Hi,
I am a commercial electrician. I have a question about reverse feeding a transformer at medium voltage. We never get into the medium voltage work. 480 volts is about the highest voltage we work with.
I eavesdropped on a discussion the other day while at a code change class. It started getting me thinking and thought I would ask here. A pretty large facility is expanding. They have some sort of distribution equipment, switchgear, something that is running at 12,470. Big stuff in my book. What ever they want to energize does not have final power installed yet. Like I said, I just heard bits and pieces. It kind of caught my attention when I heard about the 12,470. The other interesting thing was the amount of power they needed. It was something like a Meg of power. They were thinking about running two 500 KW gen sets and were looking into seeing about buying a used Xform on E-bay or somewhere until final power could be up and running. They were having a hard time finding a step up Xform, but there were a lot of step down Xforms in the size they wanted. I am sure it must have been Delta ? Delta. I can only imagine they were thinking about just reverse feeding it. I think they were getting 480 Delta from the generators. They were talking very casual about it, but it would have scared me to death. The first thing that came to mind was 110.3. But beyond that, was it even safe to reverse something like that? After thinking about it some more, I realized I don?t know very much about transformers. I understand electrical theory, turn ratio, magnetic induction, all the code issues of feeding transformers, but that is all by the book, but I honestly couldn?t come up with a problem with it. Would it be safe to say that a distribution transformer could be reverse fed in this example and be perfectly safe if fused correctly?? I guess it?s an engineering question, heck maybe I should know the answer, but I thought this forum would be a good place to ask.
I hope I gave enough information to formulate an opinion.
I am a commercial electrician. I have a question about reverse feeding a transformer at medium voltage. We never get into the medium voltage work. 480 volts is about the highest voltage we work with.
I eavesdropped on a discussion the other day while at a code change class. It started getting me thinking and thought I would ask here. A pretty large facility is expanding. They have some sort of distribution equipment, switchgear, something that is running at 12,470. Big stuff in my book. What ever they want to energize does not have final power installed yet. Like I said, I just heard bits and pieces. It kind of caught my attention when I heard about the 12,470. The other interesting thing was the amount of power they needed. It was something like a Meg of power. They were thinking about running two 500 KW gen sets and were looking into seeing about buying a used Xform on E-bay or somewhere until final power could be up and running. They were having a hard time finding a step up Xform, but there were a lot of step down Xforms in the size they wanted. I am sure it must have been Delta ? Delta. I can only imagine they were thinking about just reverse feeding it. I think they were getting 480 Delta from the generators. They were talking very casual about it, but it would have scared me to death. The first thing that came to mind was 110.3. But beyond that, was it even safe to reverse something like that? After thinking about it some more, I realized I don?t know very much about transformers. I understand electrical theory, turn ratio, magnetic induction, all the code issues of feeding transformers, but that is all by the book, but I honestly couldn?t come up with a problem with it. Would it be safe to say that a distribution transformer could be reverse fed in this example and be perfectly safe if fused correctly?? I guess it?s an engineering question, heck maybe I should know the answer, but I thought this forum would be a good place to ask.
I hope I gave enough information to formulate an opinion.
