Regenerative Brake Pre-alarm

What does Regenerative brake pre-alarm mean?

The regenerative brake duty has reached 85% or higher of the Pr. 70 Special regenerative brake duty setting. This warning indicates that the regenerative braking capacity is approaching its limit. If deceleration demands continue to be high without sufficient energy dissipation (e.g., a braking resistor), it could lead to an overvoltage fault.

• Frequent starts and stops or rapid deceleration cycles pushing the regenerative braking capacity (duty cycle) close to its limit.
• Pr. 70 (Special regenerative brake duty) set too low for the application's required braking frequency and duration.
• The connected regenerative braking resistor (if external) is undersized or its resistance has increased due to thermal stress.
• Insufficient cooling for the internal braking transistor or external braking resistor, leading to premature temperature rise.

Click steps to track your progress.

1. 1

   Review the application's braking profile and reduce the frequency or intensity of regenerative braking cycles if possible.

2. 2

   Increase the deceleration time (e.g., Pr. 8) slightly to reduce the peak regenerative energy during each stop.

3. 3

   Verify the resistance of the external regenerative braking resistor (if used) using an ohmmeter and ensure it matches the inverter's specifications.

4. 4

   Consider upsizing the external regenerative braking resistor to one with a higher power rating and/or lower resistance (within inverter limits).

5. 5

   Adjust Pr. 70 (Special regenerative brake duty) to a higher percentage if the current setting is overly conservative for the actual resistor and cycle time.