MIL-HDBK-1003/11
permissible interruption may be as long as 4 hours; for others it is only a
few seconds.
2.3.2.3 Uninterruptible (No-Break) Power Supplies. Uninterruptible Power
Supply (UPS) systems are required for certain electronic equipment and for
other equipment performing critical functions which cannot tolerate any
power interruption. An UPS system provides continuous disturbance-free
(regulated) electric power and contains a battery bank which
"floats-on-the-line." Standby/emergency diesel-electric generators are
provided to backup such systems, since battery installations normally are
sized to supply power for not more than 15 minutes.
2.3.3 Electrical Loads. Facility electrical loads, defined in NAVFAC
DM-4.01, are categorized for each electrical source.
2.3.3.1 Primary Load. The primary load, which includes the critical load,
is the peak electrical demand under peacetime conditions.
2.3.3.2 Minimum Essential Operating Load. This constitutes the minimum
electric load necessary to support absolutely essential operations.
Illumination is reduced to the bare minimum; all convenience and other loads
are suspended. Refer to NAVFAC DM-4.01 and to the National Fire Protection
Association, Inc,. (NFPA) No. 70 National Electrical Code (NEC); Articles
517, Health Care Facilities, 700, Emergency Systems and 701, Legally
Required Standby Systems for specific criteria and guidance in determining
this load.
2.3.3.3 Vital Operation Loads. Vital operations are defined as those
activities where an outage will cause the loss of the ability to perform
primary missions. The loss of the ability to satisfy these loads could
result in disastrous situations or in extreme safety hazards as compared to
minor disruptions and inconveniences.
2.3.3.4 Critical Loads. The critical electric load is that part of the
electrical load which requires continuous quality electric power. Examples
include facilities such as hospitals, dry docks, shipyards, cold-iron
support, and those facilities with computers or electronic equipment, as
found in data processing and communications centers.
2.4
Planning Considerations.
2.4.1 Methods of Satisfying Electric Loads. The following alternate
methods of satisfying electric load demands should be considered:
a)
rehabilitation of existing equipment,
b)
replacement of existing installations,
c)
new installations,
d)
consolidation of electric generating installations,
e)
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