Good day

I have a 20kVA generator conected to a lister engin and a 2.2kw 3phase motor. I asume that the AVR is blown and dont know how to test it? It gives out 400V, but as soon as you start the motor the voltage drops to 300V till the engin cuts out.

The motor is fine, as I did test it with portable generator. I have had issues before with generators hunting and dont think it is that.

Any ideas what and how to resolve this issue?