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step up transformer

step up transformer

step up transformer

(OP)
Hello,

I am trying to run a 1 HP 440 volt 3 phase motor off of 240 single phase.  Since I can't find a VFD with 240 in and 440 out, I was investigating using a step up transformer to get to 480v and a VFD to create 3 phase.  

I found a 1KVA transformer with a primary of 480v and secondary of 240v.  Technical support for the transformer manufacturer said you can't reverse the primary and secondary to create a step up transformer.  They offered to build a custom wound transformer.  

Why couldn't this transformer work as a step up transformer, and what might they do differently in a custom wound transformer?

Thanks.

RE: step up transformer

A standard transformer will work in either direction.   Perhaps they have some magic parts inside that would know the difference, but the core and coils won't care.

But have you verified that this 1 HP motor cannot be re-connected for operation at 230 V?  That is very common for motors this small.  

Your idea is sound.  You just need to find another source for your transformer.   You might want to oversize the transformer beyond 1 kVA a little to account for the additional harmonic losses associated with the VFD and the VFD internal losses.  

 

David Castor
www.cvoes.com

RE: step up transformer

(OP)
Thanks for the reply.

The motor only runs on 440v, perhaps because it is a two speed motor. I'm planning on just using high speed and using the VFD to vary the speed.  The motor is very precisely balanced, otherwise I would replace it with a 230v motor.

I'll look for another transformer source.

RE: step up transformer

Most motors are very precisely balanced.  

Bill
--------------------
"Why not the best?"
Jimmy Carter

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