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 TM 5-685/NAVFAC MO-912
LOAD
Figure 5-7. AC control circuits with tie circuit breaker.
program that is built around equipment and system
secondaries are connected to the proper control bus
records and visual inspections. The program is de-
through contacts on the synchronizing switch, or
through contacts on certain auxiliary relays. The
scribed in the manufacturer's literature furnished
synchronizing switch would be used for manual op-
with the components. If a problem develops, the
eration and the auxiliary relay would be used when
user should perform general troubleshooting proce-
automatic synchronizing is provided.
dures. The program includes appropriate analysis of
(3) DC control circuits. DC control circuits de-
the records.
rive their power from a battery source consisting of
(1) Record keeping. Equipment and system log
a bank of batteries and a battery charger that main-
sheets are important and necessary functions of
tains the batteries at the proper charge. The battery
record keeping. The log sheets must be specifically
bank can be rated at various levels ranging between
developed to suit individual application (i.e., auxil-
24 volts and 125 volts DC. Those circuits that re-
iary use).
(2) Troublesh oo ting. Perform troubleshooting
quire a source of control power completely indepen-
dent of the power system are connected to the DC
procedures when abnormal operation of the system
control bus. Examples of these are the prime mover
or equipment is observed. Maintenance personnel
starting circuits, and in some cases, the trip circuits
must then refer to records for interpretation and
for the circuit breakers when devices, other than
comparison of performance data (i.e., log sheets).
the direct-acting overcurrent trip devices, are used.
Comparisons of operation should be made under
Also, the closing circuits for the circuit breakers are
equal or closely similar conditions of load and ambi-
sometimes connected to the DC control bus.
ent temperature. The general scheme for trouble-
shooting is outlined in the following paragraphs and
f. Service practices. Service practices for low volt-
troubleshooting table.
age switchgear consist of a complete maintenance
5-7
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