Glossary of Terms | About Energy | Mississippi Power | A Southern Company

Glossary of Electric Terms

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ampere Unit of measurement of electric current, akin to cubic feet of water flowing per second.
base load The nearly steady level of demand on a utility system.
British thermal unit (Btu) Standard unit of heat measurement, equal to raising one pound of water one degree Fahrenheit at sea level pressure.
capacity The load for which an electric generating unit, other electrical equipment or power line is rated.
Certificate of Convenience and Necessity A term used by public service commissions in granting authority to a company to render utility service, usually specifying the area and other conditions of service.
cogeneration Joint production of electricity and useful heat/steam from a common source.
conductor Any material (such as a power line) that allows its electrons to be easily transferred.
demand charge A separate charge based upon the demand for electric service by a commercial or industrial customer, based on the investment in facilities necessary to serve them.
distribution lines Power lines, like those in neighborhoods, used to carry moderate voltage electricity which is "stepped down" to household levels by transformers on power poles.
electricity The motion of electrons through a conductor.
electrostatic precipitators Pollution control devices attached to fossil fuel generating plants which prevent the vast majority of fly ash from being released into the air.
eminent domain The authority to acquire land from a private owner for the benefit of public use.
fly ash Small particles of airborne ash produced by burning fossil fuels.
franchise fee A local tax imposed on utilities for the privilege of providing a service within city limits.
fuel adjustment clause An annual adjustment in rates based on changes in the price of fuel used to generate electricity.
high voltage Voltage greater than 100,000 volts.
kilowatt (kW) 1,000 watts
kilowatt-hour (kWH) A unit of electricity consumption. A kilowatt-hour equals the amount of electricity needed to burn ten, 100-watt light bulbs for one hour.
kilovolt (kV) 1,000 volts
load The total customer demand for electric service at any given time.
megawatt (mW) One million watts or 1,000 kilowatts.
natural monopoly When the cost of utility service, such as gas, water or electric service, is minimized to customers if a single enterprise is the only seller in the market.
off-system sales Sales by a utility to a customer (usually another utility) outside of its authorized market.
peak demand a one hour period in a year representing the highest point of customer consumption of electricity.
power pool A regional organization of electric companies interconnected for the sharing of reserve generating capacity.
public utility A business enterprise rendering a service considered essential to the public and, as such, subject to regulation.
scrubbers Equipment designed to reduce sulfur emissions from coal-fired generating plants.
service area The territory in which a utility has the right to supply service.
substation A facility where the voltage of electricity is reduced prior to distribution to customers.
transformer Equipment vital to the transmission and distribution of electricity designed to increase or decrease voltage.
transmission lines Power lines normally used to carry high voltage electricity to substations which then is "stepped down" for distribution to individual customers.
volt* The unit of electromotive force or electric pressure, akin to water pressure in pounds per square inch.
watt* The electrical unit of power or rate of doing work.

*The difference between a watt and a volt can be visualized by imagining water flowing through a hose into a bucket. Voltage is similar to the water pressure in the hose and wattage is the amount of water going into the bucket.

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