Term
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Definition
| The coil of a watt-hour meter through which a magnetic field is produced that is proportional to the amount of current being drawn by a customer. |
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Term
Counter-Electromotive Force
(CEMF) |
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Definition
| Voltage that pushes against the current which induces it. |
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Term
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Definition
| Ground connection for transformer housing; on single-bushing transformers, a connection point to one end of the primary winding. |
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Term
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Definition
| A device that protects substations and switchyard equipment by resisting the flow of fault current. |
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Term
| Conservator-Type Sealed Transformer |
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Definition
| Power transformer that uses an expansion tankv(conservator tank) above the transformer to prevent air and moisture from entering the transformer enclosure. |
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Term
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Definition
| Network of buried conductors that form a ground grid under a transmission system. |
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Term
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Definition
| A switch on a dual voltage transformer that determines the operating voltage of a transformer. |
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Term
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Definition
| A transformer that is switchable to allow for operation at either of two voltages. |
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Term
| Distribution Automation System |
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Definition
| A system that generally monitors and controls components in the distribution system between the substation and customers. |
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Term
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Definition
| The transfer of electricity from an energized conductor to a de-energized conductor through a medium such as air. |
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Term
| Electromagnetic Induction |
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Definition
| Process by which power is transmitted from primary winding to secondary winding when an expanding and contracting magnetic field sweeps across the secondary winding. |
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Term
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Definition
| A.C. values for current and voltage based on the relationship that one ampere, peak value, of A.C. current produces the same heating effect as .707 amperes D.C. current; a.k.a. RMS values. |
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Term
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Definition
| A tendency of one unit in a 3Ø transformer bank to take on more than its proper share of the load; can lead to premature failure and outages. |
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Term
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Definition
| A load on a T&D system that is commonly caused by industrial customers with large electric motors. |
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Term
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Definition
| A process of creating a physical and visible break in an electrical circuit. |
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Term
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Definition
A physical property of all A.C. circuits that opposes a change in current.
(Measured in Henrys) |
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Term
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Definition
A measure of the opposition to current that is created by inductance.
(Measured in Ohms) |
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Term
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Definition
| A process that produces voltage due to interaction of a conductor, a magnetic field and relative motion between them. |
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Term
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Definition
A ratio of average load over period of time to peak load in that period.
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Term
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Definition
| Transfer of electrical charges from an energized line to a de-energized line through a magnetic field. |
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Term
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Definition
A tap changer operated only when a transformer is
de-energized. |
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Term
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Definition
Voltage and current not used to perform work.
(VAR - Volts Ampere Reactive) |
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Term
| Power Line Carrier System |
|
Definition
| A system for sending/receiving communication signals over power lines between substations and a control center. |
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Term
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Definition
| A condition in a transformer bank when a fused cutout blows and causes arcing. Air around arc becomes ionized and provides a path for current. |
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Term
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Definition
| Re-energizing a circuit one section at a time to determine the location of the problem. |
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Term
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Definition
| A condition in which 1 or 2 transformers in a 3Ø bank become overloaded trying to supply a full load of current. |
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Term
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Definition
| A device used in substations to improve system efficiency. Adds inductive load to a T&D system to counterbalance capacitive load. |
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Term
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Definition
| A protective switch that opens a faulted circuit after the circuit has been de-energized by a recloser or other protective device. |
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Term
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Definition
| A trasient wave of current, potential or power that occurs when breakers or switches are opened or closed. |
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Term
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Definition
| A change in the electromagnetic field around a single condcutor that induces voltage in that conductor; lines of force in the field that cut across the conductor itself. |
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Term
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Definition
| A point in an alternating current cycle when there is no current flow. |
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Term
| Gas Puffer Circuit Breaker |
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Definition
| A circuit breaker that directs a flow of insulating gas from a compression chamber through an arc to lengthen and cool the arc until the arc extinguishes at a current zero. |
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Term
| Hydraulic Operating Mechanism |
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Definition
| A circuit breaker operating mechanism that relies on a motor, opening springs and closing springs to provide the forces necessary to open and close circuit breaker contacts. |
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Term
| Pneumatic Operating Mechanism |
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Definition
| A circuit breaker operating mechanism in which compressed air provides the force necessary to close breaker contacts; an operating spring provides the force necessary to reopen the contacts. |
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Term
| Solenoid Operating Mechanism |
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Definition
| A circuir breaker operating mechanism that relies on a solenoid and an opening spring to provide the foce necessary to open and close circuit breaker contacts. |
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Term
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Definition
| A type of watt-hour meter base that has connecting terminals on the bottom. |
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Term
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Definition
| A test of a watt-hour meter's operating status as it is found in the field, before any maintenance is performed. |
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Term
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Definition
| Magnetic fields induced onto a watt-hour meter disk as the result of current flow through the meter's potential and current coils. |
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Term
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Definition
An isolating transformer used to protect personnel and equipment from exposure to high voltages and currents in a circuit. |
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Term
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Definition
An electro-mechanical device for measuring the power consumed by a utility customer; commonly referred to as a watt-hour meter. |
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Term
|
Definition
A transformer used during a meter accuracy test to ensure a regulated current output. |
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Term
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Definition
| The coil of a watt-hour meter through which a magnetic field is produced that is proportional to the amount of applied voltage. |
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Term
|
Definition
A type of watt-hour meter base that has connecting terminals on the back side; also referred to as "socket type." |
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Term
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Definition
A watt-hour meter that requires an external isolating transformer to isolate voltage, current, or both; also called a non-self-contained meter.
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Term
|
Definition
An instrument transformer in which the primary coil is connected to the service voltage and induces voltage into the secondary coil. The secondary coil supplies voltage to the potential coil of a watt-hour meter. |
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Term
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Definition
| A voltage regulating device on many power transformers that adjust voltage by moving its contacts to different points in relation to coils of wire in the transformer. |
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Term
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Definition
| Ratio between the # of turns on the primary winding and the # of turns on the secondary winding. |
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Term
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Definition
| The maximum instantaneous current at the major peak of an offset power frequency sinusoidal current that a switch is required to carry. |
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Term
| Short Time (Symmetrical) Withstand Current |
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Definition
| An abnormal power frequency current, the initial portion of which may have a DC offset that a switch is required to carry. |
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Term
| Short Time (Symmetrical) Withstand Current Duration |
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Definition
| The maximum duration of short time withstand current that a switch is required to carry. |
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Term
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Definition
| The maximum voltage that a station grounding grid may attain relative to a distant grounding point assumed to be at the potential of remote earth. |
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Term
| Temporary Protective Ground (TPG) |
|
Definition
| Devices to limit the voltage difference between any two accessible points at the work site to a safe value, and having sufficient withstand rating. |
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Term
| Temporary Protective Ground (TPG) Assembly |
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Definition
| A combination of cables, cable terminations and clamps assembled for use in temporary protective grounding. |
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Term
| Ultimate Rating (Capacity) |
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Definition
| A calculated maximum symmetrical current that a TPG is capable of carrying for a specified time without fusing or melting. TPGs are usually rated by this value. |
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Term
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Definition
| The current a TPG should conduct for a specified time without being damaged sufficiently to prevent reuse. |
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Term
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Definition
| The axially aligned fibre reinforced resin rod that forms the machanical load-bearing component of the insulator. |
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Term
|
Definition
| The insulator attachment hardware that is connected to the core. |
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Term
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Definition
| A device for controlling the potential gradient at the end fittings, such as a metal ring or various semiconductive polymeric devices. |
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Term
|
Definition
| The external polymeric covering insatlled over the insulator core to afford it protection. |
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Term
|
Definition
| An insulator coupling two phases together as a means for controlling conductor spacing during galloping. It is intended to be loaded in tension, torsion, bending or compression. |
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Term
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Definition
| The loss of material by the physical action of leakage current, corona discharge or dry band arcing. |
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Term
| Maximum Design Withstand Load (MDWL) |
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Definition
| The maximum cantilevel load in service that the insulator is designed to carry. |
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Term
|
Definition
| Irreversible deterioration of surface material from the formation of conductive carbonized paths. |
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Term
|
Definition
| Irreversible internal deterioration by the formation of conductive or nonconductive filamentary channels. |
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Term
|
Definition
| The separation between two conductors, between conductors and supports or other objects or between conductors and ground. |
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