Re: [CAD_CAM_EDM_DRO] Power needed to drive 3 nema 42 motors?

Don't go the 'Variac route'. It's essentially an 'auto-former', and as
such, isn't "isolated". "What's that", you say. Simply; if you ever
lose the portion of the winding to ground (neutral), your output will
be Line Voltage. Potential disaster, for any electronics that can't
stand the shock. If you can find a big battery charger, or small AC
welder, you could probably re-work the windings to make yourself a
suitable 3kva isolation transformer. I could post a reasonable design,
if you could tell me what size of lamination you can get your hands
onto. Contact me off-list

RayHex jnr@...

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> From: bdrmachine <bdrmachine@...>
>
> I have a bp clone that I'm retrofitting with 3 nema 42 1070 oz-in
> motors. They draw 6 amps per phase each. I'm driving them with
> Gecko 201 drives. What amperage power supply will I need? Three
> motors times 2 phases times 6 amps equals 36 amps! Do I need to
> shoot for this size supply? Where do you get a transfomer that size
> ( 70v, 40a )? Can I uses a variable transformer and a full bridge
> recitifier set to approx. 70 volts?
>