Glossary

If a term is not available, you can submit your suggestion. A German version of the glossary is also available.

Actuator: In electrical engineering, the term actuator refers to a mechanism that causes a device to be turned on or off, adjusted or moved, usually in response to an electrical signal. In some literature the terms actor or effector are also used. The term “effector” is preferred by programmers, whereas engineers tend to favor “actuator.” An example of an actuator is a motor that closes the blinds in response to a signal from a sunlight detector. Actuators enable computers to control complex manufacturing processes without human intervention or supervision.

Air-insulated switchgear: see Switchgear.

Algorithm: A set of (mathematical) instructions or procedures for carrying out a specific task such as defining the steps taken by an automation system.

Alternating current (AC): Alternating current is a form of electricity in which the current alternates in direction (and the voltage alternates in polarity) at a frequency defined by the generator (usually between 50 and 60 times per second, ie, 50-60 Hertz). AC was adopted for power transmission in the early days of electricity supply because it had two major advantages over direct current (DC): its voltage could be stepped up or down according to need using transformers (see Transformer), and it could be interrupted more easily than DC. Neither advantage is as relevant today as it once was because power electronics can solve both issues for DC. (See also Direct current and Transmission and distribution.)

Alternator: See Generator

Ampere: The standard unit of electrical current (see also Current).

Arc welding: A group of welding procedures that fuse metal pieces by melting them together, using heat from an electric arc between an electrode and the work piece. The arc is caused by electrical current flowing though plasma consisting of ionized air molecules and metal ions. Material from the electrode is transferred to the work piece, and the electrode is consumed over time. Arc welding processes are attractive because of their low capital and running costs.

Arc-welding cell: The area of a factory set up to weld metals using electric arcs. ABB provides modular robotic arc welding cells that are ready to install in a customer’s plant.

Azipod: The registered trademark of a family of modular electric propulsion systems for ships, the first of which was co-developed by ABB in the 1980s. The Azipod unit is fitted to the ship's hull externally in a pod, or casing, and combines the functions of a propulsion motor, main propeller, rudder and stern thruster. Since these functions are no longer installed as separate units inside the ship, space on board can be used for other purposes. Azipods also contribute to improved hydrodynamics, which result in fuel savings of around 15 percent compared to conventional propulsion systems.
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B

Bandwidth: 1) In computing, bandwidth is often a synonym for the rate of information transmitted by a network connection or interface. For example, a modem’s bandwidth might be described as 56K, which means it is capable of transmitting 56,000 “bits” of information per second. A bit is the smallest unit of computerized data, comprising a single binary digit (ie, 1 or 0). 2) Bandwidth in electronic communication is the difference between the highest- and the lowest-frequency signal in a given transmission medium. It is measured in Hertz.

Biofuel: Fuel derived from biomass, ie, (recently) living organisms. This does not include fossil fuels such as coal and oil, which are derived from ancient organisms. Bioethanol, a fuel derived from sugar cane, corn and similar materials is an example of a biofuel. (See also Carbon cycle)

Blackout: A complete loss of power resulting from damage or equipment failure in a power station, power lines or other parts of the distribution system, caused by a short circuit, equipment failure, overloading of the power transmission and distribution system, etc. A blackout may also be referred to as a power outage or power failure. (See High-current transients, Reactive power, Wide-Area Monitoring Systems.)

Brownout: A dip in the voltage level of a power system, which can damage electrical equipment or cause it to under perform, eg, lights dim. (See Voltage drop.)

Busbar: An electrical conductor that makes a common connection between several circuits. Sometimes, electrical wire is not big enough to accommodate high-current applications, and electricity must be conducted using a busbar — a thick bar of solid metal (usually copper or aluminum). Busbars are uninsulated, but are physically supported by insulators. They are used in electrical substations to connect incoming and outgoing transmission lines and transformers; in a power plant to connect the generator and the main transformers; in industry, to feed large amounts of electricity to equipment used in the aluminum smelting process, for example, or to distribute electricity in large buildings.
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C

Capacitance: The ability of a device to store an electrical charge (electrical charge is what flows in electric current). Capacitance is used in many different applications. (See Capacitor.)
The unit of capacitance is the Farad, though it can also be referred to in Coulombs per volt (Coulomb being the standard unit of electrical charge). The Farad is a very large unit and capacitances are usually on the order 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 multi-purpose device that can store electrical charge in the form of an electric field. It is used, for example, for power factor correction in (inductive) AC circuits. Capacitors are used to buffer electricity (smooth out peaks) and to guard against momentary voltage losses in circuits (when changing batteries, for example). (See also Capacitance.)

Capacitor bank: A number of capacitors connected in parallel (see also Parallel).

Carbon cycle: The circulation of carbon through its various forms in the environment. Briefly, carbon dioxide in the atmosphere is fixed (ie, converted into solid matter) by the process of photosynthesis in plants and green algae. These then die and rot under the influence of bacteria and fungi or are consumed by higher organisms in the form of food or fuel (burning plant matter or fossil fuels). Either way, carbon is released into the atmosphere as carbon dioxide and is available again for fixation (ie, incorporation into biomass).

Cascading power failure: A cascade happens when a part of the power grid fails, and shifts its power load to other elements in the grid. Overloaded, these elements also begin to shut down and shift their power load onto other elements, and so on. The resulting surge current can induce ongoing failures and take down an entire power system in a very short time, "cascading" through parts and systems like a ripple on a pond until the grid collapses.

Closed Control System (CCS): This is a system used to regulate a process using feedback control (as opposed to an open control system, which relies on feed forward control). A closed system responds to actual system conditions with a range of responses. It is slower to react to changes in process conditions than an open system, but it is more specific in its responses and is able to deal with a broader range of conditions. An example of closed loop control is a driver steering a car. If the car veers to the left, the driver steers right to compensate.

CHP: Combined heat and power, an acronym for the co-generation of heat and power (see Co-generation).

Circuit breaker: Devices that interrupt high currents to protect electrical equipment from damage caused by current surges, eg, from a short circuit or a lightning strike. (On a much smaller scale, they are used as an alternative to fuses in the home.)

Co-generation: A particularly efficient method of electricity generation that diverts heat, produced as a by-product of the power generation process, to domestic and industrial heating systems. The heat is produced by combustion of fuel in the power station to create the steam that drives the generating turbines. It would otherwise be released to the atmosphere.

Conductor: An electrical conductor is any substance through which electrical current can flow. Since electrical current is a process involving the flow of electrons, how well a material conducts electricity depends on its atomic structure and chemical consistency. Conductivity also depends on how strong the bond is between electrons and the metallic ions with which they are associated. The weaker the bond, the better the conductor. All metals are conductors, and copper is a particularly good one. Plastic and rubber are not good conductors, but make good insulators. Semi-conductors are materials whose ability to conduct electricity can be controlled. Super-conductors, under special conditions, offer no electrical resistance, so electricity can flow indefinitely.

More generally, a conductor refers to a material that can transmit electricity, heat or sound.

Converter station: Special equipment is needed to convert electricity from alternating current (AC) to direct current (DC), and then back to AC. High-voltage DC (HVDC) converter stations use devices called thyristor valves to make these conversions. (See also HVDC and HVDC Light.)

Current: The rate at which electrons flow through a circuit is defined as the current. If an electric circuit is likened to water flowing through a system of pipes, the current is analogous to the rate at which the water is flowing. Electric current is measured in amps.
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D

Direct current (DC): This is electrical current that does not alternate (see Alternating current), the electrons flow through the circuit in one direction. As a result, DC does not generate reactive power (see Reactive Power). This means that, in a DC system, only real (or active) power is transmitted, making better use of the system’s capacity. In order to transmit electrical power as DC, the alternating current generated in the power plant must be stepped up to the appropriate voltage and converted into DC. At the other end of the process, the DC power must be converted back into AC, its voltage stepped down, and fed into the AC-distribution network. The conversion between the two forms of power, known as rectification, incurs additional power losses and so it is worth while only when these losses are less than would be incurred by AC transmission, ie, over very long distances (~600 km for overhead lines, ~50 km for underwater). The other situation in which DC transmission is advantageous is when connecting asynchronous grids, ie, where adjoining electricity grids have different frequencies (eg, 50 or 60 Hz, as happens in some parts of Brazil and the U.S.) (see HVDC).

Direct torque control: A drive system (see Drive) that controls the speed of an electric motor, and hence the torque it can produce on a rotating shaft (see torque shaft). The drive works by regulating the amount of power the motor draws from the grid. Torque is an angular force that causes rotation, as seen for example in a car’s engine, which turns the vehicle’s drive shaft.

Distributed Control System (DCS): A control system that regulates a process (manufacturing, chemical or other) from a series of strategic positions in the processing plant, as opposed to from a single, centralized control unit.

Distributed generators: Small-scale electricity generators such as microturbines or fuels cells. Such generators are usually located near the facilities they serve.

Distribution substation: A distribution substation comprises medium-voltage switchgear, transformers and low-voltage distribution equipment. It is used to transfer power from a medium-voltage electricity distribution system to a low-voltage distribution system that serves groups of domestic or industrial consumers.

Distribution transformers: Distribution transformers are used to regulate the supply of power to residential premises, factories and elsewhere. (See also Transformers.)

Drive: A drive is an electronic device used to regulate the performance of an electric motor. It works by controlling the power, frequency and current the motor draws from the grid. Drives (also referred to as a variable-speed motor drive) can lead to considerable energy savings as most motors are fixed-speed devices that run at full speed, even when a lower speed would suffice. Many motors are controlled by “throttling down,” which is equivalent to slowing a car by using the brake, rather than taking your foot off the accelerator, and does not save energy. Reducing a motor’s speed by half using a drive can reduce the energy it consumes to one-eighth of its consumption at full speed.

Dynamic compensation device: A power electronics installation that compensates for reactive power (see Reactive power compensation). Unlike a static compensator (see SVC), a dynamic compensation device contains rotating parts.

Dynamic shunt compensation: A technology used to stabilize voltage by introducing reactive power at specific points of a power transmission grid. The system helps to avoid sudden power surges and improves the overall stability of the grid. Dynamic shunt compensation is one of the two main FACTS (Flexible Alternating Current Transmission Systems) technologies, the other being series compensation. (See also Series and Shunt.)
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E

Electrical Balance of Plant (eBoP): The sum of all electrical equipment required for safe and coordinated operation of various parts of a power plant.

Eco-efficiency: Combining efficiency and ecological aspects in the pursuit of sustainable development.

Energy efficiency: Defined as output energy divided by input energy, and, if necessary, averaged over time. The electrical efficiency of an appliance is defined as the amount of that energy that is converted into a useful form, divided by the total energy it draws. For example, an incandescent light bulb (one with a filament inside the bulb) is said to be inefficient because much of the energy it uses (around 95 percent) is converted into heat rather than light. A fluorescent lamp that works on a different principle is somewhat more efficient because more of the energy it uses is converted into light and less is lost as heat (around 80 percent).

Electric motor: A device that converts electrical energy into mechanical energy that can be used to drive mechanical equipment.

Electrical units:

	Quantity	Name	Symbol
	Current	Ampere	A
	Voltage	Volt	V
	Power	Watt	W

Watt = Ampere x Volt
1,000 A = 1 Kiloampere (=kA)
1,000 V = 1 Kilovolt (= kV)
1,000 W = 1 Kilowatt (= kW)
1,000,000 W = 1,000 kW = 1Megawatt (= MW)

Some examples:

Voltage
In a home the voltage in the outlets is normally 220 or 110 Volt.
Large power transmission lines have voltages in the range of 220 - 800 kV.

Power
A typical incandescent (not fluorescent) light bulb consumes 40 - 100 Watt.
A normal home in North America or Europe consumes power in 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).

Electromagnetic fields: All stationary charged particles are surrounded by an electric field (measured in volts/meter). Charged particles in motion (eg, electrons in an electrical current) are also surrounded by a magnetic field (measured in amps/meter). The combination of an electric field (around the charged particles) and the magnetic field (generated when the charged particles flow) is known as an electromagnetic field (sometimes abbreviated to EMF). Radio waves are a form of electromagnetic radiation.
Note: the terms “electric field” and “magnetic field” are not interchangeable.

Emissions: The release or discharge of substances, effluents or pollutants into the environment.

Engineering Procurement and Construction (EPC): Term used to describe contracts in which a company assumes full responsibility for project engineering, material procurement and construction. EPC is also used to describe companies that are contracted to perform these services.
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F

FACTS (Flexible Alternating Current Transmission Systems): Refers to a group of technologies that enhance the security, capacity and flexibility of power transmission systems. The technologies can be installed in new or existing power transmission lines. Examples of FACTS products are:
Static VAr compensation (SVC), uses an electrical device (see Static VAr compensator) to regulate and stabilize voltage in bulk power systems. The most advanced version of this technology is called SVC Light™ and has additional features, in particular more powerful flicker compensation to stabilize high and rapidly fluctuating electricity loads, for example arc furnaces, and to smooth flicker voltage.
Series Compensation can be fixed or controllable. The latter is called Thyristor Controlled Series Capacitor (TCSC). Series compensation is a straight forward and cost effective way to preserve voltage stability, particularly in bulk transmission corridors. Thyristor-controlled series compensation is especially useful in stabilizing voltages at interconnections between transmission girds.
ABB’s FACTS devices optimize power flow to maximize the capacity of power lines and improve voltage stability by compensating for reactive power (see Reactive power and Power factor compensation). In some cases, network capacity can be more than doubled. The equipment also makes the system more resilient to ‘system swings’ and other disturbances.

Fault-closing device: A system of circuit breakers that serves to contain a fault in a grid, preventing it from spreading to other areas and causing widespread disruption.

Feeder: Overhead lines or cables that are used to distribute electrical power to consumers. Feeders connect distribution substations and consumers.

Frequency converter: An electronic device that can convert alternating current from one frequency to another. It is used to convert bulk power from one distribution standard to another, and also to control the speed or torque of AC motors - frequently used in pump or fan applications to achieve significant energy savings.

Fuel cell: A device in which chemical energy released by the oxidation of a liquid (such as methanol) or gaseous fuel is converted directly into electrical energy.
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G

Gas-insulated switchgear: see Switchgear.

Generator: A device that converts rotating mechanical movement into electric power. The current generated can be either alternating (AC) or direct (DC). ABB manufactures a range of generators, including wind-turbine generators. In a simple AC generator, a loop of wire is placed between the poles of a permanent magnet. The magnet is then rotated and the electromotive force produced by the movement of the electric field causes a current to flow in the wire. This is the principle of the synchronous motor and big generators in power plants. A DC generator operates on the same principle as the AC generator, but includes a device (a commutator), which effectively prevents the current from alternating.

Grid reliability: Power utilities strive to maintain electricity supplies without unexpected dips or surges that can cause disruptions ranging from flickering lights to equipment damage. To avoid these problems, utilities therefore need to control the flow of power under normal running conditions and in emergency situations. This is done by installing 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 strategic points on the grid. The monitoring units measure the rate and direction of power flow, its stability, the temperature of hot power lines, and other parameters critical to the normal functioning of the grid. The data are transmitted to a central computer, which uses them to calculate the settings for the control equipment housed in the substations and generating plants. This allows power flow to be directed, compensating for overloaded sections of the grid and even shutting down certain connections to prevent the spread of disturbances or to allow maintenance work to be carried out. (See FACTS, Network control, SCADA, Wide-Area Monitoring Systems.)
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H

Harmonics: Generally, harmonics are oscillations in the base power frequency. In electrical AC systems, the base frequency is typically 50 or 60 Hertz (Hz) and harmonics occur in multiples of this, for example 100 Hz, 150 Hz, 200 Hz, etc. where the base frequency is 50 Hz. Harmonics occur whenever there is a disturbance of the voltage or current, eg, if the current is interrupted or if AC current is synthesized in a converter. The problem with harmonics is that electrical devices may react differently when exposed to a different frequency than the one they are designed for, which may cause damage. Harmonics are an increasing problem in power systems as most power electronics solutions cause harmonics. Harmonics can be reduced by the use of power filters.

High-current transients: Short spikes of high electrical current in a grid, caused by lightning strikes, or rapid switching of electrical devices in the grid, especially capacitors. These transients, or surges, cause cables to overheat, potentially damaging insulation and leading to short circuits. Equipment can be protected from high-current transients by using a surge protector.

High-voltage direct current (HVDC): A technology developed by ABB in the 1950s to move large amounts of power over substantial distances - typically by overhead transmission lines, but also by way of underground/submarine cables. Transmitting DC power over long distances is more efficient than AC transmission (see Direct current and Transmission and distribution) and is a cost-effective method of connecting two asynchronous grids (grids operating at different frequencies).
An HVDC system takes electrical power from an AC network, converts it to DC at a converter station and transmits it to the receiving point by line or cable, where it is turned back into AC by using another converter. The conversion is carried out with high power, high voltage electronic semiconductor valves, which only allow power to flow in one direction. These valves are controlled by a computer system, so the transmitted power can be precisely controlled, a feature unique to HVDC systems. Another important aspect of HVDC lines is that they can never be overloaded.
Because HVDC transmits only active (real) power, no line capacity is wasted on transmitting reactive power. This means that the same power can be transmitted over fewer (or smaller) transmission lines than would be required using AC, and less land is needed to accommodate the lines. HVDC induces minimal magnetic fields, so the power lines may be built safely closer to human habitation.

HVDC Light: An adaptation of classic HVDC, developed by ABB in the 1990s. It can be used to transmit electricity in lower power ranges (tens of megawatts) to an upper range of 1,100 megawatt (MW) (±300 kilovolts). By comparison, classic HVDC (see High-voltage direct current) systems typically transmit electricity in the 1,000 to 3,000 MW power range. Offering both HVDC and HVDC Light systems extends the economical power range of HVDC transmission.
HVDC Light offers the same benefits as traditional HVDC systems, but also provides more secure power control (superior to classic HVDC) and quick power restoration in the event of a blackout. Because of its superior ability to stabilize AC voltage at the terminals, it is the ideal technology for wind parks, where the variation in wind speed can cause severe voltage fluctuations.
HVDC Light is environmentally friendly, featuring oil-free cables, compact converter stations and cables that can be laid underground (thereby avoiding local planning difficulties associated with overhead lines) as well as underwater. It is the only technology available that allows long-distance underground high-voltage transmission. It is rarely used for power transmissions using overhead lines.
Because of its lower power rating, underground cable technology and superior controllability, HVDC Light has many more potential applications than classical HVDC, for example: feeding power into cities and offshore oil and gas platforms; strengthening power networks in areas where there is opposition to new overhead lines; and extracting marginal power generation resources that are too small to warrant a costly extra high voltage AC line.
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I

I/O(Input/output): A device that enables communication between electronic equipment and external devices, including human operators. Examples of I/O devices include computer keyboards, printers, sensors and all type of interface cards.

IEC 61850: The International Electrotechnical Commission standard for substation automation replaces a great many communication protocols that require the use of use protocol converters, which are basically “translators” that help electronic devices using different machine languages transmit information to each other. The problem is that protocol converters can cause messaging errors and delays. A single communication standard for substation automation removes the need for a "translator," helps customers lower maintenance and operating costs, and makes installations easier to expand or modify.

Industrial IT: A series of interoperable software and hardware products and systems from ABB and/or third parties that are designed to communicate with each other and work together as part of a larger system for a specific application.

Industrial productivity: Raising industrial productivity means lowering costs for each unit (eg, car, ton of paper, etc.) produced. Global manufacturers are under intense pressure to improve productivity and performance to remain competitive, and avoid losing business to more efficient rivals. New technologies and business models are allowing companies to break apart and reassemble the component parts of their business - things like procurement, manufacturing, research, sales, distribution, and so on - in new combinations and locations that let them connect ever more closely with partners, suppliers, and customers. Productivity improvements can be achieved by automating operations, improving the management of assets, running factories at optimal levels, outsourcing, or improving the supply chain. (See Industrial IT, Model predictive control, Optimization, Process automation.)

Infrared thermography: A method used to measure the status of equipment by analyzing the amount of heat it radiates.

Instrumentation: Electronic or electromechanical devices, often referred to as meters, used to measure the flow, level, temperature and pressure of processes in different industrial applications. They monitor processes in power generation, manufacturing and refining plants. Information collected by various instruments is processed by analyzers and used to assess performance, sending alerts if readings are not as expected.

Insulator: A material that does not conduct electric current, such as plastic, some kinds of silicon or glass. The term can also refer to a material that does not conduct heat. For clarity, the terms thermal insulator and electrical insulator may be used. (See also Conductor.)

Inverter: An electrical device for converting direct current (DC) into alternating current (AC). A rectifier is used to convert AC to DC (See also Rectifier).

ISO 9000: International standards for quality assurance set by the International Standards Organization. It includes some 20 elements of quality process performance, and is a prerequisite for delivering predictable, quality products to customers.

ISO 14000: International standards for environmental management systems set by the International Standards Organization.
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J

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K

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L

Lights-out factory: An automated factory that requires no light because no people work in it.

Line thermal monitoring (LTM): Process that measures average power-line temperature and detects temperature changes in power lines. It is important because heat causes wires to expand and sag, resulting in short circuits, fires and blackouts if they contact treetops etc. (See also WAMS.)

Load: A load in electrical terms is the power consumed by a device or a circuit. Load is also used to describe the total of all electricity consumers in a power system.

Load management: Controlling loads in a utility system to limit peak demand, reduce costs, improve load factor, or in some other way improve the stability and reliability of electrical power distribution.

Loop flow: Inadvertent transmission of power through an unnecessary diversion in the transmission network. It is undesirable because it serves no purpose and incurs losses.
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M

Megawatt (MW): One million watts. One megawatt would be needed to light 10,000 one-hundred-watt light bulbs. If those bulbs were powered for 1 hour, 1MWh of electrical power would be used. (See also Watt and Watt hour.)

Meters: see Instrumentation

Microturbine: A small turbine generator, of 30 -250 kilowatts (kW) generating capacity, which can be located near a customer load.

Mobile substation: A substation that can be transported, usually by truck, to temporarily replace equipment at the site of a failure or in the event of planned maintenance.

Model predictive control (MPC): The online control of an industrial process (such as oil refining) that uses a virtual model of the process, which allows the computer to predict appropriate control settings.
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N

Network control: Network control systems monitor and control the electricity network to keep power flowing and to preserve the balance between power generation and consumption.

Network management: A system that uses network control and asset management to oversee all aspects (operational and maintenance) of a network.
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O

Original Equipment Manufacturer (OEM): Manufacturers who produce an end product such as automobiles, machines or switchboards, incorporating components from sub-suppliers, such as ABB.

Ohm: Unit of electrical resistance. If a 1-volt source is connected to a wire with a resistance of 1-ohm, then 1-ampere of electric current will flow.

Optimization: The process of making a system as near to perfect or as effective as possible.
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P

Parallel: Electrical components that are connected in such a way that the flow of electricity can take multiple, or parallel, paths through the circuit are said to be connected “in parallel” or “in shunt,” as opposed to “in series.” If one of the components in a parallel circuit was to fail, the electricity would continue to flow through an alternative path. (See also Series.)

Phase angle monitoring (PAM): A device that monitors power-network stresses caused by heavily loaded lines. This is part of the Wide-Area Monitoring System, which relies on a number of phasor measurement units (PMUs) to collect data from strategic positions in the grid. (See also Wide-Area Monitoring System and Phasor Measurement Units.)

Phase-shifting transformer (also known as a quadratic booster): A specialized type of transformer used on 3-phase power grids (AC) to balance the active (real) and reactive power in the system (see Reactive power, Power factor correction and Three-phase power), preventing the loss of lines through physical overloading.

Phasor Measurement Units (PMUs): Monitoring devices that are installed at critical nodes in a power network where they collect data on power flow. (See also Wide-Area Monitoring System, Thermal line monitoring, etc.) Signals sent from the units via satellite to a central control room, enabling operators to identify and counteract any instabilities before they spread through the grid.

Polyethylene: Plastic material with excellent properties of electrical insulation.

Power factor: Power factor is the ratio of real power to reactive power in an electric circuit and a measure of whether the system’s voltage and current are “in phase.” When no reactive power is present, voltage and current are in phase and the power factor is 1. This is the ideal for power transmission, but is, in practical terms, impossible to attain. Variation in power factor is caused by different types of electrical devices connected to the grid that consume or generate reactive power. (See also Power Factor Correction.)

Power factor correction (also known as reactive power compensation): Depending on the type of equipment a consumer connects to the electricity supply (whether there is a net consumption or generation of reactive power), power factor varies. Unless this variation is corrected, higher currents are drawn from the grid, leading to grid instability, higher costs and reduced transmission capacity. Most utilities impose penalties on consumers who fail to correct errant power factors. (See also Power Factor.)

Power loss: This term generally refers to electrical energy that is lost to inefficiencies in transmission, distribution, or in the use of electricity. As electricity flows through a conductor, individual electrons collide with the atoms of the conductor and transfer energy to them, causing them to heat up. This heat is lost to the atmosphere in the form of thermal radiation. Some power is also lost to electromagnetic radiation. Losses in an electricity distribution system depend on the length of the cable (the longer the cable, the greater the losses); the conductivity of the material (higher resistance means greater losses); the square of the current (at twice the current, there will be four-time the losses); and the cross-sectional area of the cable. Therefore, to minimize losses, power should be transmitted at the highest practical voltage. This reduces the current and therefore the amount of power lost in transmission. Most electrical transmissions are AC (alternating current) at voltages between 110 and 1200 kV. (See also HVDC).

Process Industry: an industry in which raw materials are treated and converted into products by means of a series of stages (or processes). Process industries include oil and gas refining, pharmaceutical and chemical production, water and sewerage treatment etc.

Process automation: The term process automation is used to refer to an automation system whose principal purpose is to automate or support the operator of a manufacturing process. Such a process can be the manufacturing or treatment of any goods made in a continuous or quasi-continuous manner such as fuel, paper, cement, steel, chemicals, food.
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R

Reactive Power: It is a concept that describes the loss of power in a system resulting from the production of electric and magnetic fields in it. Reactive loads in a power system drop voltage and draw current, which creates the impression that they are using up power, when they are not. This “imaginary power” or “phantom power” is called reactive power, and is measured in Volt-Amps-Reactive (VAR). Reactive power is significant because it must be provided and maintained to ensure continuous, steady voltage on transmission networks. Reactive power is produced for maintenance of the system, and not for end-use consumption. If elements of the power grid cannot get the reactive power they need from nearby sources, they will pull it across transmission lines and destabilize the grid. In this way, poor management of reactive power can cause major blackouts.

Recloser: A circuit breaker designed to interrupt short-circuit current and reclose (ie, reconnect) the circuit after interruption.

Rectifier: An electrical device used to convert alternating current (AC) into direct current (DC). (See also Inverter.)

Regenerative braking: A braking method that is used to recoup some of the energy lost as vehicles slow down or brake against an incline (downhill). It exploits the ability of electric motors to work as generators during breaking. This enables the mechanical energy from the load to be converted into electric energy and returned to the electricity supply system for use either by other vehicles, or by the braking vehicle at a later time if on-board energy storage system such as batteries or super-capacitors are available. The method can be used improve the energy efficiency of cranes and elevator systems, trains and hybrid cars.

Relays: 1) a switch that can be operated remotely. 2) control and protection relays are switches used to signal and control the operation of electrical equipment and systems. They include electronic and electromechanical relays and components; high-voltage (HV) protection, substation control and communications; automated substation components; and distribution relays.

Regenerative braking: A braking method that is used to recoup some of the energy lost as vehicles slow down or brake against an incline (downhill). It exploits the ability of electric motors to work as generators during breaking. This enables the mechanical energy from the load to be converted into electric energy and returned to the electricity supply system for use either by other vehicles, or by the braking vehicle at a later time if on-board energy storage system such as batteries or super-capacitors are available. The method can be used to improve the energy efficiency of cranes and elevator systems, trains and hybrid cars.

Resistance: Cables and electrical devices resist the movement of electrons that constitute the current passing through them. This is known as electrical resistance and is measured in Ohms. If an electric circuit is likened to water flowing through a system of pipes, the resistance in a wire is analogous to the restriction of the water flow imposed by the diameter of the water pipe, or any obstacles within the pipe.

Resistor: A resistor is any electrical component that resists the flow of electrical current. Resistors can be used to control current and therefore protect a circuit from overload. Resistors are also an important component in instrumentation and are used together with capacitors in power filters to eliminate unwanted harmonics.
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Robot, industrial: An industrial robot is defined by ISO 8373 as an automatically controlled, reprogrammable, multipurpose, manipulator, programmable in three or more axes, which may be either fixed in place or mobile for use in industrial automation applications. Typical robot applications include welding, painting, assembly, pick and place, packaging and palletizing, product inspection, and testing, all accomplished with high endurance, speed, and precision. ABB developed the first commercially available electric robot almost 40 years ago.

S

SCADA (Supervisory Control and Data Acquisition): A SCADA system is a computer system that gathers and analyses data on equipment and processes in industrial processing plants such as pulp and paper mills, oil refineries and water treatment facilities. It may perform other functions in power networks, such as load management, load curtailment and restoration, distribution automation, and facilities management functions.

Series: Electrical components that are connected in an unbranched line are said to be “in series,” as opposed to “in parallel” or “in shunt.” If any one of the components in a series circuit was to fail, the circuit would be broken and no electricity would flow. (See also Parallel.)

Short circuit: An electric contact between parts of an electric circuit, which causes a very high current, increases in temperature and potentially fire, if the circuit is not properly protected. This can occur if two live wires come into contact with each other, perhaps because of worn insulation. The term is also used when defining the safe operating conditions for electrical devices. If a device is said to have a short-circuit resilience of 400 Amps (A), that means that it can be subjected to up to 400 A before it will shut itself down.

Shunt: See Parallel

Smart grids: Smart grids are modern power transmission and distribution systems that are capable of accepting power of any quality from any source and delivering it to consumers of all kinds via a bidirectional supply system. They are an evolutionary development of traditional grids (which are based mainly on centralized generating plants, supplying power via long-established, unidirectional transmission and distribution systems whenever consumers request it). Smart grids are being developed in response to rising demand for power and the increasing need to incorporate renewable or distributed, less predictable generation into the grid.
ABB’s smart grid concept is of an observable and controllable system, based on industry-wide standards, providing a stable, secure, efficient and environmentally sustainable network. The system will cross national and international borders. It must be able to detect and react automatically to disturbances and changes in supply and demand, re-establishing balance and maintaining the stability demanded by both end-users and government legislation. This is achieved by an automation and information technologies infrastructure integrating the whole supply chain from production to consumption, based on an infrastructure of enabling smart grid components. Thus smart grids also accommodate customer response management systems that allow utilities to optimize the performance of the grid and to integrate consumption into balancing load and generation.
Many of the technologies and standards that will be needed to establish smart grids on a large scale have been the subject of research and development at ABB for some years and many are already in use.

Submetering: Metering of individual units in multi-unit properties.

Substation: Substations are key installations in the power grid. They house equipment for the protection and control of electrical power transmission and distribution, including power transformers, switchgear and measuring equipment. (See also Reactive Power, Power Factor Correction, Circuit Breaker and Switchgear).

Surge protector: Also known as a surge arrester, this is a device used to protect equipment from damage caused by high-voltage power surges. These can occur when substations are hit by lightning or as a result of switching operations in high-voltage transmission.

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 and maintain than dynamic compensation devices, such as synchronous compensators (See also FACTS), SVC has no rotating parts (it is static). It compensates for fluctuations in the voltage and current of an electric grid, thereby allowing more power to flow through the network while maintaining safety margins, increasing network stability.

Switchgear: Equipment used to control, protect, and regulate the flow of electrical power in a transmission or distribution network. It is often located in substations, but can be associated with any electrical equipment that might need to be isolated for fault correction (eg, if a voltage drop occurred in one part of the grid, it might be necessary to shut off the affected section to prevent the fault spreading), or for maintenance purposes. The main components of switchgear are circuit beakers, which interrupt high-voltage current to protect electrical equipment from excessive current.
The terms gas- and air-insulated switchgear (GIS and AIS) refer to switchgear equipped with gas- and air-insulated circuit breakers. The gas-insulated variety is more costly than the air, but it takes up less space and is therefore the preferred option when installing switchgear in urban environments (the substations can be one fifth the size of a conventional AIS substation).

System 800xA: An Industrial IT-compatible control system that provides a means of achieving measurable productivity and profitability improvements. The full name is Extended Automation System 800xA, and it is used in many industry sectors to oversee and control a wide range of processes. It extends the scope of traditional control systems to include all automation functions within a single operations and engineering environment. This enables plants to perform in a more intelligent and cost-effective way, and to improve productivity.
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Three-phase power: A form of electricity used to supply heavy loads (power-hungry electrical equipment) such as industrial air conditioning units, grinding machines etc. Almost all power is generated as three-phase and, with the exception of HVDC, most transmission lines are three-phase. Three-phase is a more efficient way of delivering heavy loads and the three-phase motors it supplies are more efficient, smaller and cheaper to build than their single-phase counterparts. Wiring is simplified because no neutral return path is provided. Residential premises, however, are supplied with single-phase power.

Traction motor: A traction motor is typically used to power the driving wheels of a railroad locomotive, a tram or 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 of their design. They must be extremely compact, because of the limited space available on the locomotives, and highly reliable as there is no room for any backup systems. (See also Traction Transformer.)

Traction transformer: This is a fundamental component or a railroad locomotive’s traction chain. It adapts the catenary (overhead) voltage to the various low voltage levels needed by the train, mainly for traction, but also for lighting, heating and ventilation, passenger information and safety systems such as door blocking, brakes, signaling and communication. The traction transformer is the unique energy transfer point between high voltage (HV) and low voltage (LV) and therefore must achieve the highest availability and reliability levels to guarantee uninterrupted train service.

Transformer: A transformer is a device used to transfer energy 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 electrical grid. Electricity generated in a power station must be stepped up to the appropriate voltage for transmission (between 100 and 800 kV) and then stepped down again to the distribution voltage (110-230 V), which is delivered to homes. Note that the voltage of DC cannot be transformed in the same way as it can for AC. (See Alternating Current.)

Transmission and distribution (T&D): The term refers to the transport of electricity from the power station to the end user. Transmission is the movement of power at high voltage (above ca. 50 kV), usually over long distances. Raising the voltage allows power to be transmitted more efficiently (ie, with fewer losses - at lower voltages, more electrical power is converted to heat and lost to the atmosphere) over a wide area. Distribution is the transport of electricity at medium voltage (between ca. 1 and 50 kV) over shorter distances to industrial, commercial and residential areas. Transformers are generally, though not always, housed in substations.

Turbine: A propeller-like device that is turned by a stream of 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 gases cause it to rotate); or wind (as in a wind farm). The rotation of the turbine drives the generator that converts the mechanical rotation into electrical power. (See also Generator.)

Turbocharger: An air compressor that is used to boost the oxygen intake of a motor. In an internal combustion engine, a mixture of fuel and air is pumped into the confined space 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 pushes the piston up, turning the crankshaft that drives the engine. The amount of fuel that can be ignited in the cylinder, and therefore the power generated, is limited by the amount of oxygen present. If there is too little oxygen, not all the fuel will burn. By compressing the air that is fed into the cylinder, more oxygen is made available for the combustion process, allowing more fuel to be burned, more completely, leading to more power obtained at higher efficiency.

Turbogenerator: a collective term referring to a turbine and the generator to which it is connected.
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U

Ultrahigh voltage (UHV): This term refers to voltages in excess of 500 kilovolts (kV). UHV transmission using alternating current (AC) has been possible for several decades, and it is now also possible to transmit power this way using direct current (DC). DC transmission has lower losses and requires fewer overhead lines than AC transmission. Ultrahigh-voltage DC links will make it viable to produce electricity in remote regions and transmit it to centers of demand via energy "superhighways." The efficient transmission of electricity at 800 kilovolt DC power transmission is now feasible over distances as far as 3,000 km. UHVDC systems are cheaper, smaller and more efficient than comparable AC transmission systems.
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V

Vacuum interrupter: A vacuum interrupter is a device that uses a vacuum to extinguish the arc formed when a circuit breaker is opened. It also insulates the contacts after the arc has been interrupted. ABB has more than 20 years’ experience in vacuum interrupter technology and the ABB family of interrupters serves a wide range of applications. Vacuum interruption is seen as the ideal switching technology for medium-voltage applications. Excellent switching capabilities, combined with high reliability and a compact design, provide economical switching solutions with virtually no maintenance requirements.

Vacuum interruption offers the lowest environmental impact of all medium-voltage switching technologies over the entire product life cycle. Vacuum interrupters are comprised of materials that are environmentally benign and safe to handle during periodic out-of-service maintenance and at end-of-life disposal. The devices perform well in all medium-voltage switching applications required in modern power systems. They have exceptionally long life and are virtually maintenence free.

Variable-speed drive: (see Drive)

Volt: standard unit of electrical “pressure” in a circuit. (See also Voltage.)

Voltage (potential difference): The voltage between two points in an electrical circuit is a measure of the potential difference, or the force, that is pushing electrons between these two points. It is analogous to water pressure in a water system. Voltage is measured in volts, and is directly proportional to the current and resistance of a circuit: V=IR, where V = potential difference in volts, I = current in amperes (amps) and R = resistance in ohms. This is Ohm’s law.

Voltage drop: A voltage drop is a reduction in the force that “pushes” current through a circuit. Under these conditions, resistive loads, such as light bulbs, will give suboptimal performance- lights will flicker or become dimmer because less current is flowing. Inductive loads, such as motors, respond to voltage drops by working harder to obtain the same power, which can cause overheating, increased operating costs and the risk of equipment failure. Devices such as computers often have sensors that warn of suboptimal voltage or excess heating and will shut down automatically in response to a voltage drop.

Voltage rating: The maximum voltage that can be applied to an electronic device.
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W

Wide-Area Monitoring System (WAMS): WAMS is an advanced early warning technology for power grids that helps operators prevent system instabilities and overloads, as well as cascade tripping that leads to power blackouts. It comprises a series of phasor measurement units, set up in strategic positions around the grid. These monitor stresses (loads and temperatures) on the power lines and send data back to a central control station via a GPS satellite link. This allows operators to identify problems at an early stage and prevent widespread disruption of the grid (ultimately rolling blackouts). WAMS is used in conjunction with phase shifting transformers to protect and stabilize power grids.

Watt (W): Standard unit of electrical power (1 Watt = 1 amp at 1 volt). The Watt is also a general unit of power. One Watt = 1 joule per second.

Watt hour (Wh): 1 watt hour is the amount of electrical energy consumed by a 1-watt load over a period of one hour. 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 energy transferred, ie, the product of power (kW) x time (hours).
Confusion can also arise when describing electricity generation. For example, a wind farm described as “150 MW” has a peak power output of 150 MW. If the farm was 100 percent efficient, it would transfer 150 MW x 24 hours = 3600 MWh to the electricity grid every day. Because of various inefficiencies and the fact that wind blows erratically, wind turbines are actually only about 30 percent efficient. This means that 150 MW (theoretical maximum) x 24 h (number of hours in a day) x 30% (efficiency) = 1080 MWh will be produced each day.
Cables can also be described as, for example, 350 MW. This is the capacity of the cable, ie, the maximum amount of power it can carry. In an hour, a 350 MW cable could (theoretically) deliver 350 MWh of electricity.
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