2
Inverter Control Power Supply Undervoltage
Fanuc · Series 30i/31i/32i-MODEL B Plus
What does 2 mean?
This alarm indicates an undervoltage condition in the control power supply of the Inverter (Servo Amplifier). This can be caused by low three-phase input voltage, insufficient 24V power supply from the Power Supply, or issues with the CXA2A/B connector and cable.
Common Causes
- Three-phase input voltage of the amplifier lower than 85% of its rated input voltage.
- 24V power supply voltage output from the Power Supply lower than 22.8V.
- Faulty connector or cable (CXA2A/B).
Repair Steps
- 1
Check the three-phase input voltage of the amplifier — ensure it is not lower than 85% of the rated input voltage.
- 2
Check the 24V power supply voltage output from the Power Supply — ensure it is not lower than 22.8V.
- 3
Check the connector and cable (CXA2A/B) for proper connection and integrity.
- 4
Replace the Servo Amplifier if voltage and cable checks are satisfactory.
Verified technical data. Last updated: March 2026
Source: Fanuc Series 30i/31i/32i-MODEL B Plus