22.214.171.124 Environmental stress screening. Requirements
for environmental stress screening (ESS) shall be tailored from
126.96.36.199 Electrical power. The equipment shall operate from electrical
power sources as specified herein.
188.8.131.52.1 Electrical power input connections. The
input power connector pin assignments and conductor color code shall be as
specified in Table VI.
184.108.40.206.2 Color code. The color code for
conductors shall be maintained from the input power connections to all
components having the same voltage and frequency as the input power.
220.127.116.11 Electrical equipment protection. Electrical equipment shall
employ electrical protection as specified herein.
interlocks. The number of personnel safety, maintenance, and equipment
protective interlocks shall be kept to a minimum. Safety interlocks shall be
provided where personnel could be exposed to circuits powered by greater than
30V rms or 30 Vdc during operations or maintenance actions. As an alternative
to safety interlocks, protective shields may be applied. These shields shall
be hinged to prevent removal, shall be such that they can only be opened using
tools, and shall be labeled as being a protective shield. Interlock circuits
shall be provided to protect against catastrophic failure of the equipment.
Particular care shall be taken in the specification of interlocks, especially
coolant flow and coolant level sensors, to preclude equipment shutdown caused
by transients of momentary duration.
18.104.22.168.2 Battery systems.
Battery charging systems shall be provided with built-in protection to prevent
damage to batteries due to overcharge or thermal runaway. SHARP Standard
Battery Systems shall be used when possible. The NWSCC shall be consulted for
the method of battery charging.
22.214.171.124.3 Dielectric withstanding
voltage. The equipment shall prevent electrical breakdown such as corona
(defined in ASTM D 1868), flash-over (surface discharge), spark-over (air
discharge) or breakdown (puncture discharge) when the electrical power
circuits are subjected to the dielectric test voltages shown in Table VII for
1 minute at 60 Hz.
126.96.36.199.4 Insulation resistance. Insulation
resistance of the equipment shall be not less than 10 megohms at specified
environmental service conditions, measured at 500 Vdc. Each circuit shall be
measured against all other circuits connected together and to the chassis.
188.8.131.52.5 Clearance and leakage distances. Clearances between solder
connections or bare conductors, such as on terminal strips, stand-offs, or
similar connections shall be so that no accidental contact can occur between
adjacent connections when subjected to service conditions of the equipment
specification. Particular attention shall be paid to case deflection due to
shock. Spacing requirements for electrical clearance and leakage distances
shall be tailored from articles 384 and 710 of NFPA 70.
Electrical overcurrent protection. The use of circuit breakers in combat
system equipment shall be minimized. Circuit breakers shall be coordinated so
that the circuit breaker closest to a fault will trip before other circuit
breakers trip. Multi-phase circuit breakers shall disconnect all phases when
an overload occurs in any one phase. Protective devices shall not be installed
in the neutral unless neutral power sensing is essential to proper operation
of the equipment and the overcurrent protective device simultaneously opens
all conductors of the circuit and is designed so that no pole can operate
independently. When electrical overcurrent protection devices are used
internally, the status (that is, open or closed) shall be displayed on the
operating panel and the restoration of the device can be controlled from the
front panel. Circuit breakers used in shipboard equipment shall be in
accordance with DESC 87060 through 87062, and shall be mounted in the
184.108.40.206.6.1 Fuses and circuit breakers.
Fuseholders shall provide blown fuse indication. All fuses and circuit
breakers shall be readily accessible from the front panel without removal of
any panels. A minimum of two spare fuses shall be provided for each fuse used
(that is, four fuses for each pair of fuses), mounted adjacent to the fuse
holder for which it is intended. When fuses are used, they shall be
electrically located on the load side of the on-off switch. If extractor post
type fuse holders are used, they shall be connected so that the load is
connected to the fuse terminal which terminates in the removable cap assembly.
220.127.116.11 Main power on-off. The main power on-off switch located on the
equipment shall de-energize the equipment. The switch shall open all
conductors except the safety ground. The main power on-off switch shall be
clearly labeled as such. A green lamp shall be mounted on or near the
equipment to indicate when the equipment is energized. The lamp shall be
connected to the load side of the switch. Unless specifically needed for
overload protection, circuit breakers shall not be used for turning equipment
on and off.
18.104.22.168 Equipment capacitance and EMI filters. Where EMI
filters are required, line-to-line filters are preferred to line-to-ground
filters (see 22.214.171.124.1).
AC line-to-ground capacitance shall be in accordance with MIL-STD-1399, section
300 and MIL-STD-461. Line-to-ground capacitance of dc input power lines
shall be in accordance with MIL-STD-1399, section 390.