MIL-HDBK-1004/5
Section 8:
RELIABILITY AND AVAILABILITY OF 400-HERTZ SYSTEMS
8.1
Requirement. The continuous operation of loads served by the 400-Hz
generation system is essential.
8.2
Discussion. The coupling effect between feeder cables will be
reduced by a factor of two when two generators are operating in parallel. The
effective impedance that couples the transient voltage between feeders comes
from each operating generator's transient reactance and the impedance of each
generator's step-up transformer. When a transient occurs, the change in
voltage at the generator transformer's 4,160-volt side is coupled to all
feeder cables. For one generator in operation, the percent voltage coupling
to feeder cables is less than 4 percent for a 100-ampere load transient. When
two generators are operating, the percent-voltage coupling is less than 2
percent for the same load transient.
8.3
Central Plant Design. Centralized 400-Hz power systems shall be
designed for parallel operation of all generators with automatic startup of
each generator as the load increases enough to demand it. Such operation
provides increased reliability and availability of 400-Hz power over that of a
system which dedicates one generator to a feeder.
8.4
Distribution System Design. Frequent switching of many large power
loads causes transient voltage oscillations. Oscillations must be limited to
MIL-STD-704 requirements. The distribution system must also be designed to
carry each feeder cable's demand load without exceeding steady state
requirements.
80
Previous Page
