Brake resistor overtemperature
Vacon · NX Liquid-Cooled Drive
What does 42 mean?
Overtemperature has been detected in the brake resistor. Subcodes S1-S5 (BCU related) specify the issue: S1 (Internal brake chopper overtemp), S2 (Brake resistance too high), S3 (Brake resistance too low), S4 (Brake resistance not detected), or S5 (Brake resistance leakage/earth fault).
Common Causes
- Brake resistor temperature exceeding its limit.
- Brake resistor failure or short circuit.
- Excessive regenerative braking causing resistor overheat.
- Resistor temperature sensor fault (P1-21).
Repair Steps & Checklist
Click steps to track your progress.
- 1
Reset the unit to clear the fault.
- 2
Increase the deceleration time setting to a longer duration to reduce the amount of braking energy dissipated.
- 3
Verify the dimensioning of the brake chopper and external brake resistor for the application's braking requirements.
- 4
If an internal brake chopper overtemperature (S1) is the cause, consider implementing or replacing with an external brake resistor system.