High Leg Delta Transformer

pudge565

Ok I have a question about a high leg delta transformer. I know that phases A and C to neutral you get 120 and that phase B to neutral you get 208. I also know that between any two phases you get 240. My question is why don't you get 328 volts from phase B to either phase A or C? I believe it has to do with the was the sine waves are off from each other but am not totally sure. Does any one have a good explaination? Or maybe a diagram of the sine waves?

InPhase277

Draw the pic of a delta setup. You will see that between each phase is 240 V. With the high leg setup, all we've done is tap the center of the coil between A and C, giving us a neutral. We have not changed the relationship between each phase.

In other words, between any two phases, is one full transformer coil. Between B and N, there is a coil and a half. And the phase relation between the two sine waves is such that we get 208 V.

Magnettica

What would you need 328 volts for?

Like 277 said, an open delta is just a regular single-phase set up with an additional transformer that's not center tapped. The 208 volts is a math equation. It's just a cheap way for the power company to deliver 3-phase power to it's customer but they are slowly but surely doing away with this set up.

pudge565

I don't know what you would need 328 volts for but I was just curious as to why you don't get it.