Re: capacitance on underground powerlines

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Jim Lux by way of Terry Fritz <twftesla-at-qwest-dot-net>" <jimlux-at-earthlink-dot-net>

Capacitance is one of the BIG problems with underground power lines.  Run a
few km of a line and you've got a dandy distributed inductance/capacitance
setup with all sorts of transmission line (RF wise) problems, particularly
with transients.

For your case, you're probably looking at a few pF (1 inch of twisted pair
wire is roughly 1 pF.. to give a comparison), so the distributed C from the
wire in grounded romex isn't particularly huge.  There are potential
problems reported from folks with high frequency harmonics and standing
waves and/or transients, but, if you design with a factor of 3 or 4
overdesign on insulation strength, that shouldn't be an issue (reflected
waves can give a maximum of a doubling of voltage...))

----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Sunday, December 23, 2001 3:30 PM
Subject: capacitance on underground powerlines


> Original poster: "by way of Terry Fritz <twftesla-at-qwest-dot-net>"
<Tesla729-at-cs-dot-com>
>
> Hey all,
>
> I've been thinking about the underground utility HV power
> lines that I've seen going down a pole in a conduit into the
> ground. I'm aware that if you run a HV conductor with an
> oppositely charged outer jacket that there will be a certain
> amount of capacitance that will be imposed upon the "hot"
> HV conductor,which is directly proportionate to the length of
> the run of  the wire. I realize that this isn't exactly on-topic, but
> this principle would apply to my coil setup, since I run my HV
> transmission line from my pole pig to my coil assembly
> via heavily insulated wire ran thru a grounded flexible Ro-
> mex conduit to protect the transmission line from streamer
> strikes. Anyway, as a non-engineer, i was just curious about
> this issue.
>
> David Rieben
>
>
>