Delta · MS300Fault Code GFFCritical
Delta MS300 — GFF Ground Fault
Raised when leakage current to ground is detected on the output. Motor/cable insulation breakdown is the main cause.
Updated: 2026-07-05
Symptoms
- GFF trip on start
- Frequent with damp/old motors
- Tends to occur with long cables
Probable Causes
- Motor winding insulation breakdown
- Ground leakage in the motor cable
- Moisture/contamination
Checkpoints
- Disconnect the motor; megger phase-to-ground
- Measure the motor cable separately
- Check for moisture/dirt in terminals and junction box
Solution
A ground fault is an electrical-safety risk. Do not restart the drive before replacing the motor/cable with failed insulation.
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