Does 480V @ 200amp become 400amps at 220V

[Smatthew 219]

Hello All,
A simple question for you:

I have 480V @ 200 Amp service and a step-down transformer that will give us 220V so we can use it for our distro purposes. The 480V service is 200amps 3-phase. When it is stepped down to the 220V, will we then have 400 amps per/leg? I think that is the case but I'd like to be sure about that.

Many Thanks,
Smatthew

 

[LarryFine]

Matt, loosely speaking, yes. Presuming 100% efficiency, when you halve the voltage, you double the current. You also have to know what kind of transformer you should use; typically delta primary to wye secondary. And, what your loads require.

480 x 200 = 96kw. 96kw / 240 = 400. (You should use 240, not 220, and don't say "per leg" - you'll look way cooler )