Brake Resistor Excess Temperature

What does A793 mean?

The temperature of the brake resistor has exceeded its configured warning limit (parameter 43.12). Continuous operation under this condition will lead to premature failure of the resistor and inability to dissipate regenerative energy, risking DC link overvoltage.

• Brake resistor continuously dissipating energy due to frequent or prolonged braking cycles, exceeding its duty cycle rating.
• Brake resistor rated power (P43.02) or nominal resistance (P43.01) incorrectly set lower than the actual installed resistor or application requirement.
• Inadequate cooling for the brake resistor (e.g., blocked vents, insufficient airflow, ambient temperature too high) preventing proper heat dissipation.
• Drive acceleration/deceleration times (P21.01, P21.02) set too short for the kinetic energy of the load, causing excessive regenerative braking.
• Parameter P43.12 (Brake resistor temperature warning limit) set too low, triggering premature warnings under normal operating conditions.

Click steps to track your progress.

1. 1

   1. Verify the brake resistor's physical installation for proper ventilation and airflow, ensuring no obstructions or excessive dust buildup.

2. 2

   2. Measure the resistance of the brake resistor using an ohmmeter to confirm it matches the nominal value set in P43.01.

3. 3

   3. Confirm the brake resistor's continuous power rating and duty cycle are suitable for the application's braking demands, comparing with P43.02.

4. 4

   4. Increase the deceleration time (P21.02) to reduce the rate of regenerative energy flow into the brake resistor, if the application allows.

5. 5

   5. Monitor the actual brake resistor temperature (if a sensor is present and accessible) and compare it to the warning limit set in P43.12.

6. 6

   6. Consider installing a brake resistor with a higher continuous power rating or a larger heat sink if frequent braking is unavoidable.