So what is maximum actual voltage ?


I tried 378, 388V and 392V.
I also tried 410V and it would only start at 9A and shutdown after 1s.


Could the problem just be that you are exceeding the power limit of the unit? 410V and 9A would be 3690W. Maybe try 410V and 8A?
At 95% eff and 240VAC ...

Still available? Can’t PM yet