sizing transformer

Som_P

480 V primary
120 V secondary.

9 temperature controllers and 2 power supplies coming off the 120VAC

total Amps are ~10A

This is 3-phase. How do I find the right size transformer?

sophiecentaur

You go to a catalogue and buy one with the right specification. It is the only way to be sure. You will not be able to make one for yourself (if you need to ask this particular question).

Carl Pugh

Do you require a 3 phase transformer or a single phase transformer?
My guess is a single phase transformer.
How did you calculate the 10A?

sophiecentaur

It always helps to describe your problem is more depth than you have done. On the face of it, the requirement is relatively low power and it does seem unlikely that you would need 3Phase.
If it is a one-off piece of equipment then there is no harm in going a bit bigger than you think you may need. If you are doing this in hundreds, then the economics of a cheaper and smaller transformer may make it worthwhile to get your estimate more accurate.