Kohler — Frequency Adjustment Procedure
Adjustments · Governor system
From a Kohler service manual covering: 12RES, 8.5/12 RES, 8.5RES. Check it applies to your exact model before use.
Applies to: Kohler 12RES, Kohler 8.5RES, Kohler CH20 engine, Kohler CH 740 engine
Before you start
- Hazardous voltage. Operate the generator set only when all guards and electrical enclosures are in place.
Procedure
- Open the generator set line circuit breaker.
- Attach a frequency meter to the AC output leads.
- Start and run the generator set until normal operating temperature (at least 10 minutes).
- Use the ADC controller to adjust the electronic governor speed (parameter 4P) for 60 Hz (or 50 Hz).
- Check stability with no load; decrease gain (parameter 5P) until stable if speed hunts or surges.
- Repeat steps 4 and 5 to obtain rated frequency and stable operation.
- Save the settings.
- Apply rated load and observe frequency; no load and full load frequencies should be within 0.4 Hz of rated.
- Check for hunting and surging at full load; increase gain until engine hunts, then decrease in small steps.
- Remove the load and observe frequency; repeat step 4 if frequency changed.
Tools required
- frequency meter Amazon
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- 60 Hz units operate at 3600 rpm; 50 Hz units run at 3000 rpm
- No load and full load frequencies within 0.4 Hz of rated
Full service-parts list: Kohler 12RES →, Kohler 8.5RES →
Source: Kohler service manual. Steps and values are as documented; always cross-check against the official manual and any later revisions for your exact serial number before servicing.