Dictionary of Electrical Engineering

Commonly used terms in the Electrical industry.

governor power flow
the inherent response of prime movers or governors to a change in the operating condition of the power system in an attempt to balance the power equation. All generators participate at some level in the change, with larger generators picking up relatively larger amounts.
common notation for power gain in decibels.

See global positioning system
grade of service (GOS)
a probabilistic measure of service or equipment availability in a telecommunications network, expressed as the probability of a particular service (e.g., a completed telephone connection) being denied at request time.
gravitational torque
torque that depends upon the position of the robot in the gravitational field.
Gray code
a code in which each of a sequence of code words differs by one bit from the preceding one, and the assigned value of each code word is one more than that of the preceding one. Such a code avoids glitches (i.e., sharp momentary unwanted spikes) when, in an electromechanical system, the sensors giving the code words are imperfectly aligned. For example, one possible three-bit Gray code is:

000 001 011 010 110 111 101 100.
(1) an earth-connected electrical conducting connection that may be designed or non-intentionally created.

(2) the electrical "zero" state, used as the reference voltage in computer systems.
ground bounce
a transient variation in the potential of the ground terminal of a logic device caused by variations in the supply current acting on the ground impedance of the circuit as seen by the device. Usually caused by simultaneous turnon of the pullup and pulldown sections of totem-pole outputs.
ground bounce noise
ground bounce occurs when a large number of semiconductor circuit components are mounted on a
common semiconductor chip substrate, so that they are imperfectly insulated from each other. In normal operation the substrate should act as an insulator; however, during certain unusual fluctuations in signal levels, the systems power and ground connections can experience fluctuations, which affect the performance of each component in a random way that has the characteristics of noise, much like capacitive coupling.
ground current
the current that flows in a power system in a loop involving earth and (in some usages) other paths apart from the three phases.
ground fault interrupter
a protective device used in commercial and residential wiring which monitors equipment connected to an electrical outlet and shuts off the power when a ground fault in the equipment is detected.
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.
ground lamp
indicator lamp on electrical distribution switchboards that darkens when a ground condition exists on one (or more) of the busses.
ground loop
an undesired conductive path between two conductive bodies in a radial grounding system that are connected to a common ground.
ground plane
a perfectly or highly conducting half space beneath an antenna. Also, an unetched layer of metal on a printed circuit board over which microstriplines and printed antennas are formed.
ground rod
a metallic, rod-type electrode designed to be driven into the earth. It serves as an earth connection for grounding purposes. Other types of earth electrodes include buried plates, rings, and grids. For buildings, its primary function is to keep the entire grounding system at earth potential.
ground wave
a vertically polarized TEM wave propagating close to the ground. It is one of the three modes of propagation (ground, sky, and space waves).
ground-fault circuit interrupter (GFCI)
a device designed to detect ground-fault current above a threshold value (several milliamperes) and then interrupt the source of electrical power by opening a circuit breaker or a set of contacts. GFCIs are designed for personnel protection and are generally available in the form of circuit breakers and receptacles.

See ground
grounding transformer
a transformer connected to an otherwise ungrounded three-phase system for the purpose of providing a path for ground current flow. Zig-zag transformers and grounded wye-delta transformers can be used as grounding transformers.