Glossary of technical terms - ABB

Glossaryof technical terms

ABB glossaryof technical termsAlthough power and automation technologies impactour lives on a daily basis, many of the terms usedto describe these fields are not part of everydayvocabulary. The purpose of this glossary is to providesimple explanations for some of the more commonlyused terms associated with ABB’s technologies andto open up the world of power and productivity to awider audience.An online version of this glossary is available at:www.abb.com/glossaryABB glossary 3

AActuator: In electrical engineering, the term actuatorrefers to a mechanism that causes a device to be turnedon or off, adjusted or moved, usually in response to anelectrical signal. In some literature the terms actor oreffector are also used. The term “effector” is preferred byprogrammers, whereas engineers tend to favor “actuator.”An example of an actuator is a motor that closesblinds in response to a signal from a sunlight detector.Actuators enable computers to control complex manufacturingprocesses without human intervention orsupervision.Advanced process control (APC): In general terms,advanced process control refers to large-scale computersystems that are used to monitor and control processingplants such as cement factories or oil refineries. Thesystems extend traditional process control, which is usedto monitor and control individual processes, by evaluatingand controlling multiple processes across the plant. Bymonitoring multiple processes, APC systems can optimizeoperations for multiple parameters, evaluating theimpact each adjustment will have on neighboring operationsby referencing current and historical data. With abroad yet detailed view of an entire plant’s operations,APC applications allow processes to operate closer totheir maximum capacity, while maintaining the necessarystandards of reliability and safety.Air-insulated switchgear: see Switchgear.Algorithm: A set of (mathematical) instructions or proceduresfor carrying out a specific task such as defining thesteps taken by an automation system.Alternating current (AC): Alternating current is a form ofelectricity in which the current alternates in direction (andthe voltage alternates in polarity) at a frequency definedby the generator (usually between 50 and 60 times persecond, ie, 50 - 60 hertz). AC was adopted for powertransmission in the early days of electricity supply4 ABB glossary

maintenance), avoiding both unnecessary equipmentinspections and unexpected breakdowns, which cancause expensive interruptions in production time. Computerizedasset management systems gather data inreal-time to ensure maximum production uptime andthroughput, with a minimum of human interaction.Asynchronous machines: see MachinesAzipod: The registered trademark of a family of modularelectric propulsion systems for ships, the first of whichwas co-developed by ABB in the 1980s. The Azipod unitis fitted to the ship’s hull externally in a pod, or casing,and combines the functions of a propulsion motor, mainpropeller, rudder and stern thruster. Since these functionsare no longer installed as separate units inside the ship,space onboard can be used for other purposes. Azipodunits also contribute to improved hydrodynamics, whichresult in fuel savings of around 15 percent compared toconventional propulsion systems.BBack-to-back connection: In HVDC terms, links used toconnect neighboring grids are often referred to as “backto-back”connections, indicating that the distancebetween the two grids is minimal. Such connections areable to link independent power grids, including thoseoperating at different frequencies, and enable power toflow from one grid to another. This means that generatorson either grid can be used to secure the supply of electricityacross the extended network. The connections canalso improve voltage and frequency stability in the linkedgrids.Note: The term “back-to-back connection” is also used todescribe a test set-up for electrical devices where amotor and a generator are connected to the same shaftlineBandwidth: 1. In computing, bandwidth is often a synonymfor the rate of information transmitted by a network6 ABB glossary

connection or interface. For example, a modem’s bandwidthmight be described as 56K, which means it iscapable of transmitting 56,000 “bits” of information persecond. A bit is the smallest unit of computerized data,comprising a single binary digit (ie, 1 or 0). 2. Bandwidthin electronic communication is the difference between thehighest- and the lowest-frequency signal in a given transmissionmedium. It is measured in hertz (Hz).Barge: In the oil and gas industry, a barge is an unpoweredmultipurpose marine vessel. Barges are used ascargo tankers, equipment and supply carriers, craneplatforms and support and accommodation bases inoffshore drilling, and as submarine pipe-laying vessels.Base-load power plant: To maintain power supplies asefficiently as possible, some power stations run near tofull capacity all the time, while others are brought onlineor increase production temporarily to meet transientpeaks in demand for electricity. The plants that maintainconstant levels of production tend to be those that rely onlower-cost fuels and are known as “base-load” powerplants.Biofuel: Fuel derived from biomass, ie, (recently) livingorganisms. This does not include fossil fuels such as coaland oil, which are derived from ancient organisms. Bioethanol,a fuel derived from sugar cane, corn and similarmaterials is an example of a biofuel. (See also Carbon cycle.)Blackout: A complete loss of power resulting from damageor equipment failure in a power station, power lines orother parts of the power system. A blackout may also bereferred to as a power outage or power failure. (SeeHigh-current transients, Reactive power, Wide-AreaMonitoring Systems.)Black-start capability: The ability of a power system (agenerator or grid subsection) to restart after a blackout,independently of the larger grid, by using local generators.For example, HVDC Light transmission systems canbe fitted with small diesel generators to provide auxiliaryABB glossary 7

power that can be operational almost immediately in theevent of a blackout. This power enables voltage control tobe established and normal operations to be resumedquickly.Brownout: A dip in the voltage level of a power system,which can damage electrical equipment or cause it tounder perform, eg, lights dim. (See Voltage drop.)Busbar: An electrical conductor that makes a commonconnection between several circuits. Sometimes, electricalwire cannot accommodate high-current applications,and electricity must be conducted using a more substantialbusbar — a thick bar of solid metal (usually copper oraluminum). Busbars are uninsulated, but are physicallysupported by insulators. They are used in electricalsubstations to connect incoming and outgoing transmissionlines and transformers; in a power plant to connectthe generator and the main transformers; in industry, tofeed large amounts of electricity to equipment used in thealuminum smelting process, for example, or to distributeelectricity in large buildings.Bushing: A bushing is a cyclindrical insulating component,usually made of ceramic, that houses a conductor.It enables a conductor to pass through a grounded enclosure,such as a transformer tank (the physical shell of atransformer), a wall or other physical barrier, to connectelectrical installations. In the case of a transformer, bushingsprotect the conductors that connect a transformer’score to the power system it serves through channels inthe transformer’s housing.CCapacitance: The ability of a device to store an electricalcharge (electrical charge is what flows in electric current).Capacitance is used in many different applications. (SeeCapacitor.) The unit of capacitance is the Farad, though itcan also be referred to in Coulombs per volt (Coulombbeing the standard unit of electrical charge). The Farad is8 ABB glossary

a very large unit and capacitances are usually on theorder of microfarads, µF (1 µF = 10 -6 F) and picofarads,abbreviated pF (1 pF = 10 -12 F).Capacitor (also referred to as a condenser): A multipurposedevice that can store electrical charge in theform of an electric field. It is used, for example, for powerfactor correction in (inductive) AC circuits. Capacitors areused to buffer electricity (smooth out peaks) and to guardagainst momentary voltage losses in circuits (whenchanging batteries, for example). (See also Capacitance.)Capacitor bank: A number of capacitors connected inparallel. (See also Parallel.)Carbon cycle: The circulation of carbon through itsvarious forms in the environment. Briefly, carbon dioxidein the atmosphere is fixed (ie, converted into solid matter)by the process of photosynthesis in plants and greenalgae. These then die and rot under the influence ofbacteria and fungi or are consumed by higher organismsin the form of food or fuel (burning plant matter or fossilfuels). Either way, carbon is released into the atmosphereas carbon dioxide and is available again for fixation (ie,incorporation into biomass).Cascading power failure: A cascade happens when apart of the power grid fails, and shifts its power load toother elements in the grid. Overloaded, these elementsalso begin to shut down and shift their power load ontoother elements, and so on. The resulting surge currentcan induce ongoing failures and take down an entirepower system in a very short time, “cascading” throughparts and systems like a ripple on a pond until the gridcollapses.Charging station: An installation at which an electricvehicle can be plugged into the grid to charge its battery.There are several types of charging station, includinglow-voltage, lower current installations that charge abattery over a period of several hours (for use in homes,for example), and higher-voltage, higher current fast-ABB glossary 9

10 ABB glossary

charging stations for a more rapid service in public places(car parks, public buildings, etc.).CHP: Combined heat and power, an acronym for theco-generation of heat and power. (See Co-generation.)Circuit breaker: Devices that interrupt high currents toprotect electrical equipment from damage caused bycurrent surges, eg, from a short circuit or a lightningstrike. (On a much smaller scale, they are used as analternative to fuses in the home.)Circuit breakers are typically classified according to themedium they use to inhibit arc formation between theopen contacts of the breaker. Media used include air,sulfur hexafluoride gas, oil and a vacuum.Closed Control System (CCS): This is a system used toregulate a process using feedback control (as opposed toan open control system, which relies on feed forwardcontrol). A closed system responds to actual systemconditions with a range of responses. It is slower to reactto changes in process conditions than an open system,but it is more specific in its responses and is able to dealwith a broader range of conditions. An example of closedloop control is a driver steering a car. If the car veers tothe left, the driver steers right to compensate.Co-generation: A particularly efficient method of electricitygeneration that diverts heat, produced as a byproductof the power generation process, to domesticand industrial heating systems. The heat is produced bycombustion of fuel in the power station to create thesteam that drives the generating turbines. It would otherwisebe released to the atmosphere.Collaborative production management (CPM):A method of unifying disparate yet interdependent productionsystems in order to optimize productivity. ComputerizedCPM solutions are software applications thatenable process manufacturers to plan, track, analyze anddirect their operations.ABB glossary 11

Combined-cycle power plant: Conventional thermalpower stations produce steam to drive turbines thatgenerate electricity. In a combined cycle plant, two turbinesare used. The first is driven by oil or gas, and wasteheat from that process contributes to the production ofsteam to drive the second turbine.Compression train: In the oil and gas industry, thecompression train is the entire line of equipment thatcontributes to process of compressing gas: It includesvalves, scrubbers, coolers and recycling loops.Conductor: An electrical conductor is any substancethrough which electrical current can flow. Since electricalcurrent is a process involving the flow of electrons, howwell a material conducts electricity depends on its atomicstructure and chemical consistency.Conductivity also depends on how strong the bond isbetween electrons and the metallic ions with which theyare associated. The weaker the bond, the better theconductor. All metals are conductors (copper is a particularlygood one). Plastics are not good conductors, butmake good insulators. Semi-conductors are materialswhose ability to conduct electricity can be controlled.Super-conductors, under special conditions, offer noelectrical resistance, so electricity can flow indefinitely.More generally, a conductor refers to a material that cantransmit electricity, heat or sound.Converter: An electrical device, comprising a rectifierand inverter, used to alter the voltage and frequency ofincoming alternating current in an electrical system. Theterm may also refer to inverters, rectifiers or frequencyconverters. (See also Converter station, Inverter, Rectifier,Frequency converter).Converter station: Special equipment is needed toconvert electricity from alternating current (AC) to directcurrent (DC), or vice versa. High-voltage DC (HVDC)converter stations use power electronic devices calledthyristors to make these conversions. (See also HVDCand HVDC Light.)12 ABB glossary

Coupling transformer: A coupling transformer is adevice that permits two (usually) separate circuits toinfluence one another. Such a setup can be desirable forcontrol purposes. It can also be used, for example, toinject high frequency signals into power lines for communicationspurposes.Current: The rate at which electrons flow through acircuit is defined as the current. If an electric circuit islikened to water flowing through a system of pipes, thecurrent is analogous to the rate at which the water isflowing. Electric current is measured in amps.DDC grid: Today’s electrical transmission systems arealmost exclusively based on alternating current (AC), butthe development of high-voltage, direct current (DC)technology has made it possible to build a DC grid (DCtransmission network) that can handle bulk power flowsover long distances. Power from such DC grids can befed into the AC networks as needed. Overlay DC gridswould handle fluctuations and instability in the networkbetter than AC systems and are a part of the “smart grid”concept (see also Smart grid).Demand-response: The term demand-response refersto a variety of technologies required to make demand forelectricity more responsive to the supply available. Asutilities generate more electricity from intermittent sourcesof energy such as wind and solar, demand-responsetechnologies are needed to help consumers use powerwhen it is plentiful and reduce their consumption whenthere is less available.Direct current (DC): This is electrical current that doesnot alternate (see Alternating current), the electrons flowthrough the circuit in one direction. As a result, DC doesnot generate reactive power (see Reactive Power). Thismeans that, in a DC system, only real (or active) power istransmitted, making better use of the system’s capacity.ABB glossary 13

In order to transmit electrical power as DC, the alternatingcurrent generated in the power plant must be convertedinto DC. At the other end of the process, the DC powermust be converted back into AC, and fed into the ACtransmissionor distribution network. The transmission ofDC current has very low losses. In the conversionbetween the two forms of power, known as rectification,incurs additional power losses and so it is worth whileonly when these losses are less than would be incurredby AC transmission, ie, over very long distances (~1000km for overhead lines, ~100 km for underwater). The othersituation in which DC transmission is advantageous iswhen connecting asynchronous grids, ie, where adjoiningelectricity grids have different frequencies (eg, 50 or 60Hz, as happens in some parts of Brazil and the UnitedStates). (See HVDC.)Direct torque control: A drive system (see Drive) thatcontrols the speed of an electric motor, and hence thetorque it can produce on a rotating shaft. The drive worksby regulating the amount of power the motor draws fromthe grid. Torque is an angular force that causes rotation,as seen for example in a car’s engine, which turns thevehicle’s drive shaft.Distributed control system (DCS): A control system thatregulates a process (manufacturing, chemical or other)from a series of strategic positions in the processingplant, as opposed to from a single, centralized controlunit. Microprocessor-based distributed control systems(DCS) originated in continous process industries (eg,refineries). and integrate distributed automation controllers,networks, application servers, workstations andother modules necessary to build a complete automationsystem.Distributed generation: This term refers to electricitygenerating installations that are scattered across the grid,rather than placed at a central location. They tend to besmall-scale generating plants – often operating usingrenewable fuels. They also include domestic powergenerators such as roof-top wind turbines and solar14 ABB glossary

panels, and microhydro installations. As more smarttechnologies are incorporated into the grid, enabling localdistribution grids to receive as well as deliver electricity,distributed generation will become an increasingly commonfeature of our power systems.Distribution substation: A distribution substation comprisesmedium-voltage switchgear, transformers andlow-voltage distribution equipment. It is used to transferpower from a medium-voltage electricity distributionsystem to a low-voltage distribution system that servesgroups of domestic or industrial consumers.Distribution transformers: Distribution transformers areused to regulate the supply of power to residential premises,factories and elsewhere. (See also Transformer.)District heating: A district heating system is one thatmakes use of heat generated at a central location, often ina thermal power plant, to heat water that is then fedthrough a communal system, delivering heat to homes inthe surrounding area.Downstream: The oil industry term “downstream” refersto all petroleum activities from the processing of refiningcrude oil into petroleum products to the distribution,marketing, and shipping of those products. See alsoUpstream.Drive: A drive is an electronic device used to regulate theperformance of an electric motor. It works by controllingthe power, frequency and current the motor draws fromthe grid. Drives (also referred to as a variable-speedmotor drive) can lead to considerable energy savings asmost motors are fixed-speed devices that run at fullspeed, even when a lower speed would suffice. Manymotors are controlled by “throttling down,” which isequivalent to slowing a car by using the brake, rather thantaking your foot off the accelerator, and does not saveenergy. Reducing a motor’s speed by half using a drivecan reduce the energy it consumes to one-eighth of itsconsumption at full speed.ABB glossary 15

Dynamic shunt compensation: A technology used tostabilize voltage by introducing or absorbing reactivepower at specific points of a power transmission grid. Thesystem helps to improve power transmission capacity aswell as the overall stability of the grid. Dynamic shuntcompensation is one of the three main FACTS (FlexibleAlternating Current Transmission Systems) technologies,the others being series compensation and dynamicenergy storage. (See also Series and Shunt.)EEco-efficiency: Combining efficiency and ecologicalaspects in the pursuit of sustainable development.Electric motor: A device that converts electrical energyinto mechanical energy that can be used to drivemechanical equipment.Electrical balance of plant (eBoP): The sum of all electricalequipment required for safe and coordinated operationof various parts of a power plant.Electrical drivetrain: In the wind power industry, thisterm refers to the combination of the a wind turbine’sgenerator, converter and transformer.Electrical units:Quantity Name SymbolCurrent Ampere AVoltage Volt VPower Watt WWatt = ampere x volt1,000 A = 1 kiloampere (= kA)1,000 V = 1 kilovolt (= kV)1,000 W = 1 kilowatt (= kW)1,000,000 W = 1,000 kW = 1 megawatt (= MW)Some examples:Voltage:In a home the voltage in the outlets is normally 220 or 110 Volt. Largepower transmission lines have voltages in the range of 220 - 800 kV.16 ABB glossary

Power:A typical incandescent (not fluorescent) light bulb consumes40 - 100 Watt.A normal home in North America or Europe consumes powerin the range of 1 - 10 kW.A large wind power unit can generate 3,000 kW (= 3 MW)A large coal or nuclear power station can generate 500 - 4,000 MW.(Individual nuclear generating units have a capacity of 1 - 1.3 GW)Electricity storage: Electricity is difficult to store. Themost effective way to store surplus electricity in terms ofcost and environmental impact is to use it to pump wateruphill into the reservoirs of hydropower plants, a processknown as pumped storage. Alternatives include largescalebatteries.Electromagnetic fields: All stationary charged particlesare surrounded by an electric field (measured in volts/meter). Charged particles in motion (eg, electrons in anelectrical current) are also surrounded by a magnetic field(measured in amps/meter). The combination of an electricfield (around the charged particles) and the magnetic field(generated when the charged particles flow) is known asan electromagnetic field (sometimes abbreviated to EMF).Radio waves are a form of electromagnetic radiation.Note: the terms “electric field” and “magnetic field” arenot interchangeable.Emissions: The release or discharge of substances,effluents or pollutants into the environment.Energy cost effectiveness: This is a key performanceindicator used to judge the productivity of a proves interms of financial gain per unit of energy consumed.Energy efficiency: Defined as output energy divided byinput energy, and, if necessary, averaged over time. Theelectrical efficiency of an appliance is defined as theamount of that energy that is converted into a useful form,divided by the total energy it draws. For example, anincandescent light bulb (one with a filament inside thebulb) is said to be inefficient because much of the energyit uses (around 95 percent) is converted into heat ratherABB glossary 17

than light. A fluorescent lamp that works on a differentprinciple is somewhat more efficient because more of theenergy it uses is converted into light and less is lost asheat (around 80 percent).Engineering Procurement and Construction (EPC):Term used to describe contracts in which a companyassumes full responsibility for project engineering, materialprocurement and construction. The term is also usedfor companies contracted to perform these services.FFACTS (Flexible Alternating Current TransmissionSystems): Refers to a group of technologies thatenhance the security, capacity and flexibility of powertransmission and distribution systems. The technologiescan be installed in new or existing power transmissionand distribution lines. Examples of FACTS devices are:Static var compensation (SVC), uses an electrical device(see Static var compensator) to regulate and stabilizevoltage in bulk power systems. The most advancedversion of this technology is called SVC Light and hasadditional features, in particular more powerful flickercompensation to stabilize heavy and rapidly fluctuatingloads, for example arc furnaces, and to smooth voltageflicker. Series Compensation can be fixed or controllable.The latter is called Thyristor Controlled Series Capacitor(TCSC). Series compensation is a straightforward andcost effective way to improve power transmission capacityand preserve voltage stability, particularly in bulktransmission corridors. Thyristor-controlled series compensationis especially useful for damping power oscillationover interconnections between transmission girds.ABB’s FACTS devices optimize power flow to maximizethe capacity of power lines and improve voltage stabilityby reactive power compensation (see Reactive power andPower factor compensation). In some cases, networkcapacity can be doubled. The equipment also makes thesystem more resilient to “system swings” and otherdisturbances.18 ABB glossary

Fault-closing device: A system of circuit breakers thatserves to contain a fault in a grid, preventing it fromspreading to other areas and causing widespreaddisruption.Fault ride-through (FRT): Refers to the ability of anelectrical device (such as a wind turbine converter) torespond to a temporary fault or voltage change in thetransmission and distribution grid, including a zero-voltagedip, and to help the system return to normal operation.Fault ride-through specifications are part of manygrid code requirements.Feeder: Overhead lines or cables that are used to distributeelectrical power to consumers. Feeders connectdistribution substations and consumers.Feedstock: A term that refers to crude oil, natural gasliquids, natural gas or other materials used as raw ingredientsfor making gasoline, other refined products orchemicals.Frequency converter (frequency changer): At ABB,this term most commonly refers to a device used to adjustthe frequency of alternating current. Frequency convertersare a central component in variable-speed drives tocontrol the speed, torque or power on the shaft of anelectric motor by adjusting the frequency and voltage ofthe electricity powering the machine. Frequency convertersare used to control the rotational speed of wind turbinesto stabilize the frequency of the electricity theyproduce.Frequency converters are also used to connect electricalsystems operating at different frequencies. For examplein shore-to-ship power connections, these devices areused to enable ships, most of which have onboard electricalsystems running at 60 Hz, to onshore power suppliesthat most commonly run at 50 Hz.Fuel cell: A device in which chemical energy released bythe oxidation of a liquid (such as methanol) or gaseousfuel is converted directly into electrical energy.ABB glossary 19

20 ABB glossary

GGas-insulated switchgear: see Switchgear.Gearless mill drive (GMD): A system consisting of aringmotor and its associated equipment such as transformersand control systems. Its main application is todrive (rotate) mills in the minerals or cement industry.Generation mix: The generation mix is a term used todescribe the contribution various sources of electricitymake to the power supply serving a particular region orpopulation. The portion of renewable energy in the globalgeneration mix is rising in response to concern overclimate change and increasing demand for electricalpower.Generator: A device that converts rotating mechanicalmovement into electric power. The current generated canbe either alternating (AC) or direct (DC). ABB manufacturesa range of generators, including wind-turbine generators.In a simple AC generator, a loop of wire is placedbetween the poles of a permanent magnet. The magnet isthen rotated and the electromotive force produced by themovement of the electric field causes a current to flow inthe wire. This is the principle of the synchronous motorand big generators in power plants. A DC generatoroperates on the same principle as the AC generator, butincludes a device (a commutator), which effectively preventsthe current from alternating.Grid code: This term refers to the requirements developedby power utilities that power generators of all kindsmust meet to ensure the proper functioning and stabilityof the electrical transmission and distribution grid. thatdefine grid fault and other conditions that must beresponded to by wind power plants. These include regulationssuch as n-1 and fault ride-through capabilities (seen-1 and Fault ride-through).Grid reliability: Power utilities strive to maintain electricitysupplies without unexpected dips or surges that canABB glossary 21

cause disruptions ranging from flickering lights to equipmentdamage. To avoid these problems, utilities thereforeneed to control the flow of power under normal runningconditions and in emergency situations. This is done byinstalling sophisticated switching and protection equipment(fuses, circuit breakers, transformers, etc.) in substations,and monitoring equipment (protection relays,phase monitoring units, thermal line sensors etc) at strategicpoints on the grid. The monitoring units measure therate and direction of power flow, its stability, the temperatureof hot power lines, and other parameters critical tothe normal functioning of the grid. The data are transmittedto a central computer, which uses them to calculatethe settings for the control equipment housed in thesubstations and generating plants. This allows power flowto be directed, compensating for overloaded sections ofthe grid and even shutting down certain connections toprevent the spread of disturbances or to allow maintenancework to be carried out. (See FACTS, Networkcontrol, SCADA, Wide-Area Monitoring Systems.)HHarmonics: Generally, harmonics are oscillations in thebase power frequency. In electrical AC systems, the basefrequency is typically 50 or 60 hertz (Hz) and harmonicsoccur in multiples of this, for example 100 Hz, 150 Hz,200 Hz, etc. where the base frequency is 50 Hz. Harmonicsoccur whenever there is a disturbance of the voltageor current, eg, if the current is interrupted or if AC currentis synthesized in a converter. The problem with harmonicsis that electrical devices may react differently whenexposed to a different frequency than the one they aredesigned for, which may cause damage. Harmonics arean increasing problem in power systems as most powerelectronics solutions cause harmonics. Harmonics canbe reduced by the use of power filters.High-current transients: Short spikes of high electricalcurrent in a grid, caused by lightning strikes, or rapidswitching of electrical devices in the grid, especially22 ABB glossary

capacitors. These transients, or surges, cause cables tooverheat, potentially damaging insulation and leading toshort circuits. Equipment can be protected from highcurrenttransients by using a surge protector.High-voltage direct current (HVDC): A technologydeveloped by ABB in the 1950s to move large amounts ofpower over substantial distances - typically by overheadtransmission lines, but also by way of submarine cables.Transmitting DC power over long distances is moreefficient than AC transmission (see Direct current andTransmission and distribution) and is a cost-effectivemethod of connecting two asynchronous grids (gridsoperating at different frequencies). An HVDC systemtakes electrical power from an AC network, converts it toDC at a converter station and transmits it to the receivingpoint by line or cable, where it is turned back into AC byusing another converter. The conversion is carried outwith high-power, high-voltage electronic semiconductorvalves. These valves are controlled by a computer system,so the amount of transmitted power and also thedirection of transmitted power can be precisely controlled,a feature unique to HVDC systems. Anotherimportant aspect of HVDC lines is that they can never beoverloaded. Because HVDC transmits only active (real)power, no line capacity is wasted on transmitting reactivepower. This means that the same power can be transmittedover fewer (or smaller) transmission lines than wouldbe required using AC, and less land is needed to accommodatethe lines. HVDC induces minimal magnetic fields,so the power lines may be built safely closer to humanhabitation.In the 1990s ABB developed the HVDC Light technologywhich made it possible to have long underground transmission(see HVDC Light). In 2006 ABB carried out thefirst test circuit on +/- 800 kV ultrahigh-voltage DC (seeUltrahigh voltage).Typical power and voltage range are:Classical HVDC: 500 - 6,400 MW (± 150 - 660 kV)UHVDC: 6000-8000 MW (± 800 kV)HVDC Light: 100-1100 MW (± 150 - 320 kV)ABB glossary 23

Hoist, friction hoist: In underground mining, a hoist orwinder is used to raise and lower conveyances within themine shaft.All hoists are powered using electric motors. Modernhoists are generally equipped with variable speed drivesthat minimize energy consumption and control the speedof the hoist.HVDC Light: An adaptation of classic HVDC, developedby ABB in the 1990s. It can be used to transmit electricityin lower power ranges (tens of megawatts) to an upperrange of 1,100 megawatt (MW) (±320 kilovolts). By comparison,classic HVDC (see High-voltage direct current)systems typically transmit electricity in the 500 to 8,000MW power range. Offering both HVDC and HVDC Lightsystems extends the economical power range of HVDCtransmission.The superior controllability is achieved by using IGBTs (ie,transistors) as the power electronic device used for theconversion (see Direct current).HVDC Light offers the same benefits as traditional HVDCsystems, but also provides more secure power control(superior to classic HVDC) and quick power restoration inthe event of a blackout. Because of its superior ability tostabilize AC voltage at the terminals, it is the ideal technologyfor wind parks, where the variation in wind speedcan cause severe voltage fluctuations.HVDC Light is environmentally friendly, featuring oil-freecables, compact converter stations and cables that canbe laid underground (thereby avoiding local planningdifficulties associated with overhead lines) as well asunderwater. It is the only technology available that allowslong-distance underground high-voltage transmission. Itis rarely used for power transmissions using overheadlines. Because of its smaller footprint, underground cabletechnology and superior controllability, HVDC Light hasmany more potential applications than classical HVDC,for example: feeding power into cities and offshore oil andgas platforms; strengthening power networks in areaswhere there is opposition to new overhead lines; anddelivering power to islands that would otherwise needlocal generating plants.24 ABB glossary

HVSC: High-voltage shore connections enable ships todraw electricity from onshore power grids while in port tooperate onboard equipment such as lighting, cooling andheating systems, instead of burning fuel oil to runonboard generators. For a large cruise ship on a 10-hourstay in port, a shore connection can cut fuel consumptionby up to 20 tons and reduce carbon dioxide emissions by60 tons.II/O(Input/output): A device that enables communicationbetween electronic equipment and external devices,including human operators. Examples of I/O devicesinclude computer keyboards, printers, sensors and alltype of interface cards.IEC 61850: The International Electrotechnical CommissionIEC standard for substation automation replaces agreat many communication protocols that require the useof use protocol converters, which are basically “translators”that help electronic devices using different machinelanguages transmit information to each other. The problemis that protocol converters can cause messagingerrors and delays. A single communication standard forsubstation automation removes the need for “translators,”helps customers lower maintenance and operating costs,and makes installations easier to expand or modify.Industrial IT: A series of interoperable software andhardware products and systems from ABB and/or thirdparties that are designed to communicate with each otherand work together as part of a larger system for a specificapplication.Industrial productivity: Raising industrial productivitymeans lowering costs for each unit (eg, car, ton of paper,etc.) produced. Manufacturers are under intense pressureto improve productivity and performance to remain competitive,and avoid losing business to more efficient rivals.New technologies and business models are allowingABB glossary 25

companies to restructure their business processes -things like procurement, manufacturing, research, sales,distribution, and so on - establishing new combinationsand locations that enable them to work more closely withpartners, suppliers, and customers. Productivity improvementscan be achieved by automating operations,improving the asset management, optimizing factoriesoperations, outsourcing, and improving the supply chainmanagement.Instrument transformer: In contrast to most transformers(which are used to convert power), instrument transformersare components of devices used for measurementor monitoring (eg, to measure voltage or current intransmission lines). As they do not actually transform anysignificant quantities of energy they are usually small andlightweight.Infrared thermography: A method used to measure thestatus of equipment by analyzing the amount of heat itradiates.Instrumentation: Electronic or electromechanical devices,often referred to as meters, used to measure the flow,level, temperature and pressure of processes in differentindustrial applications. They monitor processes in powergeneration, manufacturing and refining plants. Informationcollected by various instruments is processed byanalyzers and used to assess performance, sendingalerts if readings are not as expected.Insulator: A material that does not conduct electriccurrent, such as plastic, some kinds of silicon or glass.The term can also refer to a material that does not conductheat. For clarity, the terms thermal insulator andelectrical insulator may be used. (See also Conductor.)Integration of renewable energy: Feeding electricityfrom intermittent sources of energy such as wind andsolar into the power network without causing any disturbanceto the power supply.26 ABB glossary

Inverter: An electrical device for converting direct current(DC) into alternating current (AC). (See also Rectifier.)Ionized gas: If a material is exposed to high temperaturesor an electrical field, it can become ionized, ie, its particlescan become electrically charged. Also known asplasma, ionized gases can enable an electric current tojump across a gap in an electric circuit. To avoid thisproblem, circuit breakers are equipped with variousinsulators that inhibit arc formation. See also Circuitbreaker.ISO 9000: International standards for quality assuranceset by the International Standards Organization. Itincludes some 20 elements of quality process performance,and is a prerequisite for delivering predictable,quality products to customers.ISO 14000: International standards for environmentalmanagement systems set by the International StandardsOrganization.KKey performance indicator (KPI): A measurable objectiveused by organizations to monitor progress towards aspecific goal. Such measures are commonly used todefine and evaluate an organization’s performanceagainst internal benchmarks or those of peerorganizations.LLights-out factory: An automated factory that requiresno light because no people work in it.Line thermal monitoring (LTM): Process that measuresaverage power-line temperature and detects temperatureABB glossary 27

changes in power lines. It is important because heatcauses wires to expand and sag, resulting in short circuits,fires and blackouts if they contact treetops etc.(See also Wide-Area Monitoring System.)Load: A load in electrical terms is the power consumedby a device or a circuit. Load is also used to describe thetotal of all electricity consumers in a power system.Load management: Controlling loads in a utility systemto limit peak demand, reduce costs, improve load factor,or in some other way improve the stability and reliability ofelectrical power distribution.Load tap changer (LTC): Load tap changers are devicesused to adjust the performance of transformers. Adjustingthe tap changes the voltage of the transformer’s inputor output.Loop flow: Inadvertent transmission of power through anunnecessary diversion in the transmission network. It isundesirable because it serves no purpose and incurslosses.MMachines, electric: Motors and generators are collectivelyreferred to as “machines” or “electric machines.”Motors are machines that convert electrical energy intomechanical work in the form of a rotating shaft, whilegenerators convert the mechanical work of a rotatingshaft into electricity.The speed of a “synchronous” machine, ie, the rate atwhich its shaft rotates, is dictated by the frequency ofelectricity in the grid to which it is connected. The speedof a synchronous machine is accurately predictable. Thismeans that it maintains its speed irrespective of the loadplaced on it.Because synchronous motors can maintain a particularspeed with extreme accuracy, they are used in performance-criticalapplications such as mechanical clocks28 ABB glossary

and DVD drives. Synchronous generators are commonlyused in power plants, where their predictable, consistentperformance helps to maintain the quality and reliability ofpower supplies. Synchronous generators are alsoreferred to as alternators.The speed of an asynchronous machine is slightly slowerthan the frequency of the electricity it consumes or generates.Asynchronous motors slow down as their loadincreases and asynchronous generators change speedwith the torque (rotational force) that is applied to theirrotors. Asynchronous machines are also referred to asinduction motors/generators.Manifold: An arrangement of connected pipe and valvesused to consolidate multiple pumps, tanks, and/or pipelinesand a single unit.Mechanical drivetrain: In the wind power industry, thisterm refers to the combination of the turbine’s main rotorshaft and bearings, gearbox (if used) and generator.Megavar (MVAr): One million VAr (volt-ampere reactive).Megavoltampere (MVA): One million VA (volt-ampere).Megawatt (MW): One million watts. One megawatt wouldbe needed to light 10,000 one-hundred-watt light bulbs.If those bulbs were powered for 1 hour, 1 MWh of electricalpower would be used. (See also Watt and Watt hour.)Meters: see Instrumentation.Microgrid: A microgrid is a small-scale power networkthat comprises generating units and consumers. Oftenincluding renewable power sources such as wind turbinesand solar panels, microgrids may also be connected tothe larger-scale grids from which they can draw power iflocally generated supplies fail to meet demand.Microturbine: A small turbine generator of 30 - 250kilowatts (kW) generating capacity, which can be locatednear a customer load.ABB glossary 29

30 ABB glossary

Mobile substation: A substation that can be transported,usually by truck, to temporarily replace equipment atthe site of a failure or in the event of plannedmaintenance.Model predictive control (MPC): The online control ofan industrial process (such as oil refining) that uses avirtual model of the process, which allows a computer topredict appropriate control settings.Multiterminal: An HVDC transmission with more thantwo stations, which enables either to tap off power in astation (or stations) in the middle or to feed in more powerin the middle of the transmission link.Nn-1 (n minus one) is the operating standard to whichEuropean transmission system operators are obliged towork. It refers to a system that can maintain normaloperations despite the loss of any single component. Inthe case of a power network, a component may be atransmission line, a generating unit of a power station, etc.Network control: Network control systems monitor andcontrol the electricity network to keep power flowing andto preserve the balance between power generation andconsumption.Network management: A system that uses networkcontrol and asset management to oversee all aspects(operational and maintenance) of a network.OOhm: Unit of electrical resistance. If a 1 volt source isconnected to a wire with a resistance of 1 ohm, then 1ampere of electric current will flow.ABB glossary 31

Oil sands: Naturally occurring mixture of bitumen (aheavy, viscous form of crude oil), water, sand and clay.Using hydroprocessing technology, bitumen can berefined to yield synthetic crude oil.Optimization: The process of making a system as near toperfect or as effective as possible.Original Equipment Manufacturer (OEM): Manufacturerswho produce an end product such as automobiles,machines or switchboards, incorporating componentsfrom sub-suppliers, such as ABB.PParallel: Electrical components that are connected insuch a way that the flow of electricity can take multiple, orparallel, paths through the circuit are said to be connected“in parallel” or “in shunt,” as opposed to “in series.” Ifone of the components in a parallel circuit was to fail, theelectricity would continue to flow through an alternativepath. (See also Series.)Phase angle monitoring (PAM): A device that monitorspower-network stresses caused by heavily loaded lines.This is part of the Wide-Area Monitoring System, whichrelies on a number of phasor measurement units (PMUs)to collect data from strategic positions in the grid. (Seealso Wide-Area Monitoring System and Phasor MeasurementUnits.)Phase-shifting transformer (also known as a quadraticbooster): A specialized type of transformer used on3-phase power grids (AC) to balance the active (real) andreactive power in the system (see Reactive power, Powerfactor correction and Three-phase power), preventing theloss of lines through physical overloading.Phasor Measurement Units (PMUs): Monitoring devicesthat are installed at critical nodes in a power network32 ABB glossary

where they collect data on power flow. (See also Wide-Area Monitoring System, Line thermal monitoring.) Signalssent from the units via satellite to a central controlroom, enabling operators to identify and counteract anyinstabilities before they spread through the grid.Pig: A cleaning device placed that is used to scraperesidues from the inner wall of oil pipelines. A pig ispushed through the pipeline by the pressure of the oilflowing past. Pipelines can be equipped with pig launchsites and pig traps. These are points at which pigs can beintroduced or removed from the pipeline.Polyethylene: Also known as polythene, this plasticmaterial has excellent properties of electrical insulation.Power factor: Power factor is a measure of an electricalcircuit’s effectiveness in doing useful work on a scale ofzero (lowest) to 1 (highest). It reflects how much thewaveforms of voltage and current are in phase, usuallymeasured at the customer’s load. When the voltage andcurrent are significantly out of phase, as is common inindustrial environments with many electric motors, thecurrent will be high even at relatively low power levels.The economic result of this low power factor is expensiveelectrical losses on the circuit and underutilization of thecircuit’s power transfer capability. In these cases thecustomer or the electric utility may deploy additionalcapacitor banks near the customer load, restoring thepower factor to or near unity and improving system utilization.(See also Power factor correction.)Power factor correction (reactive power compensation):Depending on the type of equipment a consumerconnects to the electricity supply (whether there is a netconsumption or generation of reactive power), powerfactor varies. Unless this variation is corrected, highercurrents are drawn from the grid, leading to grid instability,higher costs and reduced transmission capacity. Mostutilities impose penalties on consumers who fail to correcterrant power factors. (See also Power factor.)ABB glossary 33

Power losses: This term generally refers to electricalenergy that is lost to inefficiencies in transmission, distribution,or in the use of electricity. As electricity flowsthrough a conductor, individual electrons collide with theatoms of the conductor and transfer energy to them,causing them to heat up. This heat is lost to the atmospherein the form of thermal radiation. Some power isalso lost to electromagnetic radiation.Losses in an electricity distribution system depend on thelength of the cable (the longer the cable, the greater thelosses); the conductivity of the material (higher resistancemeans greater losses); the square of the current (at twicethe current, there will be four-times the losses); and thecross-sectional area of the cable. Therefore, to minimizelosses, power should be transmitted at the highest practicalvoltage. This reduces the current and therefore theamount of power lost in transmission. Most electricaltransmission systems are alternating current at voltagesbetween 110 and 800 kV. (See also HVDC.)Process Industry: An industry in which raw materials aretreated and converted into products by means of a seriesof stages (or processes). Process industries include oiland gas refining, pharmaceutical and chemical production,water and sewerage treatment etc.Process Analytical Technology (PAT): As defined bythe United States Food and Drug Administration, PAT is amechanism to design, analyze, and control pharmaceuticalmanufacturing processes through the measurementof critical process parameters, which affect critical qualityattributes. The concept actually gains a clearer understandingof processes by defining and monitoring theircritical process parameters, in order to improve productivityby enhancing consistency and minimizing rejects.Process automation: The term process automation isused to refer to an automation system, the principalpurpose of which is to automate or support the operatorof a manufacturing process. Such a process can be themanufacturing or treatment of any goods made in acontinuous or quasi-continuous manner such as fuel,paper, cement, steel, chemicals, food.34 ABB glossary

Process historian: A process historian is a mechanismfor storing data relating to a particular process.The data stored by modern historians typically includetime-stamped information from a variety of traceablesources. The data are used for modeling, optimizationand auditing purposes.Power capacity: In terms of generation, the capacity of apower plant is the maximum power that installation iscapable of producing. It does not account for periods ofinactivity due to maintenance work, for example. Nuclearpower stations have low maintenance requirements andfew shutdowns (as do all “base-oad” power plants), whichenable them to achieve about 90 percent productivity.Gas-fired power stations, which are more expensive torun, often operate well below capacity, ramping up to fullproductivity only during periods of high demand. Thismeans that their productivity may be only 20 - 30 percentof the plant’s actual capacity. The relationship betweencapacity and output is known as the “capacity factor,”where 100 percent is the theoretical maximum.As an example, the hydropower station on the Itaipu damin Brazil has a total generating capacity of 14,000 megawattsand could therefore theoretically produce122,640,000 megawatt-hours of electricity per year(14,000 MW x 8,760 hours = 122.6 million MWh). TheItaipu dam actually produced 91,651,808 MWh of electricityin 2009. The actual production divided by thetheoretical maximum production gives Itaipu a capacityfactor of 74.7 percent. (See also Base-load power plant.)Programmable logic controller (PLC, or programmablecontroller): These are electronic devices used tocontrol equipment, especially in automation. They aresmall, programmable units that can receive informationfrom output devices, such as sensors in a control system,and transmit signals to input devices, such as actuators,that can effect changes in the control system.Pumped storage: see Electricity storage.ABB glossary 35

RReactive power: It is a concept that describes the loss ofpower in a system resulting from the production of electricand magnetic fields in it. Reactive loads in a powersystem drop voltage and draw current, which creates theimpression that they are using up power, when they arenot. This “imaginary power” or “phantom power” is calledreactive power, and is measured in Volt-Amps-Reactive(VAR). Reactive power is significant because it must beprovided and maintained to ensure continuous, steadyvoltage on transmission networks. Reactive power isproduced for maintenance of the system, and not forend-use consumption. If elements of the power gridcannot get the reactive power they need from nearbysources, they will pull it across transmission lines anddestabilize the grid. In this way, poor management ofreactive power can cause major blackouts.Real time: In business, a system is described as realtimeif it will operate in a deterministic manner, ie, it willrespond to an input within a defined time limit. For example,safety-relevant systems must always respond withinpre-determined time limits. Many automation applicationsare also real-time, as unpredictable response times andreaction delays would effectively destabilize the process.To ensure a system is real-time, it must fulfill stringentdemands with both hardware and software design.Some applications are described as near real-time. Suchsystems are sufficiently fast that it can be assumed thatcritical time limits will not be exceeded. An example wouldbe the communications between an automation systemand a business system designed to provide managementlevel information, which must be fast enough for accuratedecisions, but not instantaneous.Recloser: A circuit breaker designed to interrupt shortcircuitcurrent and reconnect the circuit after interruption.Rectifier: An electrical device used to convert alternatingcurrent (AC) into direct current (DC). (See also Inverter.)36 ABB glossary

Regenerative braking: A braking method that is used torecoup some of the energy lost as vehicles slow down orbrake against an incline (downhill). It exploits the ability ofelectric motors to work as generators during breaking.This enables the mechanical energy from the load to beconverted into electric energy and returned to the electricitysupply systems for use either by other vehicles, orby the braking vehicle at a later time if onboard energystorage systems such as batteries or super-capacitorsare available. The method can be used to improve theenergy efficiency of cranes and elevator systems, trainsand hybrid cars.Relays: 1. A switch that can be operated remotely.2. Control and protection relays are switches used tosignal and control the operation of electrical equipmentand systems. They include electronic and electromechanicalrelays and components; high-voltage protection,substation control and communications; automatedsubstation components; and distribution relays.Remote Terminal Unit (RTU): Remote terminal unitscollect data from points around a power transmission anddistribution network and transmit the information to acentral location. They are typically used to control andmonitor power networks, and are components of supervisorycontrol and data acquisition (SCADA) systems.Resistance: Cables and electrical devices resist themovement of electrons that constitute the current passingthrough them. This is known as electrical resistance andis measured in Ohms. If an electric circuit is likened towater flowing through a system of pipes, the resistance ina wire is analogous to the restriction of the water flowimposed by the diameter of the water pipe, or any obstacleswithin the pipe.Resistor: A resistor is any electrical component thatresists the flow of electrical current. Resistors can be usedto control current and therefore protect a circuit fromoverload. Resistors are also an important component ininstrumentation and are used together with capacitors inpower filters to eliminate unwanted harmonics.ABB glossary 37

Ringgeared mill drives (RMD): A system used to drive(rotate) a mill. The RMD itself is comprised of motor(s)(synchronous or asynchronous), a frequency converter,transformers and control equipment. As opposed togearless mill drives, the motor in RMD is mechanicallyconnected to the mill via a coupling, pinion(s) andringgear.Ringmotor: Also called wrap-around motor, a ringmotoris a very large synchronous motor. The poles of the motorare directly flanged on the driven equipment. (See alsoMachine).Robot, industrial: An industrial robot is defined byISO 8373 as an automatically controlled, reprogrammable,multipurpose, manipulator, programmable in three ormore axes, which may be either fixed in place or mobilefor use in industrial automation applications. Typical robotapplications include welding, painting, assembly,pick and place, packaging and palletizing, productinspection, and testing, all accomplished with high endurance,speed, and precision. ABB developed the firstcommercially available electric robot almost 40 years ago.SSCADA (supervisory control and data acquisition):A SCADA system is a computer system that gathers andanalyses data on equipment and processes in industrialprocessing plants such as pulp and paper mills, oil refineriesand water treatment facilities. It may perform otherfunctions in power networks, such as load management,load curtailment and restoration, distribution automation,and facilities management functions.Semiconductor: A semiconductor is a material whoseelectrical properties can be significantly influenced byphysical factors (mostly electrical conditions, but alsopressure, temperature, light, etc). This means that asemiconductor will behave either as an insulator or a38 ABB glossary

conductor of electricity, depending on the conditions towhich it is exposed. They are a fundamental componentof electronic devices. Because of their ability to respondto external conditions, semiconductors are commonlyused in sensor systems.Series: Electrical components that are connected in anunbranched line are said to be “in series,” as opposed to“in parallel” or “in shunt.” If any one of the components ina series circuit was to fail, the circuit would be broken andno electricity would flow. (See also Parallel.)Series capacitor: see FACTS.Ship-to-shore connection: see HVSCShort circuit: An electric contact between parts of anelectric circuit, which causes a very high current, increasesin temperature and potentially fire, if the circuit is notproperly protected. This can occur if two live wires comeinto contact with each other, perhaps because of worninsulation. The term is also used when defining the safeoperating conditions for electrical devices. If a device issaid to have a short-circuit resilience of 400 amps (A),that means that it can be subjected to up to 400 A beforeit will shut itself down.Shunt: see Parallel.Shunt reactors: Shunt reactors are used in AC highvoltage energy transmission systems to stabilize thesystem voltage during load variations. The shunt reactorcan be regarded electrically as a large coil connectedbetween the line and ground to absorb reactive power inthe system. This function is especially important at highvoltages, typically over 130 kilovolts (kV), and long transmissionlines. Cable systems require even more compensationof reactive power, also at lower system voltage dueto the high capacitance of the cable. Besides stabilizingthe system voltage, the shunt reactor increases the activeor the useful power transmitted in the system.ABB glossary 39

40 ABB glossary

SIL (Safety integrity level): The safety integration level(SIL rating) of a system indicates the level of risk associatedwith it. It is a measure of its ability to perform safelyand, in the event of failure, to fail safely. There are four SILlevels, with level 4 indicating the highest performance.Solar power (photovoltaic): Photovoltaic solar power isgenerated when the sun’s radiation is “harvested” byspecially designed panels, which absorb the radiationand emit electrons.Unlike thermal solar plants, photovoltaic power plantsgenerate direct current. This means that before it can befed into the local grid, photovoltaic power must be convertedinto alternating current using an inverter. (See alsoInverter).Smart grid: Smart grids are modern power transmissionand distribution systems, capable of accepting power ofany quality from any source and delivering it to consumersof all kinds via a bidirectional supply system. They arean evolutionary development of traditional grids, whichare based mainly on centralized generating plants, supplyingpower via long-established, unidirectional transmissionand distribution systems whenever consumersrequest it. Smart grids are being developed in responseto rising demand for power and the increasing need toincorporate renewable or distributed, less predictablegeneration into the grid. ABB’s smart grid concept is ofan observable and controllable system, based on industry-widestandards, providing a stable, secure, efficientand environmentally sustainable network. The system willcross national and international borders. It must be ableto detect and react automatically to disturbances andchanges in supply and demand, re-establishing balanceand maintaining the stability demanded by both endusersand government legislation. This is achieved by anautomation and information technologies infrastructureintegrating the whole supply chain from production toconsumption, based on an infrastructure of enablingsmart grid components. Thus smart grids also accommodatecustomer response management systems thatallow utilities to optimize the performance of the grid andto integrate consumption into balancing load and genera-ABB glossary 41

tion. Many of the technologies and standards needed toestablish smart grids on a large scale have been thesubject of research and development at ABB for someyears and many are already in use.Solar inverters: or Photovoltaic (PV) inverters convertthe variable DC output of the modules into a utility frequencyAC current that can be fed into the commercialelectrical grid (see Inverter). Solar inverters are categorizedinto off-grid and grid feeding inverters. Grid feedinginverters are categorized into central inverters, multistringinverters and string inverters.Solar power (thermal or concentrating solar power):Solar power is electricity generated using sunlight as itsprimary energy source. In the case of thermal solarpower, the sun’s heat is used to heat water, either directlyor via a heat-conducting fuid, and generate steam. Thesteam is then used to generate electricity in the same wayas it is used in conventional thermal power stations.Thermal solar power is suitable for large-scale generatingplants (eg, Desertec) and can be used in combinationwith conventional generation (eg, gas-fired).Static var (volt amperes reactive) compensator (SVC):A device that provides fast-acting reactive power compensation(see Power factor and Power factor correction)in high-voltage electricity networks. Cheaper to build andmaintain than rotating compensation devices, such assynchronous compensators (see also FACTS), SVC hasno rotating parts (it is static). It compensates for fluctuationsin the voltage and current of an electric grid, therebyallowing more power to flow through the network whilemaintaining safety margins, increasing network stability.Solar string inverters: are devices for converting DC toAC power that are designed for high voltage DC inputs.Using a string inverter, the solar panel array with panelstypically rated at 12V, 24V or 48V are wired in series,rather than in parallel, ie, the panels are arrayed in a“string” to produce the same amount of total power, butat higher voltages (typically 200-800V). This means a42 ABB glossary

lower current flows allowing a lighter weight inverterconstruction [Volts (V) x Amps (A) = Watts (W) or power].Storage: see Electricity storage.String test: In a string test, a complete drive train, comprisinga frequency converter, a motor and an application,such as a pump or a compressor, are tested in a factorysituation that simulates site conditions. String tests areperformed prior to delivery to verify the performance andfunctionality of the equipment and to ensure that the unitscomply with specifications under the working conditionsof the destination plant. String tests are time consumingand expensive but often reduce time spent on erectionand commissioning on the customer’s premises.Substation automation: The various technologies, methodsand equipment used for the automatic operation ofsubstations. This includes control and protectionfunctions.Submetering: Metering of individual units in multi-unitproperties.Substation: Substations are key installations in the powergrid. They house equipment for the protection and controlof electrical power transmission and distribution, includingpower transformers, switchgear and measuring equipment.(See also Reactive power, Power factor correction,Circuit breaker and Switchgear.)Supercritical power plant: A supercritical power plant isa thermal electricity generating station that uses steam atextremely high temperature and pressure to generateelectricity with improved efficiency. Above 374°C and22.064 MPa (the “critical” point of water), water simplyexists as super-heated steam, which can be used to drivethe turbines of a generator more efficiently than steam ata lower (subcritical temperatue).Operating under such conditions requires the use ofextremely robust equipment. The specifications for productsused in supercritical plants are higher than thoseused in subcritical plants.ABB glossary 43

Supergrid: Trademarked by Airtricity in 2006, the termSupergrid refers to a pan-European subsea power grid.The term is widely used in the context of renewableenergy. The Desertec project, for example would rely on asupergrid for the transmission of offshore wind powerfrom European coastlines, solar power from northernAfrica and southern Europe, together with hydro powerfrom northern Europe.Surge protector: Also known as a surge arrester, this is adevice used to protect equipment from damage causedby high-voltage power surges. These can occur whensubstations are hit by lightning or as a result of switchingoperations in high-voltage transmission.Switchgear: Equipment used to control, protect, andregulate the flow of electrical power in a transmission ordistribution network. It is often located in substations, butcan be associated with any electrical equipment thatmight need to be isolated for fault correction (eg, if avoltage drop occurred in one part of the grid, it might benecessary to shut off the affected section to prevent thefault spreading), or for maintenance purposes. The maincomponents of switchgear are circuit beakers, whichinterrupt high-voltage current to protect electrical equipmentfrom excessive current. The terms gas- and airinsulatedswitchgear (GIS and AIS) refer to switchgearequipped with gas- and air-insulated circuit breakers. Thegas-insulated variety is more costly than the air, but ittakes up less space and is therefore the preferred optionwhen installing switchgear in urban environments (thesubstations can be one fifth the size of a conventional AISsubstation).Synchronous machines: see MachinesSystem 800xA: An Industrial IT-compatible controlsystem that provides a means of achieving measurableproductivity and profitability improvements. The full nameis Extended Automation System 800xA, and it is used inmany industry sectors to oversee and control a widerange of processes. It extends the scope of traditional44 ABB glossary

control systems to include all automation functions withina single operations and engineering environment. Thisenables plants to perform in a more intelligent and costeffectiveway, and to improve productivity.TThree-phase power: A form of electricity used to supplyheavy loads (power-hungry electrical equipment) such asindustrial air conditioning units, grinding machines etc.Almost all power is generated as three-phase and, withthe exception of HVDC, most transmission lines arethree-phase. Three-phase is a more efficient way ofdelivering heavy loads and the three-phase motors itsupplies are more efficient, smaller and cheaper to buildthan their single-phase counterparts. Wiring is simplifiedbecause no neutral return path is provided. Residentialpremises, however, are supplied with single-phasepower.Thyristor: A thyristor is a semiconductor device used inelectrical systems, such as HVDC installations, as ahigh-speed, high-power switch, capable of turning powersupplies of many megawatts on within a split second.Thyristors are a component used in inverters and rectifiers.(See also Inverter and Rectifier).Thyristor-controlled series capacitor: see CapacitorTraction motor: A traction motor is typically used topower the driving wheels of a railroad locomotive, a tramor an electric train, like a subway or light rail vehicle.There is usually one traction motor on each driven axle.Traction motors differ from other motors in the scale oftheir design. They must be extremely compact, becauseof the limited space available on the locomotives, andhighly reliable as there is no room for any backup systems.(See also Traction transformer.)Traction substation: A substation used to feed powerinto railway electrification systems.ABB glossary 45

Traction transformer: This is a fundamental componentof a rail locomotive’s traction chain. It adapts the catenary(overhead) voltage to the various low voltage levels neededby the train, mainly for traction, but also for lighting,heating and ventilation, passenger information and safetysystems such as door blocking, brakes, signaling andcommunication. The traction transformer is the uniqueenergy transfer point between high voltage (HV) and lowvoltage (LV) and therefore must achieve the highestavailability and reliability levels to guarantee uninterruptedtrain service.Transformer: A transformer is a device used to transferenergy from one AC circuit to another and to increase(step up) or reduce (step down) voltage as required.Transformers are an essential component in an electricalgrid. Electricity generated in a power station must bestepped up to the appropriate voltage for transmission(between 100 and 800 kV) and then stepped down againto the distribution voltage (110 - 230 V), which is deliveredto homes. Note that the voltage of DC cannot be transformedin the same way as it can for AC. (See Alternatingcurrent.)Transmission and distribution (T&D): The term refers tothe transport of electricity from the power station to theend user. Transmission is the movement of power at highvoltage (above ca. 50 kV), usually over long distances.Raising the voltage allows power to be transmitted moreefficiently (ie, with fewer losses - at lower voltages, moreelectrical power is converted to heat and lost to theatmosphere) over a wide area. Distribution is the transportof electricity at medium voltage (between ca. 1 and50 kV) over shorter distances to industrial, commercialand residential areas. Transformers are generally, thoughnot always, housed in substations.Turbine: A propeller-like device that is turned by a streamof hot gas (steam in a conventional thermal power station),water (in a hydro plant), gas (in a gas power plant:here the gas burns in the turbine and exhaust gasescause it to rotate); or wind (as in a wind farm). The rotation46 ABB glossary

of the turbine drives the generator that converts themechanical rotation into electrical power. (See alsoGenerator.)Turbocharger: An air compressor that is used to boostthe oxygen intake of a motor. In an internal combustionengine, a mixture of fuel and air is pumped into the confinedspace of a piston cylinder and ignited by a spark.When it ignites, the fuel burns, using the oxygen in the air,and the remaining gasses expand almost instantly,releasing a huge amount of energy. This expansion pushesthe piston out, turning the crankshaft that drives theengine. The amount of fuel that can be ignited in thecylinder, and therefore the power generated, is limited bythe amount of oxygen present. If there is too little oxygen,not all the fuel will burn. By compressing the air that is fedinto the cylinder, more oxygen is made available for thecombustion process, allowing more fuel to be burned,more completely, leading to more power obtained athigher efficiency and “cleaner” exhaust-emissions.Turbogenerator: A collective term referring to a turbineand the generator to which it is connected.Turnkey project: A turnkey project is one in which thecontractor will design, engineer, deliver and commissionan installation, taking responsibility for all aspects of thework. A lump-sum turnkey project is one in which thecontractor undertakes a turnkey project for a set fee,agreed by the contractor and the customer before thework has begun.UUltrahigh voltage (UHV): This term refers to voltages inexcess of 800 kilovolts (kV). UHV transmission usingalternating current (AC) has been possible for severaldecades, and it is now also possible to transmit powerthis way using direct current (DC). DC transmission haslower losses and requires fewer overhead lines than ACtransmission. Ultrahigh-voltage DC links will make itABB glossary 47

viable to produce electricity in remote regions and transmitit to centers of demand via energy “superhighways.”The efficient transmission of electricity at 800 kV DCpower transmission is now feasible over distances as faras 3,000 km. UHVDC systems are cheaper, smaller andmore efficient than comparable AC transmission systems.Upstream: The oil industry term “upstream” refers to oiland natural gas exploration and extraction activities. Seealso Downstream.VVacuum interrupter: Vacuum interrupter: A vacuuminterrupter is a device that uses a vacuum to extinguishthe arc formed when a circuit breaker is opened. It alsoinsulates the contacts after the arc has been interrupted.Vacuum interruption is seen as the ideal switching technologyfor medium-voltage applications. Excellentswitching capabilities, combined with high reliability anda compact design, provide economical switching solutionswith virtually no maintenance requirements. Vacuuminterruption offers the lowest environmental impact of allmedium-voltage switching technologies over the entireproduct life cycle. Vacuum interrupters are comprised ofmaterials that are environmentally benign and safe tohandle during periodic out-of-service maintenance and atend-of-life disposal. The devices perform well in all medium-voltageswitching applications required in modernpower systems. They have exceptionally long life and arevirtually maintenance free.Variable Shunt Reactors: A traditional shunt reactor hasa fixed rating. Recently Variable Shunt Reactors (VSRs)have been developed and introduced on the market. Therating of a VSR can be changed in steps. The maximumregulation range typically is a factor of two, eg, from100-200 MVAr (see Megavar). The regulation speed isnormally in the order seconds per step and around aminute from max to min rating. VSRs are today availablefor voltages up to 550 kilovolts (kV). The largest VSRs in48 ABB glossary

operation today have a rating of 120-200 MVAr at 420 kV.The variability brings several benefits compared to atraditional fixed shunt reactor. The VSR can continuouslycompensate reactive power as the load varies and therebysecure voltage stability. Other important benefits are:−−reduced voltage jumps resulting from switching inand out of traditional fixed reactors−−flexibility for future (unknown) load and generationpatterns−−improved interaction with other transmissionequipment and/or systems such as coarse tuningof static var compensator (SVC) equipment−−limiting the foot print of a substation if parallel fixedshunt reactors can be replaced with one VSR−−a VSR can be used as a flexible spare unit and bemoved to other locations in the power grid if needed.Variable-speed drive: see Drive.Volt: Standard unit of electrical “pressure” in a circuit.(See also Voltage.)Voltage (potential difference): The voltage between twopoints in an electrical circuit is a measure of the potentialdifference, or the force, that is pushing electrons betweenthese two points. It is analogous to water pressure in awater system. Voltage is measured in volts, and is directlyproportional to the current and resistance of a circuit:V=IR, where V = potential difference in volts, I = current inamperes (amps) and R = resistance in ohms. This isOhm’s law.Voltage drop: A voltage drop is a reduction in the forcethat “pushes” current through a circuit. Under theseconditions, resistive loads, such as light bulbs, will givesuboptimal performance- lights will flicker or becomedimmer because less current is flowing. Inductive loads,such as motors, respond to voltage drops by workingharder to obtain the same power, which can cause overheating,increased operating costs and the risk of equipmentfailure. Devices such as computers often haveABB glossary 49

sensors that warn of suboptimal voltage or excess heatingand will shut down automatically in response to a voltagedrop.Voltage rating: The maximum voltage that can be appliedto an electronic device.WWaste-to-energy plant: A waste-to-energy plant producesenergy, either heat or electricity using waste as afuel. Their furnaces cannot easily be ramped up or downand so the plants are not used for peak-load generation.Due to the highly variable composition of the plants’ fuel,stringent environmental standards are imposed andwaste-to-energy plants use sophisticated flue-gas cleaningdevices and monitoring devices to ensure emissioncontrol.Watt (W): Standard unit of electrical power(1 watt = 1 amp at 1 volt). The watt is also a general unitof power. One watt = 1 joule per second.Watt hour (Wh): 1 watt hour is the amount of electricalenergy consumed by a 1 watt load over a period of onehour. For example, a 100 watt light bulb (a 100 watt load)uses 100 watt-hours of energy every hour. Rather confusingly,watt-hours are sometimes used to describe “power.”This is incorrect. Watt-hours are a measure of energytransferred, ie, the product of power (kW) x time (hours).Confusion can also arise when describing electricitygeneration. For example, a wind farm described as “150MW” has a peak power output of 150 MW. If the farm was100 percent efficient, it would transfer 150 MW x 24 hours= 3600 MWh to the electricity grid every day. Because ofvarious inefficiencies and the fact that wind blows erratically,wind turbines are actually only about 30 percentefficient. This means that 150 MW (theoretical maximum)x 24 h (number of hours in a day) x 30 percent (efficiency)= 1080 MWh will be produced each day.Cables can also be described as, for example, 350 MW.50 ABB glossary

This is the capacity of the cable, ie, the maximum amount ofpower it can carry. In an hour, a 350 MW cable could (theoretically)deliver 350 MWh of electricity.Web inspection system (WIS): Web inspection systemsare used by the pulp and paper industry to inspect thesurface of the paper as it is being produced. The systemscan detect and report many types of defects, includingholes, spots and streaks.Wide-area monitoring system (WAMS): WAMS is anadvanced early-warning technology for power grids thathelps operators prevent system instabilities and overloads,as well as cascade tripping that leads to power blackouts. Itcomprises a series of phasor measurement units, set up instrategic positions around the grid. These monitor stresses(loads and temperatures) on the power lines and send databack to a central control station via a GPS satellite link. Thisallows operators to identify problems at an early stage andprevent widespread disruption of the grid (ultimately rollingblackouts). WAMS is used in conjunction with phase shiftingtransformers to protect and stabilize power grids.Notes:ABB glossary 51

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