Re: Specs on Sigma Stepper for Series I Bridgeport?

Hi Mike,]
Like Ray says 80v. For steppers, you can overdrive the voltage rating
( more of a continous DC rating really ) by 20x or more, which is a
common practive to improve the slew rate of the coils. This means you
pulse the voltage way up to bring the current up to a limit as
quickly a possible.
Your 53vdc supply will be perfect as it gives headroom for
powersupply voltage into the geckos which can pump up if the steppers
coast and act like generators into the supply.

You are lucky, most have to go thru hoops to derive a usable supply
when using the original transformers etc. My mill used 160vdc into the
steppers, then back it off to about 12vdc holding once the current
limit was reached.

I got these specs somewhere and they may be similar to your stepper:
Sigma Instruments 21-4266D200-F022
specs as follows
8 leads
Torque at 50 SPS 910 oz/in bipolar, 20% less for unipolar.
Holding torque 1100 oz/in, 20% less for unipolar.
Detent torque 38 oz/in.
Phase current amps unipolar 9.0, Bipolar 12.7
Phase restance .21 ohm.
Phase inductance 1.6mH.
Rotor inertia 37.1 oz-in squared.
Weight 19 lbs.
series 21 = High speed, high torque thru 4500 rpm.
4266 = 4.2" dia and 6.6" long 2 stack rotor.
200 steps per rev.








--- In CAD_CAM_EDM_DRO@yahoogroups.com, "Mike Mueller"
<mueller914@y...> wrote:

> my concern is whether or not the Sigmas require over 13.25vdc, if

so, then the powersupply is not of high enough voltage (powersupply
to be at a minimum 4X of the motor) unless I read the manual wrong ...

>
>
> Mike
>
>
>
> --- In CAD_CAM_EDM_DRO@yahoogroups.com, "Raymond Heckert"

<jnr@a...> wrote:

> > My understanding is that the Geckos will handle up to 80 Vdc.
> >
> > RayHex
> >
> > ----------
> > > From: Mike Mueller <mueller914@y...>
> > >
> > > thanks !!!
> > >
> > > do you know the voltage for the sigma motors? my powersupply is

53vdc,

> > not too sure if the G201 will be happy at that voltage.
> > >
> > > thanks again,
> > >
> > > Mike