[Christopher Witmer]

Sometimes I see 3-phase components available at lower prices than their single-phase counterparts. That gets me to thinking, "Hmm, is there perhaps some way that this could be used in a single phase application?"

Through Google searches I have been able to confirm that a 3-phase EMI/RFI filter can be used in single phase applications -- you just leave one pair of connections unused. Okay, so far so good.

Ditto for line reactors . . . not that most of us would have use for a line reactor in audio applications. I have yet to see a three-phase reactor that could be used to good effect as a choke; their inductance is usually measured in mH rather than H and they are designed to pass huge amounts of current, compared with the chokes that we use in audio. But it is an example of a 3-phase device that can be used in single phase applications.

HOWEVER, in my Google searches I could find NOTHING about using a 3-phase transformer in a single-phase application. I only found the reverse situation -- where three single-phase trannies could be wired for three-phase use.

So somebody please tell me: is it possible to use a three-phase transformer in single-phase applications by leaving one pair of connections unused? Or is there something so fundamentally different about the way a 3-phase transformer is designed that makes single-phase use impossible?

THANKS!

-- Chris

[BMA]

Chris,

I believe this is what you are looking for.....you can always count on a coiler to modify something for something else so that it does something that it was not supposed to do.

www.pupman.com/listarchives/2001/October/msg01024.html

[Christopher Witmer]

I can't believe you were actually able to come up with that information for me! Thanks. I don't know if I will actually ever try it but it is good to know that it can be done. I suppose the transformer needs to be derated to 1/3 the current-carrying capacity when going from 3-phase use to single phase . . . the one that caught my eye is a 12kVA 3-phase 1:1 isolation transformer so I assume it would be 4kVA as a single-phase trannie?

-- Chris