3 phase Chinese diesel genset issue

Hi I have a 3 phase Chinese diesel genset I run my mills and hoist off it normally I lent it out and it was used to run a heavy duty plasma cutter , :~ result wasn't good apparently it was running fine the cutter went off along with power from genset , can anyone advise if the avr could be the issue and is there a test ? Genset starts and runs fine just not generating ?

Thanks in advance