Cummins/Onan 1750DQKB — Megger and PI Test
Testing & diagnosis · generator windings
For the Cummins/Onan 1750DQKB, from the Cummins/Onan service manual.
Applies to: Cummins/Onan 1750DQKB, Cummins/Onan DQKB, Cummins/Onan DQKC
Before you start
- Medium-voltage 601-15,000 volts present special hazards; windings must be dry before operation.
Procedure
- Perform the Generator Set Grounding Procedure.
- Remove electronics box cover; remove connector 10 from regulator output module.
- Disconnect AC control input leads (marked 5, 6, 7, 8) from generator output terminals.
- If RTD option installed, ground all six RTD temperature leads (18 leads total).
- Perform the Winding Resistance Test for the desired windings.
- Perform the Insulation Resistance and PI Test for the desired windings.
- If low readings, investigate and correct cause before returning to service; dry windings if moisture is the cause.
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Megger voltage selection per Table 4-1
- PI ratio of 2 or greater considered good
Full service-parts list: Cummins/Onan 1750DQKB →, Cummins/Onan DQKB →, Cummins/Onan DQKC →
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.