Electric Glossary

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*Sources:
Edison Electric Institute
US Energy Information Administration
Vectren Energy Delivery of Indiana, Inc. (Vectren South) Tariff for Electric Service

Power Industry Terms

Deregulation – The elimination of regulation from a previously regulated industry or sector of an industry.

Generating Unit – Any combination of physically connected generator(s), reactor(s), boiler(s), combustion turbine(s), or other prime mover(s) operated together to produce electric power.

Independent System Operator – An independent, Federally-regulated entity that coordinates regional transmission in a non-discriminatory manner and ensures the safety and reliability of the electric system.

Investor-Owned Utility – A class of utility whose stock is publicly traded and which is organized as a tax-paying business, usually financed by the sale of securities in the capital market. It is regulated and authorized to achieve an allowed rate of return.

Premises – A distinct portion of real estate such as the living quarters for the use of a single family, or the main building of a Non-Residential Customer and may include the outlying or adjacent buildings used by the same, provided the use of service in the outlying buildings is supplemental to the service used in the main residence or building.

Regulation – The governmental function of controlling or directing economic entities through the process of rulemaking and adjudication.

Reliability – Electric system reliability has two components--adequacy and security. Adequacy is the ability of the electric system to supply to aggregate electrical demand and energy requirements of the customers at all times, taking into account scheduled and unscheduled outages of system facilities. Security is the ability of the electric system to withstand sudden disturbances, such as electric short circuits or unanticipated loss of system facilities. The degree of reliability may be measured by the frequency, duration, and magnitude of adverse effects on consumer services.

Reserve Margin (Operating) – The amount of unused available capability of an electric power system at peak load for a utility system as a percentage of total capability.

Wholesale Power Market – The purchase and sale of electricity from generators to resellers (who sell to retail customers), along with the ancillary services needed to maintain reliability and power quality at the transmission level.

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