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

I am NOT an electrician, so don't take my word as gospel.

Are you saying that part of the house is grounded to the grounding rod, and
part is not really grounded through the plastic pipe that goes into the
well, or that the electrical system is grounded at both places? (though we
all know that the plastic well connection shouldn't be considered a ground)
The connection to the well pump my not be intended to be a ground for the
wiring in your house, but to ground the plumbing in your house, since as you
pointed out, it isn't grounded through the water inlet. Very important if
you drop a toaster or CNC mill into your tub or the house is struck by
lightning. There should also be a bare copper jumper wire around any
equipment or valves in line with your pipes, like your well pump.

I wouldn't try to float the entire mill, the liability would be tremendous
if anything happened. As Lee pointed out, the neutral line coming from your
outlet should be connected to the earth ground. They should be connected in
the fuse box BTW, not in your equipment. The frames of your mill and motors
should all be earth grounded. That may require a little work to do
successfully with the moving parts of a mill.

I also agree with John that many heatsinks need to be isolated from ground.
I am not familiar with the Geckos, so you should check with the
manufacturer, or others on the newsgroup. It is possible to attach a
heatsink to a grounded metal frame, keep it isolated, and still get good
heat transfer.

As far as the outputs from your power supplies and the geckos, etc., in a
lot of AC to DC power supplies, the output is isolated. That isn't because
it shouldn't be in most cases, but for the instances when the output needs
to be floating for whatever reason. You may need to connect the negative
outputs of your DC supplies to the neutral line of your AC inlet to have
them properly grounded. That is assuming you have positive, not negative
supplies.

I apologize if this doesn't help you.

Mike


-----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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