Substation1
Dictionary of Electrical Engineering

Commonly used terms in the Electrical industry.

G (giga)
a prefix indicating a quantity of 109. For instance, a gigabyte (GB) of storage is 1;000;000;000 (typically implemented as 230) bytes.
G-line
a line of the mercury spectrum corresponding to a wavelength of about 436 nm.
gain
(1) the ratio of the output variable of a device to its input variable. For calculation purposes, the dimensionality of the gain is simply the unit of the output variable divided by the unit of the input variable. The gain of a device is a dimensionless value only when the electrical units of both the input and output variables are the same (e.g., voltage gain, current gain, power gain, etc.). In this case, a gain greater than one indicates an increase from input to output, while a value for gain less than one is indicative of a decrease (or attenuation). The overall gain of several cascaded components is found by multiplying the individual gains of each component in the system. Gain is often expressed in decibels to facilitate calculation of cascaded gains in a system. decibel

(2) the ratio of the radiation intensity of a particular antenna to that of an isotropic radiator, in the same direction and at the same distance.
gamma-ray laser
laser producing its output in the gamma-ray region of the spectrum, often considered to be any wavelength below about 0.1 angstrom; graser, not yet demonstrated.
ganged
operation of a multiple phase device with all phases operated simultaneously.
gapless arrester
a lightning arrester which is distinguished from a gapped arrester by having a continuous conductive path between the conductor and ground.
gapped arrester
a lightning arrester whose conducting path contains a gas-or air-filled spark gap which must be broken down by the lightning impulse voltage.
gas cable
an electric power cable which is pressurized with an insulating gas, typically sulfur hexaflouride, for its primary insulation.
gas capacitor
a capacitor whose dielectric is composed of a high-pressure gas, often nitrogen or an electronegative gas such as sulfur hexaflouride.
gas circuit breaker
a circuit breaker in which the arc between the contacts is extinguished by immersion in or a blast of an electronegative gas.
gas discharge excitation
electron impact excitation or pumping of a laser medium occurring as a result of collisions between the lasing atoms or molecules and the discharge electrons.
gas dynamic excitation
excitation or pumping of a laser medium occurring as a result of heating followed by rapid expansion and cooling of a gaseous laser medium.
gas insulated switchgear
circuit breakers and switches whose primary insulation is compressed gas.
gas laser
laser in which the amplifying medium is a gas.
gas metal arc welding (GMAW)
a welding process that produces coalescence of metals by heating them with an arc between a consumable filler metal electrode and the parts to be joined. The process is used with shielding gas and without the application of pressure.
gas substation
an electric power substation in which the conductors are insulated from each other and the ground by a high-pressure gas, generally sulfur hexaflouride.
gas tungsten arc welding (GTAW)
a welding process that produces coalescence of metals by heating them with an arc between a nonconsumable tungsten electrode and the parts to be joined. The process is used with shielding gas and without the application of pressure. Filler may or may not be used.
Gauss' law
fundamental law of electromagnetic field that states that the total electric/magnetic flux through a closed surface is equal to the total electric/magnetic charge enclosed.
gd
common notation for DC drain conductance.
general-purpose motor
term often used to describe National Electrical Manufacturers Association (NEMA) class B, and less often class B, induction motors. Generalpurpose motors are those typically used when relatively low starting currents, low slip, good speed regulation, moderate starting torque, and high efficiency are the predominant concerns.