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Re: Transformers, Grounding, Cable questions.



---------- Forwarded message ----------
Date: Mon, 06 Oct 1997 09:46:03 +1000
From: Phil Chalk <philoc-at-ozemail-dot-com.au>
To: Tesla List <tesla-at-pupman-dot-com>
Subject: Re: Transformers, Grounding, Cable questions.

Tesla List wrote:

> ---------- Forwarded message ----------
> Date: Sat, 4 Oct 1997 23:36:18 -0700
> From: Jim Lux <jimlux-at-earthlink-dot-net>
> To: Tesla List <tesla-at-pupman-dot-com>
> Subject: Re: Transformers, Grounding, Cable
> questions.
>
> Re: using RG8 or 213 for HV cable
>
> The voltage rating is, of course, RMS, and also
> allows for some mismatch
> (probably 3:1 VSWR) so you can run a fair voltage
> through it without
> breaking it down.  The grounded outside is a handy
> safety precaution,
> because if the insulation does break down, it breaks
> down to ground, and
> not your hand holding the cable.

Yes, I thought of this.  Even if the insulation doesn't
break down, if the shield is not grounded, it is then
connected to the HV line thru, say, 500pF, and you're
going to feel it if you touch it !

>  Also, the shield makes the E field
> uniform, which helps with the breakdown issue in
> general.
>
> As to connectors, a popular technique is to drill out
> a PL259 and extend
> the center conductor and insulation a few inches past
> the connector. Then
> put a banana plug on the end.  The jack is fabricated
> by drilling out the
> mating SO239, mounting it on some plexiglas drilled
> to accomodate the
> center conductor with a banana jack at the bottom.
> I've used this to 25 kV
> without any problems, and I've seen variations of
> this used at 50 kV,
> although immersed in oil or SF6. At least, the ground
> connection gets made
> first.

I was also thinking of doing something along those
lines.

>
>
> There are, of course, commercially available high
> voltage connectors for
> these sorts of voltages. Pricey, but surplus they
> should be reasonable,. if
> you can find them.  For instance, Caton makes "corona
> free" cable and
> connectors.  There is also the HN, a high voltage N
> connector.

Didn't know of the HN connector, thanx.  Have seen some
HV cabling, connectors, switches, etc on surplus pages
on the web, but naturally all in the US.  These things
seem much less freely available in the land of Oz.
Will keep my eyes open.

>
>
> Good luck,
> Jim

Many Thanx,

Phil.