4.2.2.1 Surface ship electrical power. Mission critical equipment shall
remain fully operational through momentary power interruptions of 100
milliseconds or less, operate through line voltage variations of plus 35
percent to minus 20 percent, limit line current harmonics to 3 percent of the
fundamental, be suitable for continuous operation from 50 to 67 hertz (Hz),
and shall immediately (within 1 second) restart following short term power
interruptions of less than 5 minutes duration. Computers that require longer
than 1 second to "re-boot" shall be modified to retain volatile memory during
short term power interruptions. To meet this requirement, commercially
available battery backup cards can be used that plug into expansion slots.
High power transmitters shall inhibit pulses but otherwise remain fully
operational until external power has been restored. The above requirements are
to provide for continued combat capability under the casualty and emergency
conditions expected to be encountered aboard ship.
4.2.2.1.1 Navy Standard Electronic Power System. To achieve the foregoing
requirements, the Navy Standard Electronic Power System (described in
Appendix
A) may be implemented. Implementation may be either completely
internal to the equipment or as a stand alone unit supplying a group of low
powered, functionally compatible equipment.
4.2.2.1.2 Circuit breaker protection. The circuit breaker protection for the
equipment, and the interface to the electrical power system, shall coordinated
to ensure that the circuit breaker closest to the cause of an overcurrent or
fault current condition will trip first. This requirement is to prevent
inadvertent shutdown of adjacent equipment connected to a common source.
4.2.2.2 Advanced electrical distribution systems. New combat systems, for
example, high energy weapons, will put a strain upon electrical power resources
and impose significant transients on the electrical system. Specifications for
new electronic equipment shall incorporate the anticipated electrical system
characteristics and isolate the equipment as much as possible, for example,
through the use of the Navy Standard Electronic Power System.
