Cause : Power Supply Undervoltage comes when the input power supply voltage became equal to or lower than the Input Power Supply Undervoltage Detection Level.
200 V Class: Approximately 150 Vac
400 V Class: Approximately 300 Vac

1. The capacity of the power supply is too small.
2. Increase the capacity of the power supply.
3. The distortion in the power supply is too large.
4. Lower the impedance of the input power supply wiring.
5. A phase loss occurred in the input power supply.
6. Check the input power supply for phase loss or an imbalance in the interphase voltages.
7. Investigate and correct the cause and then reset the fault.