Caterpillar C15 / C15 Generator Set — Insulation - Test (Recommended Procedure for A Periodic Insulation Test)
Testing & diagnosis · Generator stator winding
For the Caterpillar C15 / C15 Generator Set, from the Caterpillar owner's manual.
Applies to: Caterpillar C15, Caterpillar C1.5 engine
Before you start
- The high voltage that is produced by an operating generator set can cause severe injury or death.
- The megohmmeter is applying a high voltage to the circuit. Do not touch the instrument leads without first discharging them.
Procedure
- Take the generator out of service.
- Visually inspect the generator for moisture. If moisture exists, dry the unit first.
- Discharge the capacitance of the windings.
- Isolate the stator windings by disconnecting all other leads and cables from the generator terminals.
- Connect the insulation tester's RED lead to ground.
- Connect the insulation tester's BLACK lead to the wye point of the generator's windings.
- Set the voltage to 500 Volts for units of 600 volts or less; 1000 Volts for units more than 600 volts.
- Apply voltage and observe readings at 30 seconds and 60 seconds. Record the 60 second reading, temperature and humidity.
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Minimum acceptable insulation resistance 1 megohm for generators below 1000 V.
Full service-parts list: Caterpillar C15 →
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.