Cause : IGBT overtemperature comes when the internal temperature of the IGBT modules has exceeded safe operating limits. This can be caused by several factors such as excessive load, inadequate cooling, or ambient conditions.

The A4A1 warning in your ABB ACS560 drive indicates an IGBT overtemperature warning. IGBTs (Insulated-Gate Bipolar Transistors) are semiconductor devices that play a vital role in controlling power flow to the motor within the VFD. This warning signifies that the IGBTs are experiencing a temperature exceeding the pre-set warning limit.

1. Check ambient conditions.
2. Check air flow and fan operation.
3. Check heatsink fins for dust pick-up.
4. Check motor power against drive power.