Glossary of Electric Utility Industry Terms
Tap – A connection point. It is applied to connection points in a transformer winding, and to connections in distribution lines. (EUSO, IESO, CAEDS, EDS)
Tap Changer – A device that changes the turns ratio in a transformer, thereby changing the output voltage. (EUSO, IESO, CAEDS, EDS)
Tap line – A distribution line that branches out from the main distribution line. ( CAEDS, EDS )
Therm – 100,000 BTUs
Ton– An air conditioning measurement. 1 ton = 12,000 BTU/ hour = 3.517 kilowatts = 4.716 horsepower.
Transistor – A solid-state device used for amplification, and also for on-and-off switching such as in binary logic in computer systems. (CAEDS, IESO)
Treeing – Treeing refers to a particular pattern of cable insulation failure. The insulation develops cracks that resemble the branches of a tree without the leaves. (CAEDS, EDS, IESO)
Thumper – A troubleshooting device for locating failed insulation in underground cable. As the device pushes current through the hole in the insulation it make a “thumping” sound. A person walking on top of the ground listens for this thump to determine the location of the failure. (CAEDS, EDS, IESO)
Thumping – A troubleshooting procedure for locating failed insulation in underground cable. A device pushes current through the hole in the insulation and it make a “thumping” sound. A person walking on top of the ground listens for this thump to determine the location of the failure. (CAEDS, EDS, IESO)
Thyristor – A solid-state device used for switching on and off. (CAEDS, IESO, System Operator classes)
Transformer – A device used to change voltage. (EUSO, IESO, CAEDS, EDS, System operator classes)
Transformer Blowing – At least 90% of the time the expression “transformer blowing” or “the transformer blew” refers to the fuse mounted above a pole-mounted transformer blowing. When these fuses melt open or “blow” during a fault, they sound like a shotgun being fired. When a transformer actually blows, it is usually an internal fault that vaporizes the mineral oil. The vaporizing of the mineral oil produces gas pressure and the gas pressure blows the transformer apart. (EUSO, IESO, CAEDS, EDS, System operator classes)
Tub - A term used by some line crews for a pole-mounted transformer. Other terms include Bug, Can, and Pot.
TVA – An acronym for the federal power corporation, the Tennessee Valley Authority. TVA’s offices are primarily located in Knoxville and Chattanooga Tennessee. TVA is responsible for providing the generating and transmission resources for the publicly owned electric utilities and very large industrial customers in its service territory.
TX – An abbreviation used in some utilities to represent transformer. A more common abbreviation is XFMR.