# Transformer question



## jeepman (Jan 2, 2013)

I need to find an amperage rating on a step-down transformer and I haven't had to do this math in quit a while so I want to double check myself. I'm coming up with 60ish amps 

Primary 277/480
Secondary 120/240. 25kva 
K

Kva


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## SteveBayshore (Apr 7, 2013)

25 kva tells me it's single phase, yes?
Primary voltage will not be 277/480, it must be 480, yes?
25,000 divided by voltage of secondary (240) = 104 secondary amps
25,000 divided by voltage of primary (480) = 52 primary amps


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## jeepman (Jan 2, 2013)

SteveBayshore said:


> 25 kva tells me it's single phase, yes?
> Primary voltage will not be 277/480, it must be 480, yes?
> 25,000 divided by voltage of secondary (240) = 104 secondary amps
> 25,000 divided by voltage of primary (480) = 52 primary amps


You are correct it is a single phase 480 primary thanks for the correction in my math


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