Re: Power supply for Servos

Yeah...I am curious about this too. I will be running the identical
motors on my BP. 4 of them counting the 4th axis/Indexer, although I
believe that it will still only be running 3 at a time.

My target voltage is about 75v running 100v/20A Rutex 990s.

If my calculations are correct, I should have something like this:

2X Toroid 1KVA 55V ---> 36A @ 55v

Bridge Rectified to 53.8v

27,000mfd 100v Cap --> 76vdc @ 26A

Using the "formula" C = (80,000 * I) / V then...

C = (80,000 * 26A) / 76volts

C = 27,368


Is this correct???

Next thing is...Where do I get the components for this?

What specs should the Bridge Rectifier be?

Thanks!
-Brady

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "turbulatordude"
<dave_mucha@y...> wrote:

>
> --- In CAD_CAM_EDM_DRO@yahoogroups.com, "cnc_4_me" <cnc4me@g...>
> wrote:
> >
> > These servo suppplys are a little hard to nail down. A couple of
> > weeks ago i tried to get a formula for making one. Both Mariss

and

> > Jon Elson gave me advice for building a supply. If i understood
> > them. The straight forward approach means you need the wattage
> > rating of the servo. Second best is the constant current spec

and

> > maybe Ke constant. Third worst is the voltage and current rating
> like
> > you gave.
> >
> > Do you have any other specs on your motors...
>
>
> PACIFIC SCIENTIFIC, Permanent magnet DC motor.
> 1 1/2 hp
> 110 VDC
> 11.6 Amps
> 3,200 RPM
> Continous Duty
>
>
> If I look at the wattage of the servo, 110VDC @ 11.6 amps, that is
> 1,276 watts.
>
> But, if I look at it with the max voltage from my power supply, it

is

> 76 volts time 11.6 amps = 881 watts.
>
> For 881, I could use 2 transformers to get 2,000 watts, that is

light

> for one calculation, and heavy for the other.
>
> I had thought there was some number one could use for duty cycle as
> the motors are not driven DC, but pulsed.....
>
> I'll go back and re-read Jon's post. IIRC, it was more guidelinesh
> than calculations.
>
> Dave