Cause : Electronic thermal relay function pre-alarm comes when the cumulative value of the electronic thermal O/L relay reaches or exceeds 85% of the preset level of Pr.9 Electronic thermal O/L relay. If the specified value is reached, the protection circuit is activated to shut off the inverter output.

1. Check for large load or sudden acceleration.
2. Check that the Pr.9 setting is appropriate.
3. Reduce the load and frequency of operation.
4. Set an appropriate value in Pr.9.