Re: Why no corona? (fwd)

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

Original poster: Tesla List Moderator <mod1-at-poodle.pupman-dot-com>



---------- Forwarded message ----------
Date: Thu, 19 Sep 2002 14:32:41 -0600
From: Nick Andrews <nicothefabulous-at-hotmail-dot-com>
To: tesla-at-pupman-dot-com
Subject: Re: Why no corona?

There are a couple of HV lines across GA from Atlanta south toward 
Jacksonville that are >1MV.   Most are about 500kV, though.  We installed 
several hundred miles of fiberoptic cable under them on the Level 3 
Communications job.  The cable was what's called "dielectric" cable, i.e. no 
steel armor, as is commonly used.  However, since there's no conductive 
layer to inject a signal for locating the line, we also pulled a #6 copper 
wire into an empty duct for this purpose.  We grounded the tracer at every 
handhole, about 2500-2600' apart.  Even so, when you had it disconnected 
from ground, it built up as much as 400V static charge in just 2500' of 
wire, buried 4-8' underground!  When discharged, it could rebuild it in as 
little as 7min or so.  So we had the guys wear lineman's boots and gloves 
when working with the tracer line.

Nick A


>From: "Tesla list" <tesla-at-pupman-dot-com>
>To: tesla-at-pupman-dot-com
>Subject: Re: Why no corona?
>Date: Mon, 09 Sep 2002 20:53:13 -0600
>
>Original poster: "Christopher Boden by way of Terry Fritz 
><twftesla-at-qwest-dot-net>" <chrisboden-at-hotmail-dot-com>
>
>They actually do have problems with corona I would guess. I know for a fact
>that I've heard the familier hiss on more than one occasion while standing
>under a HV line. Also remember that the really high voltage lines are 
>rather
>rare. Sure, there are transmission lines that run up to 768kV or better.
>I've even heard of megavolt lines (anyone know where these are?) that run
>across deserts. But the vast majority of power lines are small, under
>14.4kV. Also, while we run at 400kV regularly, their 400kV would act a lot
>differently. Even though the voltage is the same, the frequency is a lot
>different. And weather it's a megavolt line across a desert, or the 120 in
>your wall outlet, it's ALL at 60hz. Things get freaky with frequency.
>
>I've heard corona on humid or rainy days, and in the winter (when it's
>really dry) as well. I've seen the long, graceful bends in HV Buss at
>substations (corona likes sharp points). So my guess would be that they DO
>have problems with corona, you just don't notice it much because it's very
>quiet compared to the usuall surroundings, and it's not bright enough to
>attract attention, in fact, in broad daylight it's difficult to see a 6' 
>arc
>from a TC, a little purple glow, never.
>
>
>
>
>
>Christopher "Duck" Boden Geek#1
>President / C.E.O. / Alpha Geek
>The Geek Group
>www.thegeekgroup-dot-org
>Because the Geek shall inherit the Earth!
>
>"He had that rare weird electricity about him--that
>extremely wild and heavy presence that you only see in
>a person who has abandoned all hope of ever behaving
>normally." --Hunter S. Thompson
>
> >Original poster: "Richard W. by way of Terry Fritz <twftesla-at-qwest-dot-net>"
> ><potluck-at-xmission-dot-com>
> >
> >Hi list,
> >Was wondering.
> >Power transmission lines, before a substation, can carry from 100Kv to 
>more
> >the
> >600Kv. So why no corona? Seems we battle corona quite a bit at much lower
> >voltages. <shrugs>
> >
> >Rick W.
> >Salt Lake




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