Dictionary of Electrical Engineering

Commonly used terms in the Electrical industry.

angular frequency
the rate of change of the phase of a wave in radians per second.
arc fault interrupter
the mechanism that breaks the fault current arc in a power circuit breaker.
arcing fault

See arcing ground
automatic voltage regulator (AVR)
an automatic feedback control system that is responsible for maintaining a scheduled voltage either at the terminals of a synchronous generator or at the high-side bus of the generator step-up transformer. The control is brought about by changing the level of excitation.
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 lightning impulse level (BIL)
the strength of insulation in terms of the withstand voltage crest value using a standard voltage level impulse.
bell insulator
a type of strain insulator, shaped like saucer with ribs on its lower side and frequently used in insulator strings.
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.
bulb generator
a free-standing generator contained in a streamlined, waterproof bulb-shaped enclosure and driven by a waterwheel resembling a ship's propeller on a shaft which extends from one end of the enclosure. They are used in tidal power installations.
bulk power
a term inclusive of the generation and transmission portions of the power system.
bulk substation
a substation located on a high-voltage transmission line which supplies bulk power to a non-generating utility.
circular mil
the area of a circle which measures 0.001 inch in diameter. Used to specify the cross-sectional area of a wire.
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).
Coulomb blockade
the situation in which a particle has insufficient thermal energy to allow the necessary energy exchange during a tunneling process. Hence, the bias supply must supply energy to the electron to account for the stored energy change in tunneling, which requires V > e/2C, where C is the capacitance (eV << kBT ).
Coulomb force
electric force exerted on an electrically charged body, which is proportional to the amount of the charge and the electric field strength in which the charged body is placed.

Coulomb's Law
the force of repulsion/attraction between two like/unlike charges of electricity concentrated at two points in an isotropic medium is proportional to the product of their magnitudes and inversely proportional to the square of the distance between them and to the dielectric constant of the medium.
Coulomb, Charles (1763-1806)
Born: Angouleme, France
Coulomb is best known for his study of electric charge and magnetism resulting in Coulomb's Law, as well as his studies in friction. Coulomb also invented the torsion balance in 1777. He used this device in many experiments. Coulomb began his career in the military, but resigned when the French Revolution began. His experience as a military engineer involved him in a wide variety of different projects. It also gave him time to continue his own experimental work.
Coulomb's law states that the force between two charges is proportional to the product of the charges and inversely proportional to the square of the distance between the two charges. Coulomb is honored by having his name used as the unit of electric charge, the coulomb.
cumulatively compounded
a compound-wound DC machine in which the flux produced by the MMF of the shunt field winding and the flux produced by the MMF of the series field winding are in the same direction.
current regulator
a device used to control the magnitude and phase of the current in DC, AC or other electrical variable speed drives. May use different control strategies like hysteresis current control or ramp comparison current control.
the removal of some government controls on public utilities, generally including the unbundling of certain services, the dismantling of vertically-integrated utilities, and the introduction of competition among various utility companies for customer services.