MIL-DTL-17587C(SH)
3.4.17.6 Shunt trip device. When specified (see 6.2), a shunt trip device shall be provided. The device shall be
simple and compact and shall have remote control. Devices shall be available for tripping from either an AC or DC
voltage source, and in some instances, both may be required on the same circuit breaker, when specified (see 6.2).
TABLE IV. Voltages for shunt trip devices.
Direct current
Alternating current
Nominal voltage
Operating voltage range
Nominal voltage
Operating voltage range
20S /1
25180
115
80130
120
70140
450
360500
250
175355
NOTE:
/1 For use on circuit breakers to be tripped from variable voltage exciters. Unless otherwise specified (see 6.2),
the tripping current shall not exceed 30 A at the maximum voltage.
3.4.17.7 Auxiliary switches. Auxiliary switches shall have the following characteristics:
a. Unless otherwise specified (see 6.2), circuit breakers shall be provided with an auxiliary switch having the
minimum set of contacts shown in the applicable specification sheet.
b. When the circuit breaker main contacts are closed, auxiliary switch "a" contacts shall be closed and auxiliary
switch "b" contacts shall be open. When the circuit breaker main contacts are open, auxiliary switch "a" contacts
shall be open and auxiliary switch "b" contacts shall be closed.
c. An "a" contact shall be convertible to a "b" contact and a "b" contact shall be convertible to an "a" contact.
d. The auxiliary switch shall be so arranged that the switch cover or complete switch can be removed within
the width of the circuit breaker base.
e. Auxiliary switches shall have a minimum continuous current rating of 15 amps and a rated voltage of 500
volts for AC circuit breakers and 250 volts for DC circuit breakers.
3.4.17.8 Secondary disconnecting devices. Unless otherwise specified (see 6.2), each manually operated circuit
breaker shall be furnished with a secondary disconnecting device consisting of a minimum of seven contacts. Each
electrically operated circuit breaker shall be furnished with a secondary disconnecting device consisting of a
minimum of 21 contacts. Each contact shall consist of a stationary and movable component and each component
shall be provided with a screw-type terminal for fastening of the control wiring. All parts of the circuit breaker
which require connection to external wiring shall be connected to the secondary disconnecting devices of the circuit
breaker. The voltage and current rating of each secondary disconnect contact and its associated wiring for those
applications internal to the circuit breaker shall be adequate to their intended use. Secondary disconnect contacts
that access the circuit breaker auxiliary switches shall have a continuous current rating equal to the auxiliary switch.
3.4.17.9 Hold-closed mechanism. A hold-closed mechanism (see 6.3.7) shall render the trip device and trip-
free mechanism ineffective, thus permitting the circuit breaker to be closed from the open position or be held closed
when in the closed position against an overload as long as the hold-closed device is held in position by the operator.
3.4.17.10 Operations counter. When specified (see 6.2), circuit breakers shall be equipped with a mechanical
device which indicates the number of close open operations. The device may be operated on either the close or
open portion of the cycle. The read-out shall be readably visible from the front of the circuit breaker, but is not
required to be mounted on the escutcheon plate. Failure of the operations counter shall not affect circuit breaker
operation.
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