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5
mode selector switch to AUTO position for automatic
regulation.
4. Start the generator set and bring up to rated speed.
5. Verify generator voltage. Any of the following
conditions may occur:
a) Overvoltage — If this condition occurs adjust the
auto voltage adjust rheostat as described in para-
graph A, Voltage Adjustment. If condition persists,
stop the prime mover and determine cause of mal-
functions.
b) Undervoltage — If condition occurs adjust the
auto voltage adjust rheostat as described in para-
graph A, Voltage Adjustment. If condition persists,
stop the prime mover and determine cause of mal-
function.
c) No voltage buildup — If this condition exists and
an auto/manual switch is incorporated, stop the prime
mover, set auto/manual switch to manual position,
start generator set and see if voltage builds up.
NOTE: Alternative methods of testing to isolate faulty
operation and a troubleshooting chart are given in
Chapter 4.
d) Oscillating Voltage (Hunting) — If this condition
exists adjust stability control as described in para-
graph C, Stability Adjustment R7. If problem persists,
refer to troubleshooting procedures. Voltage hunting
can be caused by an unstable prime mover .
e) Voltage Unstable or Slow Response — Adjust
Stability Adjust R7 as described in paragraph C.
6. Turn auto voltage adjust rheostat to obtain desired
voltage.
7. The voltage regulator is now ready for load test.
8. Close output circuit breaker and apply load to
generator.
9. Verify that the voltage regulation is within + or - 1%.
If it is not within these limits, refer to troubleshooting
procedures.
10. Alternately remove and apply load to determine
whether the generator voltage is stable and response
is satisfactory.
11. If the generator voltage becomes unstable or
response is slow, adjust stability adjust R7.
a) Instability may occur when the no-load field re-
quirements of the exciter are near the minimum
working voltage of the regulator.
b) On engine driven or dc motor driven generator
sets, unstable speed governors are frequently the
cause of generator voltage instability. If a stability
problem still exists after performing the procedure as
described in paragraph C, check the governor.
12. After satisfactory initial operation has been
determined, remove load, open output circuit breaker
and stop generator set.
B. General Procedure for Subsequent Operation
of Unit
1. Verify that overvoltage circuitry and field circuit
breakers, when included in generating system, are
not tripped open.
2. In applications where generating system includes
both automatic voltage control and manual voltage
control, set the mode selector switch to AUTO
position.
3. Start generator set and bring up to rated speed.
4. Verify generator voltage. If voltage is not correct
adjust the voltage control rheostat as described in
Voltage Regulating Controls, paragraph A in this
section.
5. Close output circuit breaker or contactor and apply
load.
6. During operation periodically check system meters
to ensure that generator set is operating satisfactorily.
7. Before stopping generator set, remove load and
open output circuit breaker.