# What size transformer would you use



## BBQ (Nov 16, 2010)

I bet 1 KVA in a buck boost is more than enough.

Buck boost sizing is much different, that is one of the advantages of them. You can get away with much smaller transformers than if you used a regular step up transformer.


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## Service Call (Jul 9, 2011)

Any formula to size this with?


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## BBQ (Nov 16, 2010)

Service Call said:


> Any formula to size this with?


Yes, and I have done it but I need a cheat sheet to do it.

But the short explanation is that a buck boost is sized only for the KW difference between the two voltages.

I will see if I can find a link.


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## Service Call (Jul 9, 2011)

Thanks. They are wanting 107 of them done. Just want to make sure.


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## BBQ (Nov 16, 2010)

Service Call said:


> Thanks. They are wanting 107 of them done. Just want to make sure.



http://www.acmepowerdist.com/pdf/Page_104-109.pdf

The formula is in the link, I may have been wrong about the 1 kva being enough


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## Service Call (Jul 9, 2011)

I'll take a look when I get to a computer, thank you.


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## Service Call (Jul 9, 2011)

BBQ said:


> http://www.acmepowerdist.com/pdf/Page_104-109.pdf
> 
> The formula is in the link, I may have been wrong about the 1 kva being enough


I checked your link, it had the formula but not exactly. I found a buck boost calculator on the square d site and it said a 1KVA xfrmr would work. Learn something new everyday. 

Thanks for the help BBQ


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## Wireman134 (Feb 6, 2012)

1kva Boost will cover load @ 80% or 25A.


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