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 MIL-HDBK-232A
APPENDIX A.
TRANSPORTABLE FACILITIES
10. General. This appendix provides minimum guidance on the installation of
transportable information processing facilities. Although many concepts are
similar to those of fixed installations, there are some unique requirements
for transportable systems. The guidance provided will apply to all
transportable systems requiring RED/BLACK consideration and protection, and
should be complied with except when additional treatment is recommended as a
result of TEMPEST testing. Such additional treatment will be determined by
the cognizant TEMPEST authority on a case-by-case basis. See figure A-1 for
a typical transportable information processing system.
20. Power sources. Power for transportable systems may be provided by
generators, base power, or commercial sources. Unlike base or commercial
power, generators dedicated to one operational system provide adequate
isolation from other systems. However, generators may be used to provide
power for more than one shelter and for various types of equipment and
systems. In this case, the use of isolation devices may be needed. The
recommended method of accomplishing this is to use appropriate filters.
20.1 Three-phase generators. These commonly used generators supply 120/208
Vac 3-phase 4-wire power. A ground terminal is provided on the chassis or
frame of the generator. To ground the neutral conductor and provide the
fault protection subsystem (FPSS), this terminal should be connected to the
earth electrode subsystem (EESS) and the ground terminal of the shelter using
a No. 2 AWG stranded copper wire. The conductor connected to the shelter
should be spirally wrapped around the power cable in the same direction and
with the same spiral spacing as the phase and neutral conductors. When
polyphase equipment is used, it is important to ensure that each phase
conductor is properly terminated at the generator and power panel (see figure
A-2).
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