I have had this a couple of times on Otis hydros with wye delta contactors . If the contact or welds up only killing the power will save your motor from eventually burning out. Best solution is the soft start , where customers wont go for that I change the fingers inside the contactors ( front and back ) annually .correct me I wrong but if you have good connections on all 3 contacts they shouldn't weld up. I know these days none of us get the time for proper maintenance like back in the day but its a ten minute job that saves hours of headache if you have to replace a motor.
