Dictionary of Electrical Engineering

Commonly used terms in the Electrical industry.

carbon brush
a block of carbon used to make an electrical contact to a rotating coil via the commutator of a DC machine or the slip rings of a synchronous machine.
carbon dioxide (CO2)
linear gas molecule consisting of one carbon and two oxygen atoms, medium for an important class
of lasers.
carbon dioxide laser
laser in which the amplifiying medium is carbon dioxide gas; efficient, powerful, and commercially important laser that is pumped and configured in many ways and has its principal output lines in the mid-infrared.
carbon resistor thermometer
a carbon resistor whose temperature sensitivity provides good temperature resolution.
ceramic ferrite
a relatively inexpensive permanent magnet material with decent coercivity and low energy product that is composed of strontium or barium oxide and iron oxide. Also called hard ferrite.
chain reaction
a process in which high-energy neutrons emitted from fissile radioactive material are directed into more fissile material such that more neutrons are emitted. The process creates heat which is used to power thermal power plants.
charge conservation
physical law (derived from Maxwell's equations) indicating that no change in the total charge within a
certain volume can exist without the proper flow of charge (current) through that volume.
charging current
that portion of an electric power line's current which goes to charge the capacitance of the line. The charging current is not available for power transmission.
chemical laser
a laser in which the amplification results from one or more chemical reactions; potentially very powerful with principal output lines in the mid-infrared.
circle diagram
(1) graphical representation of the operation of an induction machine. It is based on the approximate equivalent circuit and expresses stator and rotor current relations for all operating modes (motor, braking, generator) and all values of slip. Several variations of the diagram exist.
(2) graphical representation of the power flow through a transmission line. The maximum power flow through the line can be determined by the impedance of the line.
a physical device consisting of an interconnection of elements, or a topological model of such a device. For example, an electric circuit may be constructed by interconnecting a resistor and a capacitor to a voltage source.
circuit breaker
a circuit breaker is a device that makes and breaks the electrical contact between its input and output terminals. The circuit breaker is capable of clearing fault currents (tripping) as well as load currents. The circuit breaker consists of power contacts with arc clearing capability and associated control and auxiliary circuits for closing and tripping the breaker under the required conditions.
circuit protection
devices or control measures used to safeguard electrical circuits from unsafe operating regions, such as over-currents and over-voltages.
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).

See coaxial cable
coaxial cable
A transmission line formed by two concentric conductors separated by a dielectric designed to confine the fields and their energy in the medium between said conductors. It is often used in applications where signal interference between the cable and its surrounds must be kept to a minimum.

See coax
code letter

See NEMA code letter
coefficient of thermal expansion (CTE) mismatch
the difference between the coefficients of thermal expansion of two components, i.e., the difference in linear thermal expansion per unit change in temperature. (This term is not to be confused with thermal expansion mismatch).
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.