discharge control, flashover mechanism, reliability,
outdoor insulators.
Electric Field Determination in DC Polymeric Power
Cable in the Presence of Space Charge and
Temperature Gradient under dc Conditions
Abstract--In direct current (dc) power cable the electric field is affected by conductivity of the material, which is a
function of both temperature and electric field. Loading in high voltage direct current (HVDC) cable results in a
temperature gradient across the insulation and hence a radial distribution of the insulation conductivity. A direct
consequence is the accumulation of space charge within the insulation bulk, which modifies the electric field across
the insulation. The coupled problems due to electric field and temperature inflict difficulties to identify the electric
field distribution in HVDC cables, which therefore poses threat to the reliability in operation of dc power cables.
Space charge in a commercial 11 kV ac XLPE power cable has been measured under a voltage application of 80 kV
dc. Space charge distributions were obtained across the insulation of the cable by means of a modified pulsed
electroacoustic (PEA) system. In this paper, COMSOL Multiphysics software package is also used to accurately
determine the electric field distribution in the dc power cable by considering the influences of both the effects of
temperature and electric field on the conductivity of the insulating material.
Analysis of AC Breakdown of Composite-

Insulation depending on Gas Pressure and Solid
Insulation Thickness
Abstract--SF6 gas used widely as insulating component inelectric power industry has excellent in
insulation and arc extinguishing performance in gas-insulated switchgear. However, the concern
about eco-friendly alternative gas is currently rising because SF6 gas is one of the main greenhouse
gases. In this paper, dry-air and composite-insulation (dry-air + epoxy) as the alternative technology
for SF6 gas insulation is studied. Under the gas pressure ranged from 0.1 to 0.6MPa, the breakdown
voltag of dry-air is measured in AC electric field. The data of composite-insulation are ac acquired
by changing the thickness of epoxy used in each composite-insulation under the same condition. As
a result, in case of dry-air, the gas pressure needs to be compressed as about 3 times as that of SF6 to
maintain the same dielectric strength. When the epoxy is applied by the thickness, the breakdown
voltage of composite-insulation is increased by the side of dry-air. However, the difference by the
thickness does not exist almost. Index Terms--dry air, solid insulation, composite insulation, ac
breakdown voltage
Role of the Voltage Zero-crossing in
the Growth of Water Trees
Abstract--The authors have examined the effects of superposition of a low-frequency ac voltage and
a high-frequency ac voltage on the growth of water trees in polyethylene, and have made it clear that
the number of voltage zero-crossings is a ecisive factor of water tree growth. In the present research,
a short-duration high-frequency (2 kHz) voltage was superposed repeatedly onto a continuously
applied low-frequency (0.5, 1.0, 3.0 or 5.0 Hz) voltage in synchronous with the low-frequency
voltage either at its positive and negative maxima or at each zero-crossing point. By applying such
superposed voltages to a low-density polyethylene sheet with a water needle electrode and a counter
plane electrode, the length of a grown water tree was evaluated. As a result, it has become clear that
the water tree length is longer when the highfrequency voltage is superposed at each zero-crossing
point of the low-frequency voltage. This result supports the above-mentioned assumption that the
number of voltage zero-crossings plays a significant role in the growth of water trees. Index
Terms--Aging, Cable insulation, Fault diagnosis, Insulation, Insulation life, Power cables, Space
charge, Trees (insulation)
Interfacial Characteristics of Space Charge in
Multi-layer LDPE
Abstract--This paper reports on the investigation into space charge characteristics at interfaces of
multi-layer polymeric materials. Planar low density polyethylene (LDPE) samples were used in this
study. DC voltage up-to 10 kV was applied to the sample and space charge measurements were
taken using the pulsed electro-acoustic (PEA) technique. Experimental results indicated that the

electrode interface plays an important role in determining the bulk charge formation and polymer
layer interface has different effects on electrons and holes trapping. Index Terms--space charge,
interface, LDPE, PEA
The study on diagnostics for aging trend of
cable termination
Abstract--The commercial diagnostics of insulation materials of cable system are the measurements
of insulation resistance, dielectric power factor, and partial discharge. However, there is no standrd
stating permissible levels for these measurements. Besides, because the material breakdown may
result from material aging or defect aging, the aging trends of different causes may be different.
Therefore, two types of defects in cable terminations are made to comparing with good cable
terminations. And two accelerating aging tests of cable system are set up in this paper. One is a
synergistic experiment of temperature and moisture. Another environment is in a constant ac
voltage of 15 kVrms with a 300 Arms current switchingregularly. The measurements of partial
discharge, insulation resistance, and dielectric power factor are all made periodically. The results
show that dielectric dissipate factor has the ability to assess the aging degree of insulation of cable
termination, and partial discharge measurement has the ability to detect defects in cable system but
can’t assess the aging degree of insulation system. The insulation resistance measurement is
improper to assess the aging degree of insulation system. Index Terms—partial discharge,
insulation testing, dielectricss.
Non-Uniform Field Breakdown Characteristics
of SF6/CF4 Mixtures at Various Pressures
Abstract-- The bre kdown and the corona inception voltages experiments of SF6/CF4 mixtures in
non-uniform field were performed. The experiments were carried out under AC, positive and
negative standard lightning impulse (SLI) voltages. The point-plane electrode was used to make
non-uniform field and gap distance was 3 mm. SF6/CF4 mixtures pressure ranged from 0.1 to 0.5
MPa and the percentage of SF6 and CF4 was 0, 20, 40, 60, 80 and 100%. Under positive SLI the
breakdown voltage was increased slowly as pressure increasing but under negative SLI the
breakdown voltage was increased slightly as pressure increasing. At low pressure the breakdown
voltage of positive and negative SLI was similar. Under AC voltage the breakdown voltage was
increased linearly but the corona inception voltage was saturated over 0.2 MPa. This paper suggests
elementary data in Gas Insulated Systems. Key Words -- Dielectric Breakdown, Corona, SF6

Evaluation Method of Deterioration of
Polyetheretherketone using Dielectric
Relaxation Characteristics
Chung Lee 1*, Boo-Hyung Ryu 2, Kee-Joe Lim 3, and Sun-Chul Jung4
1 Korea Atomic Energy Research Institute, Daejeon, 305-353, Korea
2 Dept. of Safety Engineering, Dongguk University, Kyeongju, 780-350, Korea
3 Dept. of Electrical Engineering, Chungbuk National University, Cheongju, 361-240, Korea
4 Korea Electric Power Research Institute, 305-380, Korea
*E-mail : clee@kaeri.re.kr
Abstract - A novel deterioration evaluation method of class 1Ecable insulation,
Polyetheretherketone (PEEK), are proposed busing dielectric relaxation characteristic in order to
evaluate the deterioration process for the accelerated aged PEEK. The procedure of accelerated
ageing consists of 3 steps, 60Co γ-ray irradiation, thermal ageing, and loss of coolant accident
(LOCA) simulation. Also, the proposed evaluation method was compared with the standardized
method, elongation at break, and subsidiary methods, which are weight loss temperature, the
carbonyl group concentration, indenter modulus. The novel proposed evaluation method using
dielectric relaxation characteristic will be applicable to classification of environmental qualification
(EQ), and contribute to the reliability of the life span extension in the nuclear power plants. Index
Terms – Dielectric relaxation, Environmental qualification, LOCA, PEEK insulation, Radiation,
Thermal aging
Sensitivity of UHF coupler and loop electrode
with UHF method and their comparison for
detecting partial discharge in GIS
Abstract-- We introduce in this paper the sensitivity of two UHF couplers, disc-type measuring
electrode and loop-type measuring electrode embedded in an epoxy insulator, for detecting partial
discharge (PD) and diagnosing GIS. Each of the couplers has sufficient performance for detecting
the electromagnetic waves up to 8 GHz. The attenuation characteristic of electromagnetic waves is
changed depending upon the location of defects, such as a particle on an enclosure or on a conductor.
Index Terms— Disc-type & Loop-type measuring electrodes, Gas-Insulated Switchgear, Partial
discharge, UHF Method
A Fault Detection and Service Restoration
Method by Shifting the Feeder Tie Switch for
Ungrounded Distribution System
So-young Park1*, Chang-hoon Shin1, Seong-chul Kwon2, Bok-nam Ha3, Myen-song Choi4
Korea Electric Power Research Institute of KEPCO, Daejeon, Korea*

Dept. of Electrical Engineering, Myongji University, Seoul, Korea4
Email : {parksy1*, hoony1, mindall2, gaboksa3}@kepco.co.kr, mschoi@mju.ac.kr4
Abstract-- This paper presents a fault detection and service restoration method for Distribution
Automation System(DAS) in ungrounded distribution system. Fault detection and service
restoration is principal function to supply high reliability power continuously in distribution system.
The proposed method utilizes the turning point of fault information between connected feeders in
the process of shifting the feeder tie switch. It can provide communication-based fault handling
process without ower supply interruption for ungrounded distribution system. This method is being
studied to be implemented in DAS for field test to validate the method. Index Terms— Fault
Detection, Service Restoration, Ungrounded Distribution System
Monitoring the SF6 Pressure Level in Metal-
Enclosed Switchgear to Detect Gas Leakages
Lukas Graber1* and Manoj Kumar Pradhan2
1 ETH Zurich, Switzerland
2 University of Queensland, Australia
*E-mail: lgraber@ieee.org
Abstract--Recently, electric utilities decide to permanently monitor the SF6 gas level in gas
insulated switchgear. This is mainly because of two reasons: The optimization of their maintenance
strategy and environmental awareness associated with greenhouse gas emissions. The detection of
small gas leakages is not an easy task. The authors propose a model which allows using pressure
sensors. The problem of high pressure fluctuations is solved by means of a model-based filter which
reduces the fluctuations significantly. The core of the model consists of an approximation by which
the mean temperature of the gas can be estimated. The expected pressure level can be approximated
by information about the mean gas temperature. This allows to filter the output signal from the
pressure sensor. The model was successfully tested on a gas insulated bus-bar. The filtered pressure
value is well suited to detect leakages already at an early state. Index Terms--CFD, leakage,
monitoring, pressure, SF6, switchgear, thermal network
Advanced Monitoring System for
Gas Density of GIS
Abstract--Detection of SF6 gas leakage from a gas insulated switchgear (GIS) has recently become
an important issue from an environmental standpoint in addition to the demands for the insulating
reliability. This paper describes a state-of-the-art gas leakage detection system, which consists of a
high-performance gas pressure sensor and a new algorithm improving accuracy of the leakage rate
calculation. The gas pressure sensor has enough properties, resolution of 20 Pa and the stability of
0.004 % per year. Furthermore, in order to achieve high accuracy of leakage detection in the actual
field, the new algorithm of the leakage rate calculation has been developed to cancel the interference
due to solar radiation and weather. A yearlong test of the 84 kV GIS\ ystem demonstrated that the
algorithm reduces fluctuations of obtained gas pressure to one fifth and enables to detect the leakage
of 0.5 % per year, which is standardized maximum leakage by the new standard, IEC 62271-203.
Index Terms--Gas leakage detection, Gas Density, Gas pressure sensor, Monitoring, Diagnosis,

Sulfur Hexafluoride (SF6), Gas insulated switchgear (GIS).
A Study of Flashover Voltage of Artificially
Polluted Porcelain Disc Insulator under Natural
Fog Conditions
Asfar Ali Khan*, Aejaz Masood and Ekram Husain
Department Of Electrical Engineering, Aligarh Muslim University, Aligarh, India
*Email: asfaralikhan@gmail.com
Abstract--The availability of cheap and reliable supply of electrical energy plays very important role
in the economic development and social welfare of any society. Overhead power transmission lines
cross regions which are different in environmental conditions. The reliable and uninterrupted
operation of modern power system depends on reliable insulation. Therefore outdoor insulation
cannot be selected without having knowledge of prevailing pollution severity. This paper reports
results of artificial pollution tests that have been done with different contaminants. The choice of
contaminants for use in the present artificial pollution test was done with respect to the occurrence
of soluble and non-soluble salts in natural pollution conditions. Flashover voltage (FOV) of
porcelain disc insulator for different pH values and conductivity has been recorded to relate FOV
with pH and conductivity of the contaminants. It is found that an increase in pH and conductivity of
the contaminants lower FOV of the insulators. Regular condition monitoring of porcelain insulators
can be done using pH of the contaminants as an effective pollution severity indicator, it may
further be used for devising proper maintenance schedule. Index Terms--Artificial pollution test,
Conductivity, FOV, Hydrated Ions, pH value, Porcelain insulators.
Investigation on DC Flashover Performance of
Porcelain Insulators in High Altitude Areas
Fuzeng zhang, Liming Wang, Zhicheng Guan
Graduate School at Shenzhen, Tsinghua University,
Xili, Nanshan, Shenzhen, 518055, China
Zhangfz04@mails.tsinghua.edu.cn
Abstract--In this paper, experimental studies were carried out to investigate the contamination
characteristics of porcelain insulators in natural high altitude areas (1970 m). The experimental
results indicate that the DC arcs have a significant effect on the flashover performance at high
altitudes. The insulator profiles, suspension patterns and contamination distribution have a strong
effect on the arc behaviors resulting in a big difference for the utilization ratio of leakage distance of
the porcelain insulator, and this had a strong influence on the flashover voltages. In addition, the
effect of non-soluble deposit density and contamination components (different kinds of salt) was
also investigated for porcelain insulators. Non-soluble deposit density and contamination
components also had a significant influence on the flashover voltages by changing the resistance of
the contamination layer. Index Terms--Porcelain insulator; Flashover performance; Leakage
distance
Behavior of Metallic Particles in a

Single Phase Gas Insulated System with
Dielectric Coated Electrodes
G. V. Nagesh Kumar1 , J. Amarnath2 and B.P.Singh3
1 Vignan’s Institute of Information Technology, Visakhapatnam, Andhra Pradesh, INDIA
2 Jawaharlal Nehru Technological University, Kukatpally, Hyderabad, INDIA
*E-mail : gundavarapu_kumar@yahoo.com , amarnathjinka@yahoo.com
Abstract-- The development of compressed gas insulated switchgear (GIS) equipment has
progressed rapidly. Conducting particles in transmission and switching equipment insulated by
compressed sulphur hexafluoride (SF6) can result in loss of as much as 90% of the gas dielectric
strength. These particles may be free to move in the electric field or may be fixed on the Co ductors,
thus enhancing local surface fields. In a horizontal coaxial system with particles resting on the
inside surface of the enclosure, the motion of such particles is random but the randomness depends
on the coefficient of restitution and angle of incidence when approaching the coaxial conductors.
The power industry has utilized several methods to control and minimize the effect of particle
contamination in GIS. One such technique is to apply a dielectric (high resistivity) coating to the
inside surface of the outer GIS enclosure. The electric field necessary to lift a particle resting on the
inside surface of a GIS enclosure is much increased due to the coating. The simulation of the particle
Movem nt was carried under different AC voltage levels for coated and uncoated cases. The results
have been presented and analyzed. Index Terms-- Metallic Particles, Electric Field, Gas Insulated
Substations, Particle Contamination
EHV Circuit Breaker Condition Monitoring
using Antenna-based Coupling Methods
Ramli S1, Birtwhistle D1, Lopez-Roldan J2 and Tang T1*
1 Queensland University of Technology, George Street, Brisbane, Q4001, Australia
2 Powerlink Queensland, Harold Street, Virginia, Australia
*E-mail : t.tang@qut.edu,au
Abstract-- Catastrophic failures of modern SF6 circuit breakers have been reported during shunt
reactor and capacitor bank de-energisation. In those cases, evidence of destruction of the interrupter
nozzle by cumulative re-strikes is found. Monitoring of voltage waveforms during switching using
established method would provide information about the magnitude and frequency of small
re-ignitions and re-strikes. However, waveform measurements at a moderately high frequency
require plant outages to connect equipment. A nonintrusive measurement technique has been
developed to measure the high and low frequency voltage waveforms during switching operations
without the need of an outage. The principles of this measuring technique are discussed and an
example of its
application in both shunt reactor and capacitor switching is presented. Index Terms-- High voltage
circuit breakers, shunt reactors, capacitor banks, switching overvoltages, controlled switching,
voltage sensors.
Non-Intrusive Partial Discharge Measurements

of MV Switchgears
Neil Davies1, Yuan Tian1*, Joe Cheung Yin Tang2, Paul Shiel3
1 EA Technology Ltd, UK
2 CLP Power, Hong Kong
3 ESB Networks, Ireland
*E-mail : yuan.tian@eatechnology.com
Abstract--Partial discharge (PD) activity results in the degradation of insulation systems in a range
of high and medium voltage equipment nd if left unchecked will eventually lead to disruptive
failure of the equipment. Operating MV equipment with active partial discharge increases the risk of
failure occurring at the time of switching leading to increased risk to the operator. An understanding
of the processes involved in the degradation of various insulation types has enabled the
development of instruments capable of non-intrusively detectingPD act ivity. The instruments are
designed to assess insulation condition by detecting the presence of PD activity while the HV
or MV equipment is energized and in normal service. This paper shows how two power utility
companies have successfully introduced the widespread use of PD testing, what their main drivers
are behind the adoption and the practical results, experiences and benefits gained consequently.
Index Terms--partial discharge, switchgear, condition Monitoring
Image Analysis on the Surface Hydrophobicity
of Polluted Silicone Rubber Insulators
Chengrong Li*, Xiaoming Huang and Linjie Zhao
Beijing Key Laboratory of High Voltage & EMC, North China Electric Power University, Beijing,
102206, China
*E-mail : lcr@ncepu.edu.cn
Abstract--Although the spray method (HC method) is a very useful means for periodically
evaluating the hydorphobicity of silicone rubber insulators operated in polluted area, it is extremely
depends on human subjective judgment. The development of the digital image recording and
analyzing technology provides the approach to objective identify the HC levels. However, the
criteria of the traditional spray method can not be directly used, because the parameter
receding-contactangle described in the criteria can not be measured in the digital images. This paper
presents new criteria based on two simple geometrical parameters for identifying the HC levels of
polluted
SIR insulators by using the digital image analyzing technology. Index Terms--.silicone rubber
insulators; hydrophobicity; pollution; measurement; criteria; image analysis
Monitoring The Insulator Condition By On-Line
I.A.D. Giriantari
Department of Electrical Engineering
Udayana University
Denpasar – Bali
Voltage Distribution Measurement

Indonesia
Abstract--Insulator strings in transmission system are subjected to direct weather during its service.
The withstandability to the weather is different for each insulator in a string. The withstand-ability
of an insulator drops due to defect on the surface and or internal the insulator. Defect on the surface
can be observed by using an visual detector such as daycor corona meter, however the internal
defect need a special mean of detection method. A combination of the two different detection
methods can be a useful choice. On-line detection method for an internal defect of an insulator
string being done by measuring the voltage across each insulator in a string. It attempts to find the
exact insulator unit that is damaged by plotting the voltage distribution of each insulator in a string.
It found that the voltage distribution of an insulator string was not distributed perfectly, due to many
factors on the measurement work. Decisions for replacing the insulator unit has been made by
observing the graph and find the extra ordinary value of the voltage. This monitoring method is
quite sensitive to find the damage unit in an insulator string.
Research on Detection and Recognition of
Partial Discharge in Gas Insulated System
Yanzhou Sun1*, Hua Yin2, and Laijun Zhao1
1 School of Electrical Engineering & Automation, Henan Polytechnic University, Jiaozuo, 454100,
China
2 Chongqing Electric Power Research and Test Institute, Chongqing, 400015, China
*E-mail: sunyz@hpu.edu.cn
Abstract--Partial discharge (PD) is one of the major factors causing insulation damage of gas
insulated system (GIS). The conventional PD detection methods are too susceptible to disturbances
and unsuitable for on-line monitoring. The ultra-high-frequency (UHF) PD detection technique can
detect and locate the PD sources inside GIS by detecting electromagnetic wave emitted from PD
source. The narrow band UHF method was emphasized in this paper, because it can avoid the
electromagnetic interference by selecting the appropriate frequency. A PD detection system using
narrow band UHF method was designed. The typical defects that can cause partial discharge in GIS
were simulated in laboratory. Using this detection system the PD waveform of frequency domain
and time domain could be gotten. The results show that the time domai waveforms of the same
defect have very similar distribution characteristics and those of different defect have different ones.
So it would be very convenient for therecognition of PD types. Index Terms--Frequen
Practical Application of Diagnostic Method of
Circuit Breaker by Measuring Three Current
Waveforms
T. Watanabe1*, T. Sugimoto1, H. Imagawa1, K. K. Chan2, T. Y. Chew2, and S. Z. Qin2
1 Chubu Electric Power Company, Japan
2 SP Powergrid Ltd., Singapore
*E-mail : Watanabe.Tatsuya2@chuden.co.jp
Abstract--This paper describes a practical application of diagnostic technique that captures

abnormalities of motor-spring driven-type circuit breaker (CB) by measuring three currents
and evaluating the shape of their waveforms. The proposed diagnostic technique has been applied to
117 units of 22kV vacuum circuit breakers (VCB) in Singapore. This application has detected 15
abnormal VCB units and 33 other units with symptoms of abnormality. The development and
practical application of the new diagnostic technique has prevented VCB operation failures and
improved the power supply reliability of 22kV distribution system. Index Terms--AC motor drives,
Circuit breakers, Current measurement, DC motor drives, Monitoring, Substation, Vacuum circuit
breakers, Waveforms
Real Time Embedded Maintenance System of
Hydro Generator Excitation System
Hongtao ZENG, Jiang GUO and Zhihuai XIAO
Hubei Provincial Key Laboratory of Fluid Machinery and Power Engineering Equipment
Technology, Wuhan University, P.R. China
*E-mail: zenghongtao@hotmail.com
Abstract--Hydro generator excitation system is one of the most maintenance intensive subsystem in
hydro power plants. A real time embedded maintenance system of the excitation system is studied.
A knowledge bank, which summarizes both the expert knowledge and the analytical knowledge on
the failure modes and their manifestations as well as their effects, is established. An expert system is
developed to optimize the control parameters, to detect and diagnose the equipment degradations
or/and failures, and to give both control and maintenance remedy on base of the on-line state
monitoring and performance evaluation of the regulating system. This expert system is integrated
into the powerful microcomputer of the regulator and runs in parallel with the regular regulating
tasks. A successful application in industry is presented. Index Terms--Excitation system, real time,
embedded maintenance system, diagnosis, condition based maintenance.
Design of On-line Monitoring Device for MOA
used in 10kV Distribution Network
Zhou Wenjun, Yi Xiao, Li Xiaolu
School of Electrical Engineering, Wuhan University, Wuhan 430072, China
*E-mail: wjzhou@whu.edu.cn
Abstract--Due to low cost and small failure effect, monitor of MOA used in 10kV distribution
network is always ignored. However, with massive application, wide distribution, and difficulties in
failure positioning, it is necessary to monitor MOA used in 10kV distribution network. In
accordance with the actual state of MOA monitoring in China, a kind of on-line monitoring device is
conducted. This device investigates the resistive component of leakage current, and the monitoring
reliability is greatly improved compared to the method detecting full current. When the resistive
leakage current detected reaches the set threshold, the device will give a sign of both mechanic
motion and luminescence indicating the failure. Protective measures against over-voltage and
misoperation are also considered. From spot operation results, this device can effectively decrease
the economic loss caused by overhauls and black-outs, and improve the power-supply reliability of
distribution network. Index Terms--10kV distribution network; aging test; leakage

current; MOA; on-line monitoring; resistive component
GIS Partial Discharge Examination and
Classification from the On-Line Measurements
Chien-Yi Chen1*, Cheng-Chi Tai1, Ching-Chau Su1, Ju-Chu Hsieh1, Jiann-Fuh Chen1
1Department of Electrical Engineering, National Cheng Kung University, Tainan 70101
*E-mail: n2893162@mail.ncku.edu.tw
Abstract--To detect partial discharge (PD) signal from internal defects or particles in gas insulation
system (GIS), both couple capacitor (CC) and acoustic emission (AE) methods are applied
in the examinations. According to the measured data, we need to distinguish whether it is PD or
particle impact signal. From the CC measurement we can determine whether discharge occurs in
one of the GIS chambers or not and tell what chambers are possible related to the events. By AE
sensors, we can further confirm that whether it is the chamber of PD or particle impact occurred. If
there is no discharge events measured from the CC sensors, the AE sensors would be stuck on the
chamber to furthe rdetermine whether particle impact occur in the chambers or not. The signals of
particle impact received from the online measurement of GIS are verified through the inspection
resultsof opening. Index Terms--Partial Discharge, Gas Insulation System, Couple Capacitor,
Acoustic Emission
Research of Monitoring Switching-generated
Arcing Current during Opening and Closing
Process using Rogowski Coil
Xueqin Xu1, Yanqing Li1 and Xiangyu Tan2
1. North China Electric Power University, Bao ding 071003, China
2. Xi’an Jiaotong University, Xi’an 710049, China
*E-mail : xuxueqin1024@163.com
Abstract--The arcing current signals during the breaking an dmaking operation of switches are
measured for monitoring the pening and closing process. A current transducer based on Rogowski
coil is developed to detect the arcing current with a wide bandwidth of 3 Hz to 7.54 MHz.
Experiments were performed with switching containing resistance, inductance, and capacitance
load respectively. Under the opening condition, postarc currents are carried out to describe the
conditions of the gap at current zero. Under the closing condition, both the appearance of prestrike
arc and bounce arc are indications of the contact surface condition. This makes it possible to apply
this method to online monitoring of the opening and closing process of switching. Index
Terms--arcing current; current transducer; arcing time; arc duration; switching;
Development of the On-line iPDM System for
the PD Diagnosis for 25.8kV C-GIS
Taesik Choi1*, Jae Ryong Jung1, Min soo Kim1, Jung Bae Kim1 and Hak sung Lee1
1 HYOSUNG CORPORATION, Power & Industrial system R&D center, Changwon City, 454-2,

Kyoungsang-Namdo, 641-712, KOREA
*E-mail: hstschoi@hyosung.com
Abstract-- As the recent trend of the monitoring and diagnosis technique for High-voltage GIS,
many power industrial companies are researching and developing on-line preventive anddiagnosis
system of PD (Partial Discharge) for GIS. In succession of high-voltage class, the demand in
transmission an distribution class is increasing and the scope of its application isspreading. Thus,
we developed on-line iPDM (intelligent Partial Discharge Monitoring) system for 25.8kV
Cubicle-GIS (C-GIS)We are briefly introdced the configuration of on-line iPDMsystem using UHF
methods for ffectively diagnosing the insulation condition of C-GIS. For the internal UHF sensor,
we designed the novel model with high sensitivity and checked experiment results as antenna
performance factor. Comparing of ERA method and UHF method, the relationship between pC–
dBm is described based on experimental results. The measured data is converted to frequency
domain data and we can search the frequency with peak value except external noise. And then
input data of ANN (Artificial Neural Network) model is made from normalized zero span data.
Finally, our expert system can judge the risk level from PD magnitude and its cause. In this paper,
we will describe the development results and the actual experience of the on-line iPDM system for
C- GIS in KOREA. Index Terms--On-line iPDM system, C-GIS UHF internal sensor, Preventive
monitoring and diagnostic system, Partial discharge
Motion of Free Conducting Particles in a
Single Phase Compressed Gas Insulated Bus
duct with Electromagnetic Field Effect
G. V. Nagesh Kumar1 , J. Amarnath2 and B.P.Singh3
1 Vignan’s Institute of Information Technology, Visakhapatnam, Andhra Pradesh, INDIA
2 Jawaharlal Nehru Technological University, Kukatpally, Hyderabad, INDIA
*E-mail : gundavarapu_kumar@yahoo.com , amarnathjinka@yahoo.com
Abstract-- Metallic particle contamination is one of the areasof insulation design that are considered
critical. The management and control of particle contamination are crucial considerations as the
industry moves forward to higher voltage GIS and long GITL designs using SF6 in some
components. Free conducting particles may lower the corona onset and breakdown voltage of a
GIS/GITL system considerably. Under an applied electric field aconducting particle acquires a
charge and lifts off from its resting position on the conductor when the electromagnetic force from
the field becomes equal to the gravity force. Metallic particle smove randomly in a horizontally
mounted GIS/GITL system due to the electrode surface roughness and particle irregularities. Under
50 Hz AC voltage, the particle can cross the gap at a sufficiently high voltage level. Monte Carlo
simulation is carriedout on a single phase GIS for determining the motion of free conducting
particles in the presence of Electromagnetic field. Theresults have been presented and analyzed.
Index Terms-Metallic Particles, Electromagnetic Field, Gas Insulated Substations
Research on the Model of HV SF6 Circuit
Breaker Fault Diagnosis Based on Fuzzy Theory

Huang Lingjie, Wang Wei, Wu Zhensheng, Xu Lijie
School of Electrical Engineering, Beijing Jiaotong University, Beijing 100044
*E-mail : 05121610@bjtu.edu.cn
Abstract-- High voltage circuit breaker (HVCB) is one of the most important equipments for
controlling and operating in power system. In order to increase the reliability and safety of power
system, it is necessary to carry on online monitoring and failure diagnosis on HVCB. However there
are many difficulties in HVCB failure diagnosis. Based on fuzzy diagnosis theory, a fault diagnosis
model of high voltage SF6 circuit breaker is presented in this paper. By analyzing the frequent and
common failures, this paper confirms the items of online monitoring ofHVCB. Moreover, it digs the
relationship between the characteristic parameters and the failures. Subsequently, this paper defines
the failures array, failure symptoms array and fuzzy relational matrix. Then, it gives the optimistic
fuzzy operator and diagnosis rules. For improving the veracity of fuzzy diagnosis system, this paper
also proposes adaptive correction methods of the fuzzy relational matrix. The fuzzy diagnosis
overcomes the difficulties that expert systems obtain knowledge, and neural networks need large
numbers of data to be trained.The practical examples show that the algorithm is convenient to use,
and the results are accurate. So the algorithm can be widely applied to fault diagnosis of HVCB.
Partial Discharge Monitoring System for
Cubicle Type GIS
Takao Tsurimoto1*, Manabu Yoshimura1, Hirotaka Muto1 and Masahiro Arioka2
1 Advanced Technology R & D Center, Mitsubishi Electric Corporation
2 Power Distribution Systems Center, Mitsubishi Electric Corporation
*E-mail : Tsurimoto.Takao@ab.MitsubishiElectric.co.jp
Abstract--Partial discharge (PD) monitoring system for cubicle type gas-insulated switchgear
(C-GIS) filled with compressed dry air as an insulation gas was developed. The shield electrodes
embedded in the solid insulator of bushings are used as P Dsensors. For verification of the
sensitivity of the sensors and propagation characteristics of PD pulse, artificial defects such as
fixed particle on high voltage conductor and defect on creepage surface of insulator in C-GIS were
used. It is clarified that the sensors had good sensitivity to PD pulse propagating along high voltage
conductor in the range from VHF to UHF and that the amplitude of the sensor output had good
correlation with apparent charge, pC, detected by conventional PD detector. The PD monitoring
system is connected with our condition based maintenance (CBM) controller, which also monitors
the abnormality of circuit breaker, disconnecting switch, gas pressure and so on, as a total diagnosis
tool for our C-GIS. Index Terms--Partial discharges, Cubicle type gas insulated switchgear,
Diagnosis, Condition based maintenance, Electromagnetic radiation, Electromagnetic propagation,
Very high frequency, VHF, Ultra high frequency, UHF.
Influence of Metal Flange Cover of Insulation
Spacers on Propagation Properties of PD-induced
Electromagnetic Wave in GIS
M. Sawada1*, K. Omori1, S. Isejima1, S. Ohtsuka1, H.Ikeda1, M. Hikita1, G. Ueta2, S. Okabe2, T.

Hoshino3,S. Maruyama3 and T. Sakakibara3
1 Kyushu Institute of Technology, 1-1 Sensui-cho, Tobata-ku, 804-8550 Kitakyushu, Japan
2 Tokyo Electric Power Company, 4-1 Egasaki-cho, Tsurumi-ku, 230-8510 Yokohama, Japan
3 Toshiba Corporation, 2-1 Ukishima-cho, Kawasaki-ku, 210-0862 Kawasaki, Japan
*E-mail : g346425m@tobata.isc.kyutech.ac.jp
Abstract--The authors have studied insulation diagnostic technique of gas-insulated switchgear
(GIS) by UHF method. In this paper, we investigated the effect of spacer type (metal flange
type (MT) or bush type (BT)) on the propagation properties of PD-induced EM wave in GIS with
UHF method. Low pass filtering process for cut-off frequency of TE11 mode was used to eliminate
the higher order mode above TE11 of detected signal. Results revealed that reduction of the
magnitude of measured EM waveform by passing through spacers. The reduction was found to be
not due to attenuation by the spacer, but mainly due to reduced superimposition of TE mode and
TEM mode. Furthermore, we investigated relationship between the propagating EM wave in GIS
and a leaked EM wave from a BT spacer. This result suggests that insulation diagnosis by a sensor
placed outside of GIS could be carried out to detect the leaked EM wave through a BT spacer.
Index Terms--Gas Insulate
Particle Size Identification in GIS by Ultra High
Speed Measurement of Partial Discharge
Kanako Nishizawa1*, Takashi Okusu1, Hiroki Kojima1, Naoki Hayakawa1,
Fumihiro Endo1, Masanobu Yoshida2, Katsumi Uchida2, and Hitoshi Okubo2
1 Nagoya University, Japan
2 Chubu Electric Power Co., Japan
*E-mail : nisizawa@okubo.nuee.nagoya-u.ac.jp
Abstract--Gas insulated switchgear (GIS) is reliable equipment. However, when a metallic particle
is in it, the insulation reliability of GIS sometimes reduces. Partial discharge (PD) measurement is
usually performed to detect a metallic particle in GIS. After the PD detection, the criticality of PD
must bestimated. For this purpose, identification of a particle size is very important. In this paper,
every PD pulse of various particle sizes was measured sequentially with an ultra-high speed
measuring system. And physical PD parameters weresystematically analyzed. As a result, it was
clarified that identification of the particle size was possible by considering the PD pulse number and
current at positive and negative polarities. Finally, correspondence between electromagnetic wave
emitted from PD and PD current was discussed. Index Terms--Partial discharges, Gas insulated
switchgear, SF6, UHF measurements
On-line Monitoring Technology for MOA on
HV Transmission Line
Hai-Bao Mu1, Yi-Xin Guo1, Ming Dong1, Guan-Jun Zhang1, Wei Song2
1State Key Laboratory of Electrical Insulation and Power Equipment, School of Electrical
Engineering,
Xi’an Jiaotong University, 28 Xianning West Road, Xi’an, Shaanxi 710049, China
2Henan Electric Power Grid Company, 87 Songshan West Road, Zhengzhou , Henanm 450052,

China
Abstract--Metal oxide arresters (MOAs) are widely used on HV transmission lines for over-voltage
protection. However, it is still difficult to carry out its on-line monitoring, because of some
bottlenecks such as the installation of sensor, signal transmission and on-site power supply, et al.
This paper first discusses the improved acquisition sensor for getting leakage current value
and recording the number of arrester discharge operations. It is convenient for microprocessors
obtaining data from the acquisition sensor. Then the paper presents the on-line monitoring system. It
contains an advanced RISC machine (ARM) processor responsible for acquisition and algorithm of
harmonic analysis. The high performance processor finishes complex calculation on field in order to
reduce large amounts of data transmission. The general packet radio service (GPRS)
communication technology is applied so that remote signal transmission is accomplished by
wireless network. Solar energy battery is employed to obtain continuous power. This apparatus
has low power consumption and high performance. It provides a good platform for deeply research
on monitoring and diagnosing of MOA. Index Terms— MOA
The Characteristic of Silicon Rubber Insulators
Contaminated with Concrete
Fochi Wang*, Chengrong Li, Yongjiang Bi, Linjie Zhao
Beijing Key Laboratory of High Voltage & EMC
Key Laboratory of Power System Protection and Monitoring and Control, Ministry of Education
North China Electric Power University
*E-mail : wyfc88@126.com
Abstract—Concrete-polluted silicone rubber (SIR) insulators are common nature-polluted
insulators. A type of concretepolluted SIR insulators with different content of concrete was
evaluated. The flashover voltage of concrete-polluted insulators was tested after placing in artificial
climatic chamber for 6 hours with ultrasonic fog device continual working. The incepted discharge
area always occurs at the umbrella edge and the connected area of the hardware fittings and core rod
for light concrete-polluted SIR insulators. However, the incepted discharge area always occurs at
connected place of core rod and hardware fitting for heavy concrete-polluted one. The flashover
voltage decreases with the increase of concrete content by a power function and the influence factor
of the concrete deposit density b is 0.194. Even though after a long time transfer, the hydrophobicity
of heavy concrete-polluted SIR insulators also decrease with the increase of concrete-polluted
content 。 Index Terms—concrete-pollution, SIR insulator, flashover, hydrophobicit
Application of Combined PD Sensor for GIS
PD Detection and Condition Monitoring
Chen Min1*, Koji Urano1, Li You-Cheng 2 and Atsuhide Jinno3
1 Affiliation: SE Technology Limited, Hong Kong, China
2 Affiliation: Zhuhai Electric Power Corp., China
3 Affiliation: J-Power Systems Corp., Japan
*E-mail: chen@se-tek.com
Abstract--It was reported previously that partial discharge (PD) existing in GIS can be localized

with a PD localization method based on the time difference of PD detection, in which more than one
pulse current sensors are installed at the GIS sealing end or cable termination. However, the
localization accuracy is not satisfactory since the PD propagation speed is too high and not average
inside GIS. To increase the accuracy combined PD sensors to detect pulse current and to catch the
acoustic signal were applied for the on-site PD localization. The result shows that higher location
accuracy can be obtained. Index Terms--acoustic emission (AE), AE sensor (AES), capacitive
coupling sensor (CCS), GIS, high frequency current transformer (HFCT), spacer, partial discharge
(PD), combined PD sensor, PD localization (PDL), PD measurement (PDM)
Lifetime Monitoring and Estimation Strategy
for Large Power Transformer
Guan-Jun Zhang, Jian-Lin Wei, Ming Dong, Hai-Bao Mu, Hong-Jie Li,
Yuan-Bin Zhang, Yan-Ming Li, Zhang Yan
State Key Laboratory of Electrical Insulation and Power Equipment, Xi’an Jiaotong University,
Xi’an, Shaanxi 710049, China
*E-mail : gjzhang@mail.xjtu.edu.cn
Abstract-- Large power transformers play a vital role in power system. With the operation time
going, there are more and more old transformers in China, which are still in service. However,
based on the present time-based preventive test code for electric power equipment, it is difficult to
conduct the decision-making. It is imperative to develop and carry out the condition monitoring
and diagnosis (CMD) technologies. There are several parameters to characterize the aging condition,
i.e., tensile strength (TS), degree of polymerization (DP), CO/CO2 contents, furfural
concentration, water content, etc. Based on the dielectric response theory, some promising methods
are analyzed, such as the recovery voltage method (RVM), polarization and depolarization current
(PDC), and frequency domain spectroscopy (FDS) of oil-immersed insulation. It seems possible
to achieve the water content in solid insulation by dielectric response measurement. However, the
aging of transformer insulation is a complicated kinetics process of chemical reaction, and it is
definitely urgent to combine all the effective methods together and synthetically analyze the data
and parameters for achieving a comprehensive conclusion. Index Terms-- Power transformer,
Lifetime estimation Dielectric response, Intelligent power equipment.
A Fast and Reliable Dielectric Diagnostic Method to
Determine Moisture in Power Transformers
Maik Koch and Michael Krger
Omicron Electronics, Oberes Ried 1, A-6833 Klaus
*E-mail : maik.koch@omicron.at
Abstract – This paper describes a novel dielectric diagnostic method "DIRANA" which features a
fast measurement methodology and an improved analysis algorithm for determining moisture in
pressboard and paper of oil-paper-insulated transformers Dielectric response methods provide
substantial advantages compared to moisture determination by conventional equilibrium diagrams,
for example it is unnecessary to wait for moisture equilibrium. For the new approach, combination
of time and frequency domain measurements substantially shortens the measurement time, typically

to 25 % compared to a pure frequency domain measurement. The data analysis algorithm
compares the measured dielectric properties of the actual power transformer to modeled dielectric
properties. The software features a compensation for the influences of conductive aging byproducts.
Conductive aging byproducts have similar dielectric properties as water; without compensation the
analyzed moisture content will be too high, leading to unnecessary actions like drying. This paper
also includes examples of practical onsite measurements in comparison to other measurement
methods and a guide for assessing the obtained moisture content. Index Terms – Dielectric
polarization, Frequency domain spectroscopy, Moisture measurement, Polarization and
depolarization currents, Power transformers
Advanced on-site diagnosis of power transformers
Paul P. Seitz1, Ben Quak1, Jur J. Erbrink2, Edward Gulski2, Rory Leich3
1 Seitz Instruments AG, Switzerland; 2 Delft University of Technology, The Netherlands; 3 Nuon
Tecno, The Netherlands
Abstract--This paper discusses the recently developed analysis method for service aged power
transformers. This is a complete approach to assess the condition of a power transformer, both the
on-load tap changer as well as the transformer windings. Thispaper also presents several case
studies of tap changer defects that are discovered with the dynamic resistance measurement function.
Index Terms--Automatic test equipment, contact resistance,dynamic response, power transformers,
resistance measurement, transformer windings.
Verification of a model-based diagnosis for on-line detection of the
moisture content of
power transformer insulations using finite
element calculations
Abstract--It is a well known fact that the moisture content of a power transformer insulation system
is a key parameter for the estimation of its aging condition and operation reliability. Therefore,
detection of the moisture content is a very essential task within power transformer diagnostics.
While conventional methods for estimation of the water content of the insulation system require a
transformer shutdown of several hours, the proposed method calculates the profiles of water
concentration in the cellulosic part of the insulation system, as well as theconcentration of water in
transformer oil from operational parameters. An one-dimensional model for the moisture diffusion
in paper estimates the temperature dependent moisture distributions in the paper. It includes
temperature dependent diffusion coefficients and acts as a non-linear control loop for the water
concentration in transformer oil. Beside experimental work, two-dimensional finite element (FE)
calculations of the temperature dependent water concentration distribution in thetransformer
insulation system have been performed for model verification. The calculations are based on an
opensource Whitney- Element solver. The computed results show the validityof the diffusion model
and give important guidelines for the required complexity of thermal models.
Use of Furan-in-Oil Analysis to Determine the

W. McDermid and D.H. Grant
Manitoba Hydro
Winnipeg, Canada
Condition of Oil Filled Power Transformers
E-mail : wmmcdermid@hydro.mb.ca
Abstract--This paper summarizes the experience of an electric power utility in the use of
furan-in-oil analysis to detect thermal degradation of cellulose materials in oil filled power
transformrs
used in generation, transmission and distribution. Index Terms--Cellulose insulation, mineral oil,
thermal degradation, furans.
Thermal Monitoring on Power Transformers
B. Cahyono1* , A. Pharmatrisanti1, Y. Tamsir1, Sumaryadi1 , R. Siregar1
1 PT. PLN (Persero) P3B Jawa Bali RJKB, Jalan Mayjend Sutoyo 1, Jakarta 13640, Indonesia
Phone: (62)-21-8092208; Fax: (62)-21-8091376
Email: bambang_cahyono@pln-jawa-bali.co.id
Abstract-- Transformers are one of some important equipments on electricity network. Each utility,
in this case PLN P3B Jawa-Bali, has to assure their reliability in order to maintain electrical power
system stability by assessing transformer conditions. Once transformer condition attained,
appropriate maintenance and operation strategy can be defined. Based on failure investigation,
transformer conditions are influenced by its insulation condition. PLN P3B Jawa Bali has applied
dissolved gas and oil characteristic diagnostics. Since the load grows faster than the network
expansion, our transformers tend to be operated at their nominal value or even overloaded. We also
find out that through fault current is one of transformers failure root causes. Therefore, we are
developing on-line thermal monitoring and vibration in order. The oil and winding tempertures are
dependant to loadr As the load increases to its nominal value, risk due to transformer paper
insulation damage caused by disturbances becomes higher. Subsequently the situation will
accelerate the transformer to ageing. By recognizing the raise and fall function of these temperatures
to load we can identify the thermal characteristics of the transformer. Other characteristic will be
identified is dissolved gas increase caused by feeder faults. Based on these characteristics we are
able to conduct some actions, for example: maintaining the temperatures in safe range by
controlling cooling system (prohibiting ageing) or determining the condition status of the
transformer at that particular time. In this paper we would like to describe our experience in
developing the thermal statistic characteristics using load and temperature manual data acquisition,
and dissolved gas produced by feeder faults.
Automatic Thermal Monitoring on Power
Transformers
Sumaryadi1*, B. Cahyono1, A. Pharmatrisanti1, R. Siregar1, and Y. Tamsir1
1 PT. PLN (Persero) P3B Jawa Bali RJKB, Jalan Mayjend Sutoyo 1, Jakarta 13640, Indonesia
*E-mail : sumar.yadi@yahoo.com
Abstract--In order to take any proper maintenance actions the transformers conditions should be

acquired. Since the transformer performance is limited by its main insulation condition, we focus on
the thermal monitoring. As the transformer failure statistic rises, the root cause and ways to solve
the problem should be found. Based on failure modes and ffect analysis overloaded, external
disturbances and ambient condition have affected the transformer performance. Due to this
complexity, a physical model is the fittest tool to solve the problem. In order to build such a model,
automatic thermal monitoring should be developed. The system will record any temperature
changes in any single event experienced by the transformer every 5 seconds. Three transformers that
have been chosen as the pilot project are coming from 150/20 kV 60 MVA class. In this paper we
would like to describe our experiences in installing sensors and developing the thermal modeling.
Index Terms--Automatic thermal monitoring, physical moded condition monitoring
New Tools for Diagnostic Measurements on Power
Transformers
Michael Krger, Maik Koch, Alexander Kraetge and Kay Rethmeier
Omicron Electronics, Oberes Ried 1, A-6833 Klaus
*E-mail : michael.krueger@omicron.at
Abstract-- With the advancing age of power transformers, a regular check of the operating
conditions becomes more and more important. The Dissolved Gas Analysis (DGA) is a proven and
meaningful method such that if increased proportions of H2 and hydrocarbon gases are found in the
oil, the fault must be located as soon as possible. In order to find out the reason for high gas values,
further tests have to be performed for the transformer. Common test Method s are: Winding
resistance measurement, On-Load Tap Changer (OLTC) test, turns ratio and excitation current
measurement, measurement of leakage reactance, Frequency Response of Stray Losses (FRSL),
Frequency Response Analysis (FRA), Capacitance and Dissipation factor measurement and Partial
Discharge (PD) measurement Index Terms – Power transformers, Static and dynamic resistance
measurement, OLTC test, FRSL measurement, Capacitance and dissipation factor measurement,
FRA measurement, \Partial discharge measurement, Diagnosis
Failure Statistics and Power Transformer
Condition Evaluation by Dissolved Gas
Analysis Technique
Thanapong Suwanasri1, Ekkachai Chaidee1 and Cattareeya Adsoongnoen2*
1 The Sirindhorn International Thai – German Graduate School of Engineering,
King Mongkut’s Institute of Technology North Bangkok, Bangkok, Thailand
2 Faculty of Engineering, Naresuan University, Phitsanulok, Thailand
*E-mail : cattareeyaa@nu.ac.th
Abstract--Due to the degradation of power transformer under its normal and abnormal operating
conditions, maintenance activities are vital to restore the condition. However, the preventive
maintenance costs are now of primary concern. The scattering failure data are systematically
recorded and analyzed to determine the critical component of power transformer. Two transformer

models of rated voltage 115/22kV and 230/115/22kV have been chosen in this study. The
determined critical component with high failure rate requires careful attention. The preventive
measures can be setup from the known causes of failure. Then the procedure for power
transformer condition evaluation is performed by analyzing the historical test result from the
Dissolved Gas Analysis (DGA) method. The transformer conditions are principally evaluated by the
Key Gas method and then verified by the Ratios and Total Combustible Gas method. As a result, the
aging pattern and trend of the power transformer deterioration can be determined.
Failure Statistics and Power Transformer
Condition Evaluation by Dissolved Gas
Analysis Technique
Thanapong Suwanasri1, Ekkachai Chaidee1 and Cattareeya Adsoongnoen2*
1 The Sirindhorn International Thai – German Graduate School of Engineering,
King Mongkut’s Institute of Technology North Bangkok, Bangkok, Thailand
2 Faculty of Engineering, Naresuan University, Phitsanulok, Thailand
*E-mail : cattareeyaa@nu.ac.th
Abstract--Due to the degradation of power transformer under its normal and abnormal operating
conditions, maintenance activities are vital to restore the condition. However, the preventive
maintenance costs are now of primary concern. The scattering failure data are systematically
recorded and analyzed to determine the critical component of power transformer. Two transformer
models of rated voltage 115/22kV and 230/115/22kV have been chosen in this study. The
determined critica component with high failure rate requires careful attention. Thepreventive
measures can be setup from the known causes of failure. Then the procedure for power transformer
condition evaluation is performed by analyzing the historical test resultfrom the Dissolved Gas
Analysis (DGA) method. The transformer conditions are principally evaluated by the Key Gas
method and then verified by the Ratios and Total Combustible as method. As a result, the aging
pattern and trend of the power transformer deterioration can be determined.
Failure Analysis & Diagnostics of Power
Transformer Using Dielectric dissipation factor
Mr. B.D.Malpure, Mr. K. Baburao
Transformer Division , Crompton Greaves Ltd.
Mumbai-India -400042
E-mail : bhaskar.malpure@cgl.co.in
Abstract--The quality of power transformer insulation system is evaluated on a routine basis by
measurement of the dielectric dissipation factor and capacitance of the insulation system. The use of
dielectric dissipation factor measurements at the end of the production cycle not only assures that
the quality of th transformer meets the specified levels but also provides insight into the subtleties of
the manufacturing process. This tool is used for many years for diagnosing the health of electrical
apparatus. It is a routine test conducted at site to know the dryness of insulation in transformers.
This paper highlights our experience on the measurement of dissipation factor using GST & Guar

mode techniques of earthing systems other than dryness of insulation in transformers. All our
experiences are presented in this paper.
Condition Based Maintenance of Power
Transformer: A Case Study
Ramesh Yadav1*, Santosh Kumar, A. Venkatasami, A.M. Lobo, A.M.Wagle
CMDRC, Global R&DCentre, Crompton Greaves Ltd, Mumbai?00042
*E琺 ail: rameshchand.yadav@cgl.co.in
Abstract--Power transformers are important and expensivecomponents in electric energy networks.
Unplanned outages of power transformers has a higher economical impact, which motivates,
preventive tests and diagnosis for tapping the benefit of predicting condition to optimize
maintenance and increase reliability of power system. Application of advanced
diagnostictechniques for power transformers, provide the means toenhance the conventional
maintenance program. Therefore it is necessary to change from time based maintenance program
to a condition based maintenance which uses some of the current diagnosis methods (e.g. Oil test,
DGA, PD, Thermography etc.) to determine the condition of the transformer. A Case Study on
Condition Based Maintenance of power transformer by analyzing the DGA results and zeroing
towards the problem through proper online and offline tests has been depicted in detail. Index
Terms--DGA, Partial discharges, thermovision scanning, Acoustic emission technique.
Realization of Transformer Winding network
from Sweep frequency Response Data
Shubhangi Patil 1 , A.Venkatasami1
1CG Global R&D centre, Crompton Greaves Limited, Mumbai, India
*E-mail – Venkatasami.Athikkan@rnd.cgl.co.in
Abstract-- Sweep Frequency Response analysis (SFRA) is a widely used technique for condition
assessment of power transformers and reactors. With SFRA, it is possible to analyze the integrity of
transformer without prior dismantling. Changes in geometric configuration change the impedance
of network which in turn changes the transfer function. Changes in transfer function will reveal a
wide range of failure modes. SFRA allows the detection of changes in transfer function of individual
windings within transformers and reactors and indicate movement or distortion in core and
windings of the transformer. The RLC network can be identified by its frequency dependent
transfer function. In order to create a framework to facilitate assisted interpretation algorithms,
SFRA curves are parameterized. The simplest and most useful mechanism is the reduction of the
curves to pole-zero representation. SFRA traces are characterized by having many undulations and
extending over a wide dynamic range on both axes. This can make accuratepole-zero representation
a challenge. In this paper an attempt has been made to realize the electrical network from the SFRA
response data of a high voltage reactor. 2008 International Conference on Condition Monitoring and
Diagnosis, Beijing, China, April 21-24, 2008 978-1-4244-1622-6/08/$25.00 2008 IEEE Key
words--Sweep frequency response analysis, Condition assessment, Transformer, Reactor
Partial Discharges Multi-Targets Localization in

Power Transformers Based On Spatial-Spectrum
Luo Richeng1,2*, Bai Kai2 and Gong Xuehai2
Estimation
1 North China Grid Company Limited, Beijing, 100053, China
2 North China Electric Power Research Institute Co., Ltd, Beijing, 100045, China
* E-mail :Luorich@126.com
Abstract--A new partial discharges multi-targets localization method is presented in this paper,
which is based on array signal processing. Two ultrasonic sensor arrays are located on the inner wall
of the transformer tank and detect the ultrasonic signal emitted by the partial discharge sources.
Spatial spectrum estimation technique is used in analyzing the signal characteristic information
(number of signals, direction-of-arrivals et. al) and the number of partial discharge signal estimation,
direction-of-arrival estimation and distance estimation are accomplished. The performance of
localizations is given by computer simulations. It shows that the method processes with high
resolution and good estimated accuracy and can effectively estimate the location parameter of
multiple partial discharge sources in transformer. Index Terms--power transformer; partial discharge;
array signal processing; spatial spectrum estimation; multi-targets localization
The simulation analysis of harmonics and
Negative sequence with Scott wiring
transformer
Deng Ming-li, WU Guang-ning, Zhang Xueyuan, Fan Chun-Lei, He Chang-hong, Ye Qiang
(School of Electrical Engineering of Southwest Jiaotong University, Chengdu 610031, China)
Abstract--In order to reduce the impact of harmonic and negative sequence on the power system, in
traction substation can use Scott wiring traction transformer. By using MATLAB to establish a Scott
wiring transformer model, the 110kV side of the three-phase harmonic voltage and current with its
harmonic content and negative sequence can be simulated. Comparing simulated results and actual
data of one transformer substation, the correctness and accuracy is verified. Finally analyze the two
situation of traction network with symmetrical or asymmetrical load. The results showed that
adopting Scott wiring transformer in the traction transformer substation is one effective method.
Electric Railway should be running with the symmetric load as far as possible. So can greatly reduce
the harm caused by asymmetric running of the transformer and effectively reduce the impact on
power quality. Index Terms-- power system; harmonics; negative sequence; Scott transformer
Partial Discharge Detection Using Acoustic
Emission Method for a Waveguide Functional
High-Voltage Cast-Resin Dry-Type Transformer
Ching-Chau Su1, Cheng-Chi Tai1*, Chien-Yi Chen1, Ju-Chu Hsieh1, and Jiann-Fuh Chen1
1 Department of Electrical Engineering, National Cheng Kung University, Tainan 70101, Taiwan

*E-mail : ctai666@gmail.com; ctai@mail.ncku.edu.tw
Abstract--This study adopts the acoustic emission (AE) method to measure partial discharges (PD)
in a cast-resin dry-type transformer and proposes a waveguide atop the high-voltage winding of the
transformer to improve the propagation of the PD acoustic signals occurring in winding to acoustic
emission sensors used. A waveguide is proposed to improve the signals’ quickattenuation and it also
is a safe method for electrical equipments measurement. Finally, a waveguide is practically installed
on acast-resin dry-type transformer; the measurements and the Loca ting of PDs’ AE signals for
transformer are carried out. This study demonstrates a feasible new simple, safe and economical
solution for diagnosing and locating PDs in the transformer. Index Terms--Acoustic emission,
Cast-resin dry-type transformer, High-frequency current transformer (HFCT), Partial discharges
(PD), Waveguide
Partial Discharge Signal Analysis Using HHT
for Cast-Resin Dry-Type Transformer
Ya-Wen Tang1, Cheng-Chi Tai1*, Ching-Chau Su1, Chien-Yi Chen1, Ju-Chu Hsieh1, and
Jiann-Fuh Chen1
1 Department of Electrical Engineering, National Cheng Kung University, Tainan 70101
*E-mail: ctai666@gmail.com; ctai@mail.ncku.edu.tw
Abstract--In this paper, we analyze and compare the partial discharge (PD) signals from acoustic
emission (AE) and highfrequency current transformer (HFCT) measurements with Hilbert-Huang
transform (HHT). Commonly, the Fourier transform (FT) method is used to illustrate information in
frequency domain. The HHT, a time-frequency method, provides another viewpoint to interpret the
PD signals. This method allows for collecting information on PD signals both with regards to the
time and frequency domains simultaneously. It has been verified that the HHT can provide more
information when compared with FT method. In this work, the marginal spectrum simplifies the
results of HHT method fatherly. From the marginal spectrum, the abiding and weak noise source can
be properly estimated, and the instantaneous variation can be emphasized. The results reported here
show that the HHT method has great promise for cast-resin dry-type transformer PD signals
analysis.
Analysis of Acoustic Signals Generated by
Partial Discharges in Insulation Oil
Abstract--This paper dealt with the frequency analysis of acoustic signals generated by partial
discharge (PD) in insulation oil and the positioning of PD occurrence to apply in the diagnosis of oil
insulated transformers. We assembled three types of electrode system; the needle-plane, the
plane-plane, and the floating to simulate partial discharge in insulation oil. An acoustic signal
detection device was designed to detect acoustic signal with high sensitivity. As a result of
frequency spectrum analysis, the frequency ranges of acoustic signal were 70 kHz~210 kHz in the
needle-plane, 80 kHz~270 kHz in the plane-plane, and 60 kHz~193 kHz in the floating electrode.
Their main frequencies were 132 kHz, 130 kHz and 126 kHz, respectively. The position of PD
occurrence was calculated by the time difference of arrival (TOA) using three acoustic emission
(AE) sensors and we could find the position about the error of 1% in the experimental apparatus.

Index Terms--Partial discharge (PD), Acoustic signal, Frequency spectrum analysis, Insulation oil,
Diagnosis, Electrode system, Position, Time difference of arrival (TOA)
Multi-PD Sources Location by UWB RF Detection
on Power Transformers and a Case Study on-site
Tang Zhiguo*, Chang Wenzhi, Li Chengrong, Wang Caixiong, Zheng Zhong, Sheng Kang
Beijing Key Laboratory of High Voltage & EMC
Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control,
Ministry of Education
*E-mail :tangzhyguo@163.com
North China Electric Power University
Abstract -- Ultra-Wideband (UWB) RF sensor-array PD location is a novel technology based on
antenna array detection and time-difference algorithm for power transformers. It has demonstrated
high sensitivity and accuracy for single PD source by experiments in laboratory. In this paper, a
further study has been carried out for multi-PD sources location using the UWB RF sensor array PD
location method. Moreover, a practical location case is given on a real transformer. The results
indicate that the method presented in the paper is effective for multi-PD source location and has
promising future in real transformers. Index Terms --Power Transformer; Partial discharge; Multi-
PD source Location; On-site
Remarkable Benefit Realization by
Application of Strategic Management in
Power Transformer Condition Monitoring and
Diagnostic Systems
Abstract-- Power transformers are usually very reliable and durable components of the power
supply network. Unfortunately, when a fault occurs in a transformer, it can develop catastrophically
and failures are usually very expensive, often resulting in the loss of what is the most expensive
plant item in a substation [1]. In order to safeguard this valuable asset, various condition monitoring
and diagnostic systems have been applied in CLP Power Hong Kong Limited with remarkable
benefit realization in enhancing the system availability, the supply reliability, the implementation of
condition-based maintenance, and the improvement in the asset life cycle management with
promising results. Index Terms-- Catastrophic Failure, Condition Monitoring and Diagnostic
Systems, Strategic Management, Remarkable Benefit Realization
Linking Engineering Knowledge and Practical
Experience to Investment Planning by Means of
David Hughes1, Tracy Pears1 and Yuan Tian1*
Condition Based Risk Management

1 EA Technology Limited, Capenhurst Technology Park, Chester, CH1 6ES, UK
*E-mail : yuan.tian@eatechnology.com
Abstract--Condition based risk management (CBRM) is a process developed by EA Technology in
conjunction with several major electricity companies to assist with the tasks of defining, justifying
and subsequently targeting spending to achieve defined levels of performance. The process has
delivered major benefits. If fully embraced, CBRM can provide the basis for effective asset
management programmes that address the critical issues of network renewal and reliability within
the increasingly stringent regulatory environments faced by many electricity companies
around the world. This paper describes the methodology for quantifying risk and its use in
investment planning. Index Terms--Network reliability, risk analysis
An Assessment of Insulation Condition for
Generator Rotor Windings
Young-Jun Lee1*, Young-Ho Ju1
1 Korea Electric Power Research Institute (KEPRI), Korea Electric Power Corporation (KEPCO),
Daejeon, Republic of Korea
*E-mail : leeyongj@kepco.co.kr
Abstract--Shorted-turn in a generator is scarcely happened,however, it expands severe failure such
as vibration increase, performance reduction and power limitation by deteriorating winding
insulation of generator rotor. In this paper, we experimented shorted-turn detection test in gas
turbine generator of Pyungtaek combined cycle power plant, and investigated the patterns of each
results and try to extensively notify the merit of this on-line test. The on-line shorted-turn test was
conducted using a permanent flux probe and on-line shorted-turn diagnosis system. The permanent
flux probe installed in the generator airgap senses the field winding slot leakage flux and produces a
voltage proportional to the rate of change signature unique to each field winding. We have also
applied a voltage waveform analysis technique that can identify the pole location, slot number and
number of shorted-turn with each slot. Index Terms--generator diagnosis, rotor winding, insulation,
shorted turn
Application of Statistical Tools for Assessing
Service Availability of High Voltage Power
Cables
R.A. Jongen1*, E. Gulski1, P.H.F. Morshuis1, J.J. Smit1 and A.L.J. Janssen2
1Delft University of Technology, Delft, the Netherlands
2Continuon Asset Management, Arnhem, the Netherlands
*E-mail: r.a.jongen@tudelft.nl
Abstract--The practical interest of power utilities regarding the maintenance and replacement policy
of insulating systems such as cables, switchgear and transformers is often based on experiences
knowledge and data from the past. The ages of omponents in the network are increasing and this can
result in an increase of the number of failures in coming years. To be able
to monitor the components powerful tools are diagnostic measurements performed on the network

components and analysis of life time data obtained from the exploitation of the components. In this
contribution the analysis procedure is applied to life time data of 50 kV mass-insulated cables of a
Dutch utility.To see what can be expected in the future the population in service together with the
obtained failure rate curve is used. This gives statistical information regarding expected failures and
critical connections. The analysis can help the asset manager to determine if immediate action has to
be taken to meet the business policy e.g. condition assessment, maintenance or replacement, or if the
current policy fulfils the conditions. Index Terms-
Experience with PD Measurements in GIS
Maintenance Concept
Abstract-- Since the early nineties, ultra-high-frequency (UHF) partial discharge (PD)
measurements are being applied to SF6 gas-insulated equipment. Over the years, PD measurements
revealed the presence of some insulation defects in the 380 kV GIS. The measuring results have
been compared to laboratory experiments. Moreover, locating was possible as well. Cigre TF
D1.03.09 has been working on a risk-assessment procedure to assess the risk for a failure for
insulation defects, based on PD measurements. So this procedure is only applicable to insulation
defects that give detectable PD activity. The paper will show examples of the application of this risk
assessment method on the different detected PD sources. Finally the actions initiated by the
DSO/TSO for these analyzed insulation defects will be described. Index Terms--Gas-Insulated
Substation, Non-Conventional Detection, Partial Discharges, Risk Assessment, Ultra-High
Frequency
The experience of DP and Furan in Remnant
Life Assessment of Power Transformer
1Mr.K Baburao, 1Mr.NM Bhangre, 1Mr.AM Wagle, 1Mr. A.Venkatasami, 1Mr. Sushil E Chaudhari
CG Global R&D Centre, Crompton Greaves Ltd, Mumbai, India - 400 042
E-mail: Baburao.Keshawatkar@cgl.co.in
Abstract-- Transformer life depends on the life of the oil impregnated paper insulation system.
Degradation of the cellulose insulation is an irreversible process. Chemical reaction of cellulose
cause opening of glucose rings providing free glucose molecules, water, CO2 and organic acids.
These glucosemonomers further decompose and produce furanic compounds as end product s. DP
and furan tests are used to identify the extent of ageing of the cellulose in paper insulation of the
transformer. Many authors including Chendong.I, have reported the empirical relations relating
furan content with DP. These empirical relations are finding application in estimating the consumed
life of the transformer. We are doing extensive DP and furan analyses for remnant life assessment of
transformers. This paper reports our experiences with DP and Furan as a diagnostics tool as applied
to a high voltage transformer. Our data is based on the DP test results conducted on the samples
collected at various strategic locations such as main lead, canopy, barrier boards etc. The furan data
collected over several years were analyzed. The past trend is used to determine the deterioration rate.
All these results are correlated and the same is presented in this article.
Thermal Condition Assessment for Power

Transformers Operated in Tropical Condition
Y. Tamsir1*, Sumaryadi1, H.Gumilang1, A. Pharmatrisanti1, B. Cahyono1and R. Siregar1
1 PT. PLN (Persero) P3B Jawa Bali RJKB, Jalan Mayjend Sutoyo 1, Jakarta 13640, Indonesia
*E-mail : yulian.t@pln-jawa-bali.co.id
Abstract--Operated transformers shall experience simultaneous stresses, for example mechanical,
thermal, and chemical stresses. In general the higher the load is, the higher the stresses will be. The
performance of a transformer is depended on its main insulation condition which is limited by the
working temperature. By considering the insulation deterioration process and based on the failure
modes and effect analysis we found out that besides overloading scheme, external disturbances and
ambient condition has affected the transformer performance. Thus we rely on the loading and
calculated hot spot temperature, dissolved gas analysis (DGA), and insulation quality as determined
parameters of transformer condition. The boundary values of loading temperature, DGA, and
insulation quality are obtained statistically while for the hot spot derived from hot spot calculation
and paper insulation standard. In this paper we would like to describe our experiences in developing
power transformer condition assessment based on thermal approaching. Index Terms—insulation
condition, loading temperature, dissolved gas analysis, insulation quality, thermal condition
assessment, external disturbances, ambient condition
The Progress and Future of CMD in China
Ming Dong*, Guan-jun Zhang and Zhang Yan
State Key Laboratory of Electrical Insulation and Power Equipment, School of Electrical
Engineering,
Xi’an Jiaotong University, Xi’an, Shaanxi 710049, P. R. China
*E-mail : dongming@mail.xjtu.edu.cn
Abstract--Based on investigation within China, The introduction of CMD to power utilities was
developed more quickly than before. And a lot of experience and useful lessons were analyzed, and
by the way many ineffective or unstable apparatuses or systems for testing or monitoring were
eliminated step by step. More utilities realized, that the first thing is how to realize the actual
condition of power equipment with those effective and economical methods and apparatuses,
whether it is leave-line or on-line, portable or fixed, with electric or nonelectric method, etc.
Secondly, based on scientific and synthetic analysis of all the data collected, choosing the suitable
decision of maintenance and management strategy. A lot of effective apparatuses and systems for
CMD were developed, and that for optimized strategy of maintenance and asset management also.
Index Terms--Condition monitoring diagnosis, Maintenance, Management
The reliability evaluation method of high voltage
overhead transmission lines
Yangchun Cheng* Chunjie Niu Chengrong Li
Beijing key laboratory of high voltage and EMC, North China electric power university, Beijing,
China
chych@ncepu.edu.cn
Abstract--The reliability of transmission lines is closely related to the reliable operation of power

grids. In this paper a subsection model based on the reliability theory is put foreward to caulcuate
the reliability of transmission lines. The whole line is devided into many section to calculate their
reliability then that of the line. In the model, how to deal with the synthetical result of each kind of
failure in each section, the failures that have relationship each other, many insulator strings and
many times of bad weather, are studied respectively. And aimed to pollutio lashover failure, based
on many research results and the force-intensity interference theory, the f ail ure
probabilitycalculation method is put forward considering to not only the soluble dep osit density but
also the non-soluble deposit density. Aimed to ice flashover failure, the failure probability
calculation method is brought out by contrasting with that of pollution flashover failure. As a result,
the reliability of transmission lines can be evaluated more accurately . Index Terms--Ice flashover,
Pollution flashover, Reliability, Transmission lines
Structural Learning Approach to Replacing
Unreliable Units in a Power System
Shamshul Bahar Yaakob 1 , Tsuguhiro Takahashi 2, Tatsuki Okamoto 2,
Toshikatsu Tanaka 1, Tran Duc Minh3, Junzo Watada 1, Zhang Xiaojun 1
Graduate School of Information, Production and System,Waseda University, Fukuoka 808-0135,
Japan
2 Electric Power Engineering Research, CRIEPI, Yokosuka 240-0196, Japan
3Software Engineering in Management Dept.Institute of Information Technology, VAST, Vietnam
*E-mail : shamshul@fuji.waseda.jp
Abstract--Power supply failure will cause major social loss. Therefore, power supply systems have
been required to be highly reliable. This research deals with a significant and effective method to
decide the investment in a power system damage of the power supply on the society. In CMD2007
Korea, we proposed mean-variance approach to replacing unreliable units in a power system. This
paper extends the method so as to solve a problem efficiently. In this research, we will propose the
structural learning of a mutual connective neural network. The proposed method e nables us to solve
the problem defined in terms of mixed integer quadratic programming. In this research, an analysis
is performed by using the concepts of the reliability and risks of units evaluated using a
variance-covariance matrix and also the effect and expenses of replacement are measured.
Mean-variance analysis is formulated as a mathematical programming with two objectives to
minimize the risk and maximize the expected return. Finally, we employ a Boltzmann machine to
solve the meanvariance analysis efficiently. The result of our method is exemplified using a power
network system in Tokyo Metropolitan. By using this method, a more effective selection of results is
obtained. In other words, the decision makers can select the expected investment rate and risk of
each ward depending on the given total budget. For this reason, the effectiveness of the decision
making process can be enhanced. Index Terms--Mean-variance analysis, Unit replacing, Power
system maintenance, Boltzmann machine.
Condition Monitoring and Plenary Diagnostics
Strategy Based on Event Driven Threads
Wenjun Xi1*, Yuguang Feng1, Yu Zhou2 and Bo Xu1

1 Department of Enginery Science and Technology, NAAU, Yantai 264001, China
2 Navy Aviatic Military Representative Office in Shanghai Area, Shanghai 200233, China
*E-mail : usb20@126.com
.
Abstract--Condition monitoring and fault diagnosis is the roundwork of condition-based
maintenance, and much research has been done about diagnostic algorithm and monitoring
manufactures, but less research about diagnostics strategy and anagement. Plenary diagnostics
based on event driven threads of data propagated through successive diagnostic levels is an
improving attempt about it. In this approach, abnormities are irstly detected or isolated in
operational level. Then the anomalous event data is transmitted from low diagnostic level to higher
levels, collected and centrally analyzed and finally fed back as diagnostic updates to improve
diagnosis modules. This paper describes the diagnostic data flow and the management strategy of
plenary diagnostics, and the difference between which and conventional diagnostics strategy.
Finally, an example about power equipments fault diagnosis is given. Index Terms--abnormity,
condition monitoring , event driven threads, fault, field level, intermediate level, logistics data
system (LDS), operational level, plenary diagnostics , power equipments
Study of Maintenance Strategy Support Tools
for Electric Power Apparatus
Tsuguhiro Takahashi* and Tatsuki Okamoto
Central Research Institute of Electric Power Industry, Japan
*E-mail : shodai@criepi.denken.or.jp
Abstract-- The development of decision support tools for creating a maintenance strategy for
electric power equipment based on asset management technique has become very intensive to
reduce maintenance costs due to the liberalization of the power industry. In recent years, many
papers have been presented about asset management in this area, but there have not yet been
many concrete proposals. In this article, we introduce two approaches of decision support tool
development for power equipment in CRIEPI. One is to support the evaluation of dissolved gas
analysis for oil-immersed transformers. The tool provides comparison with data obtained from the
same kind of transformers, and gives criteria among them. The other approach is to evaluate the
average annual maintenance cost of equipment by considering the overhaul effect and failure risk,
which provides an optimum overhaul strategy with suitable parameters. Index Terms—asset
management, electric power equipment, maintenance, renewal, repair cost, support tools
Development of CMMS (Computerized
Maintenance Management System) in Yogyakarta
Electric Power Distribution Network Company To
Support The Strategic Maintenance
Abstract--Reliability of service has always been an important priority in electric delivery planning
and operation; traditionally it was treated as an implicit goal. Reliability as normally applied to

power distribution means continuity of service to the utility’s customers. In the term of a glossary of
reliability standard, reliability is defined as the ability of the power delivery system to make
continuously available of sufficient voltage, of satisfactory quality, to meet the customer’s need. In
the development country like Indonesia to reach a high reliability index is still very difficult.
Yogyakarta province as a part of Indonesia, the electric power supply is managed by Yogyakarta
electric power distribution region that serve more than 650.000 customers and support by more than
11.000 power distribution transformers. These transformers are distributed along the line in the
length of more than 10.000 kms. To improve the reliability of service one aspect to be paid attention
is maintenance management of all the distribution equipments. With supported by CMMS system
that is being developed, all of the maintenance management aspects are included in the system. The
CMMS is developed on based of digitalizing distribution line networks, customers’ connection,
inventory of the assets, and man power. This CMMS also supported by GIS in conjunction with the
reduction of the time needed to restore the system during fault.
Optimization of Asset Management and Power
System Operation Based on Equipment Performance
Abstract-- odern T&D system has the issues about economical aspects, aged equipment, reliability
etc. To solve these issues, equipment should be maintained optimally and the T&D system should be
operated based on the present performance of equipment. For realization of these purposes,
Intelligent Grid Management System (IGMS) was proposed and its basic functions are being
investigated. In this paper, failure modes of a T&D system were chronologically simulated using
Monte Carlo method, and all events occurred by failures in a T&D system were evaluated as cost
with nonlinear programming. The expected T&D cost was calculated by repeating these procedure
many times. By minimizing the expected T&D cost, the most optimum maintenance strategies of
circuit breakers and transformers were derived quantitatively. Index Terms—reliability, economy,
maintenance, diagnosis, electric power system, circuit breaker, transformer
Investigation on Test Schemes for Grounding
Grids Corrosion Diagnosis
Jian Liu 1* , Shuqi Wang 1, Wei Lu 1 , Zhizhong Li 1 and Sen Wang 2
1School of Electrical Engineering, Xi’an University of Science & Technology,Xi’an,China,710054
2 Shaanxi Electric Power Research Institute, Xi’an,China,710054
*E-mail : edliu@bylink.com.cn
Abstract--The requirements of a good test scheme are described, such as independent excitation,
none-repeated measurement, large voltage signals and sensitive to the changes of branch resistances.
Reciprocity theorem and superposition theorem can be used to determine whether a test scheme i
completed. Theorem of Maximum Voltage is proved through reduction to absurdity, and its three
inferences are put forward, based on which, the theoretical best test scheme is obtained, which
suffers from the remarkable influence of grounding down line resistances. The suggested test
scheme is presented which can avoid of above problem. A grounding grid with sixty branches is
used as an example. Simulation results verify that the suggested test scheme is the most appropriate
and with high performance in the practice. Index Terms--Grounding grid, Corrosion diagnosis, Test

schemes, Measurement error
Remaining Lifetime Modelling for Replacement
of Power Transformer Populations
A. van Schijndel1*, J.M. Wetzer2 and P.A.A.F. Wouters1
1 Eindhoven University of Technology, The Netherlands
2 KEMA, Arnhem, The Netherlands
*E-mail : a.v.schijndel@tue.nl
Abstract--The age of the majority of power transformers applied in the western electricity network
varies between 25 and 50 years. Depending on the load history and time of operation,replacement
on short term is imminent. A technically sound policy concerning the replacement of these assets
must be based on knowledge of (i) the life expectancy or reliability of individual components, (ii)
how these failure probabilities cumulate to a replacement wave, and (iii) how to manage an
expected replacement wave. The population reliability is obtained from individual transformer
reliabilities usin Arrhenius based modelling of paper insulation degradation. This modelling
technique includes measures to cope with inherent uncertainties in available data. Population
reliability figures are obtained using an adapted kout- of-N failure model. The modelling method is
applied to existing populations of power transformers in The Netherlands, to evaluate their expected
replacement wave. Index Terms--Life estimation, Maintenance, Paper insulation, Power system
reliability, Power transformers, Power transformer insulation, Reliability modeling.
Determination of the Optimal Moments for
Investigating Technical State of Primary
Equipments for the Purpose of Assuring
the Safety Levels
Abstract-- The current technical condition of an equipment is best evaluated beginning with the
analysis of its components. Some of the methods used for this type of diagnose are the mathematical
methods implemented in the NOVA Predict software application. This paper briefly describes the
main issues which led to the designing of the NOVA Predict software application, the
architecture, the function, the features that it offers and practical results obtained by using it.
Index terms-- reliability, reliability indicators, Weibull, Rayleigh, MTTF, MTBF, MTTR, primary
equipments, power transformers.
J.A. Lapworth and A. Wilson
Doble PowerTest Ltd, UK
The Asset Health Review for Managing
Reliability Risks Associated with Ongoing Use
of Ageing System Power Transformers

*E-mail : jlapworth@doble.com
Abstract--One of the most important roles for a utility operating in a de-regulated environment is to
focus on effective risk management. Part of this is associated with the ongoing use of aged assets,
and specifically managing the business consequences on system availability and energy not
supplied that arise from unavailability of such equipment. The key role for the asset manager is,
therefore, to be able to define equipment risks for future operation which will then permit criticality
based decisions for managing operating and capital expenditure. Some of the processes used in UK
to achieve this task are described in this paper, with a particular focus on network transformers.
Index Terms--Asset and Risk management, Ageing of Power ransformers
Defining the life of major assets
A. Wilson and J.A. Lapworth
Doble PowerTest Ltd, UK
*E-mail: jlapworth@doble.com
Abstract-- The international trend is for power utilities having major capital equipment with service
ages in excess of their assigned lifetimes. The key role for the asset manager in this situation is to be
able to define the risks for future operation. This will then permit criticality based decisions for
managing future operating and capital expenditure. The first step is to define relevant failure modes
and from that the range of realistic life expectancies. This paper concentrates on the power
transformer where key life determinants are indeed age related, ut more dependent on the design and
build quality together with operational utilisation rather than a simple ubiquitous “time at
temperature” ageing factor. Index Terms-- Asset management and risk, Transformers, Life
performance.
Development of a Power Facility Management
System using Reliability-centered Maintenance
Hong Seok Kim*, Hang-Jun Yang, Young Jun Choi, Jung-Ki Hong, Hak Sung Lee
Hyosung Corporation, Power & Industrial system R&D center, Anyang-Si, 431-080, KOREA
Abstract-- Electric power equipment must be operated in the state of high reliability with its
responsibility in the seamless power supply. Therefore, persistent maintenance is very important.
There are many maintenance methods well known in industrial business. Among them, the
reliability-centered maintenance (RCM) is a state of the art maintenance technique. This paper
shows a RCM method for electric power equipments. This reliability-centered maintenance (RCM)
has been applied in the fields of aerospace, nuclear power plants and rail system, etc. In this paper,
we design the FMEA flow for power transformer and evaluate the importance level based on the
fault information. The importance level is applied to the inspection period, fault detection method
and operator selection. The results of the system are provided as a worksheet containing the
information that needs to be maintained. Index Terms--Reliability-Centered Maintenance, FMEA,
Transformer
Economic Evaluation of Different Rules of
Insulation Diagnosis

Minggang Gao 1*, Kai Wu 1 and Yonghong Cheng 1
1 State Key Lab. of Electrical Insulation and Power Equipment
Xi’an Jiaotong University, Xi’an 710049, China
*E-mail : gmg2719@stu.xjtu.edu.cn
Abstract—On the basis of life-cycle cost evaluation on periodical diagnosis, a modified calculation
method is put forward to evaluate the economic feasibility of the diagnosis rule suggesting an
attention value of the measurement parameter above which the apparatus should be diagnosed more
frequently. The calculation results show that this diagnosis rule is of more economic merit than the
one with a simple diagnosis period. Index Terms—Economic feasibility, Insulation diagnosis rule,
Life-cycle cost
Analysis of Integrated Monitoring of HV
Electrical Equipment in Power System
Mladen Banovic 1*, Ivan Sicaja 2 Igor Ivankovic 2
1 Koncar-Electrical Engineering Institute, Inc.
2 HEP-TSO
*E-mail : mbanovic@koncar-institut.hr
Abstract—High-voltage (HV) electrical equipment (generators, transformers and circuit breakers)
in power system has been monitored lately in certain extent. Monitoring systems (MSs) are different,
depending on the type of HV equipment witch they upervise and depending on the producer. In
plants and substations, besides MSs, are often installed different protection, control and supervision
systems, like SCADA1, SCS2, DCS3, PMS4 etc. [14]. More systems in the same plant often
measure the same parameters with individual sensors in each system, resulting in multiplication of
sensors and acquisition equipment. New standards, witch have been appeared recently, with aim to
solve this mix up [15] and to organize the area of substation automation systems (SAS) [16]. Older
standards are less suitable for communication between more systems, e.g. [17], [18].
Communication protocols can be used for data exchange between more systems. Parameters may be
measured in only one system, and then information on measured values may be sent to all systems
witch need this information. In this way multiplication of measurements will be avoided, and
sensors and acquisition equipment will not be amassed in the plant.
Condition Monitoring Plans of CLP Power
Hong Kong and its Roadmap to
Condition Based Maintenance
Joe, C.Y. Tang
Asset Utilisation Manager,
Asset Management Department, Power Systems Business Group
CLP Power Hong Kong Limited, HKSAR, PRC
Abstract -- It is a common trend of power companies to progressively change its equipment
maintenance strategies from relying on purely time-based preventive tasks to more conditionbased
predictive tasks. An important prerequisite of condition based maintenance is Condition Monitoring.

Results of condition monitoring on power equipment form useful information in formulating asset
strategies in the most cost effective manner while maximising the availability and enhancing
reliability of the equipment. This paper describes the road of CLP Power Hong Kong in developing
strategies and plans for condition monitoring and its roadmap to prepare for the implementation of
condition based maintenance. Index Terms--Reliability-centred
Maintenance,predictive/condition-based maintenance, Plant Asset, Cable Asset, Overhead Line
Asset
Apparent Mobility and its Relationship with Ageing in Polymeric
Insulation Materials
Chen G* and Van Nguyen T
School of Electronics and Computer Science
University of Southampton, United Kingdom
*E-mail : gc@ecs.soton.ac.uk
Abstract--Apparent mobility obtained from space charge decay measurement has been recently
used as an ageing marker to assess degradation of the insulation materials. The apparent mobility of
charge carriers becomes slower after experiencing electrical ageing. In this paper, we have
measured space charge decay in polymeric insulation material using the pulsed electroacoustic
technique and studied apparent mobility features in a wide range of the applied fields and poling
times. It has been found that the increase in the applied field and poling time produces more deep
trapped charges, leading to a decrease in apparent mobility with time. For a specific time, the
detrapping process is dominated by the charges of specific trap levels, resulting in a time dependent
apparent mobility. In addition it has been found a sudden increase in apparent mobility at high fields,
indicating that a precaution has to be taken when assessing the ageing using the method.
Study of DC Corona Inception and Extinction Voltage Measurement
on Electrode Surfaces Using UV Corona Monitor
Ke Wang1*, Yongli Liao1, Liming Wang1, Zhicheng Guan1, Feng Huo2, Wei Hu2 and Lili Gu2
1 Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055, China
2 Wuhan High Voltage Research Institute, Wuhan 430074, China
*E-mail : wangkewoft@163.com
Abstract--In order to guide the design and improvement of grading and shielding rings to meet the
requirements of UHV projects in China, research on corona characteristics of these components is
needed. One of the difficulties is that there is a lack of a proper definition of visible corona. It is
common using visual observation, which is easily effected by subjectivity and the observation
background. In this paper, a new definition of visible corona based on UV Corona Monitor was
presented. According to the definition, measurements of the corona inception and extinction voltage
on the rob tip in a rob-plate setting under both positive and negative DC voltage were carried out in

laboratory. The same measurements on grading rings with different diameters under positive DV
voltage were performed in Wuhan High Voltage Research Institute. The results show that the UV
Corona Monitor can be used to find out visible corona and obtain the corona inception and
extinction voltage.
Multivariate Analysis for Investigation of Outdoor Insulator
Conditions
Parouli M. Pakpahan1*, Waluyo2, Suwarno3 and Maman A. Djauhari4
1Academic staff of STEI, ITB, Indonesia
2Doctoral student of STEI, ITB, Indonesia.
3Academic staff of STEI, ITB, Indonesia and member of IEEE.
4Academic staff of Department of Mathematics, ITB, Indonesia
*E-mail : parouli@indosat.net.id
Abstract-- The works reported in this paper deals with experimental study on a porcelain outdoor
insulator, which has been installed at a coastal switchyard, during eight months. The measurements
were also carried-out on new-clean one, in order to have a comparison with the polluted one. The
insulators have been subjected under high voltage, and were measured the leakage currents, in a
hermetically sealed chamber, wherein the temperature, humidity and pressure could be controlled,
for simulating the environmental condition of site. The leakage currents were analyzed with FFT
method, and correlation coefficient and PCA of multivariate statistical tools. The correlation
coefficient shows that the humidity influenced the leakage current magnitude, phase angle and the
third harmonics as 56%, -88% and 59%, respectively, on the newcleanone. In case of polluted one,
the humidity influenced theleakage current magnitude, phase angle and third harmonics as
60%, -68% and 53% respectively.Keywords-- multivariate statistics, leakage current, humidity,
phase angle, harmonics.
Mositure Ingress in Free Breathing Transformers
Maik Koch1*, Stefan Tenbohlen2, Michael Rösner3
1 Omicron Electronics, Oberes Ried 1, 6833 Klaus, Austria
2 Universität Stuttgart, IEH, Pfaffenwaldring 47, 70569 Stuttgart, Germany
3 Areva Energietechnik GmbH, Transformers, Rheinstrasse 73, 41065 Mönchengladbach,
Germany
*E-mail : maik.koch@omicron.at
Abstract – This paper determines the moisture ingress in freebreathing transformers by analysis of
on-line monitoring data and by laboratory measurements. A grid transformer, a transformer
equipped with a heat recovery system and a generator step-up unit served as example transformers.
Approximately 1,6 kg of water enter the large grid transformer having moderate temperature
changes. The transformer with the heat recovery system suffers from rapid temperature changes,
thus approximately around 16 kg/a increase its moisture concentration. The constant load of the

generator step-up transformer let nearly no
water contaminate it. Laboratory investigations on dehydrating breathers proofed the drying
capability of these systems. They achieve at average volume flows a drying efficiency of 99 %. To
conclude, the water mass entering transformers strictly depends on the operation mode and
breather condition of the specific transformer.
Index Terms – Breathing, Conservator, Humidity, Moisture, Moisture sensors, Power transformers
Frequency Response Analysis – Status of the worldwide
standardization activities
A. Kraetge1, M. Krüger1, P. Fong²
1 OMICRON electronics GmbH, A-6833 Klaus, Austria
² OMICRON electronics ASIA Limited, Harbour City Kowloon
alexander.kraetge@omicron.at
Abstract--Frequency response analysis (FRA) is a powerfuland sensitive tool to assess the
mechanical and geometrical integrity of core, windings and clamping structures within power
transformers, by measuring their transfer functions over a wide frequency range. Despite a rapidly
increasing number of users throughout the world and a significantly growth of knowledge about the
application of the method, the only current, valid and obligatory national standard is in the People's
Republic of China. Intensive work is being carried out in organizations such as Cigré and IEEE to
create international guidelines for the use of FRA. The paper gives an overview about the status of
this work.
Index terms--power transformers, short circuit, windings, deformation, core, damage, SFRA,
frequency response analysis, standardization.
Effect of Humidity on Breakdown of Low Density Polyethylene Film
due to Partial discharge
Eka Putra Waldi*, Yoshinubu Murakami and Masayuki Nagao
Toyohashi University of Tecnology
*E-mail : ekawaldi@boss.eee.tut.ac.jp
Abstract--We have been studying the breakdown characteristic of air-polymer composite insulation
due to partial discharge (PD) under repetitive pulse voltage application using needle-plane electrode
system. The purpose of this study is to clarify the effect of varied humidity on threshold frequency
at the breakdown air polymer composite insulation caused by partial discharge in air gap. The result
showed that the threshold frequency shifted to low frequency by the increase of relative
humidity. The observation results using thermograph showed that the surface temperature at the
higher relative humidity with increasing frequency of pulse more early dissipated.

Index Terms-- Partial-discharge, Relative Humidity, Electrical Breakdown.
Correlation between UV-Vis Spectral Response and Furan
Measurement of Transformer Oil
Sin P. Lai1*, A. Abu-Siada 1, Syed M. Islam1 and Gary Lenco2
1Department of Electrical and Computer Engineering, Curtin University of Technology, Perth
6845, Australia
2 Testing and Commissioning Services Pty. Ltd. (TACS), Perth 6104, Australia
*E-mail : sinpin.lai@postgrad.curtin.edu.au
Abstract—Furans concentration presence in aged-transformer oil has been one of the key
indicators of the solid dielectric deterioration. They are the by-products from the cellulose
degradation of insulation paper caused by heat, oxidation and electrical stress. Nowadays, furans
concentration is measured by High-Performance Liquid Chromatography (HPLC) or Gas
Chromatography-Mass Spectrometry (GC/MS) based on the standard of ASTM D 5837. Both
analysis methods provide accurate and reliable results in detecting the concentration of furan
derivatives (2-acetyl furan, 2-furfural, 5-methyl-2-furfural, 5-hydroxymethyl 2-furfural, and
2-furfurylalcohol). However, these two methods need very expensive equipments and take long
time to get the results in addition an expert person is required to perform the analysis. This paper
presents a novel approach of the correlation between the Ultraviolet-to-Visible (UV-Vis) spectral
response that can be measured in a instantly with a relatively cheap equipment and does not need
an expert person and furan measurement of transformer oil. Results show that there is a good
correlation between UV-Vis spectral response and Furans concentration of transformer oil and an
accurate method that can determine the furan concentration by measuring the UVVis spectral
response can be developed.
Index Terms—Furans; Furfural; Gas Chromatography-Mass Spectrometry; Spectral Analysis;
Transformer Oil; Ultraviolet Spectroscopy
Dissolved Gas Analysis of Faults in Biodegradable Oil Transformer
Insulating Systems
N.A. Muhamad*, B.T. Phung, T.R. Blackburn and K.X. Lai
The University of New South Wales, Sydney, Australia
*E-mail : z3196785@student.unsw.edu.au, norasiah@fke.utm.my
Abstract-- This paper presents results of experimental tests performed on laboratory models of
transformer windings immersed in bio-degradable oil. The investigations covered three common
types of transformer faults: partial discharge (PD), arcing and overheating. Dissolved hydro-carbon
gas products generated by these three fault types in bio-degradable oil are analyzed and compared
with existing dissolved gas analysis (DGA) interpretation methods for mineral oil insulation. The

PD and arcing tests were performed in small test cells using mineral and vegetable oils, with and
without insulated pressboards. The overheating test was performed by heating the oils in the oven.
At the end of each test, an oil sample was extracted for dissolved gas and moisture measurement.
The results show that existing DGA interpretation techniques need to be modified if they are to be
used for insulation assessment of bio-degradable oil.
Index Terms-- Bio-degradable oil, mineral oil, partial discharge, overheating, arcing, dissolved gas
analysis (DGA), hydro-carbon gases, transformer insulation.
The Effect of Atmospheric Factor on Various Test Gaps Under
Negative Impulse Voltages
S. Chotigo ,B. Pungsiri and S.Kanchana
Department of Electrical Engineering, Faculty of Engineering, King Mongkut's University of
Technology Thonburi, 126/1 Prachauthit Road,
Bangmod, Thungkhru, Bangkok 10140 Thailand.
E-mail: supakit.cho@kmutt.ac.th ,u4305205@yahoo.com
Abstract--This paper dealt with the effect of the atmospheric factors on various test gaps under the
standard negative impulse voltage, 1.2/50µs. The atmospheric factors in this present work were
relative humidity, temperature and the ratio of the absolute humidity to the air density correction
factor(h/δ). Gaps used were sphere-sphere, rod-plane and rod-rod gaps. The diameter of the sphere
was 12.5 cm and the length of the rod was 20 cm. The dimensions of the plane were 4*4 cm2
copper, and 70*70 cm2 steel. The maximum voltage used in this present work was about 230 kV.
The results of the breakdown voltage (U50) as a function of atmospheric factors were plotted. All
the present data was obtained at the High Voltage Laboratory of King Mongkut's University of
Technology Thonburi using a 400kV 8 kJ impulse voltage generator.
Index Terms---humidity, flashover, Negative Impulse Voltage
Elongation of Overhead Line Conductors under combined
mechanical and thermal Stress
Muhr Michael1, Pack Stephan1 and Jaufer Stefan1*
1 Institute of High Voltage Engineering and System Management
Graz University of Technology
*E-mail: Jaufer@HSPT.TUGraz.at
Abstract--For a high reliably and high-capacity electrical power supply, the most technical
expedient and economized way is an intermeshed grid of power lines. For example in Europe, in
the “Union for the Coordination of Transmission of Electricity" network (UCTE) are at the
moment 24 countries with a providing area of 430 mil people with 200000 km of 230 and 400 kV
lines. Parts of this grid are in operation since 1950 or earlier. Due to the operating time of more

than 30 years each power grid operator must ask how reliable are the line components and how
much load capability is remaining. Especially the components of an overhead line which are under
mechanical stress and conducting the load current are critical parts for the personal safety and
system protection. This combined stress is significant for the condition and behaviour evaluation
of the equipment. This contribution gives an overview about the theoretical interrelationship of the
mechanical and thermal behaviour of new and aged overhead line conductors. The behaviour of
typical overhead line conductors will be shown. The mechanical and thermal elongations of the
conductor influence the sag and thereby the required safety margins to the ground or objects. The
knowledge of the sag behaviour is the base of an overhead line monitoring system based on
thermal rating.
Index Terms--aging, ACSR, elongation, overhead line, sag,
An Online Dynamic Capacity-Increase System of Transmission Lines
Huang Xinbo1,An Zonggui2
1 College of Electronics and Information, Xi’an Polytechnic University, Xi’an, 710048, China
2 Xianyang Power Supply Bureau, Xianyang 712000, China
Abstract—An Online Dynamic Capacity-Increase System of Transmission Lines is produced, by
which the dynamic capacityincrease of available transmission lines can be increased with no break
of available rules. The slave monitoring unit is designed to measure the conductor temperature
which is sent to the main monitoring by wireless communication. The master monitoring unit is
designed to measure the ambient temperature, the wind speed, and the solar radiation intensity, and
these data including the conductor temperature are sent to the municipal monitoring and controlling
center by GSM SMS/GPRS. The latent capacity can be calculated by mole formula. The hardware
design and software design of the master and slave monitoring units, and the design of expert
software are introduced in this paper.
Index Terms--Dynamic capacity increasing; Online monitoring; Conductor temperature; Latent
capacity
Condition Monitoring on HV equipment in CLP Power
Abstract-- In the past decade, CLP Power Hong Kong Limited (CLPP) has initiated the application
of a series of condition monitoring techniques on its power equipment so as to allow progressive
change of its equipment maintenance strategies fromtime-based preventive tasks to more
condition-based predictive tasks. The data collected from the HV GIS, cables and overhead lines
form useful information in maximizing the availability and enhancing reliability of the HV
equipment. This paper describes the selection, field application, practice and experience with those
on-line and off-line monitoring techniques implemented in CLPP. A variety of field applications
will be discussed, including PartialDischarge (PD) monitoring/detection on GIS and power cables
in the transmission and distribution network, SF6 gas leakage pinpointing on HV GIS, Disc

pollution supervision system (DPSS) for overhead insulation disc and leakage current monitoring of
400kV metal oxide arresters (MOA).
Index Terms-- HV Plant, Condition Monitoring and Diagnostic System, Condition-based
maintenance, Partial Discharge, Sulfur hexafluoride (SF6), SF6 Leakage Detection, OHL Insulation
Disc.
HV AC Generation Based on Resonant Circuits with Variable
Frequency for Testing of Electrical Power Equipment on Site
Dr.-Ing. S. Schierig, Dipl.-Ing. T. Steiner (FH), Dr.-Ing. M. Jochim
HIGHVOLT Prüftechnik Dresden GmbH, D-01139 Dresden, Germany
E-mail: schierig@highvolt.de, steiner@highvolt.de, jochim@highvolt.de
Abstract--The overall booming industry has great need for electrical industry. Hence, electrical
power generation, transmis¬sion and distribution have to respond to the continuously grow¬ing
demand by e.g. increased transmission capacities or trans¬mission voltages but also by longer
transmission networks. Hereby, the more and more demanding requirements for devices of power
transmission and distribution have to be fulfilled by the high voltage test equipment as well.
Massive and heavy test equipment is available for factory tests, which however cannot be used for
on-site tests. Therefore, resonant circuits are the only practicable test equipment solution in order to
facilitate physical-reasonable AC voltage tests with the respective diagnostic equipment on-site.
The specific advantages of resonant test equipment with fixedcore reactors and variable frequency
tuning, which leads to a high resonance quality factor in particular, allow providing test systems
with high power and robust design. The statistic con¬verters, especially designed for on-site
application, guarantee the wave forms of the test voltages according to the relevant stan¬dards and
allow PD measuring also under on-site conditions. Various test systems, well adapted to the test
specifications and the characteristics of the test objects, are available. There are for instance
systems on the basis of oil-cooled tank type reactors, with extremely high power which is needed
e.g. for the testing oflong cables,systems on the basis of gas-insulated, metal-enclosed re¬actors
which can be flanged directly to GIS/GIL withtest voltages of up to 1000 kV and systems optimized
for induced and applied voltage testing of power transformers.
Key words--Resonant circuit, Power equipment, On-site test, AC generation
On-Line Condition Monitoring and Diagnostics of Power Distribution
Equipment
Abstract--Continuous on-line temperature monitoring provides the means to evaluate current
condition of equipment and detect abnormality. It allows corrective measures to be taken to prevent
upcoming failure. Continuous temperature monitoring and event recording provides information on

the energized equipment’s respond to normal and emergency conditions. Online temperature
monitoring helps to coordinate equipment specifications and ratings, determine the real limits of the
monitored equipment and optimize facility operations. Using wireless technique eliminates any
need for special cables and wires with lower installation costs if compared to other types of online
condition monitoring equipment. In addition, wireless temperature monitoring works well under
difficult conditions in strategically important locations. Wireless technology for on-line condition
monitoring of energized equipment is applicable both as standalone system and with an interface
with power quality monitoring system. The paper presents the results of wireless temperature
monitoring of switchgear at a power plant over a two-year period.
Index Terms--On-line Condition Monitoring, Wireless Sensors, Contact Degradation, Thermal
Failure
OHL Condition Monitoring and Engineering Solutions to Cinch
Maximum Admissible Transmitting Capacity
A.Bondarenko1, Yu.Vasiljev2, B.Mekhanoshin3*, A.Oreshkin3, V.Shkaptsov3
1 SO-CDO, Moscow. Russia, CIGRE member
2 Network Co, Kazan, Russia
3 OPTEN Limited, Moscow, Russia, CIGRE members
*E-mail : boris@opten.ru
INTRODUCTION
ating of the most of existing overhead lines (OHL) has been established years ago as a rule during
line design and construction. For the time being the situation drastically changed and up rating for
increasing capacity of many existing lines has to be referred to the category of essentially actual
problems of network companies. For the high voltage lines 100 – 330 kV, transmitting capacity
could be increased, in general, up to the highest level of admissible high temperature operation. In
this way two very serious restrictions must be taken into account: knee point temperature of ACSR
conductors can not be exceeded and phase clearance to the ground and crossing objects (low
voltage lines, communications, etc) also can not be less than normative value accepted by the
utility’s corporate standard. To carry out verification of actual conductor clearances for some
specific points or short OHL section one can use such techniques as optical and laser range meters,
total stations and so on. But verification of the long line in available terms can only be done on the
aerial laser survey (ALS) technique basis. Because of permanent changing of OHL condition (due
to the influence of ice, wind, vegetation growth, repairing and restructuring activities), the most
rational procedure is periodical network monitoring on the ALS basis. The report covers most
efficient models of the periodical OHL monitoring and supplying network companies with
effective databases supported by actual work performance experience. Should conductor condition
check performance or additional tension adjustment activities establish clearance to ground and
crossed objects to satisfy effective standards, as well as in case safety clearance margin is detected,

necessary pre-requisites for up rating can be deemed available. Dynamic up rating implemented,
as shown in report , to increase current load of line twice and more. The report covers results of
using TMT monitoring devices, registering temperature, current and conductor X,Y,Z coordinates,
for several 110, 220 and 400 kV OHL of Russian and Slovenian networkcompanies.
The report provides results of ALS technology application for evaluation of a number of OHL
technical condition, witnessing that actual values of conductor Every Day Stress (EDS) are
considerably less than tension loads producing risk of conductor damage due to vibration and
other external impact. This makes it possible to recommend conductor retention, that ensures
clearance increase as much as it is required to increase conductor transmitting capacity up to
40-80 %.
New Sensor Technologies in Aircraft Structural Health Monitoring
SHANG Bo-lin *,SONG Bi-feng and CHANG Fei
College of Aeronautics, Northwestern Polytechnical University, Xi’an 710072,China
*E-mail : borlion@21.com
Abstract--The traditional nondestructive testing (NDT) method contributes greatly to aircraft
structural safety and reliability. However, it also significantly increases operating expense, or leads
to the decrease of the aircraft’s runtime because of the disassemble and reassemble of structural
components. Aircraft structural health monitoring (SHM) is a new in-situ, online structure detection
method which was developed on the basis of the traditional NDT method. It can increase the
reliability, safety and runtime of aircrafts while reduce the structure’s operating and maintenance
costs. This paper describes this new technology and introduces the principles and applications of
some new sensor technologies in aircraft structural health monitoring, the candidate SHM sensor
technologies including optical fiber sensors, piezoelectric sensors, MEMS sensors, wireless sensing
systems etc. The paper will finish with a perspective for further research in this field.
Index Terms--aircraft; structural health monitoring; sensors.
Cable Load Dynamic Adjustment Based on Surface Temperature and
Thermal Circuit Model
Yongchun Liang1,2, Qingrui Liu2, Huiqin Sun2, Yanming Li1
1. School of Electrical Engineering, Xi’an Jiaotong University, Xi’an China;
2.School of Electric and Infromation, Hebei University of Science and Technology, Shijiazhuang
China
*E-mail : yongchunliang@stu.xjtu.edu.cn
Abstract—The development of temperature on-lineonitoring techniques for 110kV and above
XLPE power cable gives a strong support to power cable load dynamic adjustment. The surface
temperature of power cable is depended on the current and voltage in cable conductor and other

cables nearby. The relationship between the surface temperature of power cable and current in cable
conductor can be described by thermal circuit model. The cable load can be adjusted dynamic to
prevent overheat of insulation by thermal circuit model based on surface temperature online
monitoring to prevent and prolong the life of cable operation.
Index Terms—Online monitoring; dynamic adjustment; thermal circuit model; surface temperature.
Ground Fault Path Clearance system Analysis on Oil Company’s
Power Distribution System Dewi Anggraeny Syamsir Abduh
Electrical Engineering Department, Trisakti University
Jl.Kyai Tapa No.1 Grogol Jakarta 11440
Abstract--Good quality of electricity has become the most important need that consumers ask for,
especially for industrial necessities. One of the important factor that influences the quality of
electricity is the continuity of supply (security of supply) with a good and reliable protection system.
An additional system that is capable to support the existing protection system which is
called the Ground Fault Path Clearance System (GFPC) have been applied. The function of this
system is to clear ground fault current from phase to ground fault (which always happens in the
distribution line), even though the kind of fault is just temporary but it may cause the protection
system to work and the supplying power will be stopped. With GFPC system, if temporary ground
faults occur in the distribution line, the electrical power flow is unstoppable because the faults have
been solved by GFPC system with its setting before the existing protection works. The method used
in this research is fieldwork with procedures like observations and data recording. The result of the
studies are : First, the GFPC system can reduce a number of blackouts which are caused by phase to
ground fault. Second, this system contributes to reduce loss production (economic aspect). Third,
during GFPC works, all equipment insulators of phases which are not affected will suffer phase to
phase voltage.
Index Terms-- Ground Fault, Power distribution system
Available Transfer Capability Calculations Using Neural Networks in
Deregulated Power
Narasimha Rao.K1*, Amarnath.J2 and Kiran Kumar.K3, Kamakshiah.S3,
1 St. Ann’s College of Engineering & Technology, Chirala, Andhra Pradesh, INDIA
2 Jawaharlal Nehru Technological University, Hyderabad, Andhra Pradesh, INDIA
3CVR College of Engineering, Hyderabad, Andhra Pradesh, INDIA
* Email: raosimha_k@yahoo.co.in
Abstract--This paper presents a Back propagation feed forward algorithm methodology for the
problem of Available power transfer capability calculations. The computation of ATC is very

important to the transmission system security and market forecasting in a Deregulated Power
systems. Based on the AC Power Distribution Factor formulation of the problem, the inputs for the
neural network are generator status, line status and load status and the output is the Available
Transfer Capability. The Back Propagation algorithm is used to train the neural network and tested
for the transaction between area-2 and area-1. A case study of IEEE 30-bus system is presented
demonstrating the feasibility of this approach and the results are compared. Index Terms--Artificial
Neural Network, Back Propagation algorithm, Available Transfer capability, AC Power
Distribution Factor.
Detection Algorithm of Series Arc for Electrical Fire Prediction
Dae-won Park*, Il-kwon Kim, Su-yeon Choi and Gyung-suk Kil
Korea Maritime University, Busan, 606-791, Korea
*E-mail : dwpark77@hhu.ac.kr
Abstract--In this paper, we studied on the detection of series arcing which is a main cause of
electrical fires in low-voltage indoor wiring system. To distinguish series arcing state from normal
one, we proposed a detection method based on that the magnitude of arc voltage included in AC
voltage varies at random during series arcing. We designed and fabricated a highpass filter with the
low cut-off frequency of 3kHz to attenuate AC voltage by -80dB or below, and to pass arc voltage
without distortion. Also, a phase shift algorithm which eliminates the periodic component of arc
voltage was used for nonlinear loads like incandescent lamps controlled by a dimmer.
Index Terms—Series arc, Electrical fire, High-pass filter, Phase shift algorithm, Nonlinear load,
Incandescent lamp, Dimmer
Research for Dynamic Increasing Transmission Capacity
Lijia Ren, Jiang Xiuchen, Sheng Gehao
Department of Electric Engineering, Shanghai Jiaotong University, Shanghai 200030, China
ljren@sjtu.edu.cn
Abstract--The Dynamic Line Rating (DLR) system can increase transmission capacity of overhead
line dynamically. The system is composed of sampling terminals installed on dead-end
configuration of a line and one control instrument equipped in dispatch center. The data between the
sampling terminals and the control instrument is transmitted through GPRS/GSM. Then three major
limitations governing the line rating limits were analyzed and stated. This paper analyzed the force
balance for overhead line concerned wind speeds and wind direction in a deflection plane. On this
basis, a mechanics analysis model of line’s tension and sags was established. Analyzed the
advantages and drawbacks of some mathematic model used to calculate transmission capacity. In
order that the DLR system received the optimum dynamic capacity curve, combined the WM and
TS model. Finally, the necessity and significance to use DLR in power grid are presented.

Index Terms--Dynamic Line Rating (DLR); overhead Line; Transmission Capacity; Conductor Sag;
Conductor tension;
Theoretical Study on Dynamic Capacityincrease of Transmission Lines
Huang Xinbo1, Cheng Ronggui2
1 College of Electronics and Information, Xi’an Polytechnic University, Xi’an, 710048, China
2 Basic Department, Xi’an Communication College, Xi’an 710106,China
Abstract--An online dynamic capacity-increase technology of transmission lines is designed by
author to increase transmission capacity of transmission lines with no breach of available rules.
The transient running formula of transmission lines is built, the mathematical relationship between
the conductor allowable temperature and the variety of sag of the span is presented, and the effect of
environment parameters on the transmission capacity of lines is analyzed, such as ambient
temperature, wind speed, sunshine intensity, etc..
Index Terms--dynamic capacity-increase; conductor temperature; ambient temperature; wind speed
An Improved Algorithm for Fault Location in Distribution Network
Huifen Zhang1*, Zhiguang Tian2 and Enping Zhang1
1 University of Jinan, Jinan 250022, China
2 Nanjing University of aeronautics and astronautics, Nanjing 210016, China
*E-mail : cse_zhf@ujn.edu.cn
Abstract-- Fault location is a difficult problem when a singlephase earth fault occurs in distribution
network in China. The signal inje ction method is the most effective way of localizing the
single-phase earth fault at present. But it can not automatically localize fault presently. An algorithm
of automatically localizing the fault point based on the signal injection method is proposed. It takes
the signal detectors fixed to FTU along the fault feeder as nodes. The assigned positive direction is
that the injected current is from bus-bar to fault point. The network describing matrix C is formed
by the assigned positive directions. The information vector S of injected signal is constructed
according to the detected results from each detector of the injected signal. The zero sequence fault
current information vector F is constructed according to the information of zero sequence fault
current from each FTU. The fault information vector G is formed by integrating vector S with vector
F. The fault judgment matrix D is formed by adding the elements of vector G to the diagonal of the
describing matrix C. The failure criterion and the algorithmic process of automatically localizing
the fault point are proposed according to the fault judgment matrix D. Thus the automatic fault
location is implemented. The algorithm is simple. And the automatic fault location based on the
signal injection method is implemented. This algorithm applies in the tree fault feeders which have
branches or not. Case simulation results show that the proposed algorithm is correct, effective and
precedence.
Index Terms-- Distribution automation; Fault location; Signal injection method; Single-phase earth

fault
New Distribution Class Arrester Ground Lead Disconnector Design
Abstract--This paper examines performance characteristics of existing distribution class arrester
ground lead disconnecting devices. The paper also introduces a new Distribution Class ground lead
disconnector design that not only extends the claimable detonation range well below the 20 amps
specified in industry standards, but is very durable when exposed to severe arrester durability tests.
Finally, this paper shows how this next generation disconnector interacts with the connected arrester
to improve the overvoltage withstand capability of the arrester assembly.
Index Terms--Disconnector, Distribution class arrestor, Metal Oxide varistor, Polymer-housed
design, Reliability
Investigations on the Reliability of Storage Battery Array with High
Capability
Xianfeng Liu, Jiyan Zou and Xu Zhang
(School of Electronial and Information Engineering,Dalian University of Technology, Dalian,
116024)
lxfz@vip.sina.com
Abstract: With the development of industries of electrical power, communication, railway
transportation, and traffic management, the large capacity battery systems have been widely
used. Based on theoretical evaluation of systemic MTTF(Mean Time To Failure) and
reliability, some combined methods are suggested to evaluate the reliability of battery systems.
As a result, it is demonstrated that the reliability of the parallel-series system is superior to
both series-parallel system and the combination of series and parallel systems. The findings in
the present work provide important guidelines in the design and installation of future
construction and the renovation of existing large storage battery systems.
Key Words: Storage Battery, Capability,MTTF
The Experience of Inspection of a Technical Condition of the HV
Equipment on Substation by a Method of Registration of the Own
Electromagnetic Radiations
Nikolay V. Kinsht1, Natalia N. Petrun’ko1*

1The Laboratory of Electrophysics and Power Industry of the Institute of Automation and Control
Processes
Far East Branch of Russian Academy, Vladivostok 690041, Russia
*E-mail : pnn@dvo.ru
Abstract -- The perspective modern method of the early equipment diagnostics is the analysis
of the own electromagnetic radiations (EMR) on the wide range of frequencies. The
experience of application of the method is stated. The inspections of the HV equipment EMR
were carried out in ranges of frequencies 40-460 MHz. On an offered technique more than
200 phases of the HV transformers of a class 110, 220, and 500 kV were surveyed. The
examples of results of supervision of spectra are submitted in the three-dimensional image in
coordinates: frequency - time of supervision - intensity of a spectrum. Simple criterion of a
technical condition of units of equipment is the excess of a level own EMR above a level of a
background EMR.
Index Terms -- Electromagnetic radiation, Substation, Technical condition.
Spectrum Characteristics of Piano String using Non-Harmonic
Analysis
Shogo Urabe1 and Shigeki Hirobayashi1
1 University of Toyama
*E-mail : hirobays@eng.u-toyama.ac.jp
Abstract--In this paper, we use Non-Harmonic Analysis (NHA), as recently proposed by the
author, to analyse the change of frequency of a piano string before tuning. NHA has a high
frequency resolution and the influence of the window function is smaller than DFT. The use of
A4 for the tuning standard is analysed in the experiment. The observed result is that the
variation of the frequency is large before the string is tuned. This is a phenomenon that
originates in the way that the vibration of the string combines two large and small elliptic
orbits in the direction the string was struck, as was shown by analysis of the string vibration
with optical apparatus by Tanaka et al. This paper verifies the change of frequency of the
string originating in the elliptic orbit not by using optical apparatus but by recording and
analysing the sound of the piano with high frequency resolution NHA.
Index Terms--Spectral analysis, Time-frequency analysis
Design and Construction of Grounding System in High Voltage
Laboratory at KMUTT
B.Pungsiri, and S.Chotigo*
Department of Electrical Engineering, Faculty of Engineering, King Mongkut’s University of

Technology
126 Prachauthid Road Bangmod Tungkru Bangkok 10140 Thailand
*E-mail : supakit.cho@gmail.com
Abstract—This paper proposes the design and construction of grounding system in high
voltage laboratory at KMUTT. At first, the grounding system in high voltage laboratory at
KMUTT was nine rods connected in grid connection. Each rod was 3 m long. The resistance
of this grid connection was less than 5 ohms. The grounding of each equipment was connected
to grid connected ground using copper strips placed on the cement floor. However, when the
oscilloscope protected by isolated transformer was used to measure the waveform of the AC
or impulse breakdown voltage, the 5A fuse of the isolated transformer had gone with AC
voltage of magnitude about 140 kVp or impulse voltage of magnitude of about 170 kVp
applied. The assumption for this problem was thought about the electric field at the ground
wires placed on the cement floor was quite high. Therefore, the problem was solved by adding
aluminium plates on the cement floor, then, connected the grounding of each equipment to
them. Now, the oscilloscope can be used to measure up to the maximum AC/ impulse voltage,
290 kVp/ 320 kVp, generated in the laboratory. The solution can be explained by two reasons.
The first one was the theory about the electric field configuration on conductor-conductor
and conductor-plane gaps. The other one was the value of the characteristic impedances Z of
the electrode configuration between the HV end and ground. With only copper strips on the
cement floor, the value of Z was high while the value of Z was reduced when the aluminium
plates were placed on the cement floor.
Index Terms--Grounding System, Aluminium Plates, Cement.
A Novel Algorithm of Dielectric Loss Measurement Based on
Orthogonal Decomposition
Abstract--The physical meanings and definition of dielectric loss factor-tanδ was analyzed
under the harmonic condition. Voltage and current were defined as vectors in Normed Linear
Space. By using the characteristic of orthogonal vector in inner product space, the current
signal was decomposed to active and reactive currents. Subsequently, a novel digital
algorithm of tanδ measurement, which was defined as ratio of norms of the active current and
currents, was presented based on orthogonal decomposition. Lastly, the proposed algorithm
was simulated under several conditions. The simulation results show that the proposed
algorithm is correct and predominant compared with the harmonic analysis method, and that
the algorithm has physical meanings, simple calculation, precise measurement result and
strong anti-interference capability.
Index Terms—Dielectric Loss Factor, Digital Measurement, Orthogonal Decomposition,
Active Current, Active Power Coefficient, Simulation

Analysis of Electric Field Distribution on the Surface of Polymer Post
Insulator Used in Electric Railway Catenary System
Donguk Jang1*, Keejoe Lim2 and Moonseob Han1
1 Korea Railroad Research Institute
2 Chngubuk National University
*E-mail : dujang@krri.re.kr
Abstract--In order to check the electric field distribution of polymer line post insulator, we
performed electric field simulation according to state of water droplets. Water droplets use
sea water contaminant. The water droplets may appear in different forms and sizes, therefore
the form is defined by the angle shape between the surface of the water droplet. The water
droplet may measure from less than 90 degree (hydrophilic) up to greater than 90 degree
(hydrophobic), depending on the properties of insulator surface. This paper describes
numerical analysis calculation of electric fields and its potential distribution in the
surrounding of water droplets on an insulator surface. Electric field analysis is performed
with change of contact angle, number and distance between water droplets. The computation
results show that the electric field close to the water droplets tends to be higher as number of
water droplets increases. The electric field fluxes were also affected slightly by the contact
angle.
Index Terms--electric field analysis, polymer insulator, railway, water droplet.
A Survey of IGBT Fault Diagnostic Methods for Three-Phase Power
Inverters
Bin Lu1* and Santosh Sharma2
1 Eaton Corporation, Innovation Center, Milwaukee, WI 53216, USA
2 Eaton Corporation, India Engineering Center, Kharadi, Pune-411014, India
*E-mail : binlu@ieee.org
Abstract--Fault diagnostics of power converters have draw increasing attentions due to the
widespread adoption of advanced power control devices, such as motor drives and
uninterruptible power supplies. This paper presents a literature survey on existing methods
for fault diagnosis and protection of IGBT’s, with special focus on those used in three-phase
power inverters. Eleven methods for open-circuit faults and ten methods for shortcircuit
faults are evaluated and summarized, based on their performance and implementation efforts.
The gate-misfiring faults and their diagnostic methods are also briefly discussed. Finally,
based on the survey results, the promising methods are recommended for future work.
Index Terms--Fault diagnosis, IGBT, open-circuit fault, shortcircuit fault, gate-misfiring fault,
condition monitoring, power Inverter

New Condition Monitoring Techniques for Reliably Drive Systems
Operation
Ali S. Hennache
Riyadh College of Technology, P.O.Box 42826, Riyadh 11551, Kingdom of Saudi Arabia
E-mail : alihen@hotmail.com
Abstract--The dominant application of electronics today is to process information. The
computer industry is the biggest user of semiconductor devices and consumer electronics. Due
to the successful development of semiconductors, electronic system and controls have gained
wide acceptance in power and computing technology and due to the continuous use of drive
systems (rotating machines, controlling thyristors and associated electronic components) in
industry and in power stations, and the need to keep such systems running reliably, the
detection of defects and anomalies is of increasing importance, and on-line monitoring to
detect any fault in these systems is now a strong possibility and certainly periodic monitoring
of a drive systems in strategic situations. The principal aim of the paper is to use both
software and hardware and develop a fault diagnosis knowledge-based system, which will
analyze and manipulate the output obtained from sensors using a microcomputer for
acquiring the plant condition data and subsequently interpreting them, data collected can be
analyzed using suitable computer programs, and any trends can be identified and compared
with the knowledge base. The probability of certain condition can then be diagnosed and
compared, providing the necessaryinformation on which subsequent decisions can be based
and provide any necessary alarms to the operator. To achieve this objective, the simulation
and experimental technique considered is to use sensors placed in the wedges closing the
stator slots to sense the induced voltage. The induced voltage and for each fault is shown to
have a unique voltage pattern, thus, the fault identification through voltage pattern
recognition were the basic rules for the development of the knowledge base. The predicted
results are verified by measurements on a model system in which known faults can be
established.
Index Terms--Synchronous machines, Power electronics, Turbogenerators, Drive systems,
Anomalies, Diagnosis, Signal processing, Pattern recognition.
The Measurement and Simulation Research of Electrified Railway
Harmonic
Fan Chun-lei,Wu Guang-ning, Zhang Xue-yuan, Wang Yun-fei
(School of Electrical Engineering, Southwest Jiaotong University, Chengdu 610031, China)
Abstract--Harmonic pollution in modern power system is a major problem. In order to
analyze the influence of harmonic caused by electric locomotive on power system, taking

Ynd11 Transformer Connection of a traction station as a example, this paper presents a
dynamic model of electric locomotive and traction power supply system, and conducts
simulation analysis of the injection of 110 kV side of the imbalance harmonic current, voltage.
Comparing the simulation results with the actual measurement data at a traction station is
almost the same, which verifies the correctness of the model. Finally, the paper simulates the
different locomotive traction power impact on the power system, including the current
harmonics, voltage harmonics, negative sequence voltage changes. The results show that
harmonic current and voltage increases as power increasing, but it changes trend
complicated, negative sequence voltage changes in a nearly line, which presents a reliable
basis for the further study of electric locomotive on power system.
Index Terms—harmonics, negative sequence, power system, electric locomotive, traction
power supply system
Research on Prognostic Health Management (PHM) Model for
Fighter Planes Based on Flight Data
Jianrong Wang 1, Tianbiao Yu, Wanshan Wang
1. School of Mechanical Engineering & Automation, Northeastern University, Shenyang 110004,
China
E-mail: wjrsam@163.com
Abstract--Flight data records many important state parameters, which will be useful to
process monitoring and fault diagnosis of fighter planes. Aiming at the problems of backward
data processing means, poor analytical facilities and limited range of application in the
maintenance of aircraft, this paper proposes a PHM model for fighter planes based on flight
data. Architecture of the PHM system contains onboard data acquisition subsystem and
ground-based data processing subsystem. Based on the onboard data acquisition subsystem,
function model of ground-based data processing subsystem was analyzed and the
ground-based data processing subsystem was designed in detail from software to hardware.
Some key
technologies such as data pretreatment, tendency analysis, fault forecasting, state monitoring
and decision consulting are depicted and specific methods of realization are given concretely
.
Key Words--AR(n) Model, Flight Data, Fault Diagnosis, Trend Analysis Nomenclature
Early Detecting and Protecting of Fault Arcs Based on Chaos
YANG Jian-hong1*, HUANG Yi-jian1, ZHANG Ren-cheng1, FANG Huai-ying1

( College of Mechanical Engineering and Automation Huaqiao University, Quanzhou City, Fujan
Province 362021, China)
*E-mail: yjhong@hqu.edu.cn
Abstract--In switch tank, fault arcs fault is constant and disastrous trouble. At the present
time, the protect project of fault arcs function after generating aflame arcing, which does not
avoid of generating arcing. Switch tank and electric facilities must be destructed by aflame
arcing. In the paper, simulation experimentations indicate that the method of arc sounds
detecting based on lyapunov exponents can extract arc sounds inundated background of
complicate noise. With arc sounds generated before aflame arcing, the system of fault arcs
early warning is established, which avoids endangerment brought about by aflame arcing
and establishes good foundation to fault arcs protection In switch tank. The process of fault
arcs protection is separated two stage. There are arc sounds before generating aflame arcing,
The
system send out early warning by detecting arc sounds, which can avoid of generating fault
arcs.
Index Terms-- fault arc, lyapunov exponents, arc sounds, chaos, threshold value, critical
chaotic, duffing oscillator, threshold value
The Research of Acoustic Emission Techniques for Non Destructive
Testing and Health Monitoring on Civil Engineering Structures
Baifeng JI*, Weilian QU
Hubei Key laboratory of Roadway Bridge&Structure Engineering., Wuhan University of
Technology, Wuhan 430070, China
*E-mail: jbfeng@whut.edu.cn
Abstract-- Acoustic emission (AE) technology is a powerful tool for researching the intrinsic
essence of materials and an effective method for Non Destructive Testing and Health
Monitoring. Until this time, AE technique has been applying in many fields, e.g., aircraft
structure, offshore platform, pressure equipment, rock, dam, concrete, steel, etc.AE
technique was applied into civil engineering later compared with other fields, but developed
rapidly. This paper reviews briefly the research on AE technique applications in civil
engineering. The main contents included are: 1.Structure health monitoring system,
including offshore platform, dam, masonry arch bridge, concrete structure, steel structure,
etc.2. Structural crack detection and identification, including concrete and steel
structures.3.Fatigue crack growth monitoring.4.Structure integrality detection and residual
life prediction. At last, a prospect is made about the research direction in this field by
consulting many literatures that are abreast of the times.
Index Terms--.Acoustic emission (AE) Fatigue crack Health monitoring Non destructive
testing (NDT) Residual life Prediction

A new DC power supply centralized monitoring system
Xianfeng Liu Jiyan Zou Xu Zhang
(School of Electronial and Information Engineering, Dalian University of Technology, Dalian,
116024, China)
*E-mail: lxfz@vip.sina.com
Abstract--In all rely on backup power supply for the power system, DC power supply is
important, while switching power supplies,batteries and other elements of the management
level; cleanliness of the city,the Lightning Protection and so on is directly affecting the overall
system reliability and automaticity in the very great degree.Therefore, the safe and the stable
operation of a system is the safe and stable operation of the foundation for power plants,
substations, communication stations and other systems .Many substation and
communications networks are far linked extensive, highly decentralized, so the realization of
power equipment long-distance monitor, on-line examination, automatic warning, automatic
control,not only can greatly reduce a on-duty personnel's labor intensity, the service quality
request, economical inspects, the inspection expense, but also through scientific management,
extend the service life of DC system, increase system reliability much more effectively.
Keywords--DC Power Monitor New system
Adaptive Setting of OLTC to Improve Power Transfer Capability of
Power Systems
A.Abu-Siada1* S. Islam1 and E.A. Mohamed2
1Department of Electrical and Computer Engineering, Curtin University of Technology, WA6845,
Australia
2 Electrical power and Machine Department, Ain Shams University, Cairo, Egypt
*E-mail: a.abusiada@curtin.edu.au
Abstract--On load tap changing transformer (OLTC) has become a vital link in modern power
systems. It acts to maintain the load bus voltage within its permissible limits despite any load
changes. This paper discusses the effect of different static loads namely; constant power (CP),
constant current (CI) and constant impedance (CZ) on the maximum power transfer limit
from the generation to the load centre through the OLTC branch and in turn on the static
stability margin of power systems. Then the paper introduces a novel approach for the on-line
determination of the OLTC settings in order to improve the power transfer capability of
transmission systems. The proposed approach is tested based on the simulation of a six-bus
power system. Numerical results prove that the setting of transformer OLTC in terms of the
load model has a major effect on the maximum power transfer in power systems. The
adaptive settings of OLTC improve the power transfer capability according to the system
operating condition.
Index Term--OLTC, static load, power transfer limit, stability margin, ANN

Hydromechanics Analysis for Water Cooling Stator Temperature
Field of Generator
Wang Lihui1.2, Li Junqing1, Zhang Xiaorong2
1 Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control under
Ministry of Education, North China
Electric Power University, Baoding071003, China
2 Communication Training Base of the General Staff, Xuanhua075100, China
Abstract--In order to study fluid state influence on stator temperature of generator, this paper
applies heat transfer theory and hydromechanics to analyze water cooling system. The water
velocity was studied when the water cooling winding was blocked in turbo-generators and the
stator 3D temperature field was calculated by the thermal network method. The result
showed different water velocity could be lead to different temperature. The authors put
forward block coefficient and analyze it to be feasible in the stator temperature calculation
basing on cooling winding blocked in different degree. The research provided the theories
basis for the design and on-line monitor in large generator stator cooling system.
Index Terms--cooling, hydrodynamics, temperature
Application of Independent Component Analysis on State Inspection
for Transmission Lines
Lijia Ren, Xiuchen Jiang, Gehao Sheng 1 Affiliation A
Department of Electric Engineering, Shanghai Jiaotong University,hanghai 200240, China
ljren@sjtu.edu.cn
ortheast China Grid
Abstract-- According to the serious theft of transmission tower materials, a new function in
the state maintenance for transmission lines is presented to monitor towers and examine the
vibration signal produced from the action of stealing the tower materials, in order to ensure
the reliability and safety of the power grid operation. This paper presents the FastICA using
negentropy to effectively extract and separate the vibration signals caused by human activity.
A new method combined Empirical Mode Decomposition (EMD) method with adaptive
threshold pulse distraction method is used to extract the integrity vibration pulses, and
suppress interference signals. The practical tests demonstrate the method proposed in the
paper is effective in separating and extract the vibration signals successfully.
Index Terms--state inspection; transmission lines; vibration signal; ICA; Negentropy;
Adaptive threshold; Empirical Mode Decomposition

Symptoms Detection in FMS through Performance Indicators
follow-up: A Quality-flow Approach
Achraf Jabeur Telmoudi1,3*, Lotfi Nabli2 , Alain bourjault3
1 SEPE, Ecole Supérieure des Sciences et Techniques de Tunis,5 Avenue Taha Hussein,
Montfleury 1008 Tunis- Tunisie.
2 ASTI, Ecole Nationale d’Ingénieurs de Monastir- Rue Ibn Eljazar, 5019 Monastir- Tunisie
3 LAB- 24 Avenue Alain Savary , 25000 Besançon- France.
*E-mail : achraf_telmoudi@yahoo.fr
Abstract-- In this paper, we are interested in the detection of ymptoms in Flexible
Manufacturing Systems (FMS). The goal is o contribute to the setting up of a model that
allows the detection f deficiency symptoms by the definition of correlation bonds
between the parameters of the product quality, the material flow, nd the state of the entities of
the process. We assume that the ause of a drift is related to the failing state of a resource that
implicates a decline in the product quality and/or flow before ecognizing a collapse of its
performances. This consequently esults in a delay in the accomplishment of its function
compared o the preset parameters. he principal contribution of this work is the improvement
of he symptoms detection method based on the use of Temporal bject Petri Nets (TOPN) tool,
which allows the observation of he appearance of the deficiency symptoms as signalled by
ontrol sensors.
Index Terms-- Detection, Flow, Quality, TOPN, Follow-up.
Large-scale Earthing Test Facilities at Dinorwig ower Station
D. Guo1*, D. Lathi1, N. Harid1, H. Griffiths1, A. Haddad1 and A. Ainsley2
1 High Voltage Energy Systems Group, Cardiff University, Cardiff CF24 3AA, UK
2 National Grid, UK
* Email: guod@cardiff.ac.uk
Abstract-- In this paper, experimental set and initial test results re described of low voltage DC,
AC and impulse tests on a rod lectrode immersed in a water reservoir of a large hydro power
station. A detailed water resistivity survey indicates largely niform temperature and
resistivity throughout the reservoir. alculations and simulations of the rod electrode under DC
and ower frequency AC show reasonable agreement with xperimental results. Further
investigations are required to nderstand better the behaviour of the test system under high
frequency and impulse conditions.
Design of HCI System in Monitor and Control entre Based on

Dry-type Transformer emperature Controller
Hainan Long1 and Chun Wang2*
(12College of Electronic and Information Engineering ,Hebei University ,Baoding071002 ,Heibei
province,China )
*E-mail: mldn86@sina.com
Abstract--Dry-type transformer temperature controllers are nstalled on transformers and
located in different sites outside, hich brings inconvenience to the management and operation.
The HCI(Human Computer Interface) in monitor and control entre whose function is
complete and direct-viewing can be perated simply and easily, and it can manage and operate
many emperature controllers inside the monitor and controller centre. sing RISC(Reduced
Instruction Set Computer) high speed CU(Micro Control Unit) ATmega128, a dry-type
temperature ontroller is designed, and then embedding ModBus-RS485 rotocol, realizing the
data communication between 32 emperature controllers and HCI in monitor and control
centre. n this way, a temperature control system is designed. The ardware design and
principle of temperature controller are ntroduced, main functions of HCI system that is
designed with elphi in monitor and control centre are described and design lock diagram of
the main program is given, with the troduction of embedded Modbus-RS485 protocol and
CRC-16 hecking. Practice proves that the whole system that consist of emperature controller
and HCI in monitor and control centre uns well.
Key words--dry-type transformer;HCI(Human and Computer nterface); ModBus; monitor
and control centre ; temperature ontroller
The Effect of Temperature and Humidity on orona Inception Voltage
Gradient of UHV DC ransmission Line
Abstract-- To research the effect of temperature and humidity n corona inception voltage
gradient of UHV DC transmission ine, a mini corona cage has been constructed and put in a
manual environment room, which temperature and humidity can e controlled. At the same
time, a corona inception voltage radient measuring system by using vary methods such as
current impule method, acoustic method have been set up too. he corona inception voltage
gradient of a copper line have been easured in a mini corona cage not only at different
absolute umidity from 3g/m3 to 12g/m3 but also at different temperature rom 0 ℃ to 35℃.
The relationship between corona inception oltage gradient and temperature and humidity
have been chieved.
Index Terms—Corona, DC, Effect, Hunidity, Temperature
Finally Fiber Optic Sensing of Power Transformer “Hotspots" Is

Paying Off
Thomas Lundquist Wesley Knuth
Lundquist Consulting Services, Inc. Salt River Project
Abstract--For nearly 25 years innovative transformer manufacturers, utilities and research
organizations such as EPRI have been experimentally installing fiber optic temperature
probes in the windings of power transformers. Their quest was motivated by the desire to
directly measure the actual winding temperature. These large transformers lose valuable
lifetime when the winding temperature exceeds a critical maximum value, even for a few
hours during short-term overloads.
During this lengthy experimental period the technology started with fragile laboratory
equipment, and the inability of transformer designers to accurately identify the location of
the hottest-spots in the windings. Today the technology has developed into a mature set of
equipment that is hardened to perform in the harsh environment of power apparatus. The
equipment is reliable and designers are able to precisely identify hot spot locations in the
windings.
Wireless Sensor for Managing Electrical Distribution Networks
1Department of Electrical Engineering, Dongshin University, 252 DaeHo-dong, Naju 520-714,
Korea
*E-mail : yschoi67@dsu.ac.kr
1Wireless Sensor for Managing Electrical Distribution Networks
Abstract--In this paper, methods and analysis of a simple wireless sensor concept for detecting
and locating faults as well as for load monitoring are presented. The concept is based on
distributed wireless sensors that are attached to the incoming and outgoing power lines of
secondary substations. A sensor measures only phase current characteristics of the wire it is
attached to, is not synchronized to other sensors and does not need configuration of triggering
levels. The main novelty of the concept is in detecting and locating faults by combining power
distribution network characteristics on system level with low power sampling methods for
individual sensors. This concept enables the sensor design to be simple, energy efficient and
thus applicable in new installations and for retrofit purposes in both overhead and
underground electrical distribution systems.
Index Terms--Power distribution, Power system communications, Power system monitoring,
Wireless transducers
A Program for Design of Impulse Current Generator Circuits

P. Yutthagowith and N. Pattanadech
Laboratoire d’Analyse des Signaux et des Processus Industriels (LASPI)
*E-mail : guillaume.bouleux@univ-st-etienne.fr
A Program for Design of Impulse Current Generator Circuits
Abstract--This paper presents the design and development of a computer algorithm program
based on MatLab for designing impulse current generator circuits which are linear circuit.
This algorithm program can help the test engineer for designing the components, resisters,
inductors and capacitors to meet the waveforms according to IEC standard, or other
waveforms which are in form of complex double exponential. The program uses numerical
method, Secant’s Method, and normalized circuit techniques for calculating components of
circuits, peak current, and time parameters on resistance and inductance plane (R-L plane).
The test results show that the program proposed in this paper is practicable, and should be a
useful tool for design of impulse current generator in a standard high voltage laboratory.
Index Terms--impulse current, program, design
Implementation of Multi-function ETRA Gateway
Abstract--The next generation power IT system will consist of automated transmission and
distribution systems that support efficient and reliable supply and delivery of power. The goal
is to create a power IT system capable of handling emergency and disaster situations, while
also able to accommodate current and future utility business environments, market
requirements, and customer needs. In this paper, we propose multi-function TETRA
Gateway (MFTG) that can convert various power IT protocols into TETRA protocols to show
that the next generation electric power IT system can be constructed in TETRA radio
infrastructure. Our MFTG is a TETRA network equipment that converts power IT protocols
(for example, transformer load monitoring protocol, RTU (Remote Terminal Unit) protocol
for monitoring power transmission steel tower wind direction/wind velocity, DLMS, DNP,
and IEC61850 etc...) into TETRA protocols through short data, status messaging and packet
data.
Index Terms—TETRA, Power IT Protocol
Preparation of Power Transformer’s CBM Implementation In PLN
P3B Jawa Bali

N. Ukhita A.W1*, A. Pharmatrisanti1
1 PT. PLN (Persero) P3B JB Region Jawa Barat-Indonesia
2 PT. PLN (Persero) P3B JB Region Jakarta dan Banten-Indonesia
*E-mail : ni2el@yahoo.com
Abstract--Since year of 2004 PLN P3B Jawa Bali has decided to apply a new strategy of
maintenance, i.e.: condition based maintenance (CBM) to its high voltage assets. Transformer,
which is the most crucial and expensive asset in electrical power network, becomes the first
priority to be applied on. Performing FMECA (Failure mode Effect and Criticality Analysis)
in order to find failure path of each transformer subsystem and developing model became the
first step should be done by PLN P3B Jawa Bali. There are two kinds of model developed by
PLN P3B Jawa Bali; they are statistic model and physical model. This paper focuses on
preparation of statistic model development. There are five kinds of data that PLN has been
collected for 5 last years related to critical component found by FMECA process , they are :
DGA (dissolved gas analysis), Load and Temperature (manual reading by
operator),Polarization Index, Tan delta, Oil characteristic test. Through data trending
analysis, PLN has found that the data collected was not sufficient enough for model
development. Therefore PLN has analyzed the problems and defined the new step to handle
them, i.e.: Maintenance procedure standardization, DGA oil sampling standardization,
Regular calibration of testing equipment.
Index Terms--Condition Based Maintenance, Failure Effect
and criticality analysis, modeling, transformer.
A DSP based Stator Slot Wedge Tester for Large Generators
Jia Zhidong2, Gao Shengqiang1, 2, Peng Xiang1, 2*, Wang Liming2, Guan Zhicheng2 and Wang
Tianzheng3
1 Department of Electrical Engineering, Tsinghua University, Beijing, 100084, P. R. China
2 Graduate School at Shenzhen, Tsinghua University, Shenzhen, Guangdong, 518055, P. R. China
3 Shanxi Electric Power Research Institute, Taiyuan, Shanxi, 030001, P. R. China
*E-mail: peng-x04@mails.tsinghua.edu.cn
Abstract--Loose stator slot wedges could result in excessive vibration of the stator coils in
large generators, which would accelerate the deterioration of the groundwall insulation and
even eventually lead to catastrophic failure of large generators. So it is significant to detect
loose slot wedges in stator slots to ensure generator’s normal operation. Up to now, the slot
wedges used to be tapped by hand using a small hammer with the operator making a
judgment of tight or loose based on the sound from the slot wedge. This method is workable
and has provided much useful data on the condition of the generators, but suffers from a few
of major problems.
This paper was concerned with its vibration characteristics in the loosening process of slot

wedge with different fixing style and, introduced a slot wedge automation tester which was
developed with Digital Signal Processor (DSP) technology and embedded system theory. It is
a portable tester, and easier for workers to use to judge the tightness of slot wedges than the
traditional manual method. It has also been applied to test stator slot wedges of some large
generators in China.
Index Terms-Automatic, DSP, Groundwall insulation, Large generator, Stator bar, Slot wedge,
Tightness judgment, Vibration,
Automatic Vacuum Capacitor Switch With Modified Digital Filter
Abstract—A high-speed microprocessor based automatic vacuum capacitor switch with a
modified digital filter design using distributed arithmetic has been designed in this paper. The
automation trends particularly the automatic vacuum capacitor switch has helped ameliorate
the power factor essentials and automatically triggered to close when the line current exceeds
rated value. Microprocessor relays use digital filters to extract only the fundamental and
attenuate harmonics. To provide optimum speed characteristics a distributed arithmetic
based filter design in the microprocessor controller which not only enhances filtering speed
but additionally enables lower power consumption at the cost of area has been introduced.
The result is a unified description that describes a digital filter structure down to bit level.
Index Terms—Automatic vacuum capacitor switch, Distributed arithmetic, Filter design,
Filter structure, Microprocessor relay
DSP-based high-frequency HVDC source for Verifying Internal
Pressure of Vacuum Chamber
Changlong Chen Jiyan Zou
Electrical and Electronics Engineering Department
DaLian University of Technology
NO2, LingGong street, DaLian City, LiaoNing Province,CHINA
Ch2long@163.com
Abstract--Using the HVDC source, whose Voltage is just below the breakdown voltage of the
vacuum Chamber, we can realizing the measuring of the internal pressure within the vacuum
interrupters,using only electrical parameters. The HVDC described in this paper is a
DSP-based high frequency system. The rectifier and IGBT inverter are controlled by a
TMS320LF2407 DSP system. which has the hardware feature of providing a dead-band delay
independent of the frequency of operation. This feature, together with the high speed of the
DSP, allows the use of zero current resonant switching at a high power factor for frequencies
up to 50 kHz. Resonant operation of the inverter is maintained by a simple digital PLL

scheme implemented on the DSP. An EMI filter to compensate common mode current using
high frequency transistors works just as a power active filter in the harmonic compensation in
the power system. Experiment gives out the feasibility of the method on verifying internal
pressure in vacuum interrupter.
Key-Words--HVDC, DSP-based, IGBT, EMI filter, internal pressure, vacuum chamber
Development of Coaxial-to-waveguide Antenna Attached outer GIS
for Detecting Partial Discharge
Abstract-- We have developed a coaxial-to-waveguide antenna that is capable of being
attached to outer insulators in GIS. We firstly obtained the sensitivity line between output of
the antenna (mV) and magnitude of partial discharge (pC) that is obtained based on IEC
60270. We also compared spectra measured by the coaxial-to-waveguide antenna from those
measured by both spiral antenna and disc coupler so as to clarify frequency response and
attenuation characteristics of the coaxial-to-waveguide antenna.
Key words--GIS, Partial discharge, Coaxial-to-waveguide antenna
Development of The Portable Decomposed Gas Analyzer for Gas
Insulated Transformers
Toshifumi Sugimoto1*, Kazuyoshi Takahashi1, Atsuhiko Kashino2 and Takashi Hoshino2
1 Chubu Electric Power Co., Inc
2 Mitsubishi Electric Corporation
*E-mail : Sugimoto.Toshifumi@chuden.co.jp
Abstract-- Gas insulated transformers are usually installed at underground substations
located in the urban area, and it is worried that abnormalities caused by the progress of
deterioration may soon start to appear as 30 years have passed since the first gas insulated
transformer was installed in Japan. Therefore, the diagnostic technique without stopping the
gas insulated transformer operation has become necessary.
Authors focused on decomposed gas components in gas insulated transformer: F-, SO2 and
CO, and have developed and introduced an in-vehicle decomposed gas analyzer with gas
sensors that has been used as the primary equipment for diagnosis of gas insulated
transformers since 1993. The necessity of prompt arrival at small substations in case of
accidents, as well as the demand of higher diagnostic accuracy, has been increasing recently.
Thus, authors have newly developed a decomposed gas analyzer, which applies the standard
criteria for decomposed gas. This analyzer is so portable that a person can carry on the
shoulder. The performance of this analyzer was verified through field tests of transformers in

service. This has resulted in an establishment of diagnostic system for gas insulated
transformers.
Index Terms-- Gas insulated transformers, Monitoring, Measurement, Substations, gas
analysis, Electrochemical sensor, diagnosis, portable equipment
Development on the Zero-Flex Type Current Sensor
Jun Liu *, Guangning Wu, Lijun Zhou, Kegang Lei
Southwest Jiaotong University Chengdu, 610031, China
*E-mail :liu1983jun@126.com
Abstract--The on-line monitoring of high voltage equipment is an important technique to
ensure the safe of electric power transmission. And the key of the technique is the detection of
divulge current. At first, the error of the current transducer is analyzed. Then a type of low
current transducer with cored structure and high accuracy is described which is specially
designed for on line monitoring of high voltage apparatus. The circuit in the transducer can
track the variation of magnetizing current and compensate it by single chip processor systems.
Through adjusting the phase and amplitude of compensation current, to assure the magnetic
core working in zero-flux condition. The test of the current transducer shows that the design
gets satisfactory results. Its angular difference is ±2.0´, relative scale difference is under
1/1000, and its resolution is about 100µA.
Index Terms--compensation, DSP, electromagnetic induction, error, online monitoring, zero
flux
The Design of Circuit in On-line Monitoring System for Traction
Transformer Insulation
Hao Tang1*, Jianbin Fan2, Guangning Wu1 and Jinzhong Li2
1School of Electrical Engineering, Southwest Jiaotong University, Chengdu 610031, China
2 China Electric Power Research Institute, Beijing 100085, China
*E-mail : tanghao@epri.ac.cn
Abstract--In order to ensure the safety and stabilization of high-speed railway, it is very
important to implement on-line monitoring system on traction transformer. The data
acquisition, the main control circuit, the program of Single Chip Micyoco (SCM) and
communication protocol, which are the components of the on-line monitoring system of
traction transformer insulation, are roundly presented in this paper. This system is well

designed and it can be embedded in the detection system of hydrogen, mixed gas and moisture.
The simulation experiment indicates that compared with the data which acquired through
AD900 gas phase chromatography system, the relative error of the data which detected by
this on-line monitoring system is merely 5 percent.
Index Term--Data acquisition, DGA, on-line Monitor-ing ,Traction transformer.
Preliminary Investigation for Application of MEMS Acceleration
Sensor to SF6 Gas Circuit Breaker
Hisatoshi Ikeda1*, Kentaro Makisaka1, Katsutoshi Harada1, Shinya Ohtsuka1, Masayuki Hikita1,
Katsuharu Iwamoto2 and Toshikazu Nagata2
1 Kyusyu Institute of Technology : 1-1 Sensuicho, Tobataku, Kitakyusyu, 804-8550, Japan
2 Toshiba Corporation :
*E-mail : ikeda@ele.kyutech.ac.jp
Abstract—With an aim of applying a MEMS (Micro Electrical Mechanical System)
acceleration sensor as a diagnosis tool for a mechanical degradation of a SF6 gas circuit
breaker, we investigated the fundamental characteristics. It is confirmed that the MEMS
acceleration sensor with a maximum acceleration number of 250G and a frequency band
width up to 400Hz can be applied to measure an acceleration number of the model GCB,
while all tests were carried out under no electromagnetic stresses on the GCB. In addition an
optical acceleration sensor by using a photo-reflector was developed to be applied in a severe
electromagnetic field. The first model of the optical sensor showed insufficient frequency
band width for the purpose.
Index Terms—Accelerometer, Acceleration, Dead tank, Frequency band width, Hydraulic
driving mechanism, Photo-reflector, Maximum measurable acceleration number, Mechanical
degradation, Micro Electric Mechanical System, Operating rod, Optical sensor, SF6 gas
circuit breaker
The Compact Tesla Transformer for Testing Pin Insulator
Abstract-- This present work proposed the compact Tesla transformer which could generate voltage up to 155
kVp with variable frequency between 120-430 kHz. Its size was 1.40 m in length and 0.35 m in width. This
Tesla transformer set consisted of a 220V/15 kV transformer, a quenching gap, a capacitor which can
withstand the voltage up to 36 kVp and windings used air as insulator. The capacitance was 44 nF which made
of polypropylene capacitors. The energy from the storage capacitance was transferred to the primary
winding through the quenching gap made of stainless paddle driven by motor while the energy from primary
winding to the secondary winding was transferred by magnetic field through air core by wrapping the
secondary winding in the PVC pipe. This caused much smaller gap clearance between primary and
secondary windings. The output frequency depended on the capacitance of the test object which was usually

less than 50 pF. This Tesla transformer was used to test the puncture of pin insulator.
Energy Scavenging Technique for Powering Wireless Sensors
M. Zhu*, A. Reid, S. Finney and M. Judd
1 Institute for Energy and Environment, University of Strathclyde, Glasgow, G1 1XW, UK
*E-mail: minan.zhu@eee.strath.ac.uk
Abstract--A capacitive scavenging device is proposed to extract energy from the electric field
that surrounds the equipment in a substation. Related research has shown that switching
techniques can be used to increase the useful power obtained. An experiment has been set up
by putting two parallel plates of 10 cm radius in a uniform AC electric field up to 20 kV/m. A
mechanical reed relay was used at this stage to provide a high ‘OFF’ resistance. Tests were
carried out by switching the relay at different frequencies and varying the length of the
switching pulses. Initial results show that introducing switching could improve the scavenging
efficiency compare with the basic linear circuitry. The proposed device could enable simple
sensors to be energy self-sufficient, opening the way for wireless sensors to be installed widely
in the power grid.
Index Terms--condition monitoring, energy scavenging, wireless sensors
Measurement of Arc Current Using NCIT
J.N.Park1*,Y.H.Lee1,H.W.Lee,Y.S.Shin,B.W.Lee1,Y.G.Kim1,I.S.Oh1,K.J.Lim2,J.S.Lee3
1 Electrotechnology R&D center, LS Industrial systems
2 Chungbuk National University
3 Power Apparatus Testing & Evaluation Division, Korea Electrotechnology Research Institute
*E-mail : jnparka@lsis.biz
Abstract--Traditional transformers using iron cores were widely used for measuring voltage
and current for several decades. But with the introduction of new digital technologies, novel
measuring techniques were begun to apply to the transformers. Novel types of current and
voltage transformers do not adopt iron core, so these types were called as Non-Conventional
Instrument Transformers (NCIT). The common characteristics of NCIT sensors include no
saturation, wide frequency range, and suitable for digital equipment applications.
In this paper, the characteristics of Rogowski coil were compared to the conventional current
transformers in the respect of measuring accuracies when normal and fault currents were
applied. And also, effectiveness and wide range applicability of NCIT were introduced.
Index Terms-- NCIT, Rogowski coil.

FRA Low Frequency Characteristic Study using Duality Transformer
Core Modeling
Swee Peng Ang1, Jie Li1, Zhongdong Wang1* and Paul Jarman2
1 School of Electrical and Electronic Engineering, The University of Manchester, M60 1QD, UK
2 National Grid, NG House, Warwick CV34 6DA, UK
*E-mail: zhongdong.wang@manchester.ac.uk
Abstract--In this paper a simulation model for a three-phase, three-limb core-type 1000MVA
400/275/13kV autotransformer is presented to study Frequency Response Analysis (FRA).
The equivalent electric circuit of the magnetic core is derived based on the Principle of
Duality. Leakage inductances and capacitances of windings are also included in the model.
All the parameters are determined using manufacturer data sheet. FRA simulation results
up to 1 kHz are validated by the measurement results. The FRA low frequency
characteristics of transformers are first time explained through modeling and the
dominating parameters for these characteristics identified.
Index Terms--Frequency Response Analysis (FRA), Principle of Duality, Three-limb core,
Power Transformers, Antiresonance and Resonance.
Condition Monitoring and Diagnosis of Power Transformers
E. Gockenbach, H. Borsi
Leibniz Universität Hannover, Schering-Institut
Callinstr. 25A, 30167 Hannover, Germany
*E-mail : gockenbach@si.uni-hannover.de
Abstract--Power transformers are one of the most important components of electric networks.
These devices are very expensive and therefore diagnosis and monitoring systems will be
valuable for preventing damage to them. A facility for viewing the status of transformers
remotely by experts who will make an appropriate decision in case of a problem is needed to
prevent premature damage to the transformers. The transformers are geographically spread
and with the aid of Internet, it is possible to collect appropriate information from these
transformers to a central node for diagnostic purposes under the supervision of high voltage
engineering experts. The aim of this paper is to show the main problems related to power
transformers and to review mitigation methods for the monitoring and diagnosis of power
transformers.
Index Terms--High voltage technique, Insulation life, Monitoring, Power transformer
insulation

Measurement Considerations using SFRA for Condition Assessment
of Power Transformers
Peter Werelius1*, Matz Öhlen1, Lars Adeen2 and Eddie Brynjebo3
1 Pax Diagnostics, Taby, Sweden
2 ES, Upplands Vasby, Sweden
3 ES, Karlskrona, Sweden
*E-mail : peter.werelius@paxdiagnostics.com
Abstract--Sweep Frequency Response Analyzer (SFRA) measurements are now an established
method for condition assessment of Power Transformers. Since most of evaluation
procedures is based on comparison between; 1) earlier measurements on same transformer, 2)
measurements on sister transformers, or 3) phase to phase comparison on same transformer,
the measurement accuracy and repeatability is of utmost importance. This paper will
describe the influence of variation in cable setup and different kind of instrument weakness.
The theoretical description will be backed up by field experience and measurements.
Examples of measurements before and after an incident are mixed with measurements with
same and “almost” same measurement configuration. Typical sources of errors are discussed
and finally a simple guide will be presented how to achieve high reproducibility in SFRA
measurements.
Index Terms--Assessment, FRA, Frequency Response, SFRA, Transformers
Investigation of Return Voltage Measurement for the Assessment of
Power Transformers
Rui-gang Zhang, Ming Dong*, Guan-jun Zhang and Zhang Yan
State Key Laboratory of Electrical Insulation and Power Equipment, School of Electrical
Engineering,
Xi’an Jiaotong University, Xi’an, Shaanxi 710049, P. R. China
*E-mail : dongming@mail.xjtu.edu.cn
Abstract--Moisture and ageing in power transformer strongly influence the dielectric
properties of oil/paper insulation system. Moisture measurement in oil sample generally gives
inconclusive information since oil/paper moisture equilibrium is temperature dependent and
takes a long time to be in equilibrium. Direct moisture measurement of paper sample is not
practicable for inservice transformers. The measurement and evaluation of the ‘‘dielectric
response’’ is one possible way of diagnosing a transformer insulation condition. In a recent
research project, Return Voltage Measurement has been used for assessing the condition of
oil/paper insulation. The return voltage measurement analysis is a non-destructive dielectric
testing method for determining the ageing process and moisture content of insulation
materials in a transformer. This paper presents a description of Return Voltage Measurement
principle explanation and the influencing factors. Furthermore, by analyzing large number of
field test data, the criterion of oilpaper ageing is also presented.

Index Terms--Dielectric response, Return voltage measurement, Depolarization currents,
Simulation
Frequency Response Analysis as a technique for Moisture
Diagnostics of Power Transformers
Ramesh Yadav*, A.Venkatasami.
CMDRC, Global R&D Centre,
Crompton Greaves Ltd,
Mumbai-400042.
*E-mail : rameshchand.yadav@cgl.co.in
Abstract-- FRA is used to determine the mechanical and electrical integrity of the core and the
windings of power transformers. It can be used to detect core movement, winding movement,
open circuits, short circuits and problems related to core ground. Various practical case
studies demonstrate the effectiveness of this technique. This paper will demonstrate the effect
of change in moisture content on the resonance frequencies of the FRA signatures. An attempt
is made to set an approximate relation between the resonance frequency and the percentage
moisture content. Therefore, the amount of moisture content can be approximated by
identifying the shift in the resonance frequency occurring along the sweep relative to the
reference.Practical examples of the application are presented.
Index Terms: - FRA, resonance frequency, capacitance, permittivity, moisture content.
Fault Gas Generation in Ester based Transformer Fluids and
Dissolved Gas Analysis (DGA)
Abstract--Environmental concern, safety and sustainability of oil supply are the driving forces
behind research into alternative dielectric fluids to mineral oil. Natural and synthetic esters,
as the alternative fluids, need to be assessed under thermal and electrical fault conditions, and
their performance and likely impact on the established diagnostic techniques need to be
identified. In this respect, dissolved gas analysis (DGA) and online DGA monitoring play a
vital role for mineral oil filled transformers, and they are the techniques examined in this
paper. Tests were designed to produce electric faults in ester fluids in a sealed vessel. Both the
headspace gas and dissolved gas in oil results were used to calculate the generated fault gas
amount. Although DGA readings were lower than mineral oil, Envirotemp® FR3® generated
significant amount of free gases, allowing easy detection of a fault by use of a Buchholz alarm
or similar. Midel® 7131 was the most stable fluid in terms of gas generation during these tests.
With improved fluid circulation, the response time of HYDRAN® 201R was identified to be
the same as with esters as with mineral oil.

Index Terms--Condition Monitoring, DGA, Esters based Fluids, Electrical Faults and Power
Transformers.
Experiences of Dielectric Response Measurement in Frequency
Domain for Diagnostics of Transformer Insulation System
V. Ramakichenan1, Rahul Kumar Jain1, Thekkeveetil Sethumadhavan1, Sushil E. Chaudhari1, A.
Venkatasami1,
Jayalakshmi Chandle2
1CG Global R&D Centre, Crompton Greaves Limited, Mumbai, India
2VJTI, Mumbai
*E-mail: rahulkumar.jain@cgl.co.in
Abstract--Moisture and aging strongly influence the dielectric properties of composite
oil/cellulose insulation system used in power transformer. So the knowledge about moisture
content in oil impregnated paper is essential when estimating remaining life time of such
system. A scaled down transformer insulation model was developed to gain wide experiences
of on-site measurements of moisture content using dielectric response method. In order to
provide reliable diagnostics of HV transformer insulation, various aspects like sensitivity of
dielectric response to oil quality (oil conductivity and tanδ) etc. are discussed that may
benefits the utilities and the service providers while using this technique. An investigation of
moisture content on different parts of the insulation on a scaled down transformer model is
performed using chemical analysis. Variation in the moisture content measured by FDS
technique and Chemical method are also presented. The causes of variation in the results are
analyzed.
Key words--Transformer, Composite insulation system, Dielectric response method, Moisture
An Algorithm for Partial Discharge Localization in Transformers Using
Winding Design Data
A. Mazhab Jafari1,2* , A. Akbari1 , H.R. Mirzaei1,3, M. Kharezi3 and M. Allahbakhshi1
1 Department of Electrical Engineering, K.N.Toosi University of Technology, Tehran-Iran
2 Iran Grid Management Company, Tehran-Iran
3 Iran Transfo Company, Zanjan-Iran
*E-mail : mazhabjafari@igmc.ir
Abstract--In this paper an algorithm for PD localization based on using multi-conductor
transmission line model is introduced. In this algorithm sectional winding transfer functions
are computed using the winding model. To calculate the parameters of the model including
resistances, inductances and capacitances between different turns of the winding, it is
necessary to have design data of the transformer. Since different designs are used for

different transformers, it is necessary to investigate the needed design data for the algorithm
for different types of winding structures. It is shown in this paper that the algorithm can be
generalized for a wide range of transformer designs. The validity of the algorithm is verified
by performing PD test on a 15.75kV/230kV, ∆/Y, 200 MVA, step-up power transformer.
Index Terms--Design Data; Modeling; Multi-conductor Transmission Line Model; Partial
Discharge; PD localization; Transformer.
Investigating Suitable Features for Partial
Discharge Localization in Power Transformer
M.Homaei1, A.Mazhab Jafari2 and A.Akbari1
1Department of Electrical Engineering, K.N.Toosi University of Technology, Tehran-Iran
2Iran Grid Management Company, Tehran-Iran
*mohammad.homai@gmail.com
Abstract--It has been shown in the literature that Partial Discharge (PD) pulses can be
localized in transformer windings successfully using sectional winding transfer functions.
But it is necessary to have the transformer design data to use this method. So the method can
not be employed in the cases that transformer design data are not available. Another method
for estimating PD location in transformers is based on using extracted features from single
PD pulse waveforms. This method does not need transformer design data. In this paper it is
tried to find suitable features for PD localization. For this purpose, a specially prepared
research transformer is employed and different type of PD are generated and applied to
different points along the winding and are measured by means of a modern VHF PD
measuring system. The features extracted from different transforms like KLT, DST, DCT
and HADAMARD transforms are investigated and PD localization results are analyzed.
Index Terms--Power Transformer, Partial Discharge, Localization, Pattern Recognition,
Orthogonal Transform.
Online Partial Discharge Detection and Location Techniques for
Condition Monitoring of Power Transformers: A Review
A. Santosh Kumar1*, Dr. R.P. Gupta1, Dr. K. Udayakumar,2 A.Venkatasami1
1CG Global R&D Centre, Crompton Greaves Ltd, Kanjur Marg, Mumbai – 400 042
2Anna University, Chennai – 600 025
*E-mail : santosh.annadurai@cgl.co.in
Abstract--Partial discharge (PD) is an important indicator of insulation condition in a power
transformer. The PD phenomenon is exhibited in various observable forms such as electrical,
mechanical, optical and electromagnetic energy. Many modern systems use a combination of

these techniques, because electrical detection is a proven technology, combining it with
modern techniques gives the conformity and the advantage of modern digital signal
processing. This paper discusses the evolution of various techniques in partial discharge
measurement as a condition monitoring tool available for online measurement of field
transformers. This paper also discusses the recent techniques used for partial discharge
analysis with its advantages and suitability over conventional method for proper condition
monitoring of large power transformers.
Index Terms--online, offline, onsite Partial discharge detection, location techniques, acoustic
emission technique, UHF technique.
New PD Measurement Method for High Power
Transformer PDM in Service Operation
Chen Min1*, Koji Urano1, Huang Song-bo2 and Atsuhide Jinno3
1 Affiliation: SE Technology Limited, Hong Kong, China
2 Affiliation: Foshan Electric Power Corp., China
3 Affiliation: J-Power Systems Corp., Japan
*E-mail: chen@se-tek.com
Abstrac--Partial discharge measurement is a kind of effective condition check method for
high power transformer. Normally, when a high power transformer needs to be checked by
partial discharge measurement periodically, outage is required. Here, a newly developed
measurement method for transformer is introduced in which a new kind of capacitive
coupling sensor is applied. The sensor consists of a pair of metal plates and a high frequency
CT, which can be installed at the flange of the high voltage bushing of the transformer during
the transformer in commercial service operation, without any outage.
Index Terms--bushing, capacitive coupling, high frequency CT (HFCT), outage, partial
discharge (PD), partial discharge measurement (PDM), pulse current, PDM sensor,
transformer
Pulse interferences elimination and classification of
on-line UHF PD signals for power transformer
Tang Zhiguo1, Wang Caixiong1, Li Chengrong1, Zhao Dianquan2, Xu Runguang2
1 A Beijing Key Laboratory of High Voltage & EMC
Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control,
Ministry of Education
North China Electric Power University Dewai, Zhuxinzhuang, Beijing, 102206, China
2 Changchun UHV Corporation, Changchun, China

*E-mail : tangzhyguo@163.com
Abstract-- Raw on-line monitoring PD data for transformers consist of true PD signals as well
as several kinds of interference signals too. Among the interference signals, pulse type
interference signals are the most difficult to eliminate. In this paper, we propose a set of
practical pulse type interference signals elimination method for an on-line UHF PD
monitoring system of a 500kV three-phase split type power transformer. That is noise sensor
method and inter-phase antitheses method to exclude external pulse type interferences. The
characteristic parameters from the pre-processed data in single cycle are extracted. The data
are then classified with fuzzy clustering and grey clustering method to make further
discrimination of all kinds of coincident pulse type interferences with true PD signals. At last,
the classified PD signals are statistically analyzed with PRPD method, the evaluation on PD
activities are then made based on the clustered PD data.
Index Terms-- Partial discharge; UHF; interference elimination; classification
Improvement for Diagnosing Internal Abnormalities in Oil-Filled
Transformers
Abstract--The dissolved gas analysis process is among the most widely used methods of
diagnosing internal transformer faults. In Japan, judgment criteria have been established
from the results of a questionnaire survey on DGA for 1,324 units of operating power
transformers. The traditional dissolved gas analysis method of identifying abnormal modes
perdorms less well at distinguishing between abnormalities in the winding, which could lead
to a transformer shutdown, and the core. Abnormalities in the winding should require
immediate intervention because they could develop into dielectric breakdown faults.A gas
generation test has been conducted by the conventional method and relationship between
equivalent overheating areas and C2H4/C2H6 ratios. And “High-accuracy dissolved gas
analysis method” implements internal diagnostics through microanalyses on the “ppb” order
to possibly improve the accuracy with which to locate gas sources in transformers. As a result,
improved accuracy to locate overheating in transformers is obtained.
Index Terms--abnormality diagnosis, dissolved gas analysis, model experiment, overheating,
ttransformer
Practical Implications of Multi-Agent
Transformer Condition Monitoring
Yong-Sung Choi1*, Ju-Ho Yun1 and Kyung-Sup Lee1
1Department of Electrical Engineering, Dongshin University, 252 DaeHo-dong, Naju 520-714,

Korea
*E-mail : yschoi67@dsu.ac.kr
Abstract--This paper describes the transition of the Transformer COndition Monitoring
Multi-Agent System (COMMAS) from an off-line partial discharge defect diagnosis system to
an online one. The practical difficulties encountered along the way have been highlighted, and
solutions outlined. The main issues were related to identifying fragility in the existing system,
and making changes to the architecture to produce a more robust system. Additionally,
considerations about the processing resources available on site and the communications links
to the site influenced the decision to distribute individual agents across multiple computers.
Adding a Substation Manager agent to COMMAS satisfies various requirements for data
storage and accessibility, and serves as a gateway between the diagnosis side of COMMAS
and the user interface. The system’s stability was improved by moving to a newer agent
platform, which brought additional benefits such as agent relocation abilities. By these means,
COMMAS is now ready to be deployed on site, to perform on-line transformer monitoring.
Index Terms--Diagnostic system, Multi-agent system, On-line monitoring, Power transformer,
Reliability, Safety
On-line and Off-line Monitoring-Diagnosis System(MDS) for Power
Transformers
Dorel NEDELCUT *, Dumitru SACERDOŢIANU*
Gabriel TANASESCU**, Serban NICOLAE**, Lucian VOINESCU**
*RESEARCH DEVELOPMENT AND TESTING NATIONAL INSTITUTE FOR ELE CTRICAL
ENGINEERING- ICMET, Craiova
e-mail: dnedelcut@icmet.ro, e-mail: micro@icmet.ro
**SC SIMTECH International SRL – Bucharest,
e-mail : gtanasescu@simtech-international.ro,
Abstract – The safe operation and the extension of the remained life of power transformers
have been dominant objectives during the last years. An accurate assessment of the remained
life could be an important instrument for the safety of the power transformers in operation.
The paper presents the structure and the using mode for an integrated monitoring-diagnosis
system (SMD) for power transformers. The monitoring-diagnosis system allows on-line
analysis on a desktop application, a web application and off-line analysis for determining the
transformer condition, by means of which there are surveyed:
• Cooling system condition;
• OLTC condition;
• Bushing condition;
• Insulation system condition;
• Partial discharge evolution;
• Transformer switching in/switching off;
• Exceeding of monitored parameter limits;

• Estimation of remained life.
SMD allows determining accurately the transformer condition and the monitored parameters
evolution in time, avoiding the appearance of incidents and failures and specifying certain
type of maintenance.
Index term: power transformers, on-line monitoring, diagnosis, maintenance.
Fault Diagnosis Model of Power Transformer
Based on Combinatorial KFDA
Yongchun Liang1,2×, Xiaoyun Sun2, Qingrui Liu2, Jianpeng Bian2, Yanming Li1
1. School of Electrical Engineering, Xi’an Jiaotong University, Xi’an China;
2.School of Electric and Infromation, Hebei University of Science and Technology, Shijiazhuang
China
*E-mail : yongchunliang@stu.xjtu.edu.cn
Abstract-- Fisher discriminant is a classical linear technique widely used in pattern
classification and feature extraction. When fisher discriminant is used in classification of
power transformer fault based on dissolved gasses analysis (DGA), it is transformed to its
nonlinear version in high dimensional feature space by means of the kernel trick. The kernel
fisher discriminant analysis (KFDA) is presented to diagnose faults in oil-immersed power
transformer. In order to improve the classification accuracy, the conception of combination is
introduced. The fault diagnosis of power transformer is consisted of 4 KFDA. KFDA1 is used
to classify the normal and fault. KFDA2 is used to classify the thermal fault and discharge
fault. KFDA3 is used to classify the general overheating fault and severe overheating fault.
KFDA4 is used to classify the partial discharge fault, energy sparking or arcing fault. The
example shows that the combinatorial KFDA have emerged with better performance, and
more flexibility.
Index Terms-- Oil-immersed transformer, fault diagnosis, DGA, combinatorial KFDA, cross
validation.
Polar Mode of Frequency Response Analysis
Used for Observation of Transformer Condition.
Edy Iskanto, Herpekik Hargono, Ari_muchtar, Nugroho
PLN State Electricity Corp Indonesia
edyiskanto@pln-litbang.co.id ;
herpekik@pln-jawa-bali.co.id ;
ari_muchtar@pln-jawa-bali.co.id
Abstract--Several tests are now available to estimate the state of insulation and mechanical

integrity of transformers following major short circuits faults without opening the
transformer tanks. Frequency response analysis is one of such a test currently used by
utilities to estimate the state of transformers. However, analyzing graphs of amplitude and
phase responses in the form of ‘bode plot’ is quite difficult and requires lot of experience, as
every single type of transformer would have quite different frequency response. It is not
unusual that significant deformation of windings or cores following severe short circuit faults
could not be revealed by the bode-plot method. Another form of graphs that is easier to
interpret the internal condition of transformers would then be useful. This paper offers a
method of visualizing the frequency response scanning data in polar forms. This is done by
simply converting the amplitude and phase graphs into nyquist-like plots, or polar plots,
where amplitude response and phase response are drawn on the same frame. This method
have been used to analyze for some new type transformer which to it applied by short circuit
type test, then compared the scanning result before and after test.
Index Terms--Frequency response, maintenance, power transformer testing, transformer
windings.
Detection of Deformation and Displacement of Transformer Winding
by Frequency Response Analysis
Satoru Miyazaki, Yoshinobu Mizutani, Hiroshi Suzuki and Michiharu Ichikawa1*
1 Central Research Institute of Electric Power Industry
*E-mail : m-satoru@criepi.denken.or.jp
Abstract--Frequency Response Analysis (FRA) is a diagnosis method to detect troubles of a
transformer, which are deformation and displacement of winging and so, by detecting change
of a transfer function compared with that measured when the transformer is normal.
However, identification of the troubles detected by FRA is not clear. In this paper, firstly,
identification method of the troubles is investigated using a model transformer. Secondly, the
proposed identification method is applied to identify a trouble of a real transformer caused by
short-circuit tests.
Index Terms--Transformers, Transformer windings,
Influence of Measurement Parameters on FRA
Characteristics of Power Transformers
Takahiro Sano1* and Katsunori Miyagi2
1 Japan AE Power Systems Corporation, Transformer Design Department, Numazu-shi, Shizuoka,
410-0865 Japan
2 Japan AE Power Systems Corporation, Research & Development Department, Hitachi-shi,

Ibaraki, 316-8501 Japan
*E-mail : sano-takahiro@mb.jaeps.com
Abstract--With the increasing average in years of use of transformers, there is an increasing
need to ascertain transformer condition. Therefore, it is of vital importance to establish
monitoring and diagnostic techniques capable of assessing transformer operating conditions.
Frequency response analysis, generally known within the industry as FRA, is one diagnostic
technology applied to transformers. The crucial advantage of the FRA method is diagnostic
results that can be clearly obtained while bypassing the costly inspection of an untanked
transformer after a failure has occurred. However, if FRA characteristics are affected by
parameters other than windings or core, fault diagnosis could not be performed with
accuracy. In order to investigate the influence of measurement parameters, FRA
measurements and simulations were carried out changing the length of the measurement
cables, presence of bushings, presence of insulating oil, and tap connection. As a result, it was
found that these measurement parameters affect the FRA characteristics.
Index Terms--Fault diagnosis, Frequency Response, Measurement, Resonance, Simulation,
Transformers.
Diagnostic Methods for Transformers
Abstract--In electrical networks are power transformers as interface between different
voltage levels of essential importance. Due to the long manufacture process they are one of the
most
critical and expensive equipment and so this is one of the reasons why condition monitoring
becomes more popular. Monitoring systems as basis for diagnostics open the possibility for
expanding the operating time, reducing the risk of expensive failures and allows several
maintenance strategies. With different monitoring techniques detailed information about the
transformer condition can be received and helps to minimize the probability of an unexpected
outage. As a traditional monitoring and diagnose techniques for transformer condition is the
periodic sample of the transformer oil and to carry out a dissolved gas analysis. This paper
gives an overview about different monitoring and diagnostic methods and techniques. With
these systems significant parameters are recorded. Based on these measured variables
conclusions of the future behaviour of the technical resources can be made. New
developments in the area of signal measuring and conditioning, data processing and analysing
as well as environmental aspects make a more precise and detailed condition evaluation
possible.
Index Terms—Dielectric diagnostics, FRA, oil analysis, partial Discharge.
Partial Discharge Pattern Analysis in Cylindrical
Insulators Model of Transformer

W. Plueksawan1 P. Apiratikul1* P.Boonchiam2 B. Plangkang2
1High Voltage Research Laboratory, Kasetsart University, Bangkok, Thailand.
2Rajamangala University of Technology Thanyaburi, Pathumtani, Thailand.
*Email: g4785014@ku.ac.th, promsaka@rmutt.ac.th
Abstract--This paper proposes a partial discharge analysis in cylindrical insulators model for
finding electrical parameters. There are three types of electric insulator, namely liquid, solid
and gas insulator. The capacitance, dielectric loss factor (tanδ) are found by measuring PD
Pattern of each insulator. The power dielectric loss (Pd) of each electric insulator also
calculates by using the result of partial discharge measurements. As we know that the partial
discharge technique can show the performance of electric insulator. The experimental results
of partial discharge analysis show that the performance of three insulators. It can be the
primary data of high voltage equipments design in electrical standard level.
Key words--Partial discharge, Cylindrical insulator, Transformer, Power dielectric loss
Condition Monitoring for Power Transformer
Dr. M.N.Bandyopadhyay*
National Institute of Technology,
Kurukshetra
*E-mail: mbandyopadhyay@yahoo.com
Abstract-- This paper deals with the practical importance of Condition Monitoring for power
transformer in the Electrical Engineering field. A review has been made of the modern
development in this technology. Some empirical relations have been established by using
several practical data of different transformers. Practical test data of one of the State
Electricity Boards of India has been taken & analysis has been made.
Keywords--FRA, DGA, RVM, FURAN, DP, PD, Borescope.
Design Review as a Diagnostic Tool for Power
Transformers – A Case Study
Abstract-- Periodic testing and analysis supported by proper diagnostic techniques is must
for better understanding and assessment of health and serviceability of the transformers.
Further, effectiveness of the diagnosis is based on proper choice of diagnostic techniques.
Design review is a powerful diagnostic tool. Now-a-days, with the advances in technology of
sensors and software integration, on-line non-invasive diagnostic techniques are gaining
wider acceptance. Case Studies on Condition monitoring of transformer by proper design
review supported by analysis of DGA case history and further confirming the problem
through proper on-line and off-line tests have been illustrated.
Index Terms-- Condition monitoring, Design review, Dissolved Gas Analysis, On-line and

off-line monitoring systems, Power Transformer.
Transformer Condition Assessment Via Oil Quality Parameters and
DGA
M. Moradi, and A. Gholami
Abstract--mineral based dielectric fluids are widely used in power and distribution
transformers worldwide. Also many transformers in power system utilizations approach
their end life time. Oils can be a good tool for transformer diagnostics. A survey of more than
300 transformers in Iranian industries has been run and different oil parameters and also gas
chromatography results (DGA) have been studied.
Index Terms--Dielectric fluids, mineral oils, power transformer diagnostics, oil quality
Diagnosis of Thermal Degradation for Thermally Upgraded Paper in
Mineral Oil
Naoki Yamagata1, Katsunori Miyagi2* and Etsuo Oe2
1 Chubu Electric Power Co., Inc., Nagoya-shi, Aichi, 459-8522 Japan
2 Japan AE Power Systems Corporation, Hitachi-shi, Ibaraki, 316-8501 Japan
*E-mail : miyagi-katsunori@mb.jaeps.com
Abstract--The life of a transformer is limited to the deterioration of its solid insulation.
Winding conductors and other solid insulation materials in oil-immersed transformers have
been insulated using cellulose products. For many years, manufacturers have met the needs
of special applications by designing transformers using thermally upgraded materials to
achieve
lighter weight, higher power density and increased life. Recently, the effect of thermally
upgraded insulation on diagnostic techniques such as gas-in oil analysis, and their indication
of insulation degradation have been reviewed. This report describes an evaluation of thermal
degradation on oil-impregnated thermally upgraded paper (“Thermo-ZA”), carried out
under conditions directly relevant to practical situations. Our results confirm that an index of
aging in the thermally upgraded paper can use both CO2 and CO contents in oil, although the
paper does not produce as much 2-Furfural as Kraft paper.
Index Terms--Aging, CO2, CO, DP, maintenance, oil, oxidation, paper, transformer,
2-Furfural, water.
Research on Insulation Condition Monitoring System for Power

Transformers
Shuangzan Ren, XuYang*, Wenhu Yang, Baofeng Xi, Xiaolong Cao
State Key Laboratory of Electrical Insulation & Power Equipment, Xi’an Jiaotong University
Xi’an, Shaanxi, 710049, China.
*E-mail:xuyang@mail.xjtu.edu.cn
Abstract--Power transformer is one of the most important components in the power system.
The operating reliability of transformers mainly depends on their insulation status. An
integrated system which contains the monitoring of gas-in-oil analysis (DGA), partial
discharge (PD), contamination of the bushing surface, the equivalent capacitance and
dissipation factor (tanδ) of the bushing is introduced in this paper. Based on the above
parameters, the engineer could get further detailed information about the insulation status of
the transformer. This system has been applied in several substations and obtained good
results.
Index Terms--condition monitoring, insulation, integrated system, transformer.
Comparison of Two Thermal Circuit Models for HST Calculation of
Oil-Immersed Transformers
Taosha Jiang, Caixin Sun, Jian Li, Weigen Chen, and Tao Zhao
State Key Laboratory of Safety and New Technology of Power Transmission & Distribution
Equipment and System, Chongqing University, Shapingba District, Chongqing 400044, China
Abstract--Oil-immersed transformers are key components in power systems. The inordinate
temperature rise in oil-immersed transformers, featured by hot-spot temperature (HST),
accelerates thermal degradation in insulation. This phenomenon may result in reduction of
service age or thermal breakdowns of transformers. HST is also an important parameter to
determine the optimum load ability of transformers. A procedure to calculate HST with
parameters, including load current, ambient temperature, and top oil temperature is
recommended by IEEE and IEC. The recommended method has been proved to be effective.
This paper presents two equivalent thermal circuit models for transformers, revealing the
relationship between HST and featured oil temperatures, which are the top oil temperature
(TOT) and the bottom oil temperature (BOT). The calculation results of the thermal models
are compared with measured data obtained from an ONAN, 100 kVA and 5 kV test
transformer equipped with temperature probes.
Index Terms-- hot spot, temperature
Transformer Condition Monitoring
Abstract-- Due to increase in age of the power transformer park it is necessary to solve the

problem a residual resource. Recently, with this purpose periodic inspection techniques of
energized and off-line transformers are used to estimate technical transformer condition and
to give recommendations on prolongation of service life. In this paper Transformer
Diagnostics Monitoring (TDM)system is described as system most fully assess condition all
transformer parts (windings, core, bushings, LTS, oil, etc).
Index Terms--condition monitoring; diagnosis (fault); monitoring; transformer.
Vibration Monitoring on Power Transformer
Abstract--Nowadays electrical utilities or industries are trying to monitor their electrical
apparatus with online monitoring, without shutting the apparatus down. We are in PLN has
taken this monitoring concept by applying vibration monitoring. This vibration monitoring
has been applied to some of the transformers as a pilot project in PLN Region Jakarta and
Banten. As voltage applied to the transformer, vibration is produced. This vibration level
depends on the transformer construction and design. Vibration level shall increased by
through fault current, phase to ground or phase to phase fault. This electrical fault will
change the transformer core or winding construction by mechanical force produced. The
effect of the fault can be found by measuring the vibration level before and after several faults
on low voltage side. In this method, vibration level is measured by putting twelve magnetic
vibration sensors on the transformer’s body in the same height, six sensors on each side. By
using this configuration, the transformer vibration can be measured confidently from
different sides. Further investigation is still needed to determine the transformer condition by
measuring the vibration level after fault on low voltage side.
Index Terms—Vibration monitoring, vibration sources, sensor, winding deformation.
Transformer Hotspot Temperature Calculation using IEEE Loading
Guide
Mohd Taufiq Ishak and Zhongdong Wang*
1 School of Electrical and Electronic Engineering, University of Manchester, M60 1QD, UK
*E-mail: zhongdong.wang@manchester.ac.uk
Abstract— The life of a transformer depends mainly on the life of its insulation system.
Ageing is a process mainly defined by the chemical reaction which primarily depends on
temperature and time. The hotspot temperature is usually taken into consideration in
investigating the remaining life of transformer. There are two models available in IEEE
Loading Guide in calculating the hotspot temperature known as Clause 7 and Annex G
methods. This paper presents a comparative study between the two methods, through
calculating hotspot temperatures of the four transformers using ONAN, ONAF, OFAF and
ODAF cooling modes under conditions of constant load, daily load and ambient temperature

profile, and a shortperiod overload. The loss of life is also estimated.
Index Terms— Thermal Ageing, Hotspot Temperature, IEEE Loading Guide, Loss of Life,
Overloading, and Power Transformers.
Partial Discharge Monitoring in Medium Voltage Cables
1 Glasgow Caledonian University, Glasgow, G4 0BA, UK
2 EDF Energy, UK
*E-mail : c.zhou@gcal.ac.uk
Abstract-- Of the vast amount of MV cables in the UK, the majority was installed in 1950’s
and 1960’s. With a design life 60- 70 years, age induced degradation and failure of the UK MV
systems is becoming increasingly prominent in the minds of plant owners and operators.
In this paper, the authors will discuss the business case for online PD monitoring vs. off-line
and compare on-line vs. off-line PD monitoring in MV cables. The paper will also present
Wavelet-based denoising techniques as applied to on-line PD test data with examples of
analysis and interpretation of practical, inservice data. The effectiveness of the Wavelet-based
technique in comparison with other techniques such as the matched filters and the traditional
filters will be discussed. Finally challenges for the employment of large amount of PD data for
degradation diagnostics purposes will be discussed.
Index Terms-- Cables, Denoising, MV cables, Partial Discharge, Wavelet Transform.
Radiometric Partial Discharge Detection
Martin D. Judd
Electrical Plant and Diagnostics Group, Institute for Energy and Environment,
University of Strathclyde, Glasgow, UK
*E-mail : m.judd@eee.strath.ac.uk
Abstract—Radio frequency (RF) detection of partial discharges (PD) is a long-established
principle, being described in the international standard for partial discharge measurement. The
growing market for mobile communication devices in recent years has led to big reductions in the
cost of electronic hardware operating in the VHF and UHF bands, making advanced
measurements of PD in these bands increasingly affordable. Some 20 years ago, ultra-high
frequency methods for PD detection were pioneered in gas-insulated substations (GIS) and have
since become widely accepted. Locating PD in GIS is essentially a onedimensional problem. More
recent research into PD location in power transformers, also using the UHF method, has had to
address the more challenging problem of PD location in threedimensions.Both the GIS and
transformer applications monitor enclosed volumes, where the PD is within a metalclad system
that traps the signal and provides good screening of external RF interference. At the same time,
other researchers have developed RF detection and location systems for open environments, such
as complete air-insulated substations. When deployed in a fixed installation or a surveying vehicle

equipped with GPS, this system is capable of monitoring insulation defects as they develop, and
provides a location capability using sophisticated signal processing. This paper begins with an
overview of some aspects of radiometric monitoring techniques and goes on to outline some
research challenges which it is hoped will attract the attention of the many researchers who are
continuing to advance the areas of radiometric PD detection, measurement and location
technology.
Index Terms—Partial discharge, radiometric techniques, condition monitoring, fault location, UHF,
VHF, couplers, sensors, antennas.
Sensitivity Check for Radio Frequency Partial Discharge Detection
for Power Transformers
Sander Meijer1*, Martin D. Judd2 and Stefan Tenbohlen3
1 Delft University of Technology, Delft, Netherlands
2 University of Strathclyde, Glasgow, United Kingdom
3 University of Stuttgart, Stuttgart, Germany
*E-mail : s.meijer@tudelft.nl
Abstract--Power and distribution transformers form important components in the electricity
grid. Failure of such important components can give rise to high costs (such as costs for repair
and cost for non-delivery). Therefore methods to determine the risk of failure of transformers
are of importance. It is known that failure due to insulation defects is often preceded by
partial discharge activity. Over recent years, on-line diagnostic means for power
transformers have been investigated. In this paper the sensitivity of one of these methods, the
UHF PD detection technique, has been analyzed on several transformers. From these
experiments, the sensitivity of the UHF technique to detect partial discharges in power
transformers has been established. Based on these results, a sensitivity check similar to the
one used for GIS is proposed in this paper. Some of the additional challenges posed by the
transformer structure will be discussed in terms of their effect on the detection sensitivity that
is needed and the PD levels that might be present while transformers are in service. Some
alternative practical methods for applying the technique during on-site tests will also be
outlined
Index Terms—Power Transformer, Partial Discharges, Ultra- High Frequency, Sensitivity
Check, Non-Conventional Detection
Attenuation of UHF signals regarding the Sensitivity Verification for
UHF PD Measurements on Power Transformers

S. Coenen1*, S. Tenbohlen1, S.M. Markalous2, T. Strehl2
1 Institut für Energieübertragung und Hochspannungstechnik (IEH), Universität Stuttgart,
Pfaffenwaldring 47, 70569 Stuttgart, Germany
2 LDIC GmbH, Zschoner Ring 9, 01723 Kesselsdorf, Germany
*E-mail : Sebastian.Coenen@ieh.uni-stuttgart.de
Abstract--The reliability of electrical energy networks depends on the quality and availability
of electrical equipment like power transformers. Local failures inside their insulation may
lead to catastrophic breakdowns and might cause high outage and penalty costs. To prevent
these destroying events power transformers are e.g. tested on partial discharge (PD) activity
before commissioning and currently also during service. The current work deals with the
electromagnetic PD detection method, also known as the UHF-Method. The disadvantage of
the UHF-Method is still the missing possibility for a calibration or at east a verification of the
sensitivity. The so-called Sensitivity Check might show in future a relation between
unconventionally measured UHF quantities to the PD apparent charge level in pC. An import
aspect is the attenuation of UHF signals within power transformers which is investigated in
this paper.
Index Terms--Power Transformer, Partial Discharges, Ultra High Frequency, UHF Method,
UHF Probe, Sensitivity Check, Unconventional Detection
Experimental Study and Feature Extraction on UHF Partial
Discharge Detection for Typical Model in Air
Abstract--In this paper, in order to represent three kinds of typical partial discharge
respectively happened in dielectric, out of dielectric and surface of dielectric, five kinds of
typical partial discharge models, which included needle to plate, needle to needle, plate to
plate, surface and air void, were designed and manufactured with aluminum. Based on the
designed models, an experiment system of ultra high frequency partial discharge detection
was comprised with non-partial discharge transformer, 2.5GHz bandwidth oscilloscope,
broad band amplifier and the developed double helical antenna. Afterwards, partial
discharge experiments were carried out in air, and the method recommended in IEC60270
was referenced to measure the apparent quantity of partial discharge in pC. The
experimental waveforms were given out. At last, the characteristics of the ultra high
frequency signals excited by partial discharge were analyzed in time domain, frequency
domain and wavelet coefficients. Using kernel principal component analysis, the feature
extraction was realized. Then, several characteristics, which included deflection, protruding,
frequency distributing, decay time, wavelet coefficients and so on, were proposed to describe
the ultra high frequency signals. The conclusion educed in this paper is significant to research
the feature extraction and pattern recognition of ultra high frequency partial discharge
detection for high voltage apparatus.
Index Terms--partial Discharge Detection, High Voltage Power Apparatus, Typical Model,
Ultra High Frequency Method, Features Extraction, Kernel Principal Component Analysis.

Propagation Properties of PD-induced Electromagnetic Wave
Through L-shaped Structure in model GIS measured with UHF
sensors
K.Omori1, M.Sawada1, S.Isejima1, S.Ohtsuka1, H.Ikeda1, M.Hikita1G.Ueta2, S.Okabe2,
T.Hoshino3,
S.Maruyama3 and T.Sakakibara3
1Kyushu Institute of Technology, 1-1 Sensui-cho, Tobata-ku, 804-8850 Kitakyushu, Japan
2Tokyo Electric Power Company, 4-1 Egasaki-cho, Tsurumi-ku, Japan
3Toshiba Corporation,2-1Ukishima-cho,Kawasaki-ku, 210-0862 Kawasaki,Japan
Email adress:g346414k@tobata.isc.kyutech.ac.jp
Abstract--The authors have studied insulation diagnostic technique of gas-insulated
switchgear (GIS) by UHF method. It is known that PD-induced electromagnetic wave is
affected by a discontinuity part of impedance such as L-shaped structure, spacers and so on.
In this paper, we experimentally investigated influence of L-shaped structure on propagation
properties of PDinduced electromagnetic wave measured with UHF sensors in a 66 kV model
GIS. Focusing on reflecting properties of TE mode at the L-shaped structure, we discussed
the effects of the Lshaped structure on the peak to peak amplitude Vpp of propagating
electromagnetic wave by comparing the experimental results obtained under straight type
GIS. As a result, it was found that TE mode component could be reflected at the L-shaped
branch, which can result in increasing Vpp due to the superimpose of the reflected TE mode
to TEM mode component depending on the distance between sensor position and L-shaped
branch.
Index Terms--gas insulated switchgear (GIS), partial discharge induced electromagnetic wave,
electron magnetic wave mode, L-shaped structure
Partial Discharge Monitoring in a Noisy Environment
A. M. Gaouda1, A. H. El-Hag2 and M. M. A. Salama3
1 United Arab Emirate University, Al-Ain, UAE
2 American University of Sharjah, Sharjah, UAE
3 University of Waterloo, Waterloo, Canada
agaouda@uaeu.ac.ae
Abstract-- Defining the resolution levels where a PD signal is localized and selecting an
automated threshold values for on-line de-noising and measurement are the main challenging
task in wavelet multi-resolution analysis (WMRA) application for PD detection and
measurement. This paper proposes a new waveletbased technique for monitoring PD signals

embedded in high noise levels. The data is decomposed while sliding into Kaiser's window.
Only the maximum coefficients extracted at each resolution level are used to extract the PD
signal from noise and measure its magnitude. No thresholding or reconstructions of the
thresholded coefficients are required. The extracted data-size of PD signal is very small as
compared with actual signal. The proposed monitoring technique is applied on simulated
data and laboratory data and gave good results. The simulated data are constructed by using
real noise collected from laboratory measurements.
Index Terms—Partial discharge, de-noising, wavelet.
Design and Testing of UHF Sensors for Partial Discharge Detection in
Transformers
J. Lopez-Roldan1*, T. Tang2 and M. Gaskin2
1 Powerlink Queensland, Australia
2 Queensland University of Technology, Australia
*E-mail : jlopez-roldan@powerlink.com.au
Abstract-- Fifteen years since the first application of the UHF method for Partial Discharge in
Gas Insulated Switchgear, this has become widely used and the preferred method for PD
diagnostics in GIS. Same technique is currently starting to be applied for onsite PD testing of
Power Transformers. Significant advantages of this UHF method include the reduction of
background noise and the possibility of on-line testing. It does provide a relief of background
noise by selecting a working freq uency band where interference is minimal or absent. In
order to apply this technique to power transformers in service, a specific UHF sensor which
can be fitted in a transformer without the need of a power outage has been developed. The
process followed to design several suitable sensors and the experimental tests chosen to select
and validate the best of these designs are presented in the paper.
Index Terms-- Transformers, Partial Discharges, UHF method, sensor design, antennas.
Wide and narrow band PD detection in plug-in cable connectors in
the UHF range
Abstract--Experience in on-line UHF partial discharge detection on high voltage plug-in cable
connectors (terminations) for GIS and transformers are presented. Narrow vs. broadband,
as well as zero-span measurements were carried out using a spectrum analyzer on a
laboratory setup with a built-in artificial PD defect of variable intensity. A sensitivity below 5
pC turned out to be detectable by the presented UHF method. The results of the laboratory
experiments demonstrate high effectiveness of the on-line UHF PD detection in plug-in cable
terminations. The method can be applied to proof the quality of assembly work during

commissioning as well as on a regular basis after many years in service to detect aged and
risky terminations as a part of the condition-based maintenance.
Index Terms--Cable termination, on-line diagnostics, partial discharge, UHF,
wide/narrowband.
Methods for Distinguishing between Partial Discharges based on the
UHF Detection Technique
T. Pinpart*, J.E. Fletcher and M.D. Judd
Department of Electronic and Electrical Engineering, University of Strathclyde, Glasgow, UK.
*E-mail: tanya.pinpart@eee.strath.ac.uk
Abstract— Partial discharges (PDs) are a cause of concern in power systems. Many detection
methods and analysis techniques for PDs are available, such as UHF detection, conventional
IEC 60270 method, acoustic detection, etc. This paper focuses on analysing signals obtained
by the UHF method in order to distinguish between different sources of PD. Two methods
based on the frequency and time characteristics are investigated with the aim of testing PD
recognition based on the calculation of similarity or difference of two UHF signals. It has
previously been shown that PDs can be recognized by a similarity function based on a
time-frequency representation constructed using a wavelet transform. However, this is a
computationally intensive process that needs to be simplified for practical implementation.
Two new approaches are investigated in this paper. The first method uses spectrogram
analysis to represent the UHF signal in terms of time, frequency and amplitude, from which
a few key features can be extracted. The second method uses a smoothing kernel to capture
the envelope of the UHF signal, effectively reducing the quantity of data to be analysed. The
results from the two methods of comparing PD signals are discussed to determine their
ability to measure similarity, while the results of non-PD signals are compared to show the
different behaviours between PD and non-PD signals.
Index Terms-- Partial discharges, Similarity calculation, Spectrogram, UHF technique.
Generation of UHF Band Aerial Noise in HVSubstation and its
Invasion Properties into GIS
S.Ohtsuka1, K.Omori1, S.Isezima1, H.Ikeda1, M.Hikita1,
T.Hoshino2, S.Maruyama2, Y.Taniguchi2, T.Sakakibara2
1 Kyushu Institute of Technology, 1-1 Sensui-cho, Tobata-ku, 804-8550 Kitakyushu, Japan
2 Toshiba Corporation, 2-1 Ukishima-cho, Kawasaski-ku, 210-0862 Kawasaki, Japan
Abstract-- This paper describes the GHz order electromagnetic (EM) wave generator we have
developed that simulates UHF band aerial noise occasionally measured in HV substation.

Using this generator and the model GIS, we investigated the invasion properties of such UHF
band aerial noise into the model GIS by changing the location of the generator, i.e. partial
discharge (PD) source. As a result, PDinduced EM wave generated outside GIS can invade
into GIS inside with GHz order frequency component if PDs were generated near the GIS
components worked as an aperture for EM wave
Index Terms-- Insulation diagnosis, UHF band, Aerial discharge,GIS
Experimental investigation of positional accuracy for UHF partial
discharge location
Abstract—UHF methods for locating partial discharges (PD) in power transformers are
under development and are increasingly being applied in the field. Due to the complexity
and variation of internal structures in power transformers, a useful starting point is to assess
the accuracy of PD location in a simple environment. Therefore, tests have been carried out
in a metal tank to assess the difference between calculated and actual positions of a PD
source when the source is located at various positions within the tank. The tank was fitted
with three UHF sensors. A contact discharge test cell was used to generate PD–type current
pulses that excite UHF signals. Signals from each sensor were captured and their recorded
differences in arrival time at the sensors were compared with expected time differences
based on the known coordinates of the PD source and sensors. Two methods for estimating
the onset point of the UHF signal at each sensor were evaluated, using experimental data as
a basis for determining which technique might be most useful for locating PD.
Index Terms—Power Transformers, partial discharge location, UHF, sensors.
Sensitivity Analysis of RF Measurements to Detect PD in Power Cable
Accessories
1 Delft University of Technology, Delft, Netherlands
2 Seitz Instruments A.G., Niederrohrdorf, Switzerland
3 Prysmian Cables and Systems B.V., Delft, Netherlands
*E-mail : s.meijer@tudelft.nl
Abstract-- The VHF/UHF PD detection technique is a nonintrusive method for power cable
PD diagnostics. It incorporates a VHF/UHF current probe placed at the grounding of the
cable and a measuring device (e.g. spectrum analyzer or tunable filter) connected to the probe.
This way it is possible to obtain phase resolved patterns with very high signal to noise ratio.
For successful narrow-band PD measurements at HF/VHF/UHF parts of the spectrum,
basically three things are necessary: 1) a proper transfer of the concerning centerfrequency
through the object under test and the sensor system, 2) low ambient noise in the frequency

spectrum around this frequency and, most important, 3) presence of PD frequencies around
the center frequency. The paper presents aspects related to a sensitive PD detection, based on
theoretical models which have been validated on an actual high voltage power cable. Secondly
the paper shows examples of partial discharges in a power cable system due to different
insulation defects. Important phase resolved patterns of certain insulation defects will be
presented in frequency and phase-resolved domain and will be compared to measurements
according to the IEC60270 requirements.
Index Terms--After-laying testing, Non-Conventional Detection, Partial Discharges, Power
Cable, Radio Frequency Detection, Sensitivity Check
Propagation Characteristic Study of Partial Discharge UHF Signal
outside Transformer
LI Jun-hao, SI Wen-rong, YUAN Peng, LI Yan-mu, LI Yan-ming
School of Electrical Engineering, Xi’an Jiaotong University, Xi’an 710049
E-mail:xjtuhvljh@gmail.com
Abstract-- In the UHF detection of power transformers, the main method is detecting the UHF
signals through UHF sensor in the transformer. The sensibility of this method is high but
mounting way is trouble. Field detection and lab testing show that the UHF signals can
diffract from the transformer’s joint. Some PD detector using external detection has used in
field. But, the difference of signals in transformer and external transformer is not clear. In
this paper, the feasibility of using external UHF sensor for detecting partial discharge
activities is discussed, and then external propagation characteristic of UHF E-M wave is
studied by lab experiments. Wavelet packet analysis of signals show the high frequency of
external signals is bigger than inside signals. The relationship of distance of joint and UHF
sensor is studied in this paper. The results show that UHF signals could leak outside the
transformer through the joints after multiple refraction and reflection in the transformer
tank. An antenna outside the tank could receive the signals. Study result will supply some
signal acquisition direction for the UHF detection transformer PD.
Key words-- partial discharge, UHF signal, external detection, power transformer
UHF Characteristic of PD in Oil-Paper Insulation under DC Voltage
Wenrong Si, Junhao Li, Peng Yuan and Yanming Li
School of Electrical Engineering, Xi’an Jiaotong University, Xi’an 710049, China
*E-mail : siwenrong@gmail.com
Abstract--A test system with UHF and UWB detection technologies developed to measure PD
under DC voltage is introduced in this paper. According to the typical defects in oilpaper
insulation of converter transformer, six corresponding PD models are designed. The test

esults of PD UWB detection under DC voltage show that the PD current pulses have a very
short rise-time, which are capable of radiating UHF signals at frequencies up to at least 300
MHz, and these electrical magnetic waves can be picked up by the UHF sensor. The DBM
spectrum analysis is made for all UHF signals of the models, which shows that they differ with
various defects, and the maximum amplitudes of the energy distribution against the UHF are
also different. These indicate the on-line monitoring for the UHF PD signal under DC voltage
should be realized utilizing the narrowband filter with adaptive center frequency.
Index Terms-- PD, UHF detection, DBM spectrum, DC, oilpaper Insulation.
Application of Cross-correlation Denoising Algorithm for UHF
Partial Discharge Detection
Boxue Du, Yuhang Lu and Yangcheng
Tianjin University Tianjin, 300072, China
*E-mail : duboxue@tju.edu.cn
Abstract--For insulation condition assessment of HV power apparatus, partial discharge (PD)
monitoring is one of the most effective techniques. However, on-line PD measurements are
affected by high levels of electromagnetic interference (EMI) that makes sensitive PD
detection very difficult. On the basis of crosscorrelation algorithm, this paper described a new
PD extraction method which can reject noise from weak UHF signal. According to the
analysis of PD feature, a double exponential model was setup. Then a damped oscillatory
pulse (DOP) based on this model was applied for cross-correlation calculation with the test
signal. In order to stimulate the noisy on-site testing environment, narrow band interference
and Gaussian white noise was used in the laboratory tests. The noises have been successfully
eliminated because the signal and noise was incorrelate with each other. The denoising
performance of cross-correlation algorithm was analyzed by Signal-to-Noise (SNR) and
correlation coefficient. The results showed that the method was effective in rejecting noise in
high levels of interference environment. In addition, PD pulse integrity has been greatly
improved.
Index Terms--cross-correlation algorithm; denoising; interference; irrelevancy; partial
discharge; power equipment; self-correlation algorithm; UHF;
Study of Time Delay of UHF Signal Arrival in Location Partial
Discharge
Yang Jing-gang, Li Da-jian, Li Junhao, Yuan Peng, Li Yan-ming
School of Electrical Engineering, Xi’an Jiaotong University, Xi’an 710049

E-mail : huziyang@stu.xjtu.edu.cn
Abstract--In the study of Location Partial Discharge in transformer based on the UHF method,
in order to accurately locate partial discharge source, precisely achieving time delay of
different signals which are received by different UHF sensors and radiated from the same
partial discharge source is essential. Three methods of time delay estimation are introduced
and compared, including the initial peak, the inflection point of cumulative energy curve,
cross correlation, and the measures of signal de-noising based on the wavelet transform and
cubic splines interpolation are introduced to optimize the methods mentioned above. Then
the pin-to-flat electrode model and the wedge model are adopted respectively to experiment
these
methods. Results demonstrate that absolute error between the time delay estimation through
optimized cross correlation and the time delay in theory, which is less than 30ps, is the least
among the errors through other methods mentioned above, and the optimized cross
correlation analysis can achieve the highest precision among other methods and can be used
to accurately locate partial discharge source.
Index Terms--Partial Discharge (PD); Time Delay of Arrival (TDOA); Time Delay Estimation;
Cross Correlation
On-line PD monitoring system for rotating machines using narrow
band detection of EM wave in GHz range
Abstract--On-line PD monitoring system with higher sensitivity and low noise features was
developed for rotating machines such as turbine generator and high voltage motor. By using
narrow band detection in GHz region, the features were achieved. The system is composed of
an antenna, a specifically designed signal processing circuit and data acquisition equipment.
The antenna is so-called patch antenna and its dimension is approximately 120x120mm and is
designed for detecting a specific narrow band frequency in GHz range. This type of antenna
is very easy to install because the thin plate structure does not interfere other high voltage
parts inside the rotating machine if installed on the inner wall of the machine housing. The
antenna is connected to the amplifier adjusted for the frequency band of the antenna
resulting in superior noise suppression. The sensitivity of the system was measured and
confirmed to have a good linear correlation with conventional off-line Qmax value from
several hundreds pico Coulomb. This sensitivity is enough for on-line insulation monitoring
for rotating machines because the low level PD activity during operation does not infer
abnormality of the machines.
Index Terms-- Coils, Diagnosis, Generators, Insulation, Micro strip antennas, Motors, Partial
discharges
Study of Anti-interference Technology for UHF PD-Detection in

Power Transformers
P.Yuan, X.H.Zhao, J.G.Yang,J.H.Li, W.R.Si,Y.M. Li
Xi’an Jiaotong University, Xi’an, 710049, China
E-mail: Y5anpeng@126.com
Abstract--In this paper, the anti-interference technology for UHF PD-detection in power
transformers is described. When we detect PD on power transformers using an UHF PD
online monitoring system made by us, several kinds of interference signals are found in
substations in China. The interference signals may cause that the sensitive of the measuring
system get lower and the system give out a wrong indication. The interference signals include
GSM mobile signal, TV and communication and some other signals with certain frequencies,
partial discharges of other power equipments that are near the equipment to be measured.
According to the characteristic of the interference signals, the solving methods are found to
avoid to be influenced during the measurement. The new UHF PD online monitoring system
with the methods of anti-interference can get rid of every pulse that is not created by the
power transformer to be measured. The results show the methods are available and effective..
Index Terms--anti-interference technology, UHF PDdetection, power transformer
A Novel Complex Algorithm for Denoising Partial Discharge Signals
Sang-Hwa Yi1*, Young-Woo Youn1, Sang-Bo Han1 and Dong-Sik Kang1
1Industry Applications Research Laboratory, Korea Electrotechnology Research Institute (KERI)
* e-mail: shyi@keri.re.kr
Abstract--This paper introduces an evaluation code, which can numerically express the noise
possessing degree of signals. By using this code, the best kind and setting of noise suppressing
techniques can be chosen automatically. This code is applied to three kinds of specific
denoising techniques; those are simple noise removing method in the count versus phase
distribution, fuzzy logic method based on noise type in magnitude versus phase plot, and
lastly, the technique using grouping characteristics of PD pulses in 3D plot of magnitude
versus phase versus cycle. The algorithm shows good performance in the various real PD
signals measured from various high voltage apparatuses in Korea.
Index Terms--Noise, Partial discharges, Software.
A Wavelet Transform Technique for De-noising Partial Discharge
Signals
Vidya H.A1, V. Krishnan1 and Mallikarjunappa K2
1 M S Ramaiah Institute of Technological , Bangalore, India
2 Central Power Research Institute, Bangalore, India

*E-mail : vidyakrishna_ag@yahoo.co.in
Abstract--Partial discharge (PD) diagnosis is essential to identify the nature of insulation
defects causing discharge. The problem of PD signal recognition has been approached in a
number of ways. Most of the approaches are based on laboratory experiments or on signals
acquired during off-line tests of industrial apparatus. On-line testing is vastly preferable as
the equipment can remain in service, and the operators can monitor the insulation condition
continuously. Interferences from noise sources have been a persistent problem, which have
increased with the advent of solid-state power switching electronics. Use of wavelet transform
technique offers many advantages over conventional digital filters and is ideally suited to
process nonstationary signals (transients) often encountered in high voltage testing and
measurements. In this paper, an empirical waveletbased method is proposed to recover PD
pulses mixed with excessive noise/interference. A critical assessment of the proposed method
is carried out by processing simulated PD signals along with noise signals using MAT LAB
software.
Index Terms--Continuous wavelet transforms, Discrete wavelet transforms, Interferences,
Multi resolution analysis, Multi resolution decomposition, Noise, Partial discharges,
Quadrature mirror filter, Mother wavelet, Signal denoising.
Experience of GIS Condition Diagnosis using Partial Discharge
Monitoring by UHF Method
Masatomo Ono1, Yoshimune Matsuyama1, Nobuko Otaka1*, Tokio Yamagiwa1 and Tatsuro Kato2
1Japan AE Power Systems Co., Nishi-Shimbashi, Minatoku, Tokyo, 105-0003 JAPAN
2 Hitachi, Ltd, Hitachi-shi, Ibaraki, 316-8501 JAPAN
* E-mail: Otaka-nobuko@mb.jaeps.com
Abstract-- Partial discharge (PD) monitoring system by UHF method is suitable for internal
condition diagnosis of gasinsulated switchgear (GIS) due to its high sensitivity. We have
developed the UHF method diagnostic system, which uses the neural network. Through the
experience of using PDM system, we have built confidence in its performance. The GIS
condition diagnosis using PDM by UHF method is quite useful on site. This paper describes
outline of our PDM system and also introduces some examples of our experiences during both
factory test and on-site test with which we have ensured advance diagnoses for insulation
reliability of GIS.
Index Terms-- Partial-Discharge, UHF-Method, Partial- Discharge-Monitoring for GIS,
Transfer Function as Tool for Noise Suppression and
Localization of Partial Discharges in Transformers
during On-site Measurements
E. Gockenbach, H. Borsi

Leibniz Universität Hannover, Schering-Institut
Callinstr. 25A, 30167 Hannover, Germany
*E-mail : gockenbach@si.uni-hannover.de
Abstract—Partial discharge (PD) measurements are one the most important non destructive
test methods to evaluate the integrity of the insulation system of power transformers. PD
measurements on site are strongly influenced by noise and besides the level of the PD activity
the location of the PD source is of importance. Using the well known transfer function from
transformer impulse tests the variation of the PD signal travelling trough the transformer
winding are the basis for the separation between noise and PD signals and also for the
localization of the PD source. Laboratory tests show very good results. With a simple
capacitive coupler and signal transmission via fibre optic cable the system can also be used
satisfactorily on site.
Index Terms--High voltage technique, Partial Discharge measurement, Noise suppression,
Localization
Enhanced Signal Processing for Conventional and Unconventional PD
Measuring Methods: Wavelet De-noising, Automatic Detection
Algorithms and Averaging for Arrival Time-based PD Location in
Transformers and Power Cables
Sacha Markalous1*, Thomas Strehl1, Christoph Herold2 and Thomas Leibfried2
1 LDIC GmbH, Kesselsdorf, Germany
2 Institute of Electrical Energy Systems and High Voltage Technology, University of Karlsruhe,
Karlsruhe, Germany
*E-mail : markalous@ldic.de
Abstract--Two major tasks of partial discharges (PD) measurements may be distinguished, (i)
providing general evidence and the type of PD (detection) and (ii) the location of the PD.
Dependent on the type of device under test the two issues have changing priority. For the
on-line/on-site PD location in power transformers unconventional PD measuring methods
like acoustic ultra-sonic measurements or electromagnetic measurements up to the UHF
(ultra high frequencies) range are performed, while the Time Domain Reflectometry (TDR)
of electric PD signalsis a standard technique for the location of PD in power cables.
Index Terms--partial discharges, electromagnetic interference, location, signal detection,
delay estimation, time domain reflectometry, wavelet transforms, power transformers,
power cables.

Sensor Response Characteristics for UHF Location of PD Sources
Philip J. G. Orr, Alistair J. Reid and Martin D. Judd*
Institute for Energy and Environment, University of Strathclyde, Glasgow, UK
*E-mail : m.judd@eee.strath.ac.uk
Abstract--Ultra-high frequency (UHF) systems are well established for monitoring partial
discharges (PD) in gasinsulated substations (GIS) and are increasingly being used on power
transformers. Different sensor designs such as disk sensors, spiral sensors, monopoles and
dipoles have been used depending on the application. A primary concern is to ensure that the
sensitivity of these different sensors can meet the CIGRE requirement for detecting 5 pC
partial discharges GIS. Recent work on locating PD in power transformers has focused
attention on recording the arrival time of the received UHF signal, which is important for
locating insulation defects in three dimensions. An accuracy of 1 ns or better is desirable for
time-of-flight measurements to locate a PD source. In some situations, a clear arrival time for
the signal can be identified but in other cases the arrival time can be uncertain within a
tolerance of several nanoseconds. Therefore, a number of sensors were tested for their speed
of response using a transient calibration system. Results suggest that more complex sensor
structures have a slower build-up of energy at their output, while simple sensors exhibit less
of a 'blurring' effect on the leading edge of the signal.
Index Terms--Partial discharges, fault location, UHF, couplers.
Development and on-site application of UHF PD detection system to
estimate the insulator condition of MV switchgear
D. M. Kim2, K. J. Lim3
1 Electrotechnology R&D center, LS Industrial systems
2 Korea Electric Power Corporation (KEPCO)
3 Chungbuk National University
*E-mail : wjkang@lsis.biz
Abstract-- Defects in the SF6 medium voltage (MV) switchgear can result in failure. Therefore
it is important to detect defects, such as protrusions and particle, in time and to determine
their risk for a possible breakdown. For high voltage apparatus, the ultrahigh frequency
(UHF) partial discharge (PD) detection technology has proven to be a sensitive method. In
this contribution the development of UHF PD detection system for the MV switchgear and its
application are described. Experimental studies show that the PD detection of the MV
switchgear defects is possible
Index Terms—MV Switchgear, diagnosis, UHF PD

Recent Progress and Future Perspective on Condition Monitoring and
Diagnostic Techniques For Power Equipments in China
Li Chengrong, Tang Zhiguo, Zheng Zhong
Beijing Key Laboratory of High Voltage & EMC
Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control,
Ministry of Education
North China Electric Power University, Beijing, China, 102206
*E-mail : lcr@ncepu.edu.cn
Abstract-- Under the general backgrounds of fast development of economy, China’ power
industry is undergoing a new upsurge of infrastructure construction. With the urgent need of
the whole society for reliable power supply, Condition Based Maintenance strategy is
becoming the mainstream of the operation and management of the power system. In this
paper, recent progress of Condition Monitoring and Diagnostic technologies for major power
apparatus are reviewed. Also, some statistical data on practical on-line monitoring
applications in China are introduced. At last, the key problems and trends of CMD are
discussed with a viewpoint future perspective.
Index Terms--Condition Based Maintenance; On-line Monitoring; Power Apparatus; Fault
diagnosis
Insulation Condition Assessment of Power Equipments in Electrical
Assets Based on On-line Monitoring of Partial Discharges
G. C. Montanari, A. Cavallini Dept. of Electrical Engineering, University of Bologna Viale
Risorgimento 2, 40136 Bologna, Italy giancarlo.montanari@unibo.it
Abstract – Partial discharge (PD) measurements performed online can provide important
information regarding insulation system reliability. However, PD detectors suitable for online
measurements (or monitoring) should be endowed at least with tools that are able to deal with
noise and multiple PD sources. PD source identification tools that can exploit data streams
from other sensors are, moreover, very important in order to provide an accurate failure risk
assessment. This paper gives specifications about PD detection systems suitable for
monitoring purposes, describes a detector that fits these requirements and provide examples
of processing and analysis of PD data detected on in-service apparatus. Index terms – Asset
management, monitoring, condition assessment, insulation systems, partial discharges.

Recent Progress and Future Perspective on Condition Monitoring and
Diagnostic Techniques for Power Equipment in Japan
Hitoshi Okubo
Nagoya University, Nagoya, Japan
E-mail : okubo@nuee.nagoya-u.ac.jp
Abstract- In this paper, recent progress in condition-monitoring and diagnostic techniques for
power equipment in Japan is reviewed and discussed with a future technical perspective. In
particular, the dissolved gas-in-oil analysis (DGA) technique for power transformers and the
UHF partial discharge detection technique for gas insulated systems are introduced in order
to both enhance measurement reliability and optimize total cost, as effective methods for
maintaining the equipment. Moreover, the combined and systematized application
techniques are explained and discussed, together with fundamental research on partial
discharge mechanisms from the viewpoint of diagnosis evaluation criteria.
Index Terms—Maintenance, Condition monitoring, Diagnosis, Power equipment,
Transformer, Gas insulated switchgear (GIS), Partial discharge (PD), Breakdown (BD),
Dissolved gas-in-oil analysis (DGA), Power system, Integrated grid management system
(IGMS)
Recent Progress and Future Perspectives on Condition Monitoring
and Diagnostics for Power Equipment in Korea
Kyu-Bock Cho1, Kee-Joe Lim2*, Dong-Sik Kang3, Hyun-Hoo Kim4,and Il-Keun Song5
1 Dept. of Electrical Engineering, Hanseo University, Haemi, Seosan, Chungnam, Korea, 360-706
2 School of Electrical and Computer Engineering, Chungbuk National University, Cheongju,
Chungbuk, Korea, 361-763,
3 Power Facilities Diagnosis Research Group, Korea Electrotechnology Research Institute,
Changwon, Gyeongnam, Korea, 641-120
4 Display Engineering Division, Doowon Institute of Technology, Paju, Kyeonggi, Korea, 413-861
5 Power Distribution Laboratory, Korea Electric Power Research Institute, Daejeon, Korea,
305-380
*E-mail : kjlim@cbnu.ac.kr
Abstract--Recent R&D progress on condition monitoring and diagnosis for power apparatus
such as substation equipments including GIS and main transformer, rotating machineries
including hydro-generator, turbo-generator, and HV motor, and power distribution
equipments including power cable, overhead line system and lightning arrester, and so on in
Korea are investigated in this paper. The fields experiences on the CMD carried out by

KEPCO are also introduced.
Index Terms--Algorithm for diagnosis, Asset management, Condition monitoring and
diagnosis for power facilities, CBM, Monitoring sensor, Diagnosis for substation facilities,
Diagnosis for distribution facilities, Diagnosis for rotating machinery, Predictive maintenance,
TBM, RCM.
Insulation Condition Assessment of HV Cables
Abstract-- In the rapidly developing countries, there is an obvious trend of increasing utilisation of
underground HV cables rather than overhead lines. The requirement of safe and reliable cable
operation calls for a sound and extensive knowledge in the condition monitoring and maintenance
of power cables. In this paper, are presented some important condition assessment techniques
approved in industrial practices in Singapore and Australia will be discussed including partial
discharge (PD) detection and location, DGA incipient fault diagnosis, hotspot detection, mitigation
and dynamic rating management and destructive/non-destructive tests for distribution cables.
Index Terms-- Power Cable, Condition Assessment, condition Monitoring, Diagnosis, Incipient
Fault.
Estimation of Transmission Line Parameters for Single-Core XLPE
Cables
Abstract -- A power cable model for partial discharge (PD) pulse propagation requires
knowledge of all factors influencing the transmission line parameters of the cable
(characteristic impedance, attenuation coefficient and propagation velocity). These
frequency dependent quantities depend, amongst others, on the dielectric properties of the
semi-conducting layers. For existing power cable connections, but often also for newly
manufactured cables, these quantities, which vary between different cable types, are not
known with acceptable accuracy. This paper discusses methods to estimate the characteristic
impedance and propagation velocity using the cable geometry and the dielectric properties
of XLPE, but without using the dielectric properties of the semiconducting layers.
Measurements on cable samples show that these approximations are valid with sufficient
accuracy. The attenuation of PD signals can only be accurately predicted with detailed
knowledge of the dielectric properties of the semi-conducting screens.
Index Terms –-modeling, parameter estimation, power cables, transmission lines, cross linked
polyethylene insulation.

On-site Application of Dielectric Response Diagnosis on Service Aged
Oil-impregnated HV Power Cables
Piotr Cichecki1*, L.P.A. Onderwater 1, Edward Gulski1, J.J Smit 1, P.P. Seitz2 and F.de Vries3
1 Delft University of Technology, The Netherlands
2 Seitz Instruments, Switzerland
3 NUON, The Netherlands
*E-mail : p.cichecki@tudelft.nl
Abstract--Knowledge rules for paper/oil insulated High Voltage (HV) power cables are
necessary to support asset management decision processes. For development of these
knowledge rules investigation has been done into a diagnostic method, for integral condition
assessment of paper/oil insulation to DC voltage charging. This method is called the
Recovery
Voltage Measurement and is based on the dielectric response of cable insulation. In the
Recovery Voltage (RV), parameters have been investigated on possibility to indicate
insulation degradation. In this paper single and periodic measurements with different
temperatures have been performed. These measurements result in the conclusion that an
increase in insulation degradation can be observed by selected recovery voltage parameters
as well as dielectric losses behavior in function of test voltage. Measurement results of HV
power cables performed at two temperatures can be used in line with dielectric losses
measurements to support condition assessment.
Index Terms-- condition assessment, dielectric losses measurements, HV power cable,
insulation degradation, paper/oil insulation Recovery Voltage Measurement.
High Precision Methods for Online Measurement of Capacitance in Power
Capacitors
Henning Fuhrmann1* and Tord Bengtsson2
1 ABB Switzerland, Corporate Research
2 ABB Sweden, Corporate Research
*E-mail : henning.fuhrmann@ch.abb.com
Abstract-- In the development of metallized film power capacitors, accelerated aging
experiments are carried out in order to predict the lifetime of a capacitor under nominal
operating conditions. For metallized film capacitors the decrease of capacitance with time is
very small even in accelerated aging. Consequently, these experiments require extremely
precise measurement methods for the capacitance. We have developed two different
approaches for the precise calculation of the capacitance from voltage and current data
measured during aging. The first method works with calculations in the time domain,
whereas the second method works with Fourier transforms of the data. In this paper, we
show results of long term measurements on power capacitors during which both

measurement methods were applied in parallel. Both methods permit to measure the
capacitance with a relative statistical error of only 4·10-5. We show that at this low noise
level, even small capacitance changes caused by the temperature dependence of the dielectric
constant together with small voltage fluctuations become measurable.
Index Terms--Capacitance measurement, power capacitors, thin film capacitors, aging
Advanced Solution for On-site Diagnosis of Distribution Power
Cables
Abstract--This paper describes important aspects of PD diagnostics of distribution power
cables. PD parameter were discussed under consideration of attenuation and dispersive
effects of cable characteristics. Field experiences with PD diagnosis on PILC and XLPE
cables by energizing with Damped AC Voltage demonstrate relevant demands and the
effective outcome for asset management decision support. The main difficulty is to evaluate
the risc of PD occurrences on the reliability of the cable system. If an sufficient amount of
PD diagnostic data for the cable components is available statistical methods can be used for
determing threshold levels and relevant condition indexes for the asset management.
Index Terms--Power cables, partial discharges, PD pulse attenuation, dispersion, knowledge
rules, asset management
Dielectric Response Measurements at High Voltage Bushings
Sumereder C. and Muhr M.
Institute of High Voltage Engineering and System Management
Graz University of Technology
Inffeldgasse 18, 8010 Graz, Austria
E-mail : sumereder@hspt.tu-graz.ac.at
Abstract-- High voltage bushings are the link to connect outer and inner insulating systems.
The high voltage is fed into the vessel of the transformer and has to withstand high loads, as
electric field strength, mechanical forces, thermal pollution and contaminations due to
environmental and chemical loads. For this reason the workability of the bushings plays an
important role in the error free operation of high voltage equipment. In this paper the
condition of high voltage bushings was investigated by the means of the dielectric response
analysis. In the foreground the Frequency Domain Spectroscopy (FDS) was applied to
determine the condition and to observe the thermal behavior of different types of bushings.
Several test objects of Resin Impregnated Paper (RIP) and Resin Bonded Paper (RBP)
Bushings were thermal cycled. The measurement results were analyzed and shown as
Dissipation Factor (tan δ) plots in dependence of test frequency.
Index Terms-- Bushings, Condition Evaluation, Dielectric Response, Dissipation Factor

Measurement, Frequency Domain Spectroscopy (FDS)
Diagnosis on MV XLPE Power Cable by Using Frequency Variance
Leakage Current Analysis
Muhammad Azizi Abdul Rahman1*, Prodipto Sankar Ghosh2
1 Tenaga Nasional Berhad, Wisma TNB, Jalan Timur, 46200 Petaling Jaya, Selangor, Malaysia
2 RUP Consultants Plus Inc., 43 Maranda Close, N.E. Calgary, Alberta, T2A3E7, Canada
*E-mail : Azizi@tnb.com.my
Abstract--Distribution network system owners and managers are increasingly more
conscious on the significance of their ability to improve the condition and reliability of their
network
system. A combination of pertinent diagnostic testing are sought after for condition
assessment. Adoption of the most appropriate diagnostic system between the one that are
already developed and practiced and others that are promising but still in development is
not an easy task to achieve. The paper presents several case studies conducted on medium
voltage XLPE cables. Frequency domain spectroscopy was used for the field measurement.
The leakage currents were derived from the measurement and the results were scrutinized
on the trends for various cable condition. The information acquired from the results is very
important to justify the applicability of the assessment and to develop local database. The
evaluations are then utilized to come up with recommendation for the next course of action
to be taken, if necessary, on the tested cables.
Index Terms--Dielectric spectroscopy, XLPE cable, Dielectric losses, Tangent delta, Leakage
current.
Development of External Diagnosis for Terminals in XLPE Cables
Yukinobu Morishita1, Kazuhisa Miyajima1,
Tomonori Kamibayashi2, Tadanori Nagayama2, Tugio Saito2
Kazutoshi Abe3, Hiroshi Suzuki3*
1 Chubu Electric Power Co.,Inc. 2-3-24, Yokota, Atsuta-ku, Nagoya, 456-0022, Japan
2 Tohoku Electric Power Co.,Inc. 7-1, Hon-cho, 1-Chome, Aoba-ku, Sendai, Miyagi 980-8550,
Japan
3 J-Power Systems Corp. 5-1-1, Hitaka-cho, Hitachi-shi, Ibaraki-ken, 319-1414, Japan*
*E-mail : suzuki.hirosi@jpowers.co.jp
Abstract--To develop diagnostic method for terminals in aged XLPE cable lines, an external
diagnosis of deterioration signals relating to partial discharge generated in the aged terminal
has been investigated. The authors focused on acetylene as the particular gas produced by

discharge from the results on partial discharge experiment using sheet specimens with a void.
It was indicated from the results that gas analysis, aimed at detection of acetylene in air in
the metal casing of the terminal, had possibility to be applied to the external diagnosis. As a
result, gas analysis was carried out for actual prefabricated terminals in aged 66-77kV
XLPE cables lines. It was also indicated from the results that acetylene gas analysis had
possibility as an effective method for the external deterioration diagnosis for terminals in
aged XLPE cable lines.
Index Terms--Acetylene, External diagnosis, Gas analysis, Partial discharge, Terminal, XLPE
cable
Comparison of Arrival Time Estimation Methods for Partial
Discharge Pulses in Power Cables
Abstract -- Accurate location of partial discharges in power cable systems, based on arrival
times, is critical for the identification and assessment of defects. This paper evaluates
different time-of-arrival algorithms in order to determine which method yields most
accurate location under different circumstances. These methods are based on threshold,
Akaike’s information criterion, energy criterion, Gabor’s signal epoch and phase in
frequency domain. Several criteria are defined by which the algorithms are evaluated. These
criteria include the sensitivity to noise, pulse shape and effect of load impedance.
Thesensitivity of the methods upon varying these quantities is evaluated analytically and by
means of simulations. From the results the energy criterion method and the phase method
show the best performance.
Index Terms -- Delay estimation, defect location, partial discharges, power cables, signal
analysis.
A Centralized Condition Monitoring System for MV Power Cables
Based on On-line Partial Discharge Detection and Location
Peter C.J.M. van der Wielen 1* and E. Fred Steennis 1,2
1 KEMA Nederland B.V., T&D Testing Services, P.O. Box 9035, 6800 ET Arnhem, The
Netherlands
2 Eindhoven University of Technology, Faculty of Electrical Engineering, P.O. Box 513, 5600 MB
Eindhoven, The Netherlands
*E-mail: Peter.vanderWielen@kema.com
Abstract--This paper presents the principles and the first results of a new and unique on-line
partial discharge (PD) based diagnostic system for medium-voltage power cables, which

enables monitoring the condition of complete cable connections up to several kilometers in
length over a long period of time. It allows locating the weak spots along the cable
connection and identifying the development over time for each individual location. The
system, called PD-OL (PD On-line with Location), covers the complete process from on-line
measurement to
centralized data processing and obtaining appropriate recommendations regarding all the
cable connections monitored. The paper discusses the various principles behind both the
measurement technique and the centralized data processing. Furthermore, the experience
and results obtained from various pilots with field installations are presented. These results
show the functioning of the system, together with its broad applicability.
Index Terms--The cable insulation, defect location, fault diagnosis, partial discharges, power
cables, power cable insulation, power cable testing
The Application of On-Line PDM on in-service MV Cable
Terminations
Abstract-- The majority of cable failures on distribution system is caused by the defects in cable
terminations and cable joints. Failure mechanisms reported in cable accessories are predominantly
involve partial discharge deterioration caused by voids, contaminants and workmanship problems.
Therefore, partial discharge measurement (PDM) is an effective diagnostic preventing cable
system failure. However, conventional PDM needs outage and time consumption, and it is not
practice for routine test in field. Then on-line PDM is an alternative diagnostic. This paper utilizes
electromagnetic field coupling mode for on-line PDM on MV cable terminations. Hence, the
background noise, usually less than 40 Mhz in authors’ experience, could be eliminated by means
of using ultra-high frequency as mid-band frequency. A performance check of on-line PDM shows
good agreement with conventional PDM. Among more then 5,000 cable terminations diagnosed
by on-line PDM, there are about 200 cable terminations having PD signals. Disqualified cable
terminations are dissected, and the defects and PD patterns have some relationships between them.
Therefore, on-line PDM is practicable for cable termination diagnostics onsite.
Index Terms-- Partial Discharge, Cable insulation, Diagnostic
Analysis of On-line Power Cable Signals
Donald M Hepburn1*, Chengke Zhou1, Xiaodi Song1, Guobin Zhang1 and Matthieu Michel2
1 Glasgow Caledonian University, Glasgow, G4 0BA, UK
2 EdF Energy, West Sussex, RH10 1QQ, UK
*E-mail : dmhe@gcal.ac.uk
Abstract--For many years identification of incipient Partial Discharge (PD) faults in power

cables has been made through off-line investigation techniques. The periodic monitoring of
power cables resulted in unexpected failures, with consequent financial penalties for the
utilities. More recently, in an effort to allow continuous asset management of the medium
voltage cable network to be carried out, on-line monitoring systems are being installed with
the aim of reducing unexpected failures. This paper presents work on the analysis and
handling of data acquired from an on-line system. A short review of on-line vs. off-line cable
PD monitoring will be presented, in terms of their respective advantages and disadvantages.
The authors’ experience of applying Wavelet-based denoising techniques to extract PD data
from external noise interference will be presented. Analysis of PD activity and noise
interference, with respect to time-of-day, will offer insight into the challenges relating to
these systems. Finally, a means of handling the vast amounts of data and of acquiring
knowledge from on-line condition monitoring data will be discussed.
Index Terms--Cables, Monitoring, Partial discharges, Power distribution, Wavelet
Development of Distributed On-line Monitoring System for Dielectric
Loss Tangent of High Voltage Capacitive Apparatus
Abstract--This paper presents a distributed measuring system for on-line monitoring of
dielectric loss factor tan δ, and capacitance of HV apparatus. The method employs the
Discrete Fourier Transform (DFT) which is performed on the scaled down analog voltage
and current signals obtained using digital signal processing (DSP) technology. The
measuring unit of the on-line monitoring system takes a series of measures in the hardware
circuit design to improve the effectiveness of the DFT algorithm. The lab test results of
measuring unit show that the measuring unit has high precision of measurement based on
the DFT method. Field tests at a regional substation to evaluate the insulation of two groups
of 220kV current transformer units using the developed system.
Index Terms-- dielectric loss factor, Discrete Fourier Transform, distributed measuring
system, DSP, on-line Monitoring
Experimental Study on Relationships between Partial Discharge
Signals and Apparent Discharge Magnitude in XLPE Cable
Wei Wang1*, Xu Cheng2, Chong Liu1, Fei Zong1, Xueliang Shen1
1 Beijing Key Laboratory of High Voltage & EMC;
Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control,
Ministry of Education, North China Electric Power University, Beijing, 102206, China
2 Beijing Electric Test And Research Institute, Beijing, 100075, China

* E-mail: wwang-bj@ieee.org
Abstract --Based on the experiment carried out in the lab on several cables in which there are
some typical PD models, the relationship between the single acoustic signal generated by the
partial discharge and the apparent discharge magnitude in a line frequency cycle are
researched. Further more, through the detection system which is combined of the VHF PD
detection method and the acoustic emission detection method, the expressions of the
relationship between the voltage value, which is gotten directly from the detection system
and the apparent discharge magnitude by the curve fitting method. At the same time, the
method of locating the defect manually with the acoustic sensor is introduced simply in the
paper.
Index Terms--acoustic emission method detection, apparent discharge magnitude calibration,
partial discharge, XLPE cable
Evaluation via PEA Measurements of Paper-Oil Insulation submitted
to Gamma Radiation
Ciobanu R.1*, Schreiner C. and Olariu M.
1 Technical University of Iasi, Dept. of Electrical Measurements and Materials, Bdul. D. Mangeron
no. 53, 700050, Iasi, Romania
*E-mail : rciobanu@ee.tuiasi.ro
Abstract -- Focused on the analysis of some parameters derived from pulse electroacoustic
measurements, the article tries to identify the evolution of space charge and field in paperoil
systems submitted to gamma radiation, and to emphasize, by comparing to unaged
structures, some aspects susceptible to lead to a higher reliability of DC cables insulation for
nuclear power.
Index Terms -- DC cables, gamma radiation, paper-oil insulation, pulse electroacoustic
measurements.
Broadband Partial Discharges Technique and Application in the field
of cable paper insulation
Ciobanu R.1*, Schreiner C. and Temneanu M.
1 Technical University of Iasi, Dept. of Electrical Measurements and Materials, Bdul. D. Mangeron
no. 53, 700050, Iasi, Romania
*E-mail : rciobanu@ee.tuiasi.ro
Abstract -- Significant differences between the evolution versus frequency of the partial
discharges and breakdown processes were emphasized, suggesting that the breakdown

analysis, if used as unique method in quality assessment of some certain insulating materials,
proves to have limits in accuracy and may even lead to errors in results interpretation.
Index Terms – breakdown voltage, cable paper, frequency dependence, insulation
coordination, partial discharges.
Investigation of Resistance Toward Water Tree Growth in XLPE
Insulated MV Cables Produced in the Arabian Gulf Region
M.I. Qureshi; N.H. Malik; A.A. Al-Arainy; M.N. Saati; O.A. Al-Nather; and S. Anam.
College of Engineering, King Saud University, Riyadh, Saudi Arabia.
mqureshi@ksu.edu.sa
Abstract--In Saudi Arabia the main electric power utilities are extensively using XLPE cables
produced in the Arabian Gulf region. Due to prevailing high temperatures and high sulphate
content in the soil coupled with high sub surface water table, these cables have suffered
serious breakdowns in a short time span after their installation. This investigation was
undertaken to compare the resistance to water treeing in 15kV, XLPE insulated cables of
four regional manufacturers that are producing these cables according to international
standards. Cable samples were aged in two stages. At first, the aging was carried out under
high
electric stress and temperature cycling in the presence of deionized water. After 120 days of
this aging, their remaining dielectric strength was determined. These results show poor
performance of one type while the others exhibit close values. In the second stage the
accelerated aging was carried out in the presence of aqueous ionic solution of CuSO4 for
aging periods that lasted in the range of 500 to 1500 hours. Water tree population and tree
lengths were compared in this case. Their number and length distributions were subjected to
statistical Weibull and Log-normal models. Water tree density as a function of aging period
was found to obey a log-linear relation. On the other hand, water tree population and their
length distributions were found to fit better on Log-normal model. These data also show that
water tree density in these cables as evaluated in the second stage of aging, comparatively
varies significantly and leads to better segregation and selection of the cable that will serve
the best in such local environmental conditions.
Index Terms--Accelerated multifactor aging, aqueous ionic CuSO4 solution, medium voltage
cables, retained dielectric strength, water tree statistics, water treeing.
On-site Condition Monitoring of HV Power Cables up to 150kV
E. Gulski1, P. Cichecki1, J.J. Smit1, P.P. Seitz2, B. Quak2, F. de Vries3
1 Delft University of Technology, Delft, The Netherlands

2 Seitz Instruments AG, Switzerland
3 Nuon Tecno, The Netherlands
*E-mail: e.gulski@tudelft.nl
Abstract--For advanced, non-destructive on-site condition monitoring of HV power cables up
to 150kV by partial discharge detection and dielectric losses measurement it is necessary to
energize the disconnected cable system. One of the methods available for this purpose is
based on applying damped AC voltages up to 150kV. In this contribution, the use of modern
technological solutions in power electronics and signal processing as well as in technical
design and production methods will be discussed on the basis of ultra light system which is
able to on-site service aged HV cables.
Index Terms-HV power cables, on-site testing, diagnosis, partial discharges, dielectric losses,
PD site localization, condition monitoring
Statistical Approach to Identify the Discharge Source in MV Cables
and Accessories
Abstract-- Partial discharge (PD) analysis is a reliable tool to assess the integrity of electrical
insulation. Representation and interpretation of the data, obtained from e.g. on-line PD
monitoring, are key issues to reveal the discharge source, i.e. defect type, as well as the
physical phenomena behind the occurrence. Analyses of various PD patterns such as
discharge height distribution presented in this work provide useful statistical parameters to
identify the discharge source. Research shows that the 2-parameter Weibull distribution is a
reliable model to quantify the characteristics of the patterns of the defect. The model fits
well to the charge-height distribution. In addition, trends in the discharge density pattern
that occur over long times, can be used as complementary information to discover the
discharge nature. It alerts for a possible failure and therefore assists in taking corrective
measures to prevent failure. This paper presents the application of such statistical modeling
to the area of on-line power cable diagnostics. Data obtained from laboratory experiments as
well as field data have been studied.
Index Terms— monitoring, partial discharges, power cable insulation, power cables.
Need for Condition Monitoring and Diagnosis of Electric Wires and
Cables Used in Nuclear Power Plants
Abstract--Electric cables in nuclear power plants have to function even after serious events
such as a loss-of-coolant accident (LOCA). In most cables, organic polymers that are very
sensitive to radiation are used. Nevertheless, much attention was not paid until recently.
Under these circumstances, the Japanese government started an extensive research project

to examine the degradation behavior of safety-related cables at three different temperatures
with three different dose rates. An interim report published recently revealed that some
cables would be unable to function after the LOCA test. In this paper, a brief outline of the
interim report is described. Categorization of all the causes of malfunctions occurred in
electric apparatus in all the Japanese nuclear power plants for recent about 40 years,
revealed that there has been only one case of a slight malfunction of cable caused by
degradation of polymer insulation, indicating that we don’t have to worry so much. It is still
very important to establish a proper condition monitoring method in order to secure much
higher reliability.
Index Terms—Accidents, Aging, Cable insulation, Diagnosis, Maintenance, Monitoring,
Nuclear power generation, Polymers, Radiation effects, Wire.
Partial Discharge Localization Method of Power Cable using
High-precision Synchronization by Atomic Clocks
Abstract—We have studied partial discharge (PD) localization method on power cable. PD
localization in power cable can be generally made from the arrival time interval measured
by two devices placed at the terminal of both ends of the measurement section. However,
there is a cost problem in this technique because of need of the optical fiber installation. In
this paper, we propose a new PD localization method in power cables using atomic clocks
that allow retention of high-precision synchronization of relative time difference between
two PD measuring devices. To evaluate overall accuracy of the proposed method,
experiments of location identification were carried out using coaxial cables which simulate
power cables. In addition, to compensate a synchronization error, we also proposed a
modified method by comparing the timing of 1PPS signal (pulse generated by atomic clocks
per second continuously) of each atomic clock, and showed how the method worked.
Index Terms—partial discharge (PD), power cable, localization, atomic clock, relative time,
synchronization, synchronous compensation
A Study on the Measurement of Partial Discharges in XLPE Power
Cables using Planer Loop Sensors
Kwang-Jin Lim1*, Kyaw-Soe Lwin1, Dong-Hoon Shin1, Noh-Joon Park1, Dae-Hee Park1
Doo-Hyun Hwang2, Jong-Cheon Lim2
1 Wonkwang University, Iksan, Chonbuk, South Korea
2 Taihan Electric Wire Co., Ltd., Seoul, South Korea
*E-mail : kwangjin@wonkwang.ac.kr
Abstract--This study designed a new type of loop antenna that is able to detect partial

discharges based on microstrip line technology. In diagnosis of power cables, partial
discharge signals are generally produced at a frequency range less than 100MHz because
high frequency PD signals are lost along a propagation path in such cables. In partial
discharge measurement experiments, a commercial HFCT sensor was used as a reference
sensor. Several experiments were made over HFCT and loop antenna sensors for detecting
partial discharges on 22.9kV MV XLPE cable. In this study, we showed the loop antenna
designed in this study that can be applied as a commercial HFCT sensor.
Index Terms-- microstrip line technology,power cables, HFCT sensor,Partial Discharges
On-line Monitoring Technology for the Insulation Condition of
Capacitive-type Substation Equipment
Xi-Wei Hao1, Guan-Jun Zhang1, Wei Zhang1, Ming Dong1, Guang-Yan Liu2
1 State Key Laboratory of Electrical Insulation and Power Equipment, School of Electrical
Engineering,
Xi’an Jiaotong University, 28 Xianning West Road, Xi’an, Shaanxi 710049, China
2 Shandong Electric Power Research Institute, 500 Erhuang South Road, Jinan, Shandong 250002,
China
*E-mail : haoxiwei123@163.com
Abstract – An on-line monitoring system for the insulation condition of capacitive-type
equipment is described. The system adopts a distributed and layered multi-CPU structure,
which is composed of the on-site measuring and processing unit, and data management and
diagnosis system in the control room of substation. The on-site measuring and processing
unit is based on DSP+FPGA hardware platform. Thus, the hardware design is simplified, the
system is easy to be modified and updated, and the reliability is also raised. The windows
and interpolation algorithm is applied to effectively reduce the influence of asynchronous
sampling caused by frequency fluctuation of power system and to increase the precision.
Moreover, many antijamming and protection methods are used in hardware and software
design for the on-site intense electromagnetic field. Based on the simulation test conducted in
the laboratory, the experimental results prove that measurement accuracy of the online
monitoring system, which can meet the demand of on-site measurement.
Index Terms-- capacitive-type equipment, on-line monitoring, DSP+FPGA, high accuracy
FFT algorithm, measurement precision.
Location of Water Tree Degraded Point Along XLPE Cable Line
Using DC Voltage
Kiyoka Suenaga1*, Katsumi Uchida2 and Naohiro Hozumi3

1 JFE Steel Corporation, Kurashiki, 712-8024, Japan
2 Chubu Electric Power Co., Inc., Nagoya, 459-8001, Japan
Aichi Institute of Technology, Toyota, 470-0392, Japan
*E-mail : ki-suenaga@jfe-steel.co.jp
Abstract--Until now many diagnosing techniques for watertree degraded MV class XLPE
cables have been proposed. However, although they can detect the average degree of
degradation throughout the cable, the degraded part can hardly be located. The
maintenance cost will be significantly reduced if the degraded part is located by repairing
only the degraded part of the cable. This presentation will introduce a new method to locate
the water-tree degraded part along a cable line by applying DC voltage. While DC leakage
current measurement is carried out for diagnosing cables degraded by water-tree, it is often
observed that the leakage current varies unstably. This phenomenon, called as "kicking", is
considered to have a relation with partial discharges accompanied by water-tree. We tried to
locate this highly degraded part along the cable length. Using a short size cable, it was
proved that partial discharges, accompanied by an electrical tree generated from a
water-tree, were taking place. The point was precisely located by using timedomain
waveform measurement. Based on the above achievement, an equipment to locate highly
degraded part along a cable line was developed. It was proved using a full-scale cable line
that the equipment could locate the degraded part with a sufficient precision.
Index Terms--MV class XLPE cable, water-tree degradation, location, kicking phenomenon,
partial discharge
The Transmission Characteristics of Sound Wave in Power Cable
Ju-Chu Hsieh1*, Cheng-Chi Tai1, Ching-Chau Su1, Chien-Yi Chen1, Jiann-Fuh Chen1, Yu-Hsun
Lin2
1Department of Electrical Engineering, National Cheng Kung University, Tainan 70101
2Department of Electrical Engineering, Nan Jeon Institute of Technology, Tainan 73746
*E-mail: n2894144@mail.ncku.edu.tw
Abstract—The cause of power electric cable fault is often source from the cable splice and
cable terminator used in the electric cable connection and the partial discharge released
from the improper construction process. It makes the insulation stuff aging and damaged.
When the insulation capability becomes worse, it could cause unexpected damage on the
high-voltage cables, many industry and research institutes have paid more and more
attention on the maintenance of high voltage cables and diagnosis techniques of fault
prediction. The acoustic emission method mentioned in this article is mainly on the
characteristics analysis of basic measurement of sound delivery characteristics during the
electric cable connection, the research on the original location of sound wave, and
distribution attenuation.
Index Terms—Partial discharges, Power cable, Acoustic emission

Partial Discharge Classification and Diagnosis of Power Cable Joint
by Statistical Processing
Kyung-Soon Cho1*, Jong-Yeol. Shin2, Young-Sang Lee3, Hyuk-Jin Lee3 and Jin-Woong Hong3
1 Seoil College, Seoul 131-702, Korea
2 Sahmyook University, Seoul 139-742, Korea
3 Kwangwoon University, Seoul 139-701, Korea
*E-mail : kscho@seoil.ac.kr
Abstract--The prefabricated type used generally in Korea to join cable runs on new
installations, because installation is very simple and save time. This type is a permanent,
shielded and submersible cable joint for direct burial or vault application. It confirms to the
requirements of IEEE std. 404-2004 by factory testing, but many problems of insulated cable
systems are caused by internal defects of the joint part which have to be mounted onsite.
Faults arise from impurities or voids. A suitable solution for a monitoring of cable joints
during the after-laying test and service is partial discharge detection. This paper described
the influence on partial discharge distribution of various defects at the model power cable
joints interface by statistical processing. As the result of analyzing Φ-q-n patterns, several
parameters i. E. maximum discharge qmax, average discharge q and average angle of
discharge θg were found to depend upon the defect type varying applied voltage. As the
result of analyzing discharge number distribution of Φ-n cluster using K-means clustering,
clusters shifted to 0° and 180° with increasing applying voltage. It was confirmed that
discharge quantity and Euclidean distance between centroids were increased with applying
voltage from the analyzing centroid distribution of Φ-q cluster.
Index Terms--cable joint, EPR, K-means, diagnosis, PD classification, statistical processing
Recognition of partial discharge defects in cable Terminations
Abstract--As reported in very researches, the majority failure mechanism in cable
terminations is predominantly involving partial discharge deterioration caused by voids,
contaminants and protrusion. The partial discharge measurement is an effective way to
detect such defects. However, no research shows the relation between the magnitude of partial
discharge and remaining life of cable termination. Hence, it is hard to make decision to
replace the unqualified cable termination immediately or lately for an in-service cable
termination, while the partial discharge activities are measured. Based on authors’
experiences, different defects have different ageing speed to breakdown. Therefore,
recognition of defects is an alternative way to assess the degree of risks. This paper sets up a
series test to figure out the properties of partial discharge activities caused by different
defects, including wrong position of stress cone, void left, tape left, and needle pricked. Test
results show the different properties of different defects, and these characteristics can be used

to recognize defects inside cable termination.
Index Terms—partial discharge, recognition, cable insulation
Study on the Frequency Spectrums of Acoustic Emission PD Signals in
XLPE Cable Accessories
Wei Wang 1*
, Xu Cheng 2
, Chong Liu 1
, Zhifu Yang 1
, Heming Huang 1
, Qiang Xue 1
1
Beijing Key Laboratory of High Voltage & EMC;
Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control,
Ministry of Education, North China Electric Power University, Beijing, 102206, P. R. China
2
Beijing Electric Test And Research Institute, Beijing, 100075, China
*Email: wwang-bj@ieee.org
Abstract--In this paper, four 110 kV prefabricated cable joints models containing four kinds of
known representative insulation defects were designed. The models can simulate some typical
PD phenomena, such as sliding discharge, floating discharge, cavity discharge and protrusion
discharge. Based on them, type frequency spectrums of AE PD signals in XLPE cable joints
were studied. The investigation indicated that the main frequency component of AE PD
signals for XLPE cable is less than 400 kHz; the attenuation of higher frequency component is
very fast; the energy is relatively centralized in 50~250kHz; the sensitivity in this band is very
high; the characteristics of different PD models are apparently dissimilar from each other.
The obtained results provided basis for future investigation on PD pattern identification.
Index Terms--AE, attenuation, frequency spectrums, insulation defects, PD characters, PD
models
Online Partial Discharge Detection in HV cables using Conventional
Current Transformers
Faisal Peer Mohamed Dr. W. H. Siew Professor QM Li
University of Strathclyde, Glasgow, Scotland , UK
Shandong University China
Abstract--This paper investigates the performance of conventional current transformer for
online partial discharge detection in high voltage cables. It is based on the frequency
response of such current transformers. The frequency behaviour was investigated using a
simulation package (Powersim) by varying parameters including core permeability, stray
capacitance, core material etc. Experimental investigation was also conducted on a 33KV
200/5A current transformer. Simulation and experimental results are presented and
compared in this paper.

Index terms-- Partial discharges, Current transformers, Frequency response
Study on Insulation Diagnosis for XLPE Cables Using Dumping
Oscillating High Voltage
Toshihiro Takahashi*, Tsuguhiro Takahashi and Tatsuki Okamoto
Central Research Institute of Electric Power Industry (CRIEPI), Japan
*E-mail : tosihiro@criepi.denken.or.jp
Abstract-- 6 kV to 60 kV class XLPE cables are widely used and have been playing important
roles in power distribution and transmission systems in Japan. For the XLPE cables in these
voltage levels, the water tree dominates aging degradation. Therefore, precise on-site
detection techniques of water trees in their length are considered to be important for
operation and maintenance of these XLPE cables. The author has been investigating the
applicability of the dumping oscillating high voltage (DOHV) to the water tree detection as
well as insulation diagnosis for these XLPE cables. This paper firstly investigates on the
partial discharge measurement under DOHV application for water tree deteriorated 6.6 kV
XLPE cable. Then, authors discuss the applicability of OHWV to the insulation diagnosis of
XLPE cables combined with partial discharge measurement under DOHV application.
Index Terms-- Aging, Cross linked polyethylene insulation, Insulation testing, Partial
discharges, Power cable insulation, Trees (insulation)
Simulation of Propagating Electromagnetic Wave due to Partial
Discharge in GIS using FDTD
Toshihiro Hoshino1*, Shiro Maruyama1 and Takaaki Sakakibara1
1 Toshiba Corporation
*E-mail : toshihiro.hoshino@toshiba.co.jp
Abstract— The finite difference time domain (FDTD) method has been applied to an
investigation on the attenuation characteristics of partial discharge (PD) pulses propagating
through various parts constituting a gas-insulated switchgear (GIS), such as insulators and
T-junctions. A simulator for analyzing three-dimensional transient electromagnetic fields
using the FDTD method is considered to be the most promising technique for evaluating
outputs from UHF couplers, and for confirming the sensitivity of couplers to satisfy
sensitivity verification according to CIGRE recommendation [1].
Index Terms—Finite difference time domain method, Partial discharge, UHF method,
Gas-insulated switchgear

Experimental Investigation of PD Diagnosis Based on Consecutive
Pulses Data
H. R. Mirzaei1, 2*, A. Akbari1 , M. Kharezi2 and A. M. Jafari1
1 K.N.T University of Technology, Tehran, Iran
2 Iran-Transfo Co. HV Test Field, Zandjan, Iran
*E-mail: hr_mirzaei@ee.kntu.ac.ir
Abstract--Nowadays partial discharge (PD) measurement and analysis has known as a most
effective tool in insulation monitoring of high voltage (HV) equipments. Almost all types of
insulation defects is more or less accompanying with PD activities, while each has its own
special patterns. To have a reliable estimation of defect type, patterns with high recognition
potential should be used. Recently some studies have been made on patterns which are based
on difference of excitation voltage magnitude at the instant of occurring PD pulses. The
reports show good results, however, more investigations are needed to make the method
applicable in practice and ensure the uniqueness of mentioned patterns for each defect type.
For this purpose some tests on artificial PD defects as well as real PD activities in power
transformers have been experienced and the test condition effects on patterns have been
investigated. The results of these experiments are studied in this contribution.
Index Terms--Instantaneous Voltage, Insulation Diagnostics, Partial Discharge, Pattern, and
Power Transformers.
Influence of Inorganic Nano-filler to Partial Discharge of Polyimide
Film under High-frequency Impulses
GUO Xiao-xia, WU Guang-ning, ZHIOU Kai, GAO Bo ,WU Jian-dong
(School of Electrical Engineering of Southwest Jiaotong Universtiy, Chengdu 610031,China
Abstract-- Presently, Polyimide film is applied widely in turn-to turn insulation and turn to
ground insulation of inverter-fed traction motors as one kind of special project plastic film.
In this paper, the measurement of partial discharge is done on nanometer hybrid polyimide
Film and non nanometer polyimide film with different frequency and different rise time
under high-frequency square impulse. Some parameters of PD are discussed based on
measurement results. The results showed : Gap surface conductivity have greater impact on
PD, the main impact of rise time on PD parameters mainly depends on the initial electron
delay and the gap dynamic electric field, the interfaces formatted by inorganic nano-filler
filling improved the conductivity of the material, the movement of charge along the gap

surface become much easier, while nano-materials exist large quantities of shallow traps, so
that the PD initial electronic selection engender easily.
Index Terms -- traction motors; high-frequency impulse; polyimide; partial discharge
Separation of Corona Noise from On-line Partial Discharge
Monitoring of Power Cables
K.X. Lai*, B.T. Phung, T.R. Blackburn, and N.A. Muhamad
University of New South Wales, Sydney, Australia
*E-mail : z3055516@student.unsw.edu.au
Abstract--The use of traditional maintenance scheme such as corrective maintenance and
preventative maintenance are insufficient to prevent costly events triggered by failure of
power system equipment. On-line condition monitoring is increasingly becoming popular. It
is non-destructive and cost-saving as it can be carried out with the equipment kept in-service.
The on-line monitoring of partial discharges (PD) in power cables in outdoor substation has
lots of background noise, especially corona discharge. Thus, it is important to remove corona
noise from the monitoring of PD in power cables. A new method to remove the corona noise
was proposed in this paper. It involved the use of simultaneous multi-channel measurement,
principal component analysis (PCA) and clustering analysis.
Index Terms--Condition Monitoring, PD, Corona, HF-CT, PCA, Clustering Analysis
Characteristics analysis of sensors for on-line partial discharge
measurement
Chang-Hsing Lee1, Min-Yen Chiu,1 Chih-Hsien Huang1, Shih-Shong Yen2, Chen-Li Fan3
1Chan-Ching Electric Technique Consulting CO.,LTD, Hsinchu, Taiwan
2Industrial Technology Research Institut, Hsinchu, Taiwan
3Taiwan Power Research Institute, Taiwan Power Company
*chan.ching@msa.hinet.net
Abstract--As the demand of high power system reliability,condition based maintenance
(CBM) becomes a better solution for maintaining equipment reliability. According to the
diagnostics of CBM, one can estimate the condition of insulator, and find an optima strategy.
Among them, on-line partial discharge measurement is one of the most important
diagnostics
assessing the condition of insulator. However, the majority problem of on-site measurement
is the noise distinguishability. Therefore, different manufactories develop their own methods
to overcome this difficulty. Unfortunately, different methods utility different sensor varying
with bandwidths, and they are difficult to compare the measurement results with each other.
Based on these problems, authors test different commercial sensors to assess their

characteristics. Authors inject different calibrating signals into the test system including a
voltage transformer, and measure the sensitivities, bandwidths, and waveforms of partial
discharges. According to results, magnetic sensor has similar sensitivity with coupling
capacitor, and UHF sensor has better signal to noise ratio. Based on this paper, one may
compare different measurement results from different instruments to estimate the condition
of insulator.
Index Terms--partial discharge, sensitivity, sensor
Experiences in On-site Partial Discharge Measurements and
Prospects for PD Monitoring
Dr. K. Rethmeier1* , Dr. M. Krüger1, Dr. A. Kraetge1, Dr. R. Plath2, Dr. W. Koltunowicz2,
A. Obralic3, Prof. W. Kalkner3
1Omicron electronics, Klaus, Austria 2Omicron electronics, Berlin, Germany 3Technische
Universität Berlin, Germany
*E-mail : kay.rethmeier@omicron.at
Abstract--With four case studies (dry-type transformer, power transformer, GIS, generator)
this paper describes the principle of synchronous multi-channel PD measurements and its
benefits for PD data evaluation. With respect to monitoring the tracing of a charge value as
QIEC over the measuring time is not sufficient to assess the PD activity of an HV apparatus.
With state-of-the-art PD evaluation techniques as 3PARD and 3CFRD a simple and fast (all
calculations during the PD measurements are carried out in real-time) tool is available to
separate PD from noise. Separated PD sources can easily be back-transformed to
phaseresolved patterns or pulse sequence patterns, for instance, to be evaluated
automatically by computerized PD expert systems or by experienced human experts.
Index Terms--Partial Discharge, PD, offline, online, monitoring, diagnosis, noise suppression,
pulse-waveform analysis, synchronous acquisition, multi-channel acquisition
Application of Statistical Analysis in the Asset Management Decision
Process
R.A. Jongen1*, J.J. Smit1 and A.L.J. Janssen2
1Delft University of Technology, Delft, the Netherlands
2Continuon Asset Management, Arnhem, the Netherlands
*E-mail: r.a.jongen@tudelft.nl
Abstract-- One of the tools to answer some typical asset management (AM) questions is the use
of statistical analysis of life time data of high voltage components. When life time data of

components is available, statistical analysis can be performed. The analysis can give
information about the failure rate of components, expected failures in the future, conditional
remaining life estimation and influence of maintenance- and/or replacement strategies. In this
contribution the general approach of the analysis is shown together with some examples of
typical AM questions for typical high voltage components. Statistical analysis is used to find
answers to these questions.
Index Terms--Decision-making, Failure analysis, Life estimation, Management, Statistics.
Statistical Analysis of Large Amount of Power Cables Diagnostic Data
Piotr Cichecki1*, Edward Gulski1, J.J Smit1, R. Jongen1and Frank Petzold2
1 Delft University of Technology, The Netherlands
2 SebaKMT, Germany
*E-mail : p.cichecki@tudelft.nl
Abstract – In this contribution statistical analysis were applied to evaluate condition of
serviced aged MV power cables systems. Analysis were based on large number of diagnostic
data as obtained from the on-site inspections of 89 mass insulated power cables, 26 XLPE
insulated power cables and 126 mixed-insulated power cable. Statistical analysis input data
was represented with several diagnostic parameters regarding to partial discharges
phenomenon (PD). Investigated parameters were obtained with application of damped AC
(DAC) diagnostic system during on-site tests. After a survey of all relevant parameters
describing condition of the particular cable system components, sub-groups of different cable
accessories were created (e.g. joints, termination, insulation types) For proper interpretation
of collected data related to cable insulation condition as well as different accessories condition,
categorization based on such diagnostic parameters e.g. PDIV (Partial Discharge Inception
Voltage), PD occurrence, and PD mappings was assumed. Moreover investigated statistically
PD parameters were employed to estimate experience norms and measuring criteria. Based
on knowledge rules and estimated statistically norms example of so called “experimental
condition index” was used to indicate overall condition of discussed MV power cables
systems.
Index Terms—Condition index, cable insulation, damped AC, diagnostic data analysis,
statistical analysis, partial discharges.
Application of Integrated Neural Network based on Information
Combination for Fault Diagnosis in Steam Turbine Generator

Abstract--In view of the disadvantage of single neural network, a fault diagnosis system based
on the integrated neural network used information combination is proposed. The preliminary
diagnosis is made for the equipment by using the sub-neural network. And then the
sub-neural networks are combined to make the decision. The simulation of steam turbine
generator sets’ fault diagnosis demonstrates that the system takes full advantages of
diversified information and improves diagnosis precision.
Index Terms--Fault diagnosis; Information fusion; Integrated neutral network; Steam
turbine-generator set
Mechanical Equations of Material Damage and Feature Variation for
Vibration-based Monitoring and Diagnosis
Xiao Jianhua
Measurement Institute, Henan Polytechnic University
High-tech Zone, Jiaozuo City, Henan, PRC. 454000
*E-mail : jhxiao@hpu.edu.cn
Abstract-- Based on additive decomposition of deformation gradient tensor, the vibration
equations for vibration-based damage monitoring and diagnosis technology are formulated
with intrinsic local rotation concept. It shows that the abnormal vibration is related with
asymmetrical stress (which is completely determined by the local rotation angular). Once the
vibration velocity is well measured, the damage evolution equation can be used to determine
the required damage evaluation parameter. Some further discussion is given out for the
cracking tip wave features, which forms the basis for sound mission based monitoring
technology. Material feature variation equations are also formulated. So, this research
supplies the essential mechanical equations for vibration-based monitoring and diagnosis.
Index Terms--sound emission, damage evolution, abnormal vibration, vibration equation,
effective constants, symmetrical stress, asymmetrical stress, motion equation, intrinsic local
rotation, deformation tensor decomposition, rational mechanics
Benefits of Comprehensive and Interactive on-line Monitoring and
Expert Systems for Power Transformers
Abstract—Modern comprehensive monitoring systems for power transformers lead to
increased operating reliability and reduction of operating and life-cycle costs.
The monitoring of all transformer main components is one requirement to achieve the

knowledge of the operation conditions of the transformer. A further improvement is achieved
by correlation of all measured and analyzed values of the transformer or even across
transformers in substation. In order to meet these requirements, specific architectures and
software models are essential.
This contribution describes the application of the above mentioned requirements in
comprehensive monitoring systems. More than 100 years of experience in the manufacturing
and service of power transformers and the knowledge gained from monitoring of several
hundred transformers made it possible, to create a transformer expert system, which features
complete data management, analysis algorithms and diagnosis functions.
The simple and interactive user interface is an essential element for the application of the
monitoring system and the built in simulator. With the use of the comprehensive monitoring
system and the derived optimized operation, the lifetime of the transformer can be extended.
The knowledge of the condition of the transformer and the early recognition of incipient
failures with the help of the monitoring system ensure the safe and enduring operation of the
power transformer.
Index Terms—power transformer, monitoring system, expert system, life management
Real Time Web Based Condition Monitoring System for Power
Transformers - Case Study
Anant. M. Wagle, A.M. Lobo, Santosh Kumar.A, Shubhangi Patil, *A.Venkatasami
1 CG Global R&D Centre, Crompton Greaves Ltd, Mumbai,India – 400042
*E-mail : Venkatasami.Athikkan@rnd.cgl.co.in
Abstract--The need for improved performance of power systems in terms of reliability and
higher productivity has necessitated more and more application of condition monitoring
techniques, which can provide early warning of potential failure with the opportunity of
organizing avoidance strategies to minimize loss of time and unexpected costs. Periodic
condition monitoring tests have limitations such as continuous availability of data and will
lead to reactive maintenance. Any event happening between the monitoring intervals is lost
and by the time it is noticed the severity of fault might have increased manifolds. To overcome
this continuous monitoring solutions are gaining demand. Many stand alone solutions are
available in the market for local SCADA applications. Development of a versatile real time
web based monitoring system (DAKSHITATM), which can take simultaneous inputs from
multiple sensors, equipments and sites, are explained in this paper.
Index Terms--Dissolved Gas Analysis, GSM & GPRS Service, Hydran sensors

A Web based Expert System Shell for Fault Diagnosis and Control of
Power System Equipment
M. Babita Jain, Amit Jain and M.B. Srinivas,
International Institute of Information Technology,
Gachiwbowli, Hyderabad 500032, India
Abstract--Power companies arrange regular training sessions to keep their operators ready to
face blackout events, and expert systems play an important role in achieving this goal. Expert
systems [1] have been proven to be an effective platform for diagnostic and control
applications in power industry. Conventional expert systems are PC based and are not of
much use where the expertise is required over a large network. The advent of the internet has
strongly influenced modern power systems. A web based expert system [2] is an apt solution
for such environments. Existing intranet solutions are being gradually replaced with www
services available everywhere and at any time. Originally expert systems have been used for
internal purposes in different organizations. The purpose of this work is to develop a web
based expert system shell and then use it for the fault diagnosis and control [3] of traditional
power system equipment with extensive information and data collected in an electrical factory.
The issues of knowledge representation, development of the knowledge base and interface
solution have been considered. The proposed solution is based on the pilot implementation of
the web based expert system package in a large electrical factory in Visakhapatnam.
This paper aims at developing a web based expert system package with a user friendly
graphical user interface and a link to the knowledge base through the expert system shell and
a link to the database using the database tools. Further the package has been used to develop
an Intelligent Fault Diagnosis and Control Paradigm (IFDCP) capable of dealing with faults
on general power system equipment and guide operators for fault diagnosis and control or
restoration in general and in the electrical factory considered in particular.
The GUI, Expert System Shell, and the Databases are developed by integrating the
standardized technologies, such as C#.NET, ASP.NET, MS Access DB tools and the dynamic
linking library (DLL) files. The knowledge base required for the package IFDCP presents
extensive data obtained from discussions with experts in different domains of the electrical
factory and the past historical data of fault occurrences and their clearance at that factory in
the form of simple IF-THEN rules. The package is capable of handling faults on
Transformers, DC Motors, AC Motors and Street Lamps. The proposed system goes beyond
imitation of expert-operators' knowledge, being able to inference fault scenarios using both
knowledge base and database of the required equipment with no limitation to the number of
pieces of equipment being handled. It is easier, flexible, and more user friendly. It can be used
for both stand-alone and Web-based applications.
Index Terms--Expert Systems, Web based Expert System, Expert System Shell, Knowledge
Base, Database, DC Motors,

An Enhancement of K-Nearest Neighbor Algorithm Using
Information Gain and Extension Relativity
Wang Baobao1, Mao Jinsheng2, Shao Minru1
1 Department Of Computer Science, Xidian University, ShaaXi, Xi’An, 710071, China
2ShanXi YunCheng Power Company, ShanXi, YunCheng, 044000 China
Email:shaominru_000@163.com
Abstract-- An enhanced K-NN algorithm is proposed in this paper to improve the
conventional K-NN algorithm. The enhanced K-NN algorithm proposed uses information
gain and extension relativity. The weight coefficient is got through computing the information
gain of attributes. In this approach, the anti-jamming ability and accuracy of the K-NN
algorithm is improved highly, and the computing time is reduced and the time is improved
greatly. The test results show that the novel K-NN algorithm is feasible and effective.
Index Terms—K-Nearest Neighbor algorithm; information gain; information entropy;
extension relativity CLC number-TP182
An Enhancement of K-Nearest Neighbor Algorithm Using
Information Gain and Extension Relativity
Wang Baobao1, Mao Jinsheng2, Shao Minru1
1 Department Of Computer Science, Xidian University, ShaaXi, Xi’An, 710071, China
2ShanXi YunCheng Power Company, ShanXi, YunCheng, 044000 China
Email:shaominru_000@163.com
Abstract-- An enhanced K-NN algorithm is proposed in this paper to improve the
conventional K-NN algorithm. The enhanced K-NN algorithm proposed uses information
gain and extension relativity. The weight coefficient is got through computing the information
gain of attributes. In this approach, the anti-jamming ability and accuracy of the K-NN
algorithm is improved highly, and the computing time is reduced and the time is improved
greatly. The test results show that the novel K-NN algorithm is feasible and effective.
Index Terms—K-Nearest Neighbor algorithm; information gain; information entropy;
extension relativity CLC number-TP182
Characteristic Extracting for Nonlinear Diagnosis

Based on Volterra Frequency-Domain Slices
Chenxi XU1,2*, Guangju CHEN1 and Guixiang LI2
1 CAT Lab of School of Automatic Engineering, UESTC, Chengdu 610054, China
2 Department of Early Warning Detection Equipment, Air Force Radar Academy, Wuhan 430019,
China
*E-mail : WHLDxcx@163.com
Abstract--Using the separability of the Volterra spectrum with the amplitude modulation
(AM) stimulation, an approach of characteristic extracting for weakly nonlinear circuits
diagnosis is presented based on the Volterra frequency domain slices (VFDS). Based on VFDS
decomposition, the nonlinear diagnosis problem can be implemented on linear sub-circuits,
and the phenomenon of faults characteristic’s overlap and cross can be decreased, even
eliminated. In paper, the conditions of stimulation and sampling for VFDS decomposition are
discussed, the fault information which including the VFDS is analyzed, then the fault
characteristics are extracted by fitting the VFDS response. Finally, with a circuit simulation
to illuminate the proposed is available.
Index Terms--AM stimulation, Faults diagnosis, Nonlinear dynamic circuits, Volterra
response
The Intelligent Fault diagnosis of Wind Turbine Gearbox Based on
Artificial Neural Network
Shulian Yang 1,2, Wenhai Li 2 , Canlin Wang2
1Computer department, ShanDong Institute of Business and Technology, Shandong
province,YanTai 264005,China
2Electronic Engineering department, Naval Aeronautical Engineering Institute, Shandong
province,YanTai 264001,China
E-mail : yy6654@yahoo.com.cn
Abstract--The vibration test system for the gearbox of wind turbine , the wavelet denoising
method , the artificial neural network' s essential principles and its features, BP network
structures model in the gearbox fault diagnosis are discussed. Tested vibration signals are
disposed by the method of wavelet denoising and than as the inputs of BP neural network. By
using classical BP neural network, four kinds of typical patterns of gearbox faults have been
studied and diagnosed ,and satisfied results have been acquired. The research results indicate
that BP neural network have the excellent abilities of parallel distributed processing,
self-study, self-adaptation, self-organization, associative memory , and simultaneously its
highly non-linear pattern recognition technology is an efficient and feasible tool to solve
complicated state identification problems in the gearbox fault diagnosis.

Index Terms--Gearbox; Back Propagation( BP) ;Artificial Neural Network(ANN); wavelet
analysis ; Fault diagnosis; Denoising; Vibration
RBFNN for Fault Diagnosis of Rotor Windings
Inter-turn Short Circuit in Turbine-Generator
Zhao Yan-jun*, Li Yong-gang , Hu Ji-wei
School of Electrical Engineering, North China Electric Power University, Baoding 071003, China
*E-mail: zhaoyanjun1982@163.com
Abstract--The electromagnetic characteristic and rotor vibration characteristic of
turbine-Generator are analyzed when rotor windings inter-turn short circuit fault has
happened. This paper also gets relevant characteristic parameters. Based on characteristic
parameters, RBFNN (radial basis function neural network) can be adequately trained and
diagnosis rotor windings inter-turn short circuit. RBFNN is independent on mathematic
models and parameters of turbine-generator. Finally practically acquired dynamic
experiment data of the MJF-30-6 generator, the results of verification show that the theory
analysis is right and the RBFNN can diagnosis rotor fault and estimate fault turns ratio.
Key words-- Turbine-Generator; rotor windings inter-turn short circuit fault; RBFNN;
vibration ; fault diagnosis
Estimating Transformer Oil Parameters Using Polynomial Networks
Abstract-- In this paper we use polynomial networks to model the relationship between the
insulation resistance measured between distribution transformer high voltage winding, low
voltage winding and the ground and the breakdown strength, interfacial tension and the
water content of the transformer oil. Polynomial networks have the advantage of effectively
capturing nonlinearities in the modeled data even when the dataset is relatively small.
The proposed model has been applied to real data collected from thirty four distribution
transformers. The modeling results showed that the proposed model can predict values of the
interfacial tension of the transformer oil with an impressive accuracy of 93% while it can
predict the breakdown down with an accuracy of 84%. On the other hand, the study showed
that this technique can’t be used to predict the transformer oil water content.
Index Terms—Transformer insulation aging, Megger test, transformer oil.

Studies on Layered Condition Monitoring Information Platform
Based on Multi-Agent Technology
Jinjiang Zhang1, Linqing Wang2*, Jianguo Zhou3, Hua Huang4
1 Zhejiang University, Hangzhou, 310027, China
2 Hangzhou Zhiguang Econ Co. Ltd., Hangzhou 310013, China
3 East China Power Grid Ltd., ShangHai 200002, China
4 East China Electric power Test & Research Ins. Ltd., ShangHai 200437, China
*E-mail :wlinq@sina.com
Abstract-- Currently, power enterprises monitor the states of electrical equipments either
with single supervisory units or within independent station control system. So all the data
disperses in substations, and can’t be effectively integrated to dispatch system. This paper
brings in the concept and architecture of layered Condition Monitoring Information
Platform (CMIP) for high voltage equipments in substation, and studies its implementation
method, based on multi-agent system technology and up to date information standard. Whit
this solution, all the dispersive condition monitoring information can be integrated, shared
and exchanged conveniently.
Index Terms-- Power enterprise, Condition monitoring, Multi-agent systems, Layered system
architecture.
Transfomer Fault Diagnosis Based on
Rough Sets Theory and Artificial Neural Networks
Xiaodong Yu1*, Hongzhi Zang2
1 Shandong Institute of Light Industry,Jinan 250061,China
2 Shandong Electric Power Research Institute, Jinan 250002,China
* E-mail : xiaodongyu2001@163.com
Abstract--Transformer fault diagnosis based on Artificial Neural Networks (ANN) is widely
used, because ANN has essential nonlinear character、parallel processing ability and the
ability of self organize and self learning. But there exist problems if we use traditional ANN
method alone to diagnose transformer fault, the large input vector dimension and complex
training database will cause the computation complexity and the space increase greatly, lead
to long training time, slow convergence and low judgement accuracy.
In this paper, a hybrid fault diagnosis method combining Rough Set (RS) theory and ANN
(RS-ANN) is presented. Taking advantage of the strong ability of RS theory in processing
large data and eliminating redundant information, this method can remove irrelevant factors

from the original data and reduce the amount of training data which helps to overcome
ANN's defect when process large database.
A number of simulation results show that RS-ANN simplifies the networks’ structure, reduces
the networks’ training epochs, improves the judgement accuracy.
Index Terms—Transformer, Fault Diagnosis, Rough Set, Artificial Neural Networks,
Reduction, Accuracy , Simulation, MATLAB, Decision Table, BP algorithm
Neural Network Approach for Fault Diagnosis of Transformers
Abolfazl Salami1*, Parvaneh Pahlevani
1 Arak Engineering and Technical Department - Iran University of Science and Technology, Arak,
Iran
*E-mail : a_salami@iust.ac.ir
Abstract-- Dissolved gas analysis (DGA) is one of the most useful techniques to detect the
incipient faults of power transformer. This paper is a study of artificial neural networks
(ANN) applications for the diagnosis of power transformer incipient fault. The fault diagnosis
is based on dissolved gas-in-oil analysis (DGA). Using historical transformer failure data, a
multi-layer perceptron (MLP) neural network is applied in this work. The proposed network
can overcome the drawbacks of conventional methods. The proposed schemes are simulated
and tested.
Index Terms--Back propagation, Condition monitoring, Dissolved gas analysis, fault
diagnostics, Neural network, Power transformers.
Development of Networks for SFRA Data Using Circuit Synthesis
G. Joginadham1*, H. A. Mangalvedekar1 and A. Venkatasami2
1 High Voltage Laboratory, Elect. Engg. Dept., V. J. Tech. Institute, Mumbai-400019, INDIA.
2 CG Global R&D Centre, Crompton Greaves Ltd., Mumbai - 400 042, INDIA.
*E-mail : santoshj_g@rediffmail.com
Abstract--Sweep Frequency Response Analysis for condition monitoring of power
transformer is today a general accepted technique to identify faults in a transformer. The aim
of this paper is to assess the possibility of generating transfer functions which could be
realized into networks using the circuit synthesis approach. In circuit synthesis the transfer
function has to satisfy the conditions of positive realness and also the Hurwitz criterion. We
have applied these conditions in selection of transfer function. Using this fitted transfer

function for FRA under open circuit and short circuit condition of a practical transformer,
networks have been developed for the above conditions. These networks indicate the physical
transformer behavior appropriately and hence could be used in condition assessment.
Index Terms--Aging, Analyticity, Frequency Response, Hurwitz Polynomials, Impedance
Functions, Positive Real Functions, Realization Theory, Residues.
A Review of Intelligent Diagnostic Methods for Condition Assessment
of Insulation System in Power Transformers
Amritpal Singh1, P.Verma2
1Lecturer, Lovely Professional University, Phagwara (Punjab), India
2Professor, Lovely Institute of Technology, Phagwara (Punjab), India
Email: amrit_lpu@hotmail.com
Abstract--Incipient fault diagnosis of a power transformer is greatlyinfluenced by the
condition assessment of its insulation system specifically oil/paper insulation. In recent times,
a number of intelligent methods based on AI techniques, Artificial Neural Network and Fuzzy
Logic have been used to predict incipient faults in a power transformer based on its insulation
studies under various kinds of stresses. This paper focuses on the different intelligent methods
which have led to the development of an expert system based on Dissolved Gas Analysis (DGA)
for on-line condition monitoring of power transformers.
Keywords--Dissolved Gas Analysis, Transformer condition monitoring, Expert System,
Artificial Neural Network and Fuzzy Logic.
A Data Acquisition Platform for the Development of a Wind Turbine
Condition Monitoring System
Grzegorz Swiszcz1*, Andrew Cruden1, Campbell Booth1 and William Leithead1
1 University of Strathclyde, Department of EEE, Glasgow, UK
*E-mail : grzegorz.swiszcz@eee.strath.ac.uk
Abstract--Often condition monitoring (CM) system developers use simulation or test rig data
due to a lack of actual wind turbine measurements however, this data may not necessarily
reflect processes happening in the real turbine application. In order to determine different
patterns of machinery deterioration, precise data of existing parameters at higher sampling
frequencies up to 20 kHz is needed. Additional parameters, not currently commonly

monitored, like turbine vibration or tower movement, are also desired. In this paper the
design of a data acquisition (DAQ) platform to be mounted on a 660kW Vestas V47 wind
turbine is presented. The requirements and limitations of the data acquisition application are
discussed. A detailed explanation of the data acquisition program developed in LabVIEW as
well as the possibilities for remotely controlling this process are given. Finally, different
methodologies for handling, storing and accessing large volumes of data are presented with
the authors’ optimal solution highlighted.
Key words--Wind turbine, Condition monitoring, Machinery deterioration, Data acquisition
Application of Wavelet Package and Neural Network in Ventilators
Fault Warning
ZHU Quan, FU Sheng, Li Jing
College of Mechanical Engineering and Applied Electronics Technology, Beijing University of
Technology, Beijing, 100022, China
Abstract-- “Energy-fault” method is introduced for faults warning of ventilators, which is
based on wavelet package analysis and BP neural network. Character vectors which reflect
different faults state of ventilators are extracted from different frequency segments with the
technology of wavelet package analysis, and taking them into BP neural network model which
is trained with character vectors of typical faults sample. The faults states of ventilators are
identified with the BP neural network model. The results of research show that this kind of
faults diagnosis technology is an effective way to implement faults warning.
Key word--wavelet package, neural network, fault diagnosis, warning, ventilator
A Method of Data Fusion System for Fault Detection Based on
Model-based Diagnosis and Evidence Theory
Yao Qin Shi Yi-kai Shan Ning
School of Mechatronic Engineering, North-west Polytechnical University, Xi’an 710072, China
E-mail: yaoqsunxm@163.com
Abstract--This paper applied first Principles that is brought forward by Reiter etc, to obtain
the conflict set and hitting set.Based this result,it introduce date fusion system with D-S
evidence theory to solve the problem of detecting multi-fault through multi-symptom of these
faults. The method is to seek for conflict set candidates through SD (system description) of the
device off-line, and then discerns minimal conflict set and minimal hitting set on-line through
the action data of the device based on the fault symptoms. Afterwards,it assigns prior
probability to each possible fault component and process data fusion on the set of possible
fault components using D-S evidence theory. Finally the probability order of the possible fault

components is proposed.
Index word--model-based diagnosis; conflict set; hitting set; Dempster-Shafer evidence
theory;data fusion