Cause : Motor fan comes when no feedback received from external fan or the cooling fan of the motor, which can lead to overheating and potential damage if not addressed.

The fault code 71B1 in your ABB ACS880 drive indicates a problem with the motor fan. There are two main possibilities:

1. Motor Fan Not Running (Most Likely): This is the most common scenario for the 71B1 fault. It means the drive is not detecting the motor fan operation, which is crucial for proper motor cooling.
2. External Cooling Fan Fault (Less Likely): In some ABB ACS880 models, the 71B1 fault can also signify an issue with an external cooling fan used for the drive itself (not the motor)

Troubleshooting for Motor Fan Not Running:

1. Check external fan (or other equipment controlled) by the logic.
2. Check settings of parameters 35.100…35.106.
3. Check Fan Operation: Physically inspect the motor fan for any visible signs of damage or debris that might hinder its rotation. Try to spin the fan blade manually to see if it moves freely.
4. Verify Fan Connection: Make sure the connection between the motor fan and its power source is secure and free of any corrosion.