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. 1

    Check the three-phase input voltage of the amplifier — ensure it is not lower than 85% of the rated input voltage.

  2. 2

    Check the 24V power supply voltage output from the Power Supply — ensure it is not lower than 22.8V.

  3. 3

    Check the connector and cable (CXA2A/B) for proper connection and integrity.

  4. 4

    Replace the Servo Amplifier if voltage and cable checks are satisfactory.

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Verified technical data. Last updated: March 2026
Source: Fanuc Series 30i/31i/32i-MODEL B Plus