Cummins/Onan — Testing Main Stator
Testing & diagnosis
From a Cummins/Onan service manual covering: C30 D6, C33 D5, C35 D6, C38 D5. Check it applies to your exact model before use.
Applies to: Cummins/Onan C30 D6, Cummins/Onan C33 D5, Cummins/Onan C35 D6, Cummins/Onan C38 D5
Procedure
- Measure resistance across each pair of stator leads U1-U2, U5-U6, V1-V2, V5-V6, W1-W2, W5-W6.
- Use Wheatstone bridge or ohmmeter with at least 0.001 ohm precision.
- Replace stator if any winding resistance not as specified in Table 6-1.
- Disconnect AVR completely before insulation test.
- Disconnect Neutral to Earth and any connections.
- Use 500 or 1000 V insulation tester for low voltage generators up to 690V.
- Minimum insulation value is 1.0 Meg-Ohm to Earth; dry windings if below.
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Minimum insulation 1.0 Meg-Ohm to Earth
Full service-parts list: Cummins/Onan C35 D6 →
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.