Dictionary of Electrical Engineering

Commonly used terms in the Electrical industry.

fixed losses
that component of the copper losses in DC shunt, short-shunt, and long-shunt machines' field circuit, that does not vary with change in the load current. With a fixed field power supply, it is an accepted industry agreement to not consider the losses in the field circuit rheostat in computing the efficiency and hence consider the field losses
as fixed losses.
fixed shunt

See shunt capacitor
FLA

See full load amperage
flat voltage start
the usual initial assumption made when beginning a power-flow study. All voltages are assumed to be 1.0 p.u., and all angles are assumed to be zero.
flat-compounded
characteristic of certain compound-wound DC generator designs in which the output voltage is maintained essentially constant over the entire range of load currents.
flexible AC transmission system
a transmission scheme in which each power line is maintained at its optimal impedance, generally by means of thyristor-controlled series compensators.
Flexible Alternating Current Transmission System

A static equipment used for the AC transmission of electrical energy. It is meant to enhance controllability and increase power transfer capability. It is generally a power electronics based device.


See FACTS
flicker
(1)the apparent variation of lighting luminance over time to an observer.

(2) the apparent visual interruptions produced in a TV picture when the field (one half of a TV frame) frequency is insufficient to completely synchronize the visual images. Occurs when the field rate is too low and the biologic characteristic of the human eye known as the persistence of vision does not give the illusion of continuous motion. Flicker is eliminated if the field rate exceeds 50 to 60 Hz.

(3) repetitive sags and swells in the electric service voltage, often accompanied by periodic harmonic distortion.
flicker fusion the perception by the human visual system of rapidly varying lights (flicker) as being steady (fused). Flicker fusion is why fluorescent lights and scenes in movies and television appear to have constant illumination.
float switch
a switch that is operated by a fluid level in a tank or process channel.
flow diagram

See flowchart
flowchart
a traditional graphic representation of an algorithm or a program, in using named functional blocks (rectangles), decision evaluators (diamonds), and I/O symbols (paper, disk) interconnected by directional arrows which indicate the flow of processing. Also called flow diagram.
flower pot
a cover for the bushing of a pad-mount transformer.
fluidized bed combustion
a method of solid-fuel combustion in which the fuel, usually coal, is pulverized and mixed with a ballasting substance and burned on a bed of pressurized air. If the ballasting agent is crushed limestone, sulfur from the coal is absorbed and carried out as solid ash.
fluorescent lamp
typically a lamp made by exciting a low pressure discharge in mercury vapor and other gases; mercury, when excited in the discharge, predominantly emits 257 nm radiation (ultraviolet) which is absorbed by a phosphor on the inside wall of the lamp tube; the phosphor fluoresces, emitting a white light spectrum in the visible.
flush
the act of clearing out all actions being processed in a pipeline structure. This may be achieved by aborting all of those actions, or by refusing to issue new actions to the pipeline until those present in the pipeline have left the pipeline because their processing has been completed.
flux
(1) lines that indicate the intensity and direction of a field. Intensity is usually represented by the density of the lines.

(2) a measure of the intensity of free neutron activity in a fission reaction, closely related to power, the product of neutron density and neutron velocity, e.g., neutrons per square cm per second.
flux density
lines of magnetic flux per unit area, measured in tesla; 1T = 1Wb/m2.
flux line

See direction line
flux linkage
quantity that indicates the amount of flux associated with a coil. Flux linkage is denoted by the symbol . and expressed in Webers (Wb) or Weber-Turns (Wb-t). For a single turn coil, flux linkage is the same as the flux. Flux linkages of an N turn coil are Nt Wb-t.
fluxmeter
an instrument that measures the change in magnetic flux within a coil by integrating the induced voltage with respect to time.
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