Generac GT-990 — Testing All Stator Windings To Ground
Testing & diagnosis
For the Generac GT-990, from the Generac service manual.
Applies to: Generac GT-990 engine
Before you start
- Disconnect and isolate all leads of the winding to be tested before measuring insulation resistance.
- Do not apply voltage longer than one (1) second.
Procedure
- Disconnect stator output leads 11 and 44 from the generator main line circuit breaker.
- Remove stator output leads 22 and 33 from the neutral connection and separate the two leads.
- Disconnect Wires 11 and 22 from the voltage regulator and ensure they are not touching other components.
- Connect the terminal ends of Wires 11, 22, 33 and 44 together, not touching any part of the frame.
- Connect the red Hi-Pot test probe to the joined stator leads; connect the black lead to a clean frame ground.
- Set the tester voltage selector to 1500 volts, turn the tester ON and observe the breakdown lamp. Do not apply voltage longer than 1 second.
- If the breakdown lamp comes on, clean and dry the stator, then repeat the test.
- If the stator fails the second test, replace the stator assembly.
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Source: Generac 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.