NVDave - 5/17/2008 17:47
That's why I thought it was a wild leg setup - you said way back up the thread that there were only "two pots" up on the pole. The only way you get three phases with two transformers is what we have here - open delta, or wild leg.
The power company is bringing in only two phases and a neutral. That's what I see in your picture up on the pole.
BTW - you get only about 58% (if my memory is correct) usable power of the aggregate power rating of these transformers if they were in a true delta or wye setup, or 87% of the sum of the two transformers up on the pole.
The "cost savings" here is in not supplying you with a third transformer, and not carrying all three phases through to your service location.
There's lots of terms EE's have to describe this setup. Not many of them can be used in polite company.
When I was working on the design on modernizing Post Offices and other public buildings in the 1960's, Probably 80% had the open delta service. I certainly agree with your last statement about that system being called lots of unprintable things. I said a lot of them myself