Ballast switch energized for too long PMx

KPS Ballast Switch Overload During Operation

Kuka · KR C2 Robot Controller

What does Ballast switch energized for too long PMx mean?

The brake resistor experienced an I²t overload during operation. This indicates that the ballast switch was energized for an excessive duration. Possible causes include a defective or incorrectly connected ballast resistor, or deceleration phases in the robot program that are too long.

Common Causes

  • Ballast switch in KPS remains energized for too long during normal operation.
  • Faulty ballast switch not de-energizing correctly.
  • Control signal for the ballast switch is stuck 'on'.
  • Overcurrent condition detected through the ballast switch.

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    Check the ballast resistor for defects, including open circuits or incorrect resistance values.

  2. 2

    Verify the correct wiring and connection of the ballast resistor to the KPS module.

  3. 3

    Review the robot program for excessively long or frequent deceleration phases and adjust if necessary.

  4. 4

    Consider implementing an energy recovery unit to manage regenerative energy and reduce stress on the ballast resistor.

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Verified technical data. Last updated: March 2026

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