Looking back up the thread to 8.31.01 and Don's (resqcapt19) question:
Utilities use a connection with two transformers in an open delta fed with two hots and a ground to provide 3 phase power. I don't know what it is called but I have one right outside my construction trailer. The two primary hots feed the ends of the open delta. The ground is connected to the point of the open delta.
Don(resqcapt19)
Sounds to me like the primary is two legs of a grounded wye. With the secondary hooked up as open delta (and presumably a grounded center tap for 120/240) one gets 240 3-phase.
The full name of the hookup is "open wye - open delta". The two transformers can deliver 86.6% of their combined KVA.
