Re: [TCML] TC for Australia's Got Talent

["Peter Terren" <pterren@xxxxxxxxxxxx>]

I did a show for the first heats of the TV show "Australia's Got Talent" 
with my 18 inch TC and 7-8 foot hot sparks.
It was done in a massive pavilion with a 50 foot ceiling. The crowd, judges 
and all the video cameras were behind plastic barriers. After much 
consideration on the day, I finally decided to go with a 9 foot high metal 
frame surround with down wires at intervals.  The concrete floor was covered 
for 20 - 30 m with builders foil with multiple links to the TC earth and 
framework. There was no direct link to the pavilion building earth but there 
may have been through some expansion joint covers. The mains earth was kept 
separate. I ran the ARSG gap and blower gap motors through back to back arc 
welders as isolation transformers. There was no clear return path for 
capacitative charges induced into the 50 foot ceiling.  There was no ground 
available for over 100 m that was not a mains ground.
Using this method of a "Faraday cage" open at the top, there was no evidence 
for interference with sound or cabled video cameras. It was close enough to 
have sparks within perhaps 10 feet of the judges (it could have safely been 
a lot closer with my design - tested to within 2 feet).
Draw was assumed to be around 75A from two paralleled 32A 250V outlets (= 
18kVA).

The grounding with downwires from the frame allowed confidence in preventing 
capacitative charges appearing on equipment and operators. It is my belief 
that this is more important than RF interference.  Certainly this was as 
close as my operators have been and no tickle from holding the variac!

http://tesladownunder.com/Media.htm#AustraliasGotTalent




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