open delta transformer

[rotee]

I am trying to calculate available fault current @ open delta transformer.
I DONT KNOW WHERE TO START.

Could anybody explain theory(V's, I's, & S) of open delta transformer or recommend some literature.

Thank you.

 

[magoo2]

You basically have 2 single-phase transformers. The primary is often connected open wye and the secondary is open delta.

On the open delta side, one of the transformers is connected with the full 240 V winding; the other one is usually connected with the 240 V winding giving you one leg, but also with the midpoint connected to ground to get 120 V.

As far as fault current calcs go, you can just consider each transformer separately. With the 120/240 V connect, you'll have the 120 V fault in addition to the 240 V fault.

If I can find a way to post an old paper, it will cover the 120 and 240 V fault calculation. I think someone recently posted a similar reference.