Re: HV xray cable revisited

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "MIKE HARDY" <MHARDY@xxxxxxxxxx>

Carl Litton was kind enough to respond to this question off-list. He sent me
a pic of 'greenmonster' doing it's spectacular thing. He mentioned you using
xray cable, but failed to tell me you use it with grounded shields in tact.
The way I see it I have 3 choices if I want to use this cable. Do as you do.
Remove the black layer all together, or run it through PVC, or another
suitable insulator. I am very apreciative of all the fascinating discussion
this thread has received.
----- Original Message -----
From: "Tesla list" <tesla@xxxxxxxxxx>
To: <tesla@xxxxxxxxxx>
Sent: Friday, January 06, 2006 11:09 PM
Subject: Re: HV xray cable revisited


> Original poster: "David Rieben" <drieben@xxxxxxxxxxxxxxx>
>
> Bart,
>
> That's the way that I do it ;^) The capacitance makes the
> exterior of the cable "charged" and it can give a little "shock"
> if handled energized without the braid being grounded. :^O This
> is exactly the way that I feed the power to the base of my
> 15 kVA "Green Monster" coil system, which can be seen
> @: http://dawntreader.net/hvgroup/david/gm.html
> The x-ray cables can be clearly seen leading up to the base
> of the primary circuit in photo # 22 (I believe), the only spark
> shot taken in daylight conditions. I ground the braiding to the
> mains ground back at the pole pig's outer tank ground. Works
> great with no failures of the insulation running up to around 17
> kVAC from the pig when overdriven by a 280 volt input from
> the control panel variac.
>
> David Rieben
>
>
>
> ----- Original Message ----- From: "Tesla list" <tesla@xxxxxxxxxx>
> To: <tesla@xxxxxxxxxx>
> Sent: Friday, January 06, 2006 9:17 PM
> Subject: Re: HV xray cable revisited
>
>
> >Original poster: "Barton B. Anderson" <bartb@xxxxxxxxxxxxxxxx>
> >Hi,
> >If this is the case, then all those coilers running xray cable
> >should be grounding the braid? It seems the proper method to use
> >this cable would be to sweat back (or strip back) the braid (~ 10")
> >on each end and then ground the braid?
> >Take care,
> >Bart
> >Tesla list wrote:
> >
> >>Original poster: Terry Fritz <vardin@xxxxxxxxxxxxxxxxxxxxxxx>
> >>
> >>Hi,
> >>
> >>The black coating is "resistive" not "conductive".  If you ground
> >>one end and run say 60Hz AC across it, the far ungrounded end can
> >>and probably does get to a pretty high voltage.
> >>
> >>For example, if the cable is ten feet long with a resistance of say
> >>10k ohms / foot, then the far end of the cable is 100k ohms to
> >>ground.  Now if we "assume" a capacitance of 10nF in the cable at
> >>60 Hz we have 265k ohms or leakage reactance to the outer
> >>layer.  If you put 15kV into the cable, the outer layer voltage is
> >>100k / (265k + 100k) x 15k = 4110 volts.  So it arcs to ground very
well...
> >>
> >>The conductive outer braid was meant to prevent that by providing a
> >>solid low resistance conductive path to ground which reduces the
> >>outer voltage to very near zero.
> >>
> >>Cheers,
> >>
> >>         Terry
>
>
>
>