Re: [CAD_CAM_EDM_DRO] servo power supply sizing

tanktemchs99 wrote:

>Hello All, Does anyone have any information on sizing a dc power
>supply? I'm using the rutex drives, as close to the 100v max as I
>can get. I'm not exactly how to calculate the amp's. Any help would
>be appreciated. Thanks, Jim
>
>

What is the peak current limit on your motors? What is their voltage/1000
RPM rating? You can figure out the worst case current demand from the
supply from this. Then, figure out how often this will occur. Buld DC
supplies can handle short duration surges above the rating, especially
when adequate filter caps are provided. In machining applications,
the accelerations are short, and the average speed is fairly low, so you
don't
need to support the peak load very often. On routers, the peak is seen
more,
because there is so much acceleration to near max speed.

Give us some more info, and we should be able to give some guidance.

But, assuming 3 axes, with 250 W 50 V motors, just to throw out random
numbers. Now, to get 250 W at 50 V, you need 5 Amps, but that is the
continuous rating of the motors. Assuming the Rutex is the limit at 15 A,
you can't get much over 750 W into each motor, ever. So, a 2250 W
transformer
will handle the absolute worst case forever. But, these motors are KNOWN to
cook if you exceed 250 W continuous. Staying inside that rating will
only require a 750 W transformer. And, we know that a 750 W transformer
can handle some momentary loads exceeding that. So, a 750 W transformer
will likely be satisfactory in home shop service on a milling machine, but
a 1000 W transformer would give some safety margin. Except for a router
in commercial service, that might just about be sufficient for all users.

Jon