Well, if it sounded normal and was not grunting and you didn't have any other abnormal activity, you might replace the thermal or pull the motor and have it tested at a motor shop. When we had the power panel go up it shook the building. When you say it burnt, you are saying physically burnt in two, or it tripped quickly? Also, I think you said that you checked the sizing on the thermals for the voltage change but I can't remember. Was this machine running when you acquired it and it was wired for 208 / 3phase or was it a non-running machine from a barn somewhere? Reason I ask is if the old owner was trying to get it to run on single phase in a barn or garage, he may have stressed the heaters enough that they just couldn't take anymore and failed. I guess I am wondering how immediate the failure was. Three phase motors don't start well when there is a lost phase. They don't run well with a dropped phase either.
