delta to delta transformer

[druski4]

im a second year apprentice that cant seem to find an answer to why when you bond the c phase of the transformer it doesn't fault. I have asked a few people who I thought might know but i seem to be getting the run around.

 

[iwire]

Because it is the only secondary line grounded.

With a delta trans you could ground A B or C it would not matter as long as you only ground one. It takes two or more phases to make a short circuit and with only one phase grounded you do not have any short.

 

[jim dungar]

As Bob said, the first connection to ground simply creates a reference point. It takes a second connection to create a short circuit.

The confusion usually comes from the fact that the neutral in wye transformers and single phase connections are always grounded (except in very rare situations). So the general perception is the simple act of a 'phase to ground' connection always causes a short circuit, when in reality it is the phase->ground->neutral that is the problem.