Transformer Connection Question

[abrahamJP]

Dear Sirs,

I have a sample question from one theory paper here;

A Three phase transformer is made of 3nos 10kva single phase transformers
connected in delta.When only two phases(instead of three phases) are feeding,what will be the output?

My answer was 2/3*30=20KVA.But answer seems to be 17.7KVA.How it comes?

regards

Abraham

 

[magoo2]

With one phase open, you get one winding energized at rated voltage. The other two will be in series and thus seeing half voltage each.

 

[waross]

Rephrase the question or draw a diagram please.

Bill
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