121

LV1-Trip (Low voltage supply undervoltage)

Kuka · KR C2 Robot Controller

What does 121 mean?

This fault indicates an undervoltage condition in the low voltage supply for the KPS-600. This means the control power supply voltage is below the operational threshold, which can affect control unit stability and lead to unexpected shutdowns or erratic behavior.

Repair Steps

  1. 1

    Measure the control voltage supply (e.g., 24VDC) at the designated control input terminals.

  2. 2

    Verify the output voltage of the external control power supply.

  3. 3

    Inspect the control wiring for excessive voltage drop due to long cable runs or undersized wire gauge.

Browse all codes in this manual (54)
Verified technical data. Last updated: March 2026