Dictionary of Electrical Engineering

Commonly used terms in the Electrical industry.

flower pot
a cover for the bushing of a pad-mount transformer.
fluorescent lamp
typically a lamp made by exciting a low pressure discharge in mercury vapor and other gases; mercury, when excited in the discharge, predominantly emits 257 nm radiation (ultraviolet) which is absorbed by a phosphor on the inside wall of the lamp tube; the phosphor fluoresces, emitting a white light spectrum in the visible.
footing impedance
the electrical impedance between a steel tower and distant earth.
forced interruption
an interruption in electric supply caused by human error, inappropriate equipment operation, or resulting from situations in which a device is quickly taken out of service by automatic or manual switching operations.
four-point starter
a manual motor starter that requires a fourth terminal for the holding coil. Because of its independent holding coil circuit, it is possible to vary the current in the field circuit independently of the holding coil
circuit. The disadvantage is that the motor starter holding relay will not drop out with loss of the field; however, proper overcurrent protection should shut down the motor in the event of field loss.
four-quadrant operation
(1) a signed representation of electrical or mechanical variables in the phase plane in order to situate the different modes for energy transfer. This term can be used both for power electronics and electrical machines. For electrical variables, the four-quadrant operation is defined by the voltage-current (or current-voltage) characteristic with the two variables expressed as instantaneous or mean values. For mechanical variables, the term is defined by the torque-speed (or speed-torque) characteristic with the same time-domain representation as previously explained. The energy transfer is defined with electrical power in the voltage-current curve and with mechanical power in the torque-speed curve. The four-quadrant operation is related to reversible power in electromechanical systems.
For example, in the case of power electronics, the four-quadrant operation is defined only with electrical variables to visualize the way of energy transfer in a static converter. For electrical machines, the same operation can
be defined with electrical variables at the input (motor) or at the output (generator) and also with mechanical variables at the output (motor) or at the input (generator).

(2) the four combinations of forward/reverse rotation and forward/reverse torque of which a regenerative drive is capable. These are: motoring: forward rotation/forward torque; regeneration: forward rotation/reverse torque; motor: reverse rotation/reverse torque; and regeneration: reverse rotation/forward torque. four-wave mixing a nonlinear optical
phenomenon in which four optical beams interact inside nonlinear media or photorefractive crystals. When four beams of coherent electromagnetic radiation intersect inside a nonlinear or photorefractive medium, they will, in general, form six interference patterns and induce six volume refractive index gratings in the medium. The presence of the index gratings will affect the propagation of these four beams. This may lead to energy coupling. The coupling of the four optical
beams is referred to as four-wave mixing. In one of the most useful four-wave mixing configurations, the four beams form two pairs of counterpropagating beams. In this particular configuration, some of the refractive index gratings are identical in their grating wavevectors. This leads to the generation of phase conjugate waves. Four-wave mixing
is a convenient method for the generation of phase conjugated waves.
fractional horsepower
National Electrical Manufacturers Association (NEMA) classification describing any "motor built in a frame smaller than that having a continuous rating of 1 horsepower, open type, at 1700 to 1800 rpm."
fuel pool
a large vat of water used to store both fresh and spent nuclear fuel at the reactor site.
full load amperage (FLA)
a value, found on the nameplate of an induction motor, indicating the expected current drawn by the motor when operating at rated voltage and load.
full-load amperage
the current measured at the input of an electrical apparatus which has a rated variable at the output. The full-load amperage is also defined as a value that permits the system to operate in a safe condition if it is equal to the rated value. The full-load amperage is equal to the rated value if and only if the voltage is at its rated value. The full load is defined with the electrical power in the case of transformers, generators, or power electronics converters and it is defined with the mechanical power for electrical motors.
full-load speed
the speed of a motor that produces rated power when operating at rated voltage and, for AC motors, frequency.
GP
common notation for power gain in decibels.
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 capacitor
a capacitor whose dielectric is composed of a high-pressure gas, often nitrogen or an electronegative gas such as sulfur hexaflouride.
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.
global positioning system (GPS)
system of 18 primary satellites in medium earth orbit, distributed so that at least four are simultaneously visible from each point on the globe; typically used in timing and positioning applications.
globally asymptotically stable equilibrium
an asymptotically stable equilibrium (see the definition) with a region of attraction (see the definition) equal to
globally asymptotically stable state

See asymptotically stable in the large
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.
Powered by The Filipino Engineer