MIL-DTL-17361G(SH)
APPENDIX A
A.3.2.1.5.2 Shunt trip and cut-off switch.
a. For SPD and Cutler-Hammer AQB-A101 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-A101 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-A101 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-A102 Type E1 (assume it will be a Type E1 manufactured after November 04) or
Cutler-Hammer AQB-A103RMS with a 1a, 1b aux switch and shunt trip is needed. The user will see the following
leads exiting the circuit breakers:
AQB-A102 Type E1: 3 leads for the 1a, 1b switch for customer use
3 leads for the shunt trip
AQB-A103RMS:
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 or 6 leads exiting the electronic circuit breakers whereas the
thermal magnetic circuit breakers have 8 leads exiting. As another example, suppose an SPD AQB-A102 Type E1
(manufactured after November 04) or Cutler-Hammer AQB-A103RMS with just a shunt trip is needed. The user
will see the following leads exiting the circuit breaker:
AQB-A102 Type E1: 3 leads for the shunt trip
AQB-A103RMS:
2 leads for the shunt trip
Note that for the same functionality, there are only 2 or 3 leads exiting the electronic circuit breakers whereas the
thermal magnetic circuit breakers have 5 leads exiting.
A.3.2.2 AQB-A100 and AQB-LF100. SPD made these circuit breaker designs obsolete many years ago. They
are not used in a wide range of ship platforms. Cutler-Hammer continues to manufacture these circuit breakers and
they are form, fit, and function replacements for the obsolete SPD designs as long as the trip unit amp ratings are the
same (there are no attachments for either design). The Cutler-Hammer circuit breakers should be used as
replacements only; they are not recommended for use in new construction.
A.3.3 250-amp frame (thermal magnetic and electronic types).
A.3.3.1 SPD.
A.3.3.1.1 Thermal magnetic.
A.3.3.1.1.1 AQB-A250. Note the following:
a. The AQB-A250 is obsolete. Although there is no new production, the stock system or other sources may
still have assets.
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