Re: Power needed to drive 3 nema 42 motors?

Brian,

It is 6 amps per motor, not per winding.
6 amps times 3 motors is 18 amps.
you do not need to achieve full nameplate amps as the chopper circuit
is not on 100% of the time. this means you only 66% of the rated
current for your power supply.

That means you have a 12 amp load.

regarding transformers, simple choices, three seperate smaller power
supplies is one choice when it starts to get huge.

Doug (www.CNCKITS.com) put together a power supply kit. Seems there
was a long discussion of why toridial and such, and he got what was
agreeed was the technically best method and put it in a kit.

Of course, I still haven't gotten one, so I can't vouch for how easy
it is to assemble, but the parts are there.

Someone posted on here that a particular wal-mart auto battery
charger has a good transformer for the purpose, and there is a thread
some time ago that offers re-wiring microwave oven transformers for
huge power needs.

Regardless, the 12 amps is probably pretty easy to find.

Dave

--- In CAD_CAM_EDM_DRO@y..., "bdrmachine" <bdrmachine@h...> wrote:
> 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?
>
> Thanks
> Brian