Cummins/Onan — Adjusting Reactive Droop Compensation
Adjustments · Voltage regulator droop trimmer
From a Cummins/Onan service manual — check it applies to your exact model before use.
Applies to: Cummins/Onan MDDC, John Deere 4045TFM engine, John Deere 6068TFM engine
Procedure
- Check for correct droop CT connections and polarity, especially if the generator has been reconnected.
- Adjust voltage in accordance with the preceding procedure.
- Push the SINGLE (PARALLEL) operation switch down to PARALLEL.
- Start the generator set and connect at least 1/2 rated load.
- Measure voltage at the voltage regulator terminals to which the droop CT leads are connected; expect less than 5 VAC.
- Multiply the reciprocal of the measured voltage by 100 to get percentage of full rotation required of the droop trimmer.
- Turn the voltage droop trimmer fully counterclockwise to zero, then clockwise the approximate percentage of full rotation.
Specs & values
- You may expect less than 5 VAC at the droop CT terminals.
- Example: (1 divided by 1.4) times 100 = 71 percent of full rotation.
Full service-parts list: Cummins/Onan MDDC →, John Deere 4045TFM engine →
Source: Cummins/Onan 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.