Glossary of Electric Utility Industry Terms

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Cable tray – An open-top rectangular trough that holds insulated wire or cable. (EUSO, IESO)

CAD – Most often acronym for computer-aided design, but it can also refer to computer-aided dispatch

Capacitance – The measure of the ability of a device to hold a voltage, after the voltage has been applied from another source and then removed. Capacitance is measured in Farads, named after Michael Faraday. (EUSO, EDS, CAEDS)

Capacitive Reactance – A quantity that reduces current flow. As a capacitive device approaches the level of being fully charged, it more and more impedes the flow of current that is charging it. This quantity that impedes current flow is capacitive reactance. (EUSO, EDS)

Can - A term used by some line crews for a pole-mounted transformer. Other terms include Bug, Pot and Tub. (EUSO-photo, CAEDS-photo, EDS-photo, IESO-photo)

Carrier Current – A communication method that uses a utility’s transmission and/or distribution line(s) for communication. A high-frequency signal that contains the communication is impressed on the power line. It is also called power-line carrier. (EUSO, CAEDS, EDS)

Cathode – One of the two terminals in a battery or fuel cell. The other terminal is the anode. Also, one end of a diode. (CAEDS)

Circuit Breaker – A device used to interrupt the flow of current during normal operation or during a fault. (EUSO-photo, CAEDS-photo, EDS-photo, IESO-photo)

Circuit Switcher – A device that combines a circuit breaker and a switch. (EUSO-photo)

CIS – An acronym for customer information system.

Combustion Turbine – A jet engine, bolted to footings, that uses its hot exhaust gas to spin an electric generator. Combustions turbines are called gas turbines in most electric utilities. (EUSO, IESO)

Coming Online – The process of connecting a price of equipment or customer to an energized electrical system.

Collector Rings – Two metal rings mounted on the shaft of an AC generator, or on the shaft of a synchronous motor. The collector rings are used to bring DC current into the rotor winding of the generator or synchronous motor. (EUSO-photo, CAEDS-photo, IESO-photo)

Concentric Neutral – A set of current-carrying conductors that are spaced evenly around the insulation on a cable. When looking at the end of the cable, the set of evenly spaced conductors form a circle around the insulation. The neutral is placed “concentrically” around the insulation. (EUSO, CAEDS, EDS, IESO)

Concentric Neutral Conductor – An underground cable in which a set of current-carrying conductors are spaced evenly around the insulation of the cable. When looking at the end of the cable, the set of evenly spaced conductors form a circle around the insulation. The neutral is placed “concentrically” around the insulation. (EUSO, CAEDS ,EDS ,IESO)

Condensing Mode – A term applied to an operating generator that is producing zero or very few megawatts, but which is producing lots of lagging or leading megavars. (EUSO, IESO, System operator classes)

Conduit – Pipe with insulated wire or cable running inside. The pipe can be steel, fiber-glass enforced epoxy, polyvinyl chloride (PVC) or aluminum. (EUSO)

Converter Station – A power station that can be used to change alternating current to direct current, and to change direct current to alternating current. (EUSO-photo)

Contacts – Two pieces of metal that move together to complete a circuit to allow current to flow, and which move apart to stop the flow of current. All circuit breakers have contacts and all electromechanical relays have contacts. (EUSO-photo)

Control Area – All of the generating plants that are under the control of a single system-control center.

Control Performance Standards – Operating guidelines developed by the North American Electric Reliability Committee for generation. (System operator classes)

Control Power Transformer – A device used to reduce a higher voltage down to a lower-level voltage that can be safely used for control circuits.

Coulomb – The charge produced by 6.28 x 10 18 electrons. Coulomb is named after Charles Augustin de Coulomb (1736 – 1806) who was the first to accurately measure the force between charges. (EUSO)

Coupling Capacitor – A device that is used to connect high frequency communication signals to a transmission or distribution line. (EDS, System operator classes)

Counterpoise – A grounding system for transmission towers in which the grounding conductors are placed horizontally in trenches and then buried. (EUSO)

CPS – See Control Performance Standards.

CPT – See Control Power Transformer

Cross Arm – A short horizontal member connected to a power pole. Cross arms hold the conductors. The cross arm, when connected to the pole, causes the pole to resemble a religious cross. (EUSO-photo, CAEDS-photo, EDS-photo, IESO-photo)

CT – An abbreviation that can either be referring to a combustion turbine, or to a gas turbine. (EUSO, CAEDS, EDS, IESO)

CT Metering – A metering system in which the amount of current is measured with a current transformer. CT metering implies a very large residence, larger commercial, and industrial customers. (EUSO, CAEDS, EDS, IESO)

Current – The flow of electrons in negative to positive flow, or the flow of holes in positive to negative flow. (EUSO)

Current Transformer – A device that measures the magnetic field around a conductor and uses this measurement to determine the amount of current flowing. (EUSO-photo, IESO-photo)

Cutout – A fused disconnect switch used in distribution that swings open when the fuse link blows, or when a line crew worker pulls it open. (EUSO-photo, EDS-photo, CAEDS-photo, IESO-photo)

Cycle – In an alternating current system, the process of voltage and/or current going from a zero value, to a positive value, back to zero, to a negative value, and back to zero. (EUSO)

Cycles Per Second – The unit of measure for frequency until the 1960s. The unit “cycles per second” was replaced by Hertz. (EUSO)

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