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Re: Transformers, Grounding, Cable questions.
---------- 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. 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.
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.
Good luck,
Jim