UFC 3 -520-01
June 10, 2002
--For relays and breakers,
a term used
to indicate that
purposely introduced in the automatic tripping of the circuit breaker.
Instantaneous Trip Circuit Breaker--A circuit breaker intended to provide short circuit
protection with no overload protection.
Integrally Fused Circu it Breaker--A circuit breaker with coordinated fuses connected
in series with the trip elements of the circuit breaker that are mounted within the housing
of the circuit breaker.
Let-Through Current--The maximum instantaneous or peak current that passes
through a protective device.
Linear Load--An electrical load device that presents an essentially constant load
impedance to the power source throughout the cycle of applied voltage in steady-state
Listed--Applies to equipment or materials included in a list published by an
organization acceptable to the authority having jurisdiction. The organization
periodically inspects production and certifies that the items meet appropriate standards
or tests as suitable for a specific use.
Low Voltage System--An electrical system having a maximum root-mean-square
(rms) voltage of less than 1,000 volts.
Medium Voltage System--An electrical system having a maximum RMS ac voltage of
1,000 volts to 15 kV. Some documents such as ANSI C84.1 define the medium voltage
upper limit as 100 kV, but this definition is inappropriate for facility applications.
Molded Case Circuit Breaker--A low voltage circuit breaker assembled as an integral
unit in an enclosing housing of insulating material. It is designed to open and clo se by
nonautomatic means, and to open a circuit automatically on a predetermined
overcurrent, without damage to itself, when applied properly within its rating.
Molded Case Switch --A device assembled as an integral unit in an enclosing housing
of molded insulating material, designed to open and close a circuit by nonautomatic
Motor Control Center--A piece of equipment that centralizes motor starters,
associated equipment, bus and wiring in one continuous enclosed assembly.
New Construction--A facility is considered new if changes to be made are more than
cosmetic or minor, such as major renovations, additions, or new facilities.
Nonlinear Load--A steady state electrical load that draws current discontinuously or
has the impedance vary throughout the i nput ac voltage waveform cycle. Alternatively,
a load that draws a nonsinusoidal current when supplied by a sinusoidal voltage source.