Author - Jerry
Submitted By -One Leg Dead O.H. transformer
I've been a journeyman for 20 years, and a troubleman for 12 years of that 20. I have had this occur on three different occasions. After finding a single phase transformer with one leg of the 120v out, I reset the secondary breaker switch on the transformer. After a time delay of 5 to 10 seconds, there have been violent explosions. One case blew the lid off the transformer, the second one blew a hole in the tank of the transformer between the hangers, and the third one shot fire out from the ring that holds the lid on. There was the warning of, a gurgling and high voltage cracking sound before the explosion. This has been an occurrence over many years so I don't know if they were a certain manufacturer, but they have all been transformers that have been in the air for over 10 years. These transformers have all been completely self protected, with the current limiting fuse in the high side bushing, and the ground connection on the case of the transformer, and the secondary breaker switch that trips on overloads and secondary faults. All I've been doing is full battle gear, and finding a place away from the lid of these cans to check my voltage when I get one of these ONE LEG DEAD.
Jerry