Brake chopper fault

What does 27 mean?

This warning/alarm indicates a short circuit in the brake IGBT, which disables the brake function. A critical consequence is that substantial power is continuously transmitted to the brake resistor, even if the brake function is inactive, creating a high voltage hazard and risking severe overheating of the resistor. This fault can also be triggered by an overheated brake resistor (using Klixon inputs 104 and 106) or in 12-pulse frequency converters if a disconnect or circuit breaker is opened while the unit is operating.

Complete Troubleshooting Guide

1. 1

   Immediately disconnect all power to the frequency converter to mitigate the risk of high voltage and further damage to the brake resistor.

2. 2

   Physically remove the brake resistor to prevent it from being continuously energized by the short-circuited IGBT.

3. 3

   Inspect the brake IGBT for visual signs of damage or short-circuiting; a qualified technician should diagnose and replace the power card or entire drive if the IGBT is faulty.

4. 4

   Check the brake resistor's thermal protection (Klixon inputs 104 and 106) for proper functionality and signs of previous overheating.

5. 5

   For 12-pulse systems, ensure that main disconnects or circuit breakers are never opened while the frequency converter is powered on.