Cause : External thermal relay operation comes when he inverter trips if the external thermal relay provided for motor overheat protection or the internally mounted thermal relay in the motor, etc. switches ON (contacts open). This function is available when "7" (OH signal) is set in any of Pr.178 to Pr.189 (input terminal function selection). This protective function is not available in the initial status. (OH signal is not assigned.)

1. Check for motor overheating.
2. Check that the value "7" (OH signal) is set correctly to any of Pr.178 to Pr.189 (input terminal function selection).
3. Reduce the load and operation duty.
4. Even if the relay contacts are reset automatically, the inverter will not restart unless it is reset.