MIL-DTL-17587C(SH)
6.3.17 Rated DC short-circuit current. The rated DC short-circuit current of a circuit breaker is the designated
limit in available (prospective) sustained current at the specified operating voltage, at which it is required to perform
its short-circuit current duty cycle at rated maximum voltage, under the prescribed test conditions.
6.3.18 Rated short-time current. The rated short-time current of a circuit breaker is the designated limit of
available (prospective) current at which it is required to perform its short-time current duty cycle at rated maximum
voltage under the prescribed test conditions.
6.3.19 Removable element of a circuit breaker assembly. The removable element of a circuit breaker assembly
is that portion which carries the circuit-switching and circuit-interrupting devices and the removable part of the
primary and secondary disconnecting devices. It can be withdrawn from the stationary element for maintenance
purposes.
6.3.20 Resettable delay of a circuit breaker. Resettable delay is defined as the maximum time the circuit
breaker will carry current in excess of the pickup current setting and still not trip when the circuit current is suddenly
reduced without interruption to the rated continuous current of the circuit breaker.
6.3.21 Stationary component of a circuit breaker assembly. The stationary component of a circuit breaker
assembly is that portion which is bolted to its enclosure and to which external current-carrying connections are
made. The removable component of the circuit breaker assembly can be inserted (connected) into the stationary
component or withdrawn (disconnected) from it.
6.3.22 Terminal. The terminal is the end of the stationary primary disconnect to which external bus or cable
connections are made.
6.3.23 Total clearing time of a circuit breaker. Total clearing time is the maximum time, measured from when
current reaches a trip value, until the interruption is completed and consists of the mechanical operating time, the
arcing time and the intentional delay time of the circuit breaker. The total clearing time is represented by the upper
limit of the time band envelope on the applicable time-current characteristic curve.
6.3.24 Trip device, AC solid-state overcurrent. An AC solid-state overcurrent trip device obtains its tripping
energy from the circuit breaker current via an overcurrent sensor. This energy is supplied to an electrical network,
which in turn operates a trip mechanism. Three sensors may be required to derive enough energy to actuate the
tripper.
6.3.25 Trip device, DC solid-state overcurrent. A DC solid-state overcurrent trip device obtains its tripping
energy from a preferred control source and senses current levels via a low-powered sensor. This energy and signal
is supplied to an electrical network, which in turn operates a trip mechanism. Multiple sensors may be required to
derive enough energy to actuate the tripper.
6.3.26 Trip device, electromechanical overcurrent. An electromechanical overcurrent trip device operated
directly by circuit breaker current to mechanically trip the circuit breaker on overcurrent. The current through the
circuit breaker directly provides the magnetic force to trip the circuit breaker.
6.3.27 Trip on power up (TOPU) device. A feature that trips a circuit breaker when the circuit breaker is left
closed in the absence of control power and the control power is subsequently restored. The purpose of a TOPU
device is to prevent unintended energization of circuit breaker loads.
6.3.28 Type. The circuit breaker type is a designation used to differentiate performance characteristics.
6.3.29 Undervoltage lockout device. A solenoid or other electronic device that will prevent a circuit breaker
from being closed if the applied voltage is below a prescribed level. Once closed, a low voltage condition will not
trip the circuit breaker.
6.3.30 Undervoltage release device. A solenoid or other electronic device that will trip the circuit breaker (or
prevent it from being closed) if the applied voltage falls below a prescribed level.
6.3.31 Withdrawal interlock mechanism. A mechanical device which will prevent the main studs from being
disconnected while the circuit breaker is closed.
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