Re: Stepper Motor Power supply Sizing.

--- In CAD_CAM_EDM_DRO@yahoogroups.com, JanRwl@A... wrote:

> In a message dated 5/30/2003 9:00:00 AM Central Standard Time,
> davemucha@j... writes:
>
> > With chopper drives the ACTUAL current is
> > different than the apparent current.
> >
>
> AND, Dave,
>
> with the Gecko chopper drive (and I assume also with better similar

chopper

> drives?), it is not the CURRENT demand of the motors one should use

to figure

> the size of the power-supply, but the WATTAGE! I.e., if you had a

3-volt/4-amp

> per coil motor, that is ONE of two coils, so you'd have a total of

24 watts

> for that motor. The power-supply for that motor, alone can be a 1-

amp/24 volt

> supply! Sure, it'd be adviseable to make it 1.5 or even 2 amps for

this

> smallish size, but it need NOT be an 8-amp or 8*(2/3) amp supply!

The chopping and

> capacitors "integrate" the power so that close to the "name-plate

current" is

> eventually fed to the windings by the wizardry of the drive! NOT

same as the

> old L/R unipolar drives of 30 years ago!
>
> I'd comment on the feebleness of my tiny mind, but that'd be

getting OT, so,

> hope this enlightens! Jan R.
>

Very interesting.

I switched from my origional 30 amp/60 V power supply to drive one
5v/1.5a nema23 stepper to an 8 amp/37 volt power supply for 4
steppers that are 1.7V/4.7A wired in series steppers (9.4 amps for
the 4 stepper) but, 1.7x9.4x2 is 31.96 watts. my 8x37 supply is
only 296 watts. much smaller than the 30A but was the next unit up
from the calculated 6.27 amps for the drives.

I am very happy with it and everything has been running great.

I connected the table with some construction 18ga/4 conductor wire I
had laying around, but it is not very flexible. Stranded
construction wire is great for installations around objects and in
panels, but is not motion control.

as you know, I just ordered 5 conductor,shielded, 14 ga for my 2
routers (only one ever operates at at time), 16ga, 12 conductor,
shielded, for the 3 steppers, and 7 conductor 18ga shielded for the
end/home and e-stop low voltage logic switches.

Getting all shielded had the guy in the supply house looking but
worth the effort. I should be getting that wire about the time I get
the Igus track so, in another week, I should have all the parts.
just in time to put it on the shelf for my June 15th wedding.

that may clue you in to why my earlier post was a little unclear. : )

New home and end switches are on their way too.

It is nice to be improving the machine now and not still planning and
building it.

I can only imagine where I would be if I tried to design my own
drivers and not buy the Geckos.

Dave