mivey
Senior Member
Very good points.Cost,cost,cost! With the wye you have to use three transformers, with the open delta, only two transformers are needed. Most POCO's stock only certain size transformers, because they are required to have spares on the lot for emergencys. The cost between hanging three 10 kva transformers versus hanging a 15 kva and a 10 kva is considerable when the payback due to low usage is a lot longer. Especially if only two phases are run on the poles from the main lines. If you have to add another line for a couple of miles, it gets even more expensive.
However, I might point out that you can make a wye with only two transformers as well.