Glossary

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.

Cooperative - A member-owned business with membership open to those who use its services. Democratically controlled and operated on a nonprofit basis, a cooperative returns any margins or profits to members on the basis of patronage.

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 Cooperative - An electric cooperative that purchases wholesale power and delivers it to consumer members.

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 (nonconductors) - 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.

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 our homes.

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 consumers.

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.