Frequency Adjustment - Kohler 8.5RES Service

6.9.5

Frequency Adjustment

The engine speed determines the generator output
frequency; 60 Hz units operate at 3600 rpm and 50 Hz
units run at 3000 rpm. Adjust the engine governor to
change the output frequency using the following
procedure.
Note: Engine governor speed (frequency) and gain
adjustments are made using the ADC controller.
See Section 4.5.3 for instructions.
Frequency Adjustment Procedure
1. Open the generator set line circuit breaker.
2. Attach a frequency meter to the AC output leads.
3. Start and run the generator set until it reaches
normal operating temperature (at least 10 minutes).
4. Use the ADC controller to adjust the electronic
governor speed (parameter 4P) to obtain a
frequency reading of 60 Hz (or 50 Hz on 50 Hz
models). See Section NO TAG.
Note: Often hunting/surging problems thought to
be caused by the governor are actually
caused by engine or carburetor problems. If
the generator set speed is unstable, hunts,
or surges, check for the cause using the
procedure
proceeding.
5. Check stability with the generator set running and
with no load applied. If the generator set speed is
unstable, hunts, or surges, use the ADC controller
to decrease the gain (parameter 5P) until the
generator set becomes stable with no hunting or
surging. Observe the frequency reading.
88 Section 6 Component Testing and Adjustment
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in Section 6.9.3
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6. Repeat steps 4 and 5 to obtain the rated frequency
and stable operation.
7. Save the settings as instructed in Section 4.5.
Note: The controller will revert to the previous
settings at the next startup if the changes are
not saved within one minute after the last
change.
8. Apply rated load to the generator set and observe
the frequency reading. The no load and full load
frequencies should be within 0.4 Hz of the rated
generator frequency; if not, check that the
carburetor throttle plate opens completely without
sticking and check the carburetor adjustment. If
these procedures do not correct the problem,
replace the controller.
9. Check for hunting and surging at full load. Use the
controller to increase the gain (parameter 5P) until
the engine hunts and surges. Then decrease the
gain in small steps using the governor gain fine
adjust parameter until the engine operation
stabilizes. Save the controller changes.
10. Remove the load and observe the frequency. The
frequency should return to the value stated in
step 4. Gain adjustment may affect the generator
set speed/frequency.
changed, repeat step 4.
before
Note: Speed adjustments have no effect on gain
adjustments. It is not necessary to repeat
the gain adjustments after adjusting the
engine speed.
Check the overspeed shutdown operation when
investigating a shutdown problem. See Section 6.11.1
for the overspeed shutdown test procedure.
If the frequency has
TP-6196 10/09