MIL-DTL-17361G(SH)
APPENDIX A
A.3.3.5.2.3 Form, fit, and function replacement considerations. Note the following:
a. SPD motor operators are interchangeable between SPD thermal magnetic and standard electronic circuit
breakers. For example, the 115VAC, 60Hz/120VDC motor operator used with an SPD AQB-A250 is the same
115VAC, 60Hz/120VDC motor operator used with a standard SPD AQB-A252.
b. The 1996 change to the SPD cannon plug connector can cause form and fit problems in the field. For
example, suppose a ship has an SPD AQB-A250 with 115VAC/60Hz/120VDC motor operator installed and the
motor operator fails. The replacement motor operator is one made after 1996. There will be an interface problem
between the existing switchboard wiring and the motor operator cannon plug. NAVSEA is working with SPD to
resolve this issue but in the meantime, users should be aware that rewiring or modification of the switchboard wiring
may be necessary to interface properly with the motor operator cannon plug.
c. An SPD AQB-A250 motor operator is not interchangeable with a Cutler-Hammer AQB-A250 motor
operator.
A.3.4 400-amp frame (thermal magnetic and electronic counterparts).
A.3.4.1 SPD.
A.3.4.1.1 Thermal magnetic.
A.3.4.1.1.1 AQB-A400. Note the following:
a. The AQB-A400 is obsolete. Although there is no new production, the stock system or other sources may
still have assets.
b.
It was available in dual-ratings (60 Hz AC and 250 VDC) and separate 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.3.4.1.1.2 AQB-LF400. Note the following:
a. The AQB-LF400 is obsolete. Although there is no new production, the stock system or other sources may
still have assets.
b.
It was available in 60 Hz AC ratings only.
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.
e.
The fuse unit plugged directly into the circuit breaker.
A.3.4.1.2 Electronic.
A.3.4.1.2.1 AQB-A402. Note the following:
a. The AQB-A402 is currently available in two different designs. One design has rating plugs to establish the
CCS while the other design has an adjustable dial on the front of the circuit breaker to establish CCS.
b. The rating plug design is available in separate 60 Hz and 400 Hz AC ratings; the CCS dial design has a
switch on the front of the circuit breaker to select 60 Hz or 400 Hz frequency. There are no DC ratings for either
design.
c. Both designs have 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-17361/8 for complete
details on available settings.
d.
Both designs are available in an "enhanced" version that includes communications capability.
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