MIL-DTL-17361G(SH)
APPENDIX A
a. Cutler-Hammer AQB-LL400 and AQB-L400 450VAC undervoltage releases require an externally
mounted step-down transformer to bring the voltage down to 115VAC.
b. Because of the undervoltage release transformer requirement, it is strongly recommended that Cutler-
Hammer AQB-LL400/L400 circuit breakers undervoltage releases not be used as replacements for obsolete SPD
AQB-LF400 circuit breakers in applications where a 450VAC undervoltage release is required.
A.3.5 800-amp frame (SPD thermal magnetic and electronic types). Details of SPD circuit breakers are
discussed in this section. At present, Cutler-Hammer only manufactures an NQB-A803; this circuit breaker has no
trip unit and it is not a form and fit replacement for the SPD NQB-A800 or NQB-A802.
A.3.5.1 AQB-A800 (thermal magnetic). Note the following:
a. The AQB-A800 is obsolete. Although there is no new production, the stock system or other sources may
still have assets.
b.
It was available in separate 60 Hz and 400 Hz AC ratings.
c. There were three adjustable instantaneous pickup setting dials under the front cover of the circuit breaker
(one on each pole).
d. The circuit breaker was delivered with the trip unit amp rating specified by the user. The trip unit was not
adjustable but trip units of different amp ratings were available as separate piece parts.
A.3.5.2 AQB-A802 (electronic). Note the following:
a.
The AQB-A802 is available in separate 60 Hz and 400 Hz AC ratings.
b. Rating plugs are used to establish CCS. It has field adjustable settings for instantaneous pickup, short-time
delay pickup, and short-time delay time band. Long-time delay features are fixed on both designs. See MIL-DTL-
17361/12 for complete details on available settings.
A.3.5.3 Form, fit, and function replacement considerations. The SPD AQB-A802 is a form and fit replacement
for the SPD AQB-A800. Attachments (if applicable) and adjustable settings must be taken into consideration to
make them functional equivalents. See A.3.5.4 for attachment information. See A.3.8 and Table A-XVII for
guidance on how to set the SPD AQB-A802 to make it a functional replacement for the SPD AQB-A800.
A.3.5.4 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.3.5.4.1,
A.3.5.4.2, A.3.7, and Table A-IV for more information on attachments.
A.3.5.4.1 Shunt trip and cut-off switch. Note the following:
a. For the AQB-800 thermal magnetic circuit breakers with shunt trips, the vendor supplies 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 AQB-A800 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 AQB-A800 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
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