Brake resistor overtemperature

What does 42 mean?

The brake resistor overtemperature protection has activated, indicating that the brake resistor is dissipating too much energy, likely due to overly heavy or frequent braking cycles. This condition can lead to premature resistor failure or a fire hazard if not addressed.

• Excessive braking frequency or deceleration rates (e.g., P2-02 set too low) causing high regenerative energy.
• Brake resistor sizing insufficient for the application's duty cycle or inertia (e.g., resistor ohmic value too high or power rating too low).
• Faulty brake choppers (e.g., internal transistor shorted or open) causing continuous current flow through the resistor.
• Incorrect brake chopper parameters (e.g., P7-05 (Brake enable), P7-06 (Brake resistor value)) leading to inefficient energy dissipation.
• External thermal protection sensor (if applicable) for the brake resistor being tripped or miscalibrated.

Click steps to track your progress.

1. 1

   Measure the resistance of the external brake resistor at terminals R+/RB to verify it matches the specified ohmic value (e.g., 20 Ohms).

2. 2

   Check the brake resistor's physical temperature and inspect for signs of overheating (e.g., discoloration).

3. 3

   Increase the deceleration ramp time (P2-02) to reduce the rate of energy regeneration.

4. 4

   Reduce the braking duty cycle or implement mechanical braking assist if the process allows.

5. 5

   Verify parameter P7-06 (Brake resistor ohmic value) matches the installed resistor's value.

6. 6

   If the resistor is hot and correct, consider installing a larger power rated brake resistor or an external braking unit.