Original poster: "MIKE HARDY" <mailto:MHARDY@xxxxxxxxxx><MHARDY@xxxxxxxxxx>
OK. I have 8" of the black conductive outer layer stripped back on both
ends, all shield removed. I know the cable is good, because it was pulled
from a functioning xray system (we just redid the test cell for a different
system). I personally think it's capacitively conducting AC. A cap (the
cable) with DC applied (the way xray PS are) charges to its value and then
just remains that way. A cap with AC applied will conduct. I just want to
use this cable safely, and without going through the hell of stripping the
black coating. Mine is a solid continuous bonded sheath, not a tape I can
peel back. I hope I'm making myself clear.
----- Original Message -----
From: "Tesla list" <mailto:tesla@xxxxxxxxxx><tesla@xxxxxxxxxx>
To: <mailto:tesla@xxxxxxxxxx><tesla@xxxxxxxxxx>
Sent: Wednesday, January 04, 2006 10:36 PM
Subject: Re: HV xray cable revisited
> Original poster: "Barton B. Anderson"
<mailto:bartb@xxxxxxxxxxxxxxxx><bartb@xxxxxxxxxxxxxxxx>
>
> Hi Terry,
>
> I understand the conductive layer technology for corona losses and
> the dielectric layer is around the conductor and then the main
> insulation followed by the jacket. But, as I understand it, only the
> outer jacket was removed so I don't think it will be a problem. The
> oddity is the cable arcing to the outer jacket before he removed it
> (which must have been observed from the ends where he striped back
> the outer insulation initially). I can only assume the cable
> insulation damaged or insufficiently rated. Regardless, if he's got
> the main insulation on the cable and routed through the pvc, it
> should be fine (that doesn't mean go grab it hot, but it should be
> arcing to anything).
>
> Take care,
> Bart
>
> Tesla list wrote:
>
> >Original poster: Terry Fritz
<mailto:vardin@xxxxxxxxxxxxxxxxxxxxxxx><vardin@xxxxxxxxxxxxxxxxxxxxxxx>
> >
> >Hi,
> >
> >It is common for HV DC cables, like used in X-ray, to have
> >conductive layers inside them in what looks like
> >"insulation". These layers are used to increase the conductor's
> >apparent radius to prevent breakdown (corona leakage) inside the
> >cable's insulation. I would never go cutting the layers off and
> >expecting it to work!! One should normally use the cable with the
> >outer grounded jacket well grounded just like they meant it to be used.
> >
> >The capacitance between the conductor and the shield "might" be a
> >problem in a given system.
> >
> >Even a perfect insulator can still carry heavy AC displacement
> >currents (at Tesla coil frequencies) and "glow" when near grounded
> >objects... If they are not designed for it, they can easily fail.
> >Thus, a DC X-Ray cable might fry under AC... Really good cables for
> >such things are teflon or polypropylene. Not much else
> >works... Note that insulators too have a breakdown voltage just
> >like air. Although much higher, there is still a limit to how much
> >RF voltage you can have on a radius. Thus is why HV cables tend to
> >be very "special"...
> >
> >Best just to not really too much on insulation in our sport. Even a
> >small coil can happily punch though a 1/4 inch thick sheet of glass....
> >
> >Cheers,
> >
> > Terry
> >
> >
> >At 06:34 PM 1/4/2006, you wrote:
> >
> >>Yes Mike, arcing is a problem. Hard to say why it is however
> >>without seeing it. The outer jacket/shield should have been
> >>stripped back several inches beyond an ability to arc. If it was
> >>still arcing, then that is odd. Anyway, stripping the entire jacket
> >>off is fine to (a lot of work though).
> >>
> >>Take care,
> >>Bart
> >>
> >>Tesla list wrote:
> >>
> >>>Original poster: "MIKE HARDY"
<mailto:MHARDY@xxxxxxxxxx><MHARDY@xxxxxxxxxx>
> >>>
> >>>So you don't think the arcing of the black coating to everything robs
any
> >>>power? Or in your case to grounded shield.
> >>>----- Original Message -----
> >>>From: "Tesla list" <mailto:tesla@xxxxxxxxxx><tesla@xxxxxxxxxx>
> >>>To: <mailto:tesla@xxxxxxxxxx><tesla@xxxxxxxxxx>
> >>>Sent: Sunday, January 01, 2006 6:27 PM
........