Caterpillar — Generator Set - Test
Testing & diagnosis
From a Caterpillar owner's manual covering: C3.3, C3.3 Rental Generator Set, C4.4, C4.4 Rental Generator Set, D4D1-Up, GLE1-Up, N3X1-UP, N4R1-Up, N4X1-Up, X3B1-UP, XYC1-Up, XYD1-Up. Check it applies to your exact model before use.
Applies to: Caterpillar C3.3, Caterpillar C4.4
Before you start
- Personal injury or death can result from high voltage
- Make sure the unit is off-line, locked out or tagged DO NOT OPERATE
- Make sure all capacitors are discharged
Procedure
- Stop the generator. Connect the potential transformer's high voltage winding to generator terminals T1 and T2.
- Connect the voltmeter to the low voltage winding. Connect a second transformer to T1 and T3 if available.
- Connect the secondary terminals corresponding to T2 of both transformers together.
- Disconnect wires "E+" and "E-" from the voltage regulator. Disconnect the generator from the load.
- Connect a 12 VDC automotive battery to wires "E+" and "E-".
- Measure AC voltage across low voltage terminals for T1-T2, T2-T3 and T3-T1. Record the voltages.
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Perform the test with the generator set under load
Full service-parts list: Caterpillar C3.3 →, Caterpillar C4.4 →
Source: Caterpillar owner's 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.