MIL-DTL-17361G(SH)
APPENDIX A
A.3.3.5 Attachments. Attachments include motor operators, undervoltage releases, shunt trips, and auxiliary
switches. Important aspects of attachments are ratings and number and type of leads or connectors exiting the
circuit breaker. These aspects can differ depending on which type of circuit breaker is involved. See A.3.3.5.1,
A.3.3.5.2, A.3.7, and Table A-II for more information on attachments/leads.
A.3.3.5.1 Shunt trip and cut-off switch. Note the following:
a. For SPD and Cutler-Hammer AQB-A250/AQB-LF250 thermal magnetic circuit breakers with shunt trips,
the vendors supply leads for an additional 1a, 1b aux switch where the "a" contact is used as the shunt trip cut-off
switch. The remaining "b" contact on this switch is not used in most cases; it is usually tied off when the circuit
breaker is installed in the switchboard. As an example, suppose an SPD or Cutler-Hammer AQB-A250 with a 1a,
1b aux switch and shunt trip is needed. The user will see the following leads exiting the circuit breaker:
3 leads for the 1a, 1b switch for customer use
3 leads for the additional 1a, 1b aux switch ("a" contact used for shunt trip cut-off switch and "b" contact tied
off and not used)
2 leads for the shunt trip
As another example, suppose an SPD or Cutler-Hammer AQB-A250 with just a shunt trip is needed. The user will
see the following leads exiting the circuit breaker:
3 leads for the additional 1a, 1b aux switch ("a" contact used for shunt trip cut-off switch and "b" contact tied
off and not used)
2 leads for the shunt trip
b. For SPD and Cutler-Hammer electronic circuit breakers with shunt trips, there are no external leads for a
1a, 1b auxiliary switch where the "a" contact is used as a cut-off switch as there are for the thermal magnetic circuit
breakers. The cut-off switch for the electronic circuit breakers is wired internally. As a comparison to the examples
above, suppose an SPD AQB-A252 or Cutler-Hammer AQB-A253 with a 1a, 1b aux switch and shunt trip is
needed. The user will see the following leads exiting the circuit breaker:
3 leads for the 1a, 1b switch for customer use
2 leads for the shunt trip
Note that for the same functionality, there are only 5 leads exiting the electronic circuit breakers whereas the thermal
magnetic circuit breakers have 8 leads exiting. As another example, suppose an SPD AQB-A252 or Cutler-Hammer
AQB-A253 with just a shunt trip is needed. The user will see the following leads exiting the circuit breaker:
2 leads for the shunt trip
Note that for the same functionality, there are only 2 leads exiting the electronic circuit breakers whereas the thermal
magnetic circuit breakers have 5 leads exiting.
A.3.3.5.2 Motor operators.
A.3.3.5.2.1 SPD. Note the following:
a. The motor operators for SPD 250 amp circuit breakers use a cannon plug connector as the interface
connection between the motor operator and the switchboard wiring. Individual leads are not provided with the
motor operator.
b.
In 1996, SPD changed the part of the cannon plug that receives wiring from the switchboard.
c. SPD manufactures motor operators for use with standard circuit breaker designs and separate motor
operators for use with "enhanced" circuit breakers (circuit breakers with communications capability).
A.3.3.5.2.2 Cutler-Hammer. Note the following:
a.
Cutler-Hammer provides leads with its 250 amp circuit breaker motor operators.
b. One type of motor operator is rated for 450VAC/115VAC with an externally mounted step-down
transformer.
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