charles hanson
New member
- Location
- Devine, Texas , Medina County
I have had occasion in my years as an electrician to run into situations where the utility has lost power on one leg of a three phase supply feeding a delta connected transformer bank with three individual transformers supplying a 120/240 delta 3 phase secondary with a high leg. When this has occurred one of the 120 volt legs was showing upwards of 300 volts and lighting ballasts and control transformers started to burn out causing a lot more problems than just a power outage while the utility supplier replaced a primary fuse. Can anyone explain to me what was happening up on the pole to cause this overvoltage, and how can it be prevented.