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Farad |
The unit of measure for capacitance. It is the
capacitance of a capacitor in which an applied voltage of one
volt will store a charge of one coulomb. The more practical
units of capacitance are the microfarad and picofarad.
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Feeder |
All circuit conductors between the service
equipment, the source of a separately derived system, or other
power supply source and the final branch-circuit overcurrent
device.
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Ferroresonance |
Resonance resulting when the iron core of an
inductive component of an LC circuit is saturated, increasing
the inductive reactance with respect to the capacitance
reactance.
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Festoon Lighting |
A string of outdoor lights that is suspended
between two points.
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Field |
A term commonly used to describe the stationary
(Stator) member of a DC Motor. The field provides the magnetic
field with which the mechanically rotating (Armature or Rotor)
member interacts.
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Filament |
In a directly heated electron tube, a heating
element which also serves as the emitter.
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Fitting |
An accessory such as a locknut, bushing, or
other part of a wiring system that is intended primarily to
perform a mechanical rather than an electrical function.
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Flashover |
Flashing due to high current flowing between two
points of different potential. Usually due to insulation
breakdown resulting from arcing.
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Fluctuation |
A surge or sag in voltage amplitude, often
caused by load switching or fault clearing.
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Flux |
The magnetic field which is established around
an energized conductor or permanent magnet. The field is
represented by flux lines creating a flux pattern between
opposite poles. The density of the flux lines is a measure of
the strength of the magnetic field.
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Form Factor |
The ratio of the r.m.s. to the average value of a
periodic wave.
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Forward Transfer Impedance |
The amount of impedance placed between the
source and load with installation of a power conditioner. With
no power conditioner, the full utility power is delivered to the
load; even a transformer adds some opposition to the transfer of
power. On transformer based power conditioners, a high forward
transfer impedance limits the amount of inrush current available
to the load.
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Frequency |
The rate at which alternating current makes a
complete cycle of reversals. It is expressed in cycles per
second. In the U.S. 60 cycles (Hz) is the standard while in
other countries 50 Hz (cycles) is more common.
The frequency of the AC will affect the speed of a motor
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Full Load Current |
The current flowing through the line when the
motor is operating at full-load torque and full-load speed with
rated frequency and voltage applied to the motor terminals.
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Full Load Torque |
That torque of a motor necessary to produce its
rated horsepower at full-load speed, sometimes referred to as
running torque.
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Fuse |
An overcurrent protective device with a circuit opening fusible part that is heated and severed by the passage of overcurrent
through it.
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