Phase Perfect Question

[bvweld]

I have ordered a DPC-A10 Phase Perfect converter and was discussing the single phase input voltage with the sales people. My L1-L2 single phase incoming is 248 volts. My mill is a TREE Journeyman 325 CNC requiring 230 volts. I am concerned this might be too high. In talking with the sales personel at Phase Perfect, I was told to figure the Kva for a buck/boost transformer (single phase primary) by the voltage drop using a 24 v bucking transformer. Basically this: 70 A input X 24 V(bucking voltage) / 1000 which is 1.68 Kva. I am no expert but this does not seem right. Should I be concerned about the over voltage? I am trying to decide if I need a transformer and what size. The full amp draw on the mill is 20amps, full input amp draw single phase on Phase Perfect is 70 amps. If you plug in 70 A x 230v/1000 it comes up 16 Kva and that is a pretty good size (expensive) transformer. Sorry for the ramble,I tried to keep it short. Any input or advice would be appreciated. Thanks

[Geof]

Here is a link to a description of solid state phase converters:

http://www.phaseperfect.com/phasewhitepaper.htm

Part way down is a description of how the phase perfect works. As far as I understand there is not any direct relationship between the incoming single phase voltage and the synthesized three phase output. The incoming voltage is converted to DC in capacitors and the three phase is digitally synthesized from the DC voltage.

[Al_The_Man]

Originally Posted by Geof Part way down is a description of how the phase perfect works. As far as I understand there is not any direct relationship between the incoming single phase voltage and the synthesized three phase output. The incoming voltage is converted to DC in capacitors and the three phase is digitally synthesized from the DC voltage.

Geof, According to the installation diagram schematic http://www.phaseperfect.com/files/al...s%20manual.pdf
The 1 phase is passed through as two phases the way it is done in a RPC.
Only the third phase is synthesized from these two, at least that is the way I interpret their diagram.
Al.

[Geof]

Originally Posted by Al_The_Man Geof, According to the installation diagram schematic http://www.phaseperfect.com/files/al...s%20manual.pdf The 1 phase is passed through as two phases the way it is done in a RPC. Only the third phase is synthesized from these two, at least that is the way I interpret their diagram. Al.

Thanks Al, I read too quickly and misinterpreted.

[bvweld]

I think I may have found the answer to my question. Look at Acme......

http://www.acmepowerdist.com/pdf/Page_104-109.pdf

If you look at Acme buck - boost transformers and pick " bucking" ,245v line voltage and 222 v load voltage,the selection chart for a transformer capable of delivering 68.6A calls for a T-1-11684. This transformer is marked "1.5KVA". But, if used as a buck-boost, it can deliver 15 KVA. I don't quite understand it yet, but it looks like the sales guy is right. Thanks