Re: High or Low voltage steppers better for Gecko

Message: 22
Date: Wed, 14 May 2003 14:39:36 -0000
From: "mayfieldtm" <mayfiet@...>
Subject: Re: High or Low voltage steppers better for Gecko

Watch out for too low of an Inductance!
I seem to remember Mariss mentioning that.
Might what to double-check with him.

Tom M.

[I'd be interested in seeing some knowledgeable discussion of this as well.
I had been under the impression that holding torque was the most important
figure to keep in mind when selecting a stepper motor, but apparently
inductance is a major factor as well. According to what I've been hearing
lately, a low-inductance motor can outperform a similar model with higher
torque, because it is quicker to charge and discharge its coils. Is a more
responsive low-inductance motor going to have adequate torque when running,
even if its holding torque is low? And like Tom asks above, is too low an
inductance a problem itself? If so, how low is too low?

There's also the issue of series versus parallel hookup. Running in series,
inductance seems to be much higher than in parallel, although torque is the
same. Speed is lower in series, given the same voltage, but the motors will
also draw less current (amps). So if one wanted the best speed, parallel
would seem to be the way to go, assuming the power supply one had was
adequate. Are there any drawbacks to parallel wiring that I'm not aware of?
What happens if the motors draw more current than the power supply wants to
supply? What melts- the fuses? Is there a maximum amperage that the Geckos
can handle? The instructions say not to exceed 80 volts, but I didn't find a
similar not-to-exceed figure for amps. If one does change from series to
parellel wiring (on an eight-wire motor, using Gecko 201 drivers) is there
anything else one must change, like a jumper setting, the capacitors, or the
fusing? Will the existing wiring (set up for series) be adequate, or must
heavier-gauge wire be substituted?]

Andrew Werby
www.computersculpture.com