Re: HV xray cable revisited

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: Terry Fritz <vardin@xxxxxxxxxxxxxxxxxxxxxxx>

Hi,

What would be ideal... Is to get your hands on this type of stuff...

http://www.okonite.com/Product_Catalog/section2/sheet14.html

Underground, 60Hz rated 15kVac... It is all 150 
amps or greater :o))) :-)))))  DigiKey don't sell 
it, but I bet they "throw away" those 200 foot 
extra lengths...  Maybe E-bay...

Note all the "semiconducting layer 
stuff"...  Don't go messing with that!!!  Just 
use the cables just like they were designed to be used...

"105°C continuous operating temperature. 140°C 
emergency rating. 250°C short circuit rating. Excellent corona resistance. "

This stuff is real "high tech" so don't go 
changing the "system"!!!  You can probably dig the sit to find the details.

http://www.okonite.com/overview.html

But all the corona, HV, leakage, shielding stuff 
has been pretty well figured out over that last 
100 years, so you should not go changing it on a 
"10 second whim"!!!...  The HV cables are darn 
good just as they are and used just as they are 
meant to be used...  Avoid the oil and paper solutions from the past :o)))

Cheers,

        Terry




At 09:51 PM 1/6/2006, you wrote:
> 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