FCC
Federal Communications Commission. In the United States, this governmental organization has authority to regulate the use of the radio frequency spectrum for communication purposes. It also regulates non-communication devices that may cause interference to communication devices. It has the legal authority to shutdown anything disrupting radio communications.

feedback
The actual operation signal that is used for comparison with the set point to establish an error signal in a closed loop control system.

FET
Field effect transistor. A semiconductor amplifying device which is voltage-operated rather than current-operated like the common bipolar transistor.

filter
(electrical) A device that passes a signal or range of signals and eliminates other signals.

floating ground
A circuit whose electrical common point is not at earth ground potential or the same ground potential as the circuitry it is associated with.

form factor
A figure of merit which indicates how much rectified current differs from pure DC current. A large variance from unity form factor will indicate increased motor heating will occur.

frequency
A measure of the cycling rate of a vibrating object or an AC signal. In electricity, the number of times alternating current changes direction during a second. It is measured in hertz (Hz) which equals one cycle per second.

full load current, or full load amps (FLA)
The current drawn by a motor when operated at its full load torque.

full load speed
see base speed

full load torque
The torque necessary to produce rated horsepower at full load speed.

fundamental frequency
The lowest frequency component of a repetitive wave. The harmonics are all multiples of this frequency. In most regions the fundamental frequency for power lines is 50 Hz. For power lines in the United States, the fundamental frequency is 60 Hz.

fused power disconnect
The fused power disconnect is commonly used with contactor bypass. It disconnects the line from both the drive and the bypass and provides motor fusing. Fused power disconnect may be required with contactor bypass unless external short circuit protection and a disconnect are provided on the input to the drive.