F1

Possible Causes

• •Moisture in the winding insulation
• •Generator set not put into service immediately
• •Accumulation of moisture in windings
• •Heat source placed less than 300 mm away from the windings during hot air drying

Suggested Actions

1. 1Dry the insulation using ambient air by disconnecting the cables from the X+ (F1) and XX- (F2) terminals of the AVR, running the generator set in a de-excited state, and operating the anti-condensation heater (if fitted).
2. 2Dry the insulation with hot air by directing hot air from one or two 1 to 3 kW electrical fan heaters into the alternator air inlet, keeping each heat source at least 300 mm away from the windings.
3. 3Ensure the winding temperature does not increase faster than 5 ºC per hour or exceed 90 ºC during drying to prevent damage from water vapor expulsion.
4. 4Dry with ambient air: Disconnect the cables from the X+ (F1) and XX- (F2) terminals of the AVR to remove excitation voltage supply, run the generator set in this de-excited state, ensure free air flow, and operate the anti-condensation heater (if fitted). Re-connect cables after drying.
5. 5Dry with hot air: Direct hot air from one or two 1 to 3 kW electrical fan heaters into the alternator air inlet, ensuring free air flow. Remove heaters and re-commission after drying.
6. 6Turn on the anti-condensation heater (if fitted) and retest the insulation resistance before use if the generator set is not put into service immediately after drying.
7. 7Make sure each heat source (electrical fan heater) is placed at least 300 mm away from the windings during the hot air drying process.

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