Dictionary of Electrical Engineering

Commonly used terms in the Electrical industry.

arc lamp
lamp made by driving a high current across a gap between two electrodes. Some types operate in air consuming the electrode, for example, a carbon arc in which the electrode material is made as a rod and fed into the discharge to replace what is consumed. Others operate in a vacuum envelop that reduces the electrode consumption.
arm pin
a pin insulator
aspect ratio
(1) the size invariant ratio of length to width for a rectangular box enclosing a shape, the orientation of the box being chosen to maximize the ratio. This measure is used to characterize object shapes as a preliminary to, or as a quick procedure for, object recognition.
(2) the ratio of width to height for an image or display.
(3) in television or motion pictures, the algebraic ratio of picture width to height. At present, the television format in the United States consists of a width to height ratio of 4 to 3.
asynchronous operation
a term to indicate that a circuit can operate or a communication system can transmit information when ready without having to wait for a synchronizing clock pulse.
atmosphere
a convenient measure of pressure. 1 std atm = 14.696 psia (pounds per square inch absolute).
atmospheric attenuation
decrease in the amplitude of a signal propagating through the atmosphere, due primarily to absorption and scatter.
average power
the average value, taken over an interval in time, of the instantaneous power. The time interval is usually one period of the signal.
band stop filter
filter that exhibits frequency selective characteristic such that frequency components of an input signals pass through unattenuated from input to output except for those frequency components coincident with the filter stop-band region, which are attenuated. The stop-band region of the filter is defined as a frequency interval over which frequency components of the input signal are attenuated.
band-pass network
a configuration of solely passive components or combination of active and passive components that will attenuate all signals outside of the desired range of frequency.
base speed
corresponds to speed at rated torque, rated current, and rated voltage conditions at the temperature rise specified in the rating. It is the maximum speed at which a motor can operate under constant torque characteristics or the minimum speed to operate at rated power.
basic impulse insulation level (BIL)
a measurement of the impulse withstand capability of a piece of electric power equipment based on its ability to withstand 50% of impulses applied at the BIL voltage.
basic input-output system (BIOS)
part of a low-level operating system that directly controls input and output devices.
basic lightning impulse level (BIL)
the strength of insulation in terms of the withstand voltage crest value using a standard voltage level impulse.
beta particle
an electron or positron emitted from a radioactive source.
branch line coupler
coupler comprised of four transmission lines, each of 90. electrical length, arranged in a cascaded configuration with the end of the last transmission line section connected to the beginning of the first transmission line to form a closed path. The input, coupled, direct, and isolated ports are located at the connection point of one transmission line with the next one.
brushless rotary flux compressor
a rotating machine designed to deliver pulsed output (1 MJ in 100 µs). The stator coils are excited by an external capacitor bank. The rotor is a salient structure that compresses the flux resulting in amplification of the electric pulse, by converting the rotating kinetic energy of the rotor to electrical energy.
bulk power
a term inclusive of the generation and transmission portions of the power system.
bundle spacer
a rigid structure which is used to maintain the spacing of wires in a bundled conductor on an overhead electric power transmission line.

See bundle
burnup
a measure (e.g., megawattt-days / ton) of the amount of energy extracted from each unit of fissile material invested in a nuclear reactor.
bus impedance matrix

See Z-bus
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