Alternating Current (AC) – Electric current that reverses direction, usually many times per second. Most electrical generators produce alternating current.
Ampere (amp) – A measure of how much electricity is moving through a conductor.
Blackout – A total power failure over a large area; usually caused by the failure of major generating equipment or transmission facilities.
Bottom Ash – Slag or other residue remaining in the boiler after coal is burned.
Brownout – A small, temporary voltage reduction implemented by a utility to conserve electric power during periods of high use.
British Thermal Unit (Btu) – Amount of heat needed to raise the temperature of 1 pound of water by 1 degree Fahrenheit.
Bus – An electrical conductor that serves as a common connection for two or more electrical circuits.
Capacitor – A device that stores electrical charges and can be used to maintain voltage levels in power lines and improve electrical-system efficiency.
Circuit – Path that electricity follows.
Circuit Breaker – A switch that opens an electric circuit when a short occurs.
Cogeneration – Using waste heat from (1) an industry to produce electricity, or (2) from electric utilities to produce steam for an industry or hot water for a building.
Conductor – A material that allows an electric current to pass through it. Also, the wire that carries electricity in an electric distribution or transmission system.
Cycle – One complete series of changes of value of an alternating current or an electromagnetic wave.
Demand - The amount of electricity drawn from an electric system at a given time, measured in kilowatts.
Demand Charge – A charge for electricity based on the maximum amount of a system’s electricity a customer uses.
Demand Side Management – A utility program aimed at reducing consumer use of energy through conservation or efficiency measures.
Deregulation – Major reduction of government oversight in a segment of private industry.
Direct Current (DC) – Electricity that flows through a conductor in a single direction.
Distribution Company – An electric utility that purchases wholesale power and delivers it to customers.
Distribution System – The poles, wire and transformers used to deliver electric energy from a bulk power supplier to the consumer.
Electric Current – A flow of electrons through a wire or other electrical conductor. Electrons are negatively charged particles of matter.
Electric Energy – The flow of charged particles (electrons).
Electricity – Electric current or power that results from the movement of electrons in a conductor from a negatively charged point to a positively charged point.
Electrostatic Precipitator – An electronic pollution-control device that removes particles of fly ash from a power plant’s waste gases.
Energy Efficiency Rating (EER) – A measure of how efficiently an appliance uses energy. Determined by dividing the Btu per hour output by the number of watts used. A higher EER means greater efficiency.
Fly Ash – Tiny solid particles of ash that escape the boiler when coal is burned; removed by pollution-control equipment.
Fossil Fuel – Materials such as coal, oil or natural gas used to produce heat or power; also called conventional fuels. These materials were formed in the ground millions of years ago from plant and animal remains.
Fuel Cells – Devices that convert the chemical energy of fuels directly into electricity.
Fuse – A protective device for electric circuits containing a wire designed to melt and open the circuit under abnormally high electric loads.
Generation and Transmission Cooperative (G&T) – A power supply cooperative owned by a group of distribution cooperatives. G&Ts generate power or purchase it from public or investor-owned utilities, or from both.
Generation Plant – A plant that has generators and other equipment for producing electricity.
Generator – A machine that converts mechanical energy into electrical energy. Electricity is produced from magnets whirling inside coils of wire in the generator core.
Geothermal Energy – Natural heat contained in the rocks, hot water and steam of Earth’s subsurface; can be used to generate electricity and heat homes and businesses.
Gigawatt (gw) – A measure of electric capacity equal to 1 billion watts or 1 million kilowatts.
Global Warming – A gradual warming of the Earth’s atmosphere reportedly caused by the burning of fossil fuels and industrial pollutants.
Greenhouse Gases – Carbon dioxide and other gases that reportedly contribute to the warming of the Earth’s atmosphere.
Grid System – An arrangement of power lines connecting power plants and consumers over a large area.
Ground-Fault Circuit Interrupter (GFCI) – A device that instantly breaks the circuit when a short develops. Required for outlets that are used in bathrooms, kitchens, outdoors or wherever electrical equipment might come into contact with water.
Hertz (Hz) – An international measure of frequency or vibration equal to 1 cycle per second. The alternative current frequency used in North America is 60 hertz. In Europe and some other parts of the world it is 50 hertz.
High Voltage – Voltage in a power line higher than the 110 to 220 volts used in most residences.
Horsepower (hp) – A measure of power equal to about 746 watts.
Hydroelectric Plant (hydro) – A facility that produces electric energy by releasing water from a reservoir through generators.
Insulator (nonconductor) – Material that does not conduct electricity, such as glass, ceramics or rubber. It prevents the passage of electricity. All transmission and distribution wires are protected by insulators.
Interconnection – A tie permitting the flow of electricity between the facilities of two electric systems.
Kilovolt (kv) – 1,000 volts. The amount of electric force carried through a high-voltage transmission line is measured in kilovolts.
Kilowatt (kW) – The basic unit of electric demand, equal to 1,000 watts; average household demand is 10 to 20 kilowatts.
Kilowatt-hour (kWh) – A unit of energy of work equal to 1,000 watt-hours. The basic measure of electric energy generation or use. A 100-watt light bulb burning for 10 hours uses one kilowatt-hour.
Lignite – A low-sulfur, low-energy coal, found primarily in the upper Great Plains.
Line – A carrier of electricity on an electric power system.
Line Loss – Electric energy lost in the process of transmitting it over power lines.
Load – The amount of electric power drawn at a specific time from an electric system, or the total power drawn from the system. Peak load is the amount of power drawn at the time of highest demand.
Load Factor – The ration of average demand to peak demand. It is a measure of efficiency that indicates whether a system’s electric use over a period of time is reasonably stable or if it has extreme peaks and valleys. A high load factor usually results in a lower average price per kilowatt-hour than a low load factor.
Megawatt (MW) – Equal to 1,000 kilowatts or 1 million watts.
Megawatt-hour (MWH) – Equal to 1,000 kilowatt-hours or 1 million watt-hours.
Meter – A device used to measure and record the amount of electricity used by a consumer.
Nitrogen Oxides – Compounds of nitrogen and oxygen formed when fossil fuels burn.
Nuclear Energy – Energy produced from the splitting of atoms.
Nuclear Fission – The splitting of an atomic nucleus, resulting in the release of large amounts of energy; the basic process a nuclear reactor uses to provide heat for the generation of electricity.
Nuclear Fusion – The combination of two light nuclei to form a heavier nucleus with the release of some binding energy.
Nuclear Power – Electric energy generated using heat produced by an atomic reaction.
Nuclear Radiation – Invisible particles or waves given off by radioactive materials such as uranium.
Off-peak Power – Electricity supplied during periods of low system demand.
Ohm – The amount of resistance overcome by one volt in causing one ampere to flow. The ohm measure resistance to current flow in electrical circuits.
Ohm’s Law - Voltage equals resistance multiplied by current. In its simplest form, Ohm’s Law states that it takes one volt of pressure to push one amp of current through one ohm of resistance.
On-line – A generating plant that is operating. When an operational plant is not on-line, it is “down.”
Outage – Interruption of service to an electric consumer because a power plant, transmission line or other facility is not operating.
Peak Demand – The greatest demand placed on an electric system; measured in kilowatts or megawatts; also, the time of day or season of the year when that demand occurs.
Peak Load – The amount of electric power required by a consumer or a system during peak demand; measured in kilowatts or megawatts.
Photovoltaics – Technology that produces electric power directly from the sunlight. A common application is in solar-powered pocket calculators, but various equipment remote from electric distribution lines also uses the technology.
Power – The term used for the product of voltage and current. It is measured in watts.
Power Plant – A place where electricity is produced.
Rotor – The rotating part of a generator.
Single-phase Power – An electric circuit that consists of one alternating current.
Slag – A residue produced by the combustion of coal. This heat-fused material accumulates on the sides and bottom of a boiler and is removed periodically and disposed of according to environmental regulations.
Stator – The stationary part of a generator within which a rotor turns.
Socket – A connecting place or junction for electric wires, plugs and light bulbs.
Solar Power – Energy from the sun’s radiation converted into heat or electricity.
Static Electricity – Created when electrons “jump” from one atom to another. You can create static electricity by rubbing certain things together, such as a brush and your hair. Lightning is also an example of static electricity.
Substation – A place that contains transformers, which lower electricity’s voltage so that it can be used in homes and businesses.
Surge Suppressor – An electronic device that protects electric equipment from short-term, high-voltage flows of electricity such as lightning strikes.
System Demand – The total amount of energy required to supply all customers.
Three-phase Power – An electric circuit that consists of three separate currents delivered at one-third cycle intervals by means of a three-wire circuit; typically used to power large industrial motors that operate at 200 volts or higher.
Transformer – A device used to raise or lower voltage in electric distribution or transmission lines. A step-up transformer raises voltage and a step-down transformer lowers voltage.
Transmission – The transfer of electric current from a power plant to a destination that could be hundreds of miles away.
Turbine – A machine with blades attached to a central shaft. The pressure of water or steam on these blades causes the turbine to spin.
Turbine Generator – The combination of a turbine and a generator working together to produce power.
Voltage – The force which pushes electricity through a wire.
Watt - A unit of electrical power.
Wheeling – Transmitting bulk electricity from a generating plant to a distribution system across a third system’s lines.