# Why 37.5 and 112.5 pole transformers



## Lone Crapshooter (Nov 8, 2008)

A coworker ask me how the arrived at such values of pole transformers. I told him that it was explained to me one time and it had something about building 3 phase transformer bank capacity but I an really not sure and I just cannot remember.

Help jog my memory 

Thanks LC


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## Big John (May 23, 2010)

I know that when you bank three 37.5kVA single phase trannys, you're getting a 112.5kVA total. So that would tend to explain one of those numbers, as it's simply a multiple of the the other, but beyond that, I don't know.

That and 333kVA are a couple of the really odd-ball ratings they've got. Seems most of the other transformers are divisible by 50 or 100.


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## Jerome208 (May 10, 2013)

25 + 50 / 2 = 37.5 (single phase) (halfway between 25 and 50)

37.5 x 3 phases = 112.5


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