MIL-DTL-17361G(SH)
6.4.3 Auxiliary switch. An auxiliary switch is a switch mechanically interlocked with the main contacts of the
circuit breaker and used for signaling, electrical interlocking, or other purposes.
6.4.4 Back-connected. A back-connected circuit breaker is one on which the main current connections are
made from the back of the circuit breaker.
6.4.5 Continuous current rating. The continuous current rating is the stated limit in rms amperes or DC
amperes which a circuit breaker will carry continuously under stated ambient conditions without either tripping or
exceeding the limit of observable temperature rise.
6.4.6 Current limiting device. A current limiting device is a device which, when interrupting currents in its
current limiting range, will reduce the current flowing in the fault circuit to a magnitude substantially less than that
obtainable in the same circuit if the device was replaced with a solid conductor having comparable impedance.
When the device is a (fuseless) current limiting circuit breaker, it will permit restoration of service by resetting, if
necessary, and returning to the "on" position without replacement of any of its parts or elements.
6.4.7 Current limiting fuse unit base. A current limiting fuse unit base is an assembly for mounting the current
limiting fuse unit. It is connected between the circuit breaker mounting base/block and the load.
6.4.8 Electric operating attachment. An electric operating attachment consists of either an electric motor or
solenoid with associated control devices and mechanical mechanisms readily attachable to a manually operated
circuit breaker to provide opening and closing from a remote source.
6.4.9 Front-connected. A front-connected circuit breaker is one on which connections are made from the front
without the necessity of access to the rear of the circuit breaker.
6.4.10 Fused circuit breaker. A fused circuit breaker is a device in which the circuit breaker mechanism will
open on overloads and low fault currents up to the point where the internal current limiting fuses take over the duty
and blow. When a fuse or fuses blow the circuit breaker mechanism opens.
6.4.11 Handle boot. A handle boot is a flexible rubber protective device for the circuit breaker handle.
6.4.12 Handle locking device. A handle locking device is a metal clip which permits securing of the circuit
breaker operating handle in either the open or closed position. This device does not affect the mechanically trip free
operation of the circuit breaker.
6.4.13 Intentional time delay. Intentional time delay is the specific time value purposely introduced in the
tripping of a circuit breaker.
6.4.14 Interrupting rating. The interrupting rating of a circuit breaker is the highest current (rms if AC) at a
specified operating voltage which the circuit breaker is required to interrupt under the operating duty specified and
with a normal frequency recovery voltage equal to the specified operating voltage. The interrupting rating is based
on asymmetrical current. Refer to 4.5.13.1.1.
6.4.15 Low voltage. Low voltage refers to voltages up to and including 1kV.
6.4.16 NQB circuit breaker. An NQB circuit breaker is a molded case circuit breaker with no trip unit installed.
6.4.17 Peak let-through current. Peak let-through current is the maximum instantaneous peak current which
passes through the circuit breaker during the total clearing time.
6.4.18 Pickup. The pickup value of the tripping device is the nominal value at which the device will operate.
6.4.19 Pulse method. Pulse method of testing the instantaneous trip is described in NEMA Standards
Publication AB-4 and provides two repeatable test results in contrast to run up method which is operator dependant
and also is not in accordance with the real current rise in case of short circuit.
6.4.20 Quick-break. A circuit breaker is quick-break when it has a high contact opening speed independent of
the operator under all conditions.
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