Cause : Damping Resistor Overheat comes when the temperature of the built-in damping resistor exceeded the set value. The capacity of the power supply is too small. The distortion in the power supply is too large.

1. Increase the capacity of the power supply. 
2. Lower the impedance of the input power supply wiring.
3. A phase loss occurred in the input power supply.
4. Check the input power supply for phase loss or an imbalance in the interphase voltages.