Re: X-ray HV cables

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "David Rieben" <drieben@xxxxxxxxxxxxxxx>

Hi Mike,

I assume that you're referring to that black tape
looking material that's spiral wound around the inner thick red 
rubber insulation and between it and the grounded metal "mesh" that's 
immediate-
ly underneath the outer rubber or plastic sleave.?
Yes, this material is often (but not always) carbon
impregnated to make it semiconductive. I'm not exactly sure why some 
manufacturers make this layer of material conductive while others don't,
but that has been my observation. Other than this
minor difference, the cross section of all x-ray ca-
bles that I have seen are basically the same. Since
the tape in yours obviously IS conductive, all that you will have to 
do is simply peel that tape back along with the grounded mesh 
sheathing by several inches from the
end and that should solve your problem ;^) BTW,
your x-ray cables are most likely rated at 75 kVDC
to ground which means that they can be used with a 150 kVp x-ray 
transformer. Most x-ray transfor-
mores are internally wired just like an NST with the
HV secondary coil midpoint grounded, so a 150 kV
output would be split from -75 kV to +75 kV on each
"side" of ground potential. Therefore the cables would
only need to be rated for 75 kV to ground. Once properly
trimmed, these cables can EASILY handle the potential
of any NST or sub-30 kVAC pole pigs or PTs without any flashover 
dangers, assuming that the rubber insulation
isn't cracked and/or dry rotted!
David Rieben

----- Original Message ----- From: "Tesla list" <tesla@xxxxxxxxxx>
To: <tesla@xxxxxxxxxx>
Sent: Tuesday, November 01, 2005 1:52 PM
Subject: X-ray HV cables


> Original poster: "MIKE HARDY" <MHARDY@xxxxxxxxxx>
> I got a 150 KV rated xray HV cable. Per D.C.'s recomendations, I 
> stripped the outer jacket, removed the braded shield, and cut off 
> the 'candlestick' ends. I then reterminated to acomadate the 
> connections as I needed. The outer jacket (what was under the shield 
> CONDUCTS !! It nicely shorted the hv output of my PT! What's going 
> on here? Is this normal? I placed the hv leads of a 15kv nst at 2 
> points on the insulation away from the conductor, and it happilly 
> arced! Any thoughts would be apreciated.