Ungrounded Wye


Senior Member

If it helps you see it, the pole-top pins have insulators to path the long run between the outside bushings to close the delta on the primary side.


Senior Member
take a second look at the primary side, you said it is delta fed, that is not correct. Delta does not have any of the three bushings paralleled. The 3 primary bushings on each can are tied together, then are bonded to ground. The secondary side is the same, but are not ground, nor have neutral wires.

The primary side would have the first and last terminal tied as phase 1, the 1st and 2nd transformer's 2 closest bushings would be tied with a jumper and fed as phase 2., and the 2nd and 3rd transformer's closes terminals would be tied together and connected to phase 3 of the incoming system. There isn't a any neutral because it was meant to be this way, to use less power. When the old timers in the industry started to fade away, so did this method, and to this day, nobody teaches this anymore. In essence, only one phase is used from the POCO to feed the facility, the last 2 phases pick up their energy by a resonance that happens within an electric motor from some strange reactive energy brought in either by induction or capacitance of some sort. Not completely understood but it happens and we still have some of this out there that hasn't been upgraded yet.

I see H1(A) tied to H2(C), H1(C) tied to H2(B), and H1(B) tied to H2(A). No ground... looks pretty Delta to me..