[James_H._Harlow]_Electric_Power_Transformer_Engin(BookSee.org)

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contains service conditions, tests, classifications, performance characteristics, and construction data for the transformers. Class 2 Transformers: These transformers are dry-type, step-down, insulating specialty transformers suitable for use in National Electrical Code Class 2 circuits. They are generally used in remote-control, low-energy power, and signal circuits for the operation of bells, chimes, furnace controls, valves, relays, solenoids, and the like. Their secondary voltage is limited to 30 V. kVA range: 0 to 5 kVA, single phase Voltage Control transformers through 4800 V Ignition and luminous tube transformers through 15,000 V 3.14.3.1.2 ANSI/UL 506, Standard for Safety for Specialty Transformers These requirements cover air-cooled transformers and reactors for general use, and ignition transformers for use with gas burners and oil burners. Transformers incorporating overcurrent or over-temperature protective devices, transient-voltage surge protectors, or power-factor-correction capacitors are also covered by these requirements. These transformers are intended to be used in accordance with the National Electrical Code, NFPA 70. These requirements do not cover liquid-immersed transformers, variable-voltage autotransformers, transformers having a nominal primary rating of more than 600 V, transformers having overvoltage taps rated over 660 V, cord- and plug-connected transformers (other than gas-tube-sign transformers), garden-light transformers, voltage regulators, swimming pool and spa transformers, or other special types of transformers covered in requirements for other electrical devices or appliances. These requirements also do not cover: Autotransformers used in industrial control equipment, which are evaluated in accordance with the requirements for industrial control equipment, UL 508. Class 2 or Class 3 transformers, which are evaluated in accordance with the Standard for Class 2 and Class 3 Transformers, UL 1585. Class 2 transformers: These transformers are dry-type, step-down, insulating specialty transformers suitable for use in National Electrical Code Class 2 circuits. They are generally used in remote-control, low-energy power, and signal circuits for the operation of bells, chimes, furnace controls, valves, relays, solenoids, and the like. Their secondary voltage is limited to 30 V. Class 3 transformers: These transformers are similar to Class 2 transformers, but their output voltage is greater than 30 V and less than 100 V. Toy transformers, which are evaluated in accordance with the Standard for Toy Transformers, UL 697. Transformers for use with radio- and television-type appliances, which are evaluated in accordance with the requirements for transformers and motor transformers for use in audio-, radio-, and television-type appliances, UL 1411. Transformers for use with high-intensity discharge lamps, which are evaluated in accordance with the Standard for High-Intensity-Discharge Lamp Ballasts, UL 1029. Transformers for use with fluorescent lamps, which are evaluated in accordance with the Standard for Fluorescent-Lamp Ballasts, UL 935. Ventilated or nonventilated transformers for general use (other than compound-filled or exposed-core types), which are evaluated in accordance with the requirements for dry-type general purpose and power transformers, UL 1561. Dry-type distribution transformers rated over 600 V, which are evaluated in accordance with the requirements for transformers, distribution, dry-type — over 600 V, UL 1562. Transformers incorporating rectifying or waveshaping circuitry, which are evaluated in accordance with the requirements for power units other than Class 2, UL 1012. Transformers of the direct plug-in type, which are evaluated in accordance with the requirements for Class 2 power units, UL 1310. Transformers for use with electric discharge and neon tubing, which are evaluated in accordance with the Standard for Neon Transformers and Power Supplies, UL 2161. A product that contains features, characteristics, components, materials, or systems new or different from those in use when the standard was developed — and that involves a risk of fire, electric shock, or injury to persons — shall be evaluated using the appropriate additional component and end-product requirements as determined necessary to maintain the level of safety for the user of the product as originally anticipated by the intent of this standard. 3.14.3.1.3 ANSI/UL 1446, Standard for Safety for Systems of Insulating Materials — General These requirements cover test procedures to be used in the evaluation of Class 120(E) or higher electrical insulation systems intended for connection to branch circuits rated 600 V or less. These requirements also cover (1) the investigation of the substitution of minor components of insulation in a previously evaluated insulation system and (2) the test procedures to be used in the evaluation of magnet wire coatings, magnet wires, and varnishes. These requirements do not cover a single insulating material or a simple combination of materials, such as a laminate or a varnished cloth. These requirements do not cover insulation systems exposed to radiation or operating in oils, refrigerants, soaps, or other media that potentially degrade insulating materials. These requirements shall be modified or supplemented as determined by the applicable requirements in the end-product standard covering the device, appliance, or equipment in which the insulation system is used. Additional consideration shall be given to conducting tests for an insulating material, such as a coil encapsulant, that is used as the ultimate electrical enclosure. Additional consideration shall be given to conducting tests for an insulating material or component that is a functional support of, or in direct contact with, a live part. A product that contains features, characteristics, components, materials, or systems new or different from those in use when the standard was developed — and that involves a risk of fire, electric shock, or injury to persons — shall be evaluated using the appropriate additional component and end-product requirements as determined necessary to maintain the level of safety for the user of the product as originally anticipated by the intent of this standard. 3.14.3.1.4 IEC TC 96 This document covers standardization in the field of safety of transformers, power-supply units, and reactors with a rated voltage not exceeding 1000 V and a rated frequency not exceeding 1 MHz of the following kinds: Power transformers and power supply units with a rated power less than 1-kVA single phase and 5-kVA polyphase Special transformers and power supply units other than those intended to supply distribution networks, in particular transformers and power-supply units intended to allow the application of protective measures against electric shock as defined by IEC TC 64 Electrical installations in buildings, with no limitation of rated power, but in certain cases including limitation of voltage Reactors with a rated power less than 2-kVAR single phase and 10-kVAR polyphase Special reactors other than those covered by IEC 289 Note: Excluded are switch-mode power supplies (dealt with by SC 22E) Safety group function: Special transformers and power supply units other than those intended to supply distribution networks, in particular transformers and power supply units intended to allow the application of protective measures against electric shock as defined by TC 64, with no limitation of rated power but in certain cases including limitation of voltage. Table 3.13.2 provides a list of relevant documents. © 2004 by CRC Press LLC © 2004 by CRC Press LLC
TABLE 3.14.2 Relevant Documents for IEC TC96 IEC TC 96 Description 61558-1 Safety of power transformers, power supply units and similar 61558-2-1 Particular requirements for separating transformers for general use † 61558-2-2 Particular requirements for separating control transformers 61558-2-3 Particular requirements for ignition transformers for gas or oil burners 61558-2-4 Particular requirements for isolating transformers for general use 61558-2-5 Particular requirements for shaver transformers and supply 61558-2-6 Particular requirements for safety isolating transformers for general use 61558-2-7 Particular requirements for toys 61558-2-8 Particular requirements for bell and chime 61558-2-9 Particular requirements for transformers for Class III handlamps (NP) 61558-2-10 Particular requirements for high insulation level transformers (NP) 61558-2-11 Particular requirements for stray field transformers 61558-2-12 Particular requirements for stabilizing transformers 61558-2-13 Particular requirements for autotransformers 61558-2-14 Particular requirements for variable transformers 61558-2-15 Particular requirements for insulating transformers for the supply of medical rooms (CDV) 61558-2-16 Particular requirements for power supply units and similar (NP) 61558-2-17 Particular requirements for transformers for switch mode power 61558-2-18 Particular requirements for medical appliances 61558-2-19 Particular requirements for mainsborne perturbation attenuation transformers w/earthed midpoint (CDV) 61558-2-20 Particular requirements for small reactors (CDV) 61558-2-21 Particular requirements for transformers with special dielectric (liquid SF 6 ) 61558-2-22 Particular requirements for transformers with rated maximum temperature for luminaries (NP) 61558-23 Particular requirements for transformers for construction sites (CDV) 3.14.3.2 Electronics Power Transformers 3.14.3.2.1 IEEE 295, Electronics Power Transformers This standard pertains to power transformers and inductors that are used in electronic equipment and supplied by power lines or generators of essentially sine wave or polyphase voltage. Guides to application and test procedures are included. Appendices contain certain precautions, recommended practices, and guidelines for typical values. Provision is made for relating the characteristics of transformers to the associated rectifiers and circuits. Certain pertinent definitions, which have not been found elsewhere, are included with appropriate discussion. Attempts are made to alert the industry and profession to factors that are commonly overlooked. This standard includes, but is not limited to, the following specific transformers and inductors. Rectifier supply transformers for either high- or low-voltage supplies Filament- and cathode-heater transformers Transformers for alternating-current resonant charging circuits Inductors used in rectifier filters Autotransformers with fixed taps kVA Range: 0 to 1000+ kVA Voltage: 0 to 15 kV 3.14.3.3 Low-Voltage Medium-Power Dry-Type Transformers 3.14.3.3.1 NEMA ST-20, Dry-Type Transformers for General Applications This standards publication applies to single-phase and polyphase dry-type transformers (including autotransformers and non-current-limiting reactors) for supplying energy to power, heating, and lighting TABLE 3.14.3 NEMA TP-1 Rating Range for Single-Phase and Three-Phase Dry-Type and Liquid- Filled Distribution Transformers Voltage Class: Primary Voltage = 34.5 kV and below Secondary Voltage = 600 V and below Transformer Type Number of Phases Rating Range Liquid rating Single phase 10–833 kVA Three phase 15–2500 kVA Dry rating Single phase 15–833 kVA Three phase 15–2500 kVA Note: Includes all products at 1.2 kV and below. circuits and designed to be installed and used in accordance with the National Electrical Code. It applies to transformers with or without accessories having the following ratings: 1.2-kV class (600 V nominal and below), 0.25 kVA and up Above 1.2-kV class, sound-level limits are supplied that are applicable to commercial, institutional, and industrial transformers. This standards publication applies to transformers, commonly known as general-purpose transformers, for commercial, institutional, and industrial use in nonhazardous locations both indoors and outdoors. The publication includes ratings and information on the application, design, construction, installation, operation, inspection, and maintenance as an aid in obtaining a high level of safe performance. These standards, except for those for ratings, may be applicable to transformers having otherthan-standard ratings. These standards, as well as applicable local codes and regulations, should be consulted to secure the safe installation, operation, and maintenance of dry-type transformers. This publication does not apply to the following types of specialty transformers: control, industrial control, Class 2, signaling, oil- or gas-burner ignition, luminous tube, cold-cathode lighting, incandescent, and mercury lamp. Also excluded are network transformers, unit substation transformers, and transformer distribution centers. 3.14.3.3.2 NEMA TP-1, Guide for Determining Energy Efficiency for Distribution Transformers This standard is intended for use as a basis for determining the energy-efficiency performance of the equipment covered and to assist in the proper selection of such equipment. This standard covers singlephase and three-phase dry-type and liquid-filled distribution transformers as defined in Table 3.14.3. Products excepted from this standard include: Liquid-filled transformers below 10 kVA Dry-type transformers below 15 kVA Drives transformers, both ac and dc All rectifier transformers and transformers designed for high harmonics Autotransformers Nondistribution transformers, such as UPS transformers Special impedance and harmonic transformers Regulating transformers Sealed and nonventilated transformers Retrofit transformers Machine-tool transformers Welding transformers Transformers with tap ranges greater than 15% Transformers with frequency other than 60 Hz Grounding transformers Testing transformers © 2004 by CRC Press LLC © 2004 by CRC Press LLC
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ELECTRIC POWER TRANSFORMER ENGINEER
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I wish to recognize the interest of
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Contents 1 Theory and Principles Ch
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1.3 Equivalent Circuit of an Iron-C
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designer starts to make a design fo
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• Transient voltages generated du
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the transformer’s bushings and, m
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% regulation = [(V NL - V FL )/V FL
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In core-form transformers, the wind
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FIGURE 2.1.14 Layer windings (singl
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the transformer design, which may b
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consumer’s service circuit is a d
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FIGURE 2.2.3 Single-phase transform
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is installed so that the tank never
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above which persons might be burned
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FIGURE 2.2.16 Two-bushing subway. (
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carbon steel or the very expensive
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FIGURE 2.2.31 Radial-style dead fro
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FIGURE 2.2.36 Complete transformer
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voltage in each winding simultaneou
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mounted transformers can have arres
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V S + V S I V L Z=R+jX a) V L V S V
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Z = jX (2.3.19) 0.7 Then the curren
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X1 L* X1 S =X1 L X2 L* X3 L* a) S L
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150 V(%) 100 50 0 -50 40 80 T(s) 12
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2.3.8.1.2 Series Connection • The
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A six-pulse single-way transformer
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The degree of coupling also influen
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where I h = current for the hth har
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In the case of liquid-filled transf
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FIGURE 2.4.21 A 36-pulse system mad
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Vacuum-pressure encaps ulated — T
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FIGURE 2.6.1 Typical wiring and sin
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a) H1 b) Ip X2 FLUX H2 LEAKAGE FLUX
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and for CTs is TCF = RCF - (PA/2600
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RCF x Bx Bt RCF t - RCF 0 co
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2000 1000 5% Vex BANDWITH FROM NOMI
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This may be more useful when operat
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also some uncertainty in repeatabil
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FIGURE 2.6.25 Standard two-element
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2.7 Step-Voltage Regulators Craig A
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Source Bypass Switch Source Bypass
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2.7.4 Theory A step-voltage regulat
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FIGURE 2.7.22 Equalizer winding inc
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TABLE 2.7.4 Increase in Ampere Load
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References IEEE, Standard Requireme
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300% FIGURE 2.8.4 Schematic of a co
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TABLE 2.8.1 Typical Sizing Workshee
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Input with Interruption Ferro Outpu
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FIGURE 2.8.20A Performance of a rid
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• Input frequency or frequency ra
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References 1. Sola/Hevi-Duty Corp.,
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FIGURE 2.9.5 Typical phase-reactor
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FIGURE 2.9.10 Two generator arrange
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• Overloading of lines • Increa
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FIGURE 2.9.23 34-kV, 25-MVAR (per p
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V 90 ( X X ) s T (2.9.10a) where,
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Therefore, Line reactive losses = (
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ate of rise of transient-recovery v
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the LLCR is provided in IEEE Std. C
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aluminum shielding, i.e., an oil-im
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Leo J. Savio ADAPT Corporation Ted
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3.1.2.2.2 Heat Dissipation A second
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FIGURE 3.2.1 Solid-type bushing. ma
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1.6 cm. This means that most of the
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where HS = steady-state bushing ho
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the conductivity of the water-solub
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of 178 ohm-m, and a test duration o
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2. Easley, J.K. and Stockum, F.R.,
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FIGURE 3.3.5 Reactance-type LTC, in
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FIGURE 3.3.10 LTC with delta connec
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3.3.5 Selection of Load Tap Changer
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FIGURE 3.3.19 Effect of the leakage
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References Goosen, P.V. , Transform
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If i 1 is the full-load current rat
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TABLE 3.4.1 Loading Recommendations
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3.5.4 Three-Phase Transformer Conne
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FIGURE 3.5.4 Interconnected star-gr
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3.6.1.1 Standards ANSI standards fo
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ANSI standards. LTC control setting
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FIGURE 3.6.7 Discharging the capaci
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FIGURE 3.6.10 Standard switching-im
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voltage of the excited winding, rea
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FIGURE 3.6.18 Current, voltage, and
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TABLE 3.6.3 Transformer Short-Circu
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FIGURE 3.7.3 Control for voltage re
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FIGURE 3.7.6A Feeder with power-fac
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3. Circulating current (current bal
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FIGURE 3.7.10 Control block diagram
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Primary Current (Amps) 60 40 20 0 -
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current transformer having two prim
Page 183 and 184: 87R1 87BL1 (A) Independent Harmonic
Page 185 and 186: Winding 1 Secondary Currents Data A
Page 187 and 188: Y Y 20 18 3 rd Harmonic CTR1=40 CTR
Page 189 and 190: 230 kV 3 180 MVA 138 kV 5 CTR1 = 2
Page 191 and 192: 29. Concordia, C. and Rothe, F.S.,
Page 193 and 194: FIGURE 3.9.1 Measurement of pressur
Page 195 and 196: H 2m 1. Vertical Forced Air 2. Prin
Page 197 and 198: Gade, S., Sound Intensity Instrumen
Page 199 and 200: nected. This steady-state voltage d
Page 201 and 202: where [A] = state matrix [B] = inpu
Page 203 and 204: where C = capacitance between the t
Page 205 and 206: L ijo = N i N j ijo (3.10.31) 1.4
Page 207 and 208: % VOLTAGE % VOLTAGE 100 BIL 90 50 3
Page 209 and 210: 29. Degeneff, R.C., Reducing Storag
Page 211 and 212: All connections should be cleaned a
Page 213 and 214: 6. Costs to set up and use a mobile
Page 215 and 216: Records of relay operation must be
Page 217 and 218: • Has heating occurred as the res
Page 219 and 220: a reference value) of the currents
Page 221 and 222: The next data-processing step is to
Page 223 and 224: temperature. As the transformer coo
Page 225 and 226: 3.13.3.2 Instrument Transformers Th
Page 227 and 228: FIGURE 3.13.5 Analysis of bushing s
Page 229 and 230: temperature. Under abnormal conditi
Page 231 and 232: 3.14.1.2 Accredited Standards Commi
Page 233: FIGURE 3.14.4 IEC technical-committ
Page 237 and 238: TABLE 3.14.5 Relevant Documents for
Page 239 and 240: TABLE 3.14.9 Relevant Documents for
Page 241: TABLE 3.14.13 Relevant Documents fo
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