MIL-DTL-17361G(SH)
APPENDIX A
c. From now on, this appendix will use "Cutler-Hammer" as the manufacturer designation for both Cutler-
Hammer and Westinghouse circuit breakers since the same information applies.
A.3. DETAILED INFORMATION BY FRAME SIZE
This section provides users with detailed information for each AQB/NQB circuit breaker frame size as it relates
to obsolescence. It is not meant to be complete. Additional information can be found by consulting the
specification sheets of MIL-DTL-17361, vendor catalogs, websites, or by contacting the vendors directly.
A.3.1 50-amp frame. This frame size has been available from vendors as a thermal magnetic design only.
There has never been an electronic version.
A.3.1.1 SPD AQB-A50. Note the following:
a. The AQB-A50 is obsolete. Although there is no new production, the stock system and other sources may
still have assets.
b.
It was available in separate 60Hz AC, 400 Hz AC, and 250 VDC ratings.
c. There were no adjustable settings available. The circuit breaker was delivered with the trip unit amp rating
specified by the user.
d.
Attachments were not available.
A.3.1.2 Cutler-Hammer AQB-A50 and AQB-A51. Note the following:
a. Cutler-Hammer continues to manufacture the AQB-A50. It is available in separate 60 Hz and 400 Hz AC
ratings; there are no DC ratings.
b. Cutler-Hammer continues to manufacture the AQB-A51. It is available in 60 Hz AC ratings; there are no
DC or 400 Hz AC ratings.
c. The AQB-A50 has overcurrent protection in two poles and the AQB-A51 has overcurrent protection in all
three poles.
d. There are no adjustable settings available for either design. Circuit breakers are delivered with the trip unit
rating specified by the user.
e.
Attachments are not available for either design.
A.3.1.3 Form, fit, and function replacement considerations (circuit breakers from same vendor). The Cutler-
Hammer AQB-A51 is a form and fit replacement for the Cutler-Hammer AQB-A50. To make the Cutler-Hammer
AQB-A51 a functional replacement for the Cutler-Hammer AQB-A50 (60 Hz ratings only), the trip unit amp rating
must be the same.
A.3.1.4 Form, fit, and function replacement considerations (circuit breakers from different vendors). Note the
following:
a. The Cutler-Hammer AQB-A50 is a form and fit replacement for the SPD AQB-A50. To make the Cutler-
Hammer AQB-A50 a functional replacement for the SPD AQB-A50 (60 Hz and 400 Hz AC ratings only), the trip
unit amp rating must be the same.
b. The Cutler-Hammer AQB-A51 is a form, fit, and function replacement for the SPD AQB-A50. To make
the Cutler-Hammer AQB-A51 a functional replacement for the SPD AQB-A50 (60 Hz ratings only), the trip unit
amp rating must be the same.
A.3.2 100-amp frame.
A.3.2.1 AQB-A101 thermal magnetic and electronic counterparts.
A.3.2.1.1 SPD.
A.3.2.1.1.1 AQB-A101 (thermal magnetic). Note the following:
a. The AQB-A101 is obsolete. Although there is no new production, the stock system or other sources may
still have assets.
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