Re: Arc Welder Power Supply for steppers

Scott,

read geckodrives.com white paper on power supplies.

I cannot see any combination of NEMA23's that could possibley use
such a huge power supply.

Run thru all the calculations for power of the steppers, then power
supply, then caps and you may be surprised at how small the
transformer you need will be.

I was fortuate enought to get a 24vac 8 amp power supply from one of
the local alamr companies in an enclosure. free. 2 of those and you
have 48V, and since mine was center tapped, I imagine I could use it
for 36 VAC.

my NEMA23 draws 1.5 amps, so 4 would draw 6 amps, or at 2/3, I would
need a 4 amp power supply. 180 amps is just a tad overkill.

Dave




--- In CAD_CAM_EDM_DRO@yahoogroups.com, "Scott Riddle"
<sariddle@l...> wrote:

> I searched and did not come up with any one else asking this

question

> so here goes. I have been looking for a cheap power source to power

3

> Nema 23 steppers and I happened upon a DC arc welder for free. It
> puts out 52 volts open circuit and 25 at max load (180 amps). I of
> course never hope to hit 180A. But what I am wondering is if I dial
> it down to its lowest amp settup ~30 could this be a viable power
> source for my steppers? Would I need to run some resistors in line
> with the welder to limit the current. I am thinking of adding a

fuse

> to prevent any high amperages from burning out the driver board or
> motors. The steppers, I think, are around 6V so the ~52V from the
> welder should work well.
>
> Another related question I have is on the rule of thumb I see often
> of supplying 20-25 times the rated voltage on the stepper motor.

Does

> this always hold true and for all Volt steppers. The reason I ask

is

> that I see some steppers rated for 12V. This would yeild 240+V

power

> supply requirements. From what I understand this higher voltage is

to

> get better responce from the steppers. At what point do you limit

the

> voltage. One sure limiter is the driver boards voltage limit but

are

> there others?
>
> Many Thanks
> Scott