Re: Stepper Drivers

From: "Matt Shaver" <mshaver@...>

> >From: Jon Elson <jmelson@...>
>> I would suspect that no manufacturer gets away with this anymore in
>> industrial equipment,

>Both Servo Dynamics and Advance Motion Control make systems that run
>directly
>off the line (no isolation transformer). How they do it? I don't know...

A goodly portion of the safety derived from an isolation transformer is the
inrush protection. It also limits any current transients in service.
Inrush and current chokes can do the same thing, apparently. There is a KB
Dc motor controller sitting across the room from me with no xformer in it,
so it is very common practice.
I wouldn't do it myself, but i'm not in the business. Having said that, if
you look at vfd's they are taking the place of something that is always at
line voltage throughout anyway so there really is very little requirement
for isolation. Stepper motor drivers are another story. I need more
practice at building switching power supplies because that would open up
lots of new projects for me to never finish:)
eric