Glossary of Terms

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.

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