Custom Search
|
|
|
||
 secondary. Figure 1-11(A) offers the least protection due to the slow acting fuses normally used
in this configuration. In the arrangement of Figure 1-11(B), the secondary circuit is
sectionalized and the faulted section can be isolated by the fuses.
The third scheme, shown in Figure 1-11(C), utilizes special transformers designed exclusively
for banked secondary operation. These transformers, known as completely self-protecting
transformers for banking (CSPB), contain in one integral unit the high-voltage protective link
and the two secondary breakers. When excessive current flows in one of the breakers, it will trip
independently of the other. Fault current protection and sectionalizing of secondary banks are
more efficiently accomplished by this method.
1.6 EMERGENCY AND STANDBY POWER SYSTEMS. The principle and practices of
emergency and standby power systems is presented in this section. Mobile equipment and
uninterruptible power supply (UPS) systems are also discussed. Technical information is
included on typical equipment and systems.
1.6.1 Definitions.
1.6.1.1 Emergency Power System. An emergency power system is an independent reserve
source of electric energy. Upon failure or outage of the normal or primary power source, the
system automatically provides reliable electric power within a specified time. The electric power
is provided to critical devices and equipment whose failure to operate satisfactorily would
jeopardize the health and safety of personnel or result in damage to property. The emergency
power system is usually intended to operate for a period of several hours to a few days. See
NAVFAC MO-322 for testing procedures.
1.6.1.2 Standby Power System. An independent reserve source of electric energy which,
upon failure or outage of the normal source, provides electric power of acceptable quality and
quantity so that the user's facilities may continue satisfactory operation. The standby system is
usually intended to operate for periods of a few days to several months, and may augment the
primary power source under mobilization conditions.
1.6.1.3 Uninterruptible Power Supply (UPS). UPS is designed to provide continuous
power and to prevent the occurrence of transients on the power service to loads which cannot
tolerate interruptions and/or transients due to sensitivity or critical operational requirements.
1.6.2 System Description.
1.6.2.1 Emergency Power Systems. Emergency power systems are of two basic types:
(a) An electric power source separate from the prime source of power, operating in
parallel, which maintains power to the critical loads should the prime source fail.
1-17
|
 
|
|
|
||
