RE: [CAD_CAM_EDM_DRO] Re: Remember Mr. Bill's servo lite?

Hi Mike:

I had a big argument/discussion about this very subject on one of these message boards a few years back. It was basically me against everyone else(who cared to comment).

The gist of the explanation that I got was, "There's no galvanic isolation", and "If you can't see that it's dangerous, I'm not going to bother telling you why". People got very upset and angry at me, but nobody seemed to be able to explain the danger.

I have since looked at it a lot more, and I believe that the danger exists because even a big transformer, if it has isolated windings, will tend to limit the current that can flow through it, and so the case where there is a direct connection to the power line "could" be more dangerous. But I have still not seen a good, easily understood explanation.



Andy Wander

-----Original Message-----
From: CAD_CAM_EDM_DRO@yahoogroups.com [mailto:CAD_CAM_EDM_DRO@yahoogroups.com] On Behalf Of mikep_95133
Sent: Friday, January 13, 2012 9:02 PM
To: CAD_CAM_EDM_DRO@yahoogroups.com
Subject: [CAD_CAM_EDM_DRO] Re: Remember Mr. Bill's servo lite?

Understood. So why do I need the power supply isolated? Everything in the shop is grounded. The floor is concrete.

When I first set this variac up, I took a voltmeter and probed from the mill to everything within 6 feet and there was no voltage delta.

Mike

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "picengraver" <picengrave@...> wrote:
>
> Mike,
> A Variac's output is NOT isolated from it's input as standard transformers are. The risk of electrocution is high if one comes into contact with the output voltage and earth ground (floor, water piping, machine frame, etc.) Why risk someone's life?
>
> Regards,
> John Champlain
> www.picengrave.com
>
> --- In CAD_CAM_EDM_DRO@yahoogroups.com, "mikep_95133" <mikep_95133@> wrote:
> >
> > Really? How so? It's only been a part of the system for years now.
> >
> > Mike
> >
> > --- In CAD_CAM_EDM_DRO@yahoogroups.com, "Dan Mauch" <dmauch@> wrote:
> > >
> > > Using a variac isn't safe. You really shouldn't use one with your servo
> > > system.
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > > Dan Mauch
> > >
> > > www.camtronics-cnc.com
> > >
> > > dmauch@
> > >
> > > Stepper and servo motors
> > >
> > > Kits, assembled and custom CNC using Gecko products.
> > >
> > >
> > >
> > >
> > >
> > > [Non-text portions of this message have been removed]
> > >
> >
>




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