Karl I found this post while searching for an answer to the same problem you had several years ago. Were you successful in running your 440/3 air dryer in this manner? Steve
Karl Townsend wrote:
I bought a 440 three phase air dryer. Didn't know until it got home that it
> doesn't do 220 3 phase.
>
> What's best system to convert power for this unit?
>
> I'm asking now because I see a fairly cheap 440 VFD unit on ebay. I'm
> wondering if some kind of step up xformer and VFD is the way to go. >
> Karl
(response)
Cap ( snipped-for-privacy@thegrid.net) The task can be accomplished by using a 'donor motor' that is normally doing the job of single to 3 phase conversion. Normally people call it a rotary phase converter. Obvisally the load needs to be figured, and any heater loads dropped down to 220/1 if possible. But is you just want to look at the 'package' conversion.. here goes.. Electric motors of the three phase garden variety type are usually 9 lead star connected 220/ 440 voltage. One of the interesting things about electric motors are that they are rotating transformers, that also can make shaft horsepower. So if you properly connect the motor and put 220/3 into it you can get 440/3 out of it. There is your cheap 220/440 transformer. But you need 440/3, so now we need to make the electric motor into a rotary phase converter, and also wire it as a step up transformer.... So we need to kill two birds with only one stone... not that hard... (snip)