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Paralleling Procedures | Up
Construction Electrician Basic - Electricity handbook for electricians | Next
Stopping Generator Set Operation, Continued |
5. Start the incoming set. The on-line set should
be in operation already.
6. After a 5-minute warmup, try the VOLTAGE
ADJUST control on the incoming set until the output
voltages of both sets are equal.
CAUTION
If the synchronizing lights do not blink on
and off in unison, the phase sequence is
incorrect.
Shut down the incoming set and
recheck the cabling to and from the incoming
set.
7. On the incoming set, position the ENGINE
M A N U A L S P E E D C O N T R O L u n t i l t h e
SYNCHRONIZING LIGHTS blink on and off as
slowly as possible.
8. With one hand on the CKT BRK switch, adjust
the ENGINE MANUAL SPEED CONTROL vernier
knob until the SYNCHRONIZING LIGHTS dim
gradually from full on to full off as slowly as possible.
Just as the SYNCHRONIZING LIGHTS dim to out, set
and hold the CKT BRK switch to close. When the CKT
BRK indicator light comes on, release the switch.
9. On both sets, check that the readings of the
PERCENT RATED CURRENT meters and
KILOWATTS meters are well within 20 percent of
each other. If not, increase the engine power of the set
with the lower readings (by adjusting the ENGINE
MANUAL SPEED CONTROL to increase the speed)
until the readings are about equal.
NOTE: The division of the kilowatt load is also
dependent on the frequency droop of the two sets and
must be adjusted at the next higher level of
maintenance. If the current does not divide as described
above, adjust the reactive current-sharing control
located at the right side of the special relay box for equal
reading on both percent rated current meters.
10. On the incoming set, readjust the voltage and
frequency of the output until it is equal to the output of
the on-line set.
Removing a Generator Set from Parallel
Operation
Refer to figure 3-19 while following the procedure
for removing a generator set from parallel operation.
3-26
CAUTION
Before removing the generator set(s) from
parallel operation, make sure the load does not
exceed the full-load rating of the generator
set(s) remaining on the line.
1. On the outgoing set, position and hold the CKT
BRK switch to OPEN until the CKT BRK indicator
light goes out. Release the switch.
2. On the outgoing set, allow the engine to operate
with no load for about 5 minutes.
3. On the outgoing set, pull the DC CONTROL
CIRCUIT BREAKER to OFF.
4. On the outgoing set, set the START-STOP-
RUN switch to STOP.
WARNING
Make certain the outgoing set is shut down
and there are no voltages at the switchgear
terminals connected to the outgoing set. Do not
take anybody’s word for it! Check it out for
yourself!
5. Disconnect the cables going from the outgoing
set to the load switchgear.
Stopping Generator Set Operation
Refer to figure 3-19 as you study this section.
1. Set the CKT BRK switch to OPEN until the
CKT BRK indicator light goes out, then release the
CKT BRK switch.
2. Allow the engine to cool down by operating at
no load for 5 minutes.
3. Set the START-STOP-RUN switch to STOP.
4. Close all generator doors.
MAINTENANCE
There are actually three major categories (or levels)
of maintenance. The three categories are (1) depot,
(2) intermediate, and (3) organizational. In depot or
intermediate maintenance, equipment is restored to
like-new condition or subjected to some degree to
detailed repairs. Under the organizational category,
generator maintenance may consist of inspection,
testing, adjustment, and so forth, and then perhaps
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