Dictionary of Electrical Engineering

Commonly used terms in the Electrical industry.

circular polarization
a polarization state of a radiated electromagnetic field in which the tip of the electric field vector traces a circle as a function of time for a fixed position. The sense of rotation of the electric field vector is either right-hand or left-hand (clockwise or counter-clockwise).
coefficient of utilization (CU)
the ratio of the lumens reaching the working plane to the total lumens generated by the lamp. This factor takes into account the efficiency and distribution of the luminaire, its mounting height, the room proportions, and the reflectances of the walls, ceiling, and floor.
dead zone

See dead band
direct axis magnetizing (armature) reactance
a reactance that represents all the inductive effects of the d-axis stator current of a synchronous machine, except for that due to the stator winding leakage reactance. In Park's d-axis equivalent circuit of the synchronous machine, this reactance is the only element through which both the stator and rotor currents flow. Its value may be determined by subtracting the stator winding leakage reactance from the steady-state value of the d-axis operational impedance or from the geometric and material data of the machine.
electric polarization vector
an auxiliary vector in electromagnetics that accounts for the creation of atomic dipoles in a dielectric material due to an applied electric field. Macroscopically, the electric polarization vector is equal to the average number of electric dipole moments per unit volume. Mathematically, P = D - Є0E, where D is the electric flux density, E is the electric field intensity, and Є0 is the free space permittivity. SI units are coulombs per square meter.
elliptical polarization
the polarization state of a radiated electromagnetic field in which the tip of the electric field vector traces an ellipse as a function of time for a fixed position. The sense of rotation of the electric field vector is either right-hand or left-hand (clockwise or counter-clockwise). Circular polarization and linear polarization are special cases of elliptical polarization.
equalization
a method used in communication systems to compensate for the channel distortion introduced during signal transmission.
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.
ground fault neutralizer
an inductor connected between the neutral of Y windings of a generator or transformer and ground. It is tuned to the machine's capacitance so as to minimize ground fault current.
hertz
a unit of frequency.
horizontal polarization
a term used to identify the position of the electric field vector of a linearly polarized antenna or propagating EM wave relative to a local reference, usually the ground or horizon. A horizontally polarized EM wave is one with its electric field vector aligned parallel to the local horizontal.
Hz
hertz
See frequency
intrinsic demagnetization curve
the second quadrant portion of the hysteresis loop generated when intrinsic induction (Bi )is plotted against applied field (H ), which is mathematically related to the normal curve; most often used to determine the effects of demagnetizing (or magnetizing) fields.
Kramer's generalization
a sampling theory based on other than Fourier transforms and frequency.
left-hand circular polarization
the state of an electromagnetic wave in which the electric field vector rotates anticlockwise when viewed in the direction of propagation of the wave.
line impedance stabilization network (LISN)
a network designed to present a defined impedance at high frequency to a device under test, to filter any existing noise on the power mains, and to provide a 50 Ω impedance to the noise receiver.
magnetic polarization vector
an auxiliary vector in electromagnetics that accounts for the presence of atomic circulating currents in a material. Macroscopically, the magnetic polarization vector is equal to the average number of magnetic dipole moments per unit volume.
magnetic stabilization
the act of purposely demagnetizing a magnet with reverse fields or a change in temperature so that no irreversible losses are experienced when the magnet operates under similar conditions in the field.
magnetization curve

See hysteresis curve
magnetizing current
the current required to magnetize the different parts of a magnetic circuit. It is calculated as the ratio of the total magnetomotive force (F) and the number of turns (N). More or less in transformers, and AC synchronous and induction machines, the magnetizing current is the current through the magnetizing inductance. Denoted by Im,it is calculated as the ratio of the induced EMF across the magnetizing inductance to its magnetizing reactance Xm.
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