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

bdrmachine 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?

My Supermax is virtually identical (three 6A/ph NEMA 42 1100 oz*in)
direct drive on ball screws using very early G201's and naturally
I used my own 1KW power supply kit.

The 1KW kit generates 14 amps continuous at 75 VDC, but can generate
several times that amperage for instantaneous peaks (due to the
energy stored in the toroids magnetic field and the generously sized
47,000uF capacitor.)

As a practical example, accelerating a 200-300 pound table with a
100 lb vise on it from zero to 2 inch/sec in 1/10th second registers
less than a 1 volt dip (using a sample & hold digital VOM). Similarly,
decelerating that fast from a previously constant 2ips registers less
than a 1 VDC voltage rise (for a similar fraction of a second).

Impressive as the voltage dip spec is, actually the voltage rise spec
is more critical, because you don't want your Geckos ever to see 80+ volts
(caused by the motors generating voltage from the decelerations) or
they may let out the magic smoke.

More details on the supply of course can be found on my website.

Doug Fortune
http://www.cncKITS.com
























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