davidoeser
Member
I work in a plant that has a High Leg Delta electric service, very old plant... we are having several VFD's tripping on bus overvoltage, across two lines. they are both fed from the same substation. when we measured the incoming voltage to the main panel we read 400 volts from each leg to ground with the high leg reading 763 volts. when you read phase to phase it reads 480 vac. last night electricians found condensation at the sub station and switched sides, problem went away, now its back...any ideas?