Danfoss · VLT FC302Fault Code Alarm 9Warning
Danfoss VLT FC302 — Alarm 9 Inverter Overload
Occurs when the drive's thermal overload curve (above 100%) is exceeded. Sustained high current or wrong sizing is the cause.
Updated: 2026-07-05
Symptoms
- Alarm 9 under sustained high load
- Heats up then trips
- Recurs at the sizing limit
Probable Causes
- Drive undersized for the load
- Sustained overcurrent
- Increased mechanical friction/resistance
Checkpoints
- Log the current profile (par. 16-xx)
- Verify drive-motor-load match
- Check the mechanical system
Solution
If load is continuously at the limit, a larger drive is recommended. For sudden/false trips, the cooling and current-sensing circuits are tested.
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