Cummins/Onan — Load Sharing Controls Troubleshoot Procedure
Testing & diagnosis
From a Cummins/Onan service manual covering: 1000DFHD-60 / 900DFHD-50, 750DFHA-60 / 620DFHA-50, 800DFHB-60 / 700DFHB-50, 900DFHC-60 / 800DFHC-50. Check it applies to your exact model before use.
Applies to: Cummins/Onan DFHA, Cummins/Onan DFHB, Cummins/Onan DFHC, Cummins/Onan DFHD, Cummins/Onan QST30 engine, Cummins/Onan QST30-G1 engine, Cummins/Onan QST30G2 engine, Cummins/Onan QST30-G3 engine, MTU QST30G3 engine
Procedure
- Measure bus voltage and frequency and generator set voltage and frequency with a true RMS digital meter; calibrate sensing circuits and match bus conditions.
- Check that the load sharing control wiring is properly connected.
- Check that each generator set in the system can carry its rated load.
- Fine adjust KW BALANCE and KVAR BALANCE settings under the paralleling setup menu.
- If sets share load approximately equally but load oscillates between them, reduce the governor gain.
- Consult factory for any other load sharing problems.
Tools required
- True RMS digital meter Amazon
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Load sharing should be within plus or minus 5%
Full service-parts list: Cummins/Onan DFHA →, Cummins/Onan DFHB →, Cummins/Onan DFHC →, Cummins/Onan DFHD →
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.