ARMY TM 9-6115-604-12
NAVY NAVFC P-8-633-12
2-6. PARALLELING THE GENERATOR SET (UNITS IN PARALLEL).
NOTE
These procedures assume that one generator set Is on-line (connected to the
distribution feeder lines through switchgear). The set that Is to be paralleled shall
be designated the "incoming set"
Refer to Figure 2-16 through Figure 2-19 for parallel operation, and to Figure 2-20 for removing a generator set from
parallel operation
When operated In parallel, generator sets must have the same output voltage, frequency, phase relation, and phase
sequence before they can be connected to a common distribution bus. Severe damage may occur to the generator sets
if these requirements are not met Adjusting engine speed of the Incoming set while observing output frequency, the
SYNCHRONIZING LIGHTS, and the SYNCHROSCOPE will bring the phase and frequency into exact agreement. As
the phase and frequency approach the same value, the SYNCHRONIZING LIGHTS will gradually turn on and off. When
the blinking slows to a rate of once or less per second, close the main circuit breaker of the incoming set while the
SYNCHRONIZING LIGHTS are at a point of being dark and the SYNCHROSCOPE is in the 12 o'clock position. Phase
sequence has to do with the order in which the generator windings are connected If phase sequence Is not correct, the
SYNCHRONIZING LIGHTS will not blink on and off together.
CAUTION
Should either generator set lose speed, "buck", or "shudder" when the
incoming set is connected to the distribution feeder lines, immediately set
BREAKER CONTROL switch of incoming set to TRIP and recheck paralleling
set-up procedures.
When the Incoming set is first connected to the load (through appropriate switchgear) the following may occur if the
phase. sequence, voltage, frequency, phase and engine performance are the same, the changeover will be smooth with
only the slightest hesitation In engine speed, if each output is slightly out of phase, one of the engines will "shudder" at
the point of changeover; if the phase sequence or voltage levels are Incorrect, the reverse power relay will trip on one of
the generator sets and open its main circuit breaker contactors, if the Incoming generator set loses speed significantly or
almost stalls, the Incoming engine governing system may be defective.
2-7. EMERGENCY STOPPING.
a.
To stop the generator set from the control room In an emergency, press the EMERGENCY SHUTDOWN
pushbutton S7 on engine control cabinet C (3, Figure 2-1).
b.
To stop the generator set from outside the housing In an emergency, pull out the EMERGENCY SHUTDOWN
control In the skid base (Figure 1-1)
c.
To stop the generator set from the remote control module In an emergency, press the EMERGENCY SHUTDOWN
pushbutton S7R (17, Figure 2-21)
d.
After stopping generator set In accordance with step a or step c, above reset the two air control valves In
accordance with Figure 3-21.
e.
After stopping generator set In accordance with step b, above, reset EMERGENCY SHUTDOWN control In skid
base (Figure 1-1).
2-31
