Re: determining stepper motor current

Hi Rich,
I'm using a bench power supply at the moment set to 30v - it can
deliver upto 3A but is only giving about 150ma at the moment per
motor. How can I determine the current rating of the motor as the
only info given is the resistence - 1.2ohm?

thanks

alan

--- In CAD_CAM_EM_DRO@yahoogroups.com, RichD <cmsteam@s...> wrote:
> alan,
> The ref volts is the chopper cutoff current setting reference.
> VRef divided by sense res ohms = current setting.
> or
> Max current times sense res = VRef
>
> The motor rating is the max setting for VRef calc.
> Set it to the max allowed for the motor.
> OTOH, what voltage is your power supply? The L298 allows ~30 max.
> This is where the Omph! comes from.
> RichD
>
> alanhunt2001 wrote:
> >
> > I have a Step 4 cnc machine for which I've built a new controller
> > based on L297/298 combo (as the original went up in smoke) I'm
> > having trouble determining the vref setting. The motors are
marked
> > nanotek - munich 1.8deg/step 1.2ohm. '17' size and I think they
were
> > originally set up for a max current of 0.8A. I am trying them at
the
> > moment with vref=0.4v and with sense resistors of 0.5ohm , but
the
> > motors do not have any of their original torque.
> >
> > As I understand, I am effectivly setting the current as the peak
> > current which will be much less then the average current. I am
wary
> > of increasing the current without any more data on the motors.
> >
> > any suggestions will be appreciated.
> >
> > alan