converting two of three phase to three phase

Thread Starter


Joined Feb 19, 2014
Hi we have a mountain top facility where the utility ran two lines of 7200 phase A and B to our site which requires 3 phase. They installed 4 transformers to obtain the required 3 phase 208. Does anyone have a schematic for this and is this typical and are there any issues with harmonics?


Joined Jul 18, 2013
If they only ran two lines, this is single phase, for two phase you need a third reference.
or neutral.
If it is two phases then the third could be at earth ground potential.

Thread Starter


Joined Feb 19, 2014
The tech out in the field told me the power company engineer says it is two of three phases and that this setup is not uncommon when dealing with rural areas. So how do you get the 3 phases from 4 transformers? I've worked here for a little over a year and this site has apparently had problems with the txing equipment for years since it was installed and the voltage between the phases seems to flucuate quite often.


Joined Nov 7, 2013
Can you take a picture?

Are there 3 wires coming in? 2 phases and common?

Max seems correct. That you need 3 phase.

There is a "T" connection that requires 2 transformers. Center tapped both primary and secondary.

Same as 4 untapped transformers.

That's the only explanation for 4 transformers I can find.