Re: High Voltage Power Arc

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "Mike" <mike.marcum@xxxxxxxxxxxx>

What happened there long story short is that was a test since a 
problem was detected. Sure enough, 1 of the sf6 switches in series 
with the air break shorted so the arc formed in air instead. When the 
arc didn't stop (usually happens when it dead shorts to ground or 
another phase) a breaker up the line manually cut the power to keep 
the whole station from going nuclear (notice the green plasma of 
vaporized copper at the arc points = damage).

Mike
----- Original Message ----- From: "Tesla list" <tesla@xxxxxxxxxx>
To: <tesla@xxxxxxxxxx>
Sent: Wednesday, November 08, 2006 7:43 PM
Subject: High Voltage Power Arc


> Original poster: "Chris Rutherford" <chrismrutherford@xxxxxxxxxxxxxx>
>
> Hi All,
>
> I put this vid on youtube and someone asked me what caused the 
> ark.  I replied but I'm not sure if I gave the correct answer, does 
> anyone have a more accurate description?
>
> <http://www.youtube.com/watch?v=sngLL29LH14>http://www.youtube.com/watch?v=sngLL29LH14
>
> When you get to high voltages i.e. 50KV with lots of inductive load 
> (long wires) its not a case of switching off the power because the 
> current doesn't want to stop. When the circuit is broken a back EMF 
> is generated that breaks down the air and causes an ark. Eventually 
> the back EMF decreases and there isn't enough voltage or current to 
> keep the air in its conducting state.
>
> Thanks
>
> Chris