Re: CMD-260 test mode?

Jeff -

Looking back on this thread, you say that the 2.1V, 9A you mention is based
on looking at a photo of the nameplate of a similar motor. I would be wary
of setting too much store by that piece of analysis - the phase
current/resistance of stepper motors can vary considerably even for
apparently similar motors. For example, take a look at this website:

http://www.mae.it/in/index.htm

Their HY 200 4270 series of steppers consists of 3 motors in the same
physical package, but with phase resistances of 1.1, 3.0, and .34 Ohms, and
phase currents of 3.4, 7.9, and 9 amps (in ascending order of rated
torque). Note that the highest current motor does not have the lowest phase
resistance.

Their spec sheets show torque curves for the three motors, parallel
connected, bipolar chopper drive, running at 120V/4.8A, 140V/10A, and 140V,
12A respectively (they have uprated the current by approx 1.4 because the
motors are parallel connected), which looks like significantly more than 25
times the "nominal" motor voltage based on the nameplate ratings.

I guess the point here is that there's no real substitute for knowing what
the manufacturers actually intended for their motors. Anything else will be
guesswork at best.

Regards,
Tony

Jeff Goldberg writes:

> I believe NEMA 42's have a nominal voltage of 2.1 volts. I've been warned
> that if I exceed 25 times the voltage, the motors run too hot. They're
> rated 9 amps so the 8 amp limit of the drive shouldn't present a problem.
>
> I can rig my other power supply for either 56.5, 62 or 67.6 volts.
>
> Any further advise would be appreciated.
>
> Regards,
> Jeff
>
> -----Original Message-----
> From: stevenson_engineers <machines@...>
> [mailto:machines@...]
> Sent: Tuesday, February 18, 2003 7:46 PM
> To: CAD_CAM_EDM_DRO@yahoogroups.com
> Subject: [CAD_CAM_EDM_DRO] Re: CMD-260 test mode?
>
> Jeff,
> With the combination you have of the 260's and the 42 series motors
> you will need all the power you can get.
> The 260's are rated for 80 volt at 8 amp and it would be adviseable
> to get somewhere near these limits.
> With a 50 volt AC supply, by the time it's rectified and smoothed,
> you will have 70 volts DC which is close enought to 80 volts but not
> too close to cause over voltage problems.
>
> John S.
>
> --- In CAD_CAM_EDM_DRO@yahoogroups.com, "washcomp <jeff@w...>"
> <jeff@w...> wrote:
> > Well I'm nearly there. I've got a power supply, 3 CMD-260 drives
> and
> > a Bridgeport with NEMA 42 steppers on the XY and Z axis. I still
> > have to get a PC connected and load some software (thinking of MACH
> > 1 - pros and cons would be appreciated).
> >
> > Until I get the PC hooked up, I'd like to test the drive/stepper
> > combination. (The motors are unmarked and I'm taking some best
> > guesses at an appropriate power supply. I'm going to try 34 volts
> at
> > 8 amps in parallel and see how hot the motors get. I can still
> > change it if things go squrilly). Anyone know if there's a way to
> > test them to see if everything works in the absence of the PC,
> > software, etc.? Can I test them unloaded or do they have to be
> > attached to the Bridgeport?
> >
> > If not, can a PC be used to test in the absence of CNC software?
> >
> > Thank for all the help.
> >
> > Regards,
> > Jeff
>
>
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