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Dictionary of Electrical Engineering

Commonly used terms in the Electrical industry.

arc fault interrupter
the mechanism that breaks the fault current arc in a power circuit breaker.
arcing fault

See arcing ground
bolted fault
a bolted fault is a short circuit fault with no fault resistance. Bolted faults deliver the highest possible fault current for a given location and system configuration, and are used in selecting equipment withstand and interrupting ratings and in the setting of protective relays.
fault detection
based on circuit duplication and comparison. One module is designed using positive logic and the other module uses negative logic. This assures detecting common mode faults.
fault
(1) in hardware, a physical defect or imperfection of hardware. Typical circuit faults are shorts opens in conductor, defects in silicon, etc. See also disturbance.

(2) in software, the manifestation of an error. fault avoidance a technique used to prevent or limit fault occurrence (for example, with signal shielding, fan-out limitation, and power dissipation decrease).
fault confinement
technique that limits the spread of fault effects to some area of the system and prevents propagation of these effects to other areas.
fault coverage
the measure of test quality expressed as the percentage of detected faults.
fault detection
the process of locating distortions or other deviations from the ideal, typically during the process of automated visual inspection, e.g., in products undergoing manufacture.
fault indicator
a small indicating unit equipped with a permanent magnet and pivoting pointer which is hung on a transmission line suffering intermittent faults of unknown origin. After a fault occurs, fault indicators are inspected. Each shows the presence and direction of a fault, thus allowing the defect to be located.
fault kva
fault kilovolt-amps (kva) is the fault level expressed in terms of volt-amps rather than amps. One advantage of using volt-amps rather than amps is that the same flow is experienced on both sides of a transformer when expressed in volt-amps, while the flow changes due to the transformer turns ratio when it is expressed in amps. Volt-amps for a three-phase fault are expressed as 1.73 x rms line-line voltage x rms symmetrical fault current. Volt-amps for a single phase fault are defined as 1.73 x rms line-line voltage x rms symmetrical current in the faulted phase.
fault latency
the length of time between the occurrence of a fault and the appearance of an error.
fault masking
a technique that hides the effects of faults with the use of redundant circuitry or information.
fault mva
fault megavolt-amps (mva) is the fault level expressed in terms of volt-amps rather than amps. One advantage of using volt-amps rather than amps is the same flow is experienced on both sides of a transformer when expressed in volt-amps, while the flow changes due to the transformer turns ratio when it is expressed in amps. Volt-amps for
a three-phase fault are expressed as 1.73 x rms line-line voltage x rms symmetrical fault current. Volt-amps for a single phase fault are defined as 1.73 x rms line-line voltage x rms symmetrical current in the faulted phase.
fault prevention
any technique or process that attempts to eliminate the possibility of having a failure occur in a hardware device or software routine.
fault resistance
the resistance that occurs at the point of fault due to voltage drop across an arc or due to other resistance in the fault path.
fault secure
pertaining to a circuit, with respect to a set of faults, if and only if for any fault in this set, and any valid input code the output is a non-code or correct code (the output is never an invalid code). The circuit
is considered to operate properly if the output is a code word.
fault simulation
an empirical method used to determine how faults affect the operation of the circuit and how much testing is required to obtain the desired fault coverage.
fault tolerance
correct execution of a specified function in a circuit (system), provided by redundancy despite faults. The redundancy provides the information needed to negate the effects of faults.
fault tree
the identification and analysis of conditions and factors that cause or contribute to the occurrence of a defined undesirable event, usually one that significantly affects system performance, economy, safety, or other required characteristics.
fault-tolerant control system
a system that exhibits stability and acceptable performance in the presence of component faults (failures) or large changes in the system that resemble failures.