Glossary F
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F – Fahrenheit. |
FA – Forced-Air, a cooling classification for transformers now classified as ONAF. Oil type, Forced circulation through cooling (i.e. cooling pumps) and natural convection flow in windings. |
Farad – The capacitance value of a capacitor of which there appears a potential difference of one volt when it is charged by a quantity of electricity equal to one coulomb. |
FAT – Factory acceptance test. Validation procedures witnessed by the customer at the factory. |
Fault Close Rating – The ability, in amps, of a switching device to “close” into a fault of specific magnitude, without excessive arcing. |
Fault Current – The current that flows as a result of a short-circuit condition. |
Fault Indicator – A device installed on a conductor to determine if current exceeded the indicator’s current rating. Fault indicators sense using use the magnetic field induced by load current. |
Federal Energy Regulatory Commission (FERC) – FERC is an independent regulatory agency within the U.S. Department of Energy that approves rates for wholesale electricity transactions and transmission of electricity in interstate commerce for utilities, power marketers, power pools and power exchanges. |
Feeder – A three phase distribution line circuit used as a source to other three phase and single phase circuits. |
FERC – Federal Energy Regulatory Commission. |
Ferro resonance – In transformers, an over-voltage condition that can occur when the core is excited through capacitance in series with the inductor. This is especially prevalent in transformers that have very low core losses. |
Fiducial Value – A specified value to which reference is made in order to specify the accuracy of the transducer. For transducers the fiducial value is the span. |
Field Current – The magnetizing current of a device such as a transformer. Also known as exciting current. |
Fill – In conduit or cable tray installations, the portion of the total cross-sectional area of the tray or conduit that can be occupied by conductors or cables. |
Filler – A material used in multiconductorcable to occupy large interstices formed by the cable assembly. Also, a material added to an insulation compound to add volume and increase impact resistance. |
Fixed Capacitor Bank – A capacitor bank installed with no automatic switching device. The bank is manually switched on and off. Also see “Capacitor Bank”. |
Fixture – With regard to lighting, a reference to Luminaire. |
Flame Resistance – The ability of insulation or jacketing material to resist the support and conveyance of fire. |
Flash Hazard – A dangerous condition associated with the release of energy caused by an electric arc. |
Flash Hazard Analysis – A study investigating a worker’s potential exposure to arc-flash energy, conducted for the purpose of injury prevention, the determination of safe work practices, and the appropriate levels of PPE. |
Flash Protection Boundary – An approach limit at a distance from exposed live parts within which a person could receive a second degree burn if an electrical arc flash were to occur. |
Flash Suit – A complete FR clothing and equipment system that covers the entire body, except for the hands and feet. This includes pants, jacket, and bee-keeper-type hood fitted with a face shield. |
Flashover – An unintended electrical discharge to ground or another phase. Flashovers can occur between two conductors, across insulators to ground or equipment bushings to ground. |
Float Charge – A method of maintaining a cell or battery in a charged condition by continuous, long-term, constant voltage charging at a level sufficient to balance self-discharge. |
Float Charge (Battery)MTI – A continuous low rate charge that compensates for the self discharge rate of a battery. Also known as Trickle Charge. |
Flooded Cell – A cell design that incorporates an excess amount of electrolyte. |
Flower Pot – Slang for “Universal Bushing Well”. |
Fluorescent Lamp – A low pressure Mercury, electric discharge lamp in which a fluorescing coating (Phosphor) transforms some of the ultraviolet energy generated by the discharge into light. |
FOB – Free on Board. The point at which liability transfers from buyer to seller. |
Foot-candle (fc) – Standard unit of measure for illumination on a surface. The Average foot-candle level on a square surface is equal to the lumens striking the surface, divided by the area of the surface. |
FPI – Fault Passage Indicator. |
Frequency – In ac systems, the rate at which the current changes direction, expressed in hertz (cycles per second); A measure of the number of complete cycles of a wave-form per unit of time. |
Frequency Transducer – A transducer used for the measurement of the frequency of an A .C. electrical quantity. |
FRP – Fiberglass Reinforced Plastic. |
Fulgurate – A glass-like structure that forms around the element of a current limiting fuse when it operates. It is causes when the heat of the arc melts the silica sand surrounding it. |
Full Duplex Communications – A communications system in which data can travel simultaneously in both directions. |
Full Scale – The specified maximum magnitude of the input quantity being measured that can be applied to a transducer without causing a change in performance beyond specified tolerance. |
Full Scale Output – The specified maximum output value for which the stated accuracy condition applies. |
Functional Block Diagram – One of the IEC 61131-3 programming languages. |
Fuse – A device installed in the conductive path with a predetermined melting point coordinated to load current. Fuses are used to protect equipment from over current conditions and damage. |
Fuse Arcing Time – The amount of time required to extinguish the arc and clear the circuit. |
Fuse Link – A replaceable fuse element used in a Fused Cutout. |
Fuse Melt Time – The time needed for a fuse element to melt, thereby initiating operation of the fuse. Also known as Melt Time. |
Fused Cutout – A device, normally installed overhead, that is used to fuse a line or electrical apparatus. |