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ErrorLib — Industrial Fault Code Library

Disclaimer: ErrorLib is an independent technical reference tool. While we aim for accuracy, always verify with the manufacturer’s official service manuals before performing maintenance on industrial equipment. ErrorLib is not affiliated with the brands listed.

12

Brake Chopper Supervision Fault

Vacon · NX Liquid-Cooled Drive

What does 12 mean?

This fault indicates a problem with the brake chopper system. Possible causes include the absence of a brake resistor, a broken or open-circuited brake resistor, or a failure of the brake chopper circuitry itself.

Common Causes

  • Brake chopper resistor disconnected or faulty.
  • Brake chopper output short-circuited.
  • DC bus voltage too high during braking, exceeding chopper limits (P0400).

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    Verify that a brake resistor is correctly installed and connected to the drive terminals.

  2. 2

    Measure the resistance of the brake resistor to ensure it is not broken or open-circuited.

  3. 3

    Inspect the cabling between the drive and the brake resistor for any damage or loose connections.

Browse all codes in this manual (52)
Verified technical data. Last updated: April 2026

Related Faults

1Overcurrent10Input Phase Failure13Undertemperature
Source: Vacon NX Liquid-Cooled Drive
Open Manual (Page 152)Search more codes in this manual