Re: [CAD_CAM_EDM_DRO] Re: Voltage to steppers

In a message dated 1/16/2003 10:55:55 AM Central Standard Time,
xylotex@... writes:

> First, doubling your voltage will significantly increase the
> performance of your motors. I would definitely recommend going to
> 24V if your Allegro parts can handle that. It is most often
> recommended to run a stepper above it's rated 'running' voltage (not
> to be confused with it's MAXIMUM voltage), but you should not run a
> motor over it's rated current.
>

Jeff:

I have forgotten who it was in the group who just asked this question, but I
see that now and then in other kinda-related groups, as well. It is clear
most folk do NOT understand that having a DC-SUPPLY voltage several times
higher than the motor's "rated coil-voltage" does NOT mean "that same
[effective] voltage will be applied to the motor"! Well, yes, it is, but not
"at stand-still". NO MORE than that rated coil-voltage should be applied,
"effectively", so that the rated CURRENT does not exceed! This concept of
the increase of coil-REACTANCE when spinning is something most folk "in here"
just don't grasp, and this is understandable! (I'm not even sure I do!!!)

We need some guru like YOU to explain about how a CHOPPER-drive keeps the
"effective" current at the proper limit, and why the HIGH voltage the drive
CHOPS does not cause excessive current (due to DUTY CYCLE of the chopping)
and that!

And how the "old" L/R "six-wire" unipolar system was WASTEFUL and
inefficient, and how a power-supply for a CHOPPER system can be much smaller
than the old L/R system, etc., etc! Do YOU volunteer???

Jan Rowland


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