RE: [CAD_CAM_EDM_DRO] Re: blown Gecko - shorted output ?

Dave:

Bad idea to float the ground. You should make sure that the water pipe has
a ground clamp on the metal on the house side. It should give a good ground
through your house on the COLD water pipe as long as you do not have any PVC
portion or rubber fittings or such between where you are picking up the
ground and the water pipe ground clamp. If you have a metallic wiring system
(Metal boxes and BX cable rather than romex and plastic boxes), you should
be able to pick up a ground from your electrical raceway system.

Floating ground -- BAD idea. You can hurt yourself if something shorts to
ground or destroy equipment with ground loops, static discharges, etc.
Grounding is a safety issue. If you have a problem with your house's
grounding system, fix that, don't try work arounds. If you go to the
library (its not on-line as far as I can tell) and pick up a reference to
the National Electric Code, it will talk about how to establish a good
grounding system.

Regards,

Jeff


-----Original Message-----
From: turbulatordude <davemucha@...> [mailto:davemucha@...]
Sent: Wednesday, February 26, 2003 3:42 PM
To: CAD_CAM_EDM_DRO@yahoogroups.com
Subject: [CAD_CAM_EDM_DRO] Re: blown Gecko - shorted output ?


Hi Lee,

One thing that bothers me is that it ran on a NEM23 for months before
I switched to the Nema34's.

now nothing seems to work. I figured it was a bad motor so switched
back to the NEMA23 and pop. as you might imagine testing with new
drives is not fun or cheap.

The house earth ground is a driven pole outside the house and for
some really stupid reason to the water pipe on the well side of the
pump, on the metal, just before it goes into plastic and leaves the
house.

I was/am thinking of floating the ground on all the stuff just to
eleminate that part of the equation.

Dave




Dave

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "Lee Studley
<indigo_red@q...>" <indigo_red@q...> wrote:

> Hi Dave,
> Just an suggestion: You might also suspect the insulation in the
> stepper. Maybe a coil is somehow shorting to gound during operation
> or vibration. Are they new or old steppers. If the Stepper has a
> ground wire or appears to have one, disconnect it, the metal case
> should be enough.
>
> Also test to see if you house wiring is really grounded correctly. You
> should get 0vac from the ground to the wider prong on the outlet, and
> 110VAC from the ground to the narrower prong on the outlet.
>
> -Lee
>
>
>
>
>
>
> --- In CAD_CAM_EDM_DRO@yahoogroups.com, "turbulatordude
> <davemucha@j...>" <davemucha@j...> wrote:
> > I bench tested a stepper, worked great. mounted it on the

machine

> > and pop. blew something in the Gecko. Mariss said it might be

the

> > outputs but only testing will reveal the answers.
> >
> > so my question is of isolation. does the Gecko frame need to be
> > isolated from the power supply ? from the 110VAC earth ground ?
> >
> > what irks me is that one axis has been solid for the duration,

runs

> > perfectly. the other had 'eaten' 4 Gecko's. as you can imagine
> I'm
> > not excited to just throw on another Gecko to see what happens.
> > What bothers me is that I ran all weekend with no problems. 2 I
> blew
> > on setting up. I assumed that I did something stupid, but now

that

> I
> > blew up another 2 with everything I knew to test, tested, I am
> > nervious.
> >
> > HELP !!!
> >
> > Dave

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