Glossary of Electric Utility Industry Terms

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Bank – A group of electrically connected devices. A capacitor bank is a group of connected capacitors. A transformer bank is a group of three, or sometimes two, connected transformers. (EUSO, EDS-photo, CAEDS-photo, IESO)

Basement – A pre-made fiberglass foundation on which pad-mounted transformers or medium-voltage switches can sit. Several inches of the fiberglass are above ground level and two feet or more below ground level, thus providing a “basement” for the transformer or switch. (EUSO,EDS,CAEDS,IESO)

Bastard Leg – In a 3-phase delta-connected system, the phase that has a voltage between itself and ground that is 1.73 times higher than the voltages between each of the other two phases and ground. It is also called the high leg, power leg, wild leg and stinger. (CAEDS, EDS)

Bell – One of the circular porcelain or glass insulators connected together to form a suspension insulator. They can be light gray or brown in color, clear or greenish glass. (EUSO-photo)

Black-out – A large number of customers losing all power from the utility. Black-outs can occur when there are too many customers connected to the system and the utility deliberately disconnects the excess customers. Black-outs can also occur when there is equipment failure and protective devices disconnect customers. (EUSO, IESO, System operator classes)

Black-out, Rolling - When there are too many customers connected to the system, the utility sometimes will deliberately disconnect the excess customers. Rather than disconnect one group of customers for a long period of time, the utility control center will disconnect a group of customers for a period of time such as for 15 minutes. After the 15 minutes, the control center will disconnect another group of customers and restore power to the first group. The control center will then disconnect a third group and restore power to the second group that was disconnected. (EUSO, IESO, System operator classes)

Bonneville Power Administration (BPA – One of four federal electric power marketing administrations. The Bonneville Power Administration markets and provides transmission for power from hydroelectric dams operated by the Bureau of Reclamation and the U.S. Army Corps of Engineers, from one nonfederal nuclear plant, and from nonfederal hydroelectric dams and wind generation sites. The 6 states covered include Idaho, Oregon, western part of Montana, northern edge of Nevada, Washington and western Wyoming. BPA is also charged with the restoration of endangered fishes in the river and tributaries with hydroelectric dams. The other federal electric power marketing administrations are the Southeastern Power Administration, the Southwestern Power Administration, and the Western Area Power Administration. (EUSO, System operator classes)

BPA – See Bonneville Power Administration

Breaker – An abbreviated term for a circuit breaker. (EUSO-photo, IESO-photo, CAEDS, EDS, System operator classes)

British Thermal Unit – The amount of heat required to raise the temperature of one pound of water one degree Fahrenheit. (It takes 143 BTU to melt one pound of ice.) (EUSO)

Brown-out – Most often, a brown-out refers to a utility control center lowering the voltage to customers to a value below the allowable minimum. It is done to decrease load in a system. Utilities call a brown-out “voltage reduction;” the media call it a brown-out. Less often, a brown-out refers to low voltage produced by utility equipment failure. (EUSO, IESO)

Brushes – Blocks of carbon or carbon alloy that slide on the surface of collector rings, slip rings or commutators. (EUSO, IESO)

BTU – An acronym for British Thermal Unit (See above) (EUSO)

Bug – A term used by some line crews for a pole-mounted transformer. Other terms include can, pot and tub. (EUSO-photo, CAEDS-photo, EDS-photo, IESO-photo)

Bundled Conductor – Transmission conductor that uses two or more smaller conductors (placed in a bundle) in place of one larger conductor. (EUSO-photo)

Bus – The definition used by more than 99% of operations people is bus is rigid conductor. It can be tubular or it can have an angle, bar or H shape. (EUSO-photo, IESO-photo)

Bus duct – Tubular or rectangular enclosures in which rigid conductor (bus) is run. The bus is supported on insulators so that the bus does not touch the duct. (EUSO-photo, IESO-photo)

Bushing – A rigid device used to bring conductor from the inside to the outside of a circuit breaker or transformer. (EUSO-photo, IESO-photo)

By-Pass Switch – A normally open switch that is closed in order to parallel an electrical device. The device is then “by-passed” and can be removed from the system without interrupting current in the system. (EUSO-photo, EDS, IESO-photo)

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