MIL-DTL-16036M(SH)
3.12 Circuit breakers. Circuit breakers shall conform to MIL-DTL-17587 (for Type ACB), MIL-DTL-17361
(for Types AQB and NQB), and MIL-C-17588 (for Type ALB). Unless otherwise specified (see 6.2), Type ACB
circuit breakers 1600-ampere frame size and larger shall be electrically-operated and circuit breakers 1600-ampere
frame size and smaller may be manually operated. Circuit breakers controlled from an EPCP, EPCC, or by the
synchronizing protective equipment specified in 3.11.5 shall be electrically-operated.
3.12.1 Mounting (AQB and NQB). Types AQB and NQB circuit breakers for switchboard use shall be
equipped with removable contacts on both line- and load-side, connections being made by use of terminal mounting
blocks in accordance with MIL-DTL-17361 for AQB and NQB. When circuit breakers are mounted vertically, the
line-side terminals shall be at the top and the operating handle shall be in the downward position when the breaker is
intentionally open. When interlocks are required for Types AQB and NQB circuit breakers, they shall be mounted
in front of the panel and shall be suitable for use with circuit breakers of any make by no further modification than
possible reassembly of the interlock. Circuit breaker escutcheon shall be centered in its panel cutout on the
switchboard.
3.12.2 Mounting (ACB). Type ACB circuit breakers shall be of a removable assembly construction. Each
circuit breaker shall be supplied as a complete removable switchboard assembly consisting of circuit breaker,
separable disconnects and associated control wiring, circuit breaker drawout mechanism, assembly structural
supports, back plate including stationary main bus connections, and stationary terminal for connection of the
necessary external control wiring. Circuit breaker stationary assembly shall be secured to the vertical member or the
horizontal structural member or both.
3.13 Switches, disconnecting devices, and transfer switches. Control and instrument switches shall be in
accordance with MIL-S-18396. For applications below 125 volts, style JR switches as specified in MIL-DTL-21604
and MIL-DTL-21604/5 may be used. Control and instrument switches shall have gray or natural light tan
escutcheon plates with black lettering. Switches shall be provided with four styles of handles to identify the function
for which the switch is provided. The handle styles and corresponding function shall be as follows:
a.
Round
-
governor control (spring return).
b.
Oval
-
synchronizing and voltage regulator, synchronizing monitor, and field flashing.
c.
Round (knurled) -
instruments (voltmeter, ammeter, frequency meter, temperature indicator).
-
test (emergency switchboard, spring return).
d.
Pistol-grip
-
circuit breaker and ground lamps (spring control).
-
control bus selector.
Control switches installed within the enclosure (such as relay defeater switches) shall be sufficiently close to the
access opening to minimize personnel exposure to energized components.
3.13.1 Disconnecting devices. Disconnecting devices and associated tools for performing power disconnecting
functions shall conform to MS17831. With full rated current through the disconnect devices, the maximum
temperature rise of the devices shall not exceed 122 °F (50 °C). Disconnect devices shall be mounted inside the
switchboard and shall be readily accessible after removal of the rear enclosure. Tools conforming to MS17832 (if
required) for operation of the devices shall be mounted outside of the switchboard enclosure adjacent to the panel
that must be removed for operation of the device. A warning plate shall be provided near the disconnect device to
read: "DO NOT OPERATE WHEN ENERGIZED". The plate shall be constructed in accordance with the
requirements of 3.20 with letters no less than 3/16 inch.
3.14 Fuses and terminal boards. Fuses shall be in accordance with MIL-PRF-15160. Fuses for 450-volt
applications shall be Characteristic C of MIL-PRF-15160. Fuses and fuseholders shall be silver plated in accordance
with MIL-PRF-15160. Fuseholders shall be dead-front type with blown fuse indicator in accordance with
MIL-PRF-19207.
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