Re: UK v USA phase converter for spark eroder

On Wed, 14 Sep 2005 12:00:29 GMT, Peter Gavin
<petespamgavin@xxxxxxxxx> wrote:

>Hi,
>
>I have an old Agemaspark H300 which i am trying to get up and running in
>my garage. Due to the control system and spark generator as well as 2
>separate 3 phase motors, which are all powered from 1 rather complex
>(415v 3 phase, no neutral) transformer, I am looking to build a 3 phase
>converter to power the whole thing. The rating plate gives 220/550v and
>2KVA which is believe is well within the 240v supply. I have seen loads
>of USA designs for phase converters BUT it seems the USA has a 2 phase
>240v supply unlike our single phase 240v supply. Having scoured MANY web
>pages I am unable to find a UK design. Does anyone have one or know of
>one I can beg, steal or borrow. I have the excellent book "electric
>motors in the home workshop" by jim cox, which shows some methods of
>converting motors and building a static converter for motors, but i am
>unsure if the resulting variations in voltages are ok to feed the
>transformer. I am sure someone has built a suitable unit and can help me
>out here.
>
>With regard to my previous endeavors I also have 1 or 2 areas of doubt
>as follows.
>
>Does a rotary converter "idle" motor need to be of the dual voltage
>variety? Some suggest using an older type of motor for this job, but the
>older type seem to be all single voltage types?????????
>
>If i use a rotary converter will I get 415v, 440v or 480v ( i suspect
>this will depend on question 1?)

If you want 440 or similar 3-phase you'll need a transformer to step
up the voltage. The usual, though maybe not the safest, way is to use
an auto-transformer (one tapped winding) . Then a normal 400+ V
3-phase motor will do as the idler.

Perhaps others here will come up with something more detailed,
eventually.

Beware that 440V is *far* more likely to kill you than 240V if you
touch it accidentally!!

Cheers
Tim

Dutton Dry-Dock
Traditional & Modern canal craft repairs
Vintage diesel engine service
.

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