Re: BIG counterpoise

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

Original poster: "Mark Broker by way of Terry Fritz <twftesla-at-qwest-dot-net>" <mbroker-at-thegeekgroup-dot-org>

I think that this last failed transformer had a couple internal 
problems.  It was quite old, the
LV bushing was cracked to the point where one terminal rotated rather 
freely.  The tar
potting was cracked deeply across the center, probably down to the core.

The leads to the RC filter are about 8 inches long of 14AWG HV wire.  From 
the filter, one
leg is about 8 inches to the main gap, the other about 32 of 4AWG Monster 
Cable.  Not
optimal, but it's what I had to do at the time.  The leads from the filter 
to the safety gap are
both about 12 inches of 14AWG HV wire.

Before the lecture hall remodel, there was a network outlet just below the 
chalkboard.  The
coil was about 6 to 7 feet from the wall throwing 4 foot streamers.  In 
pictures taken during
runs, there is an obvious spark jumping the ~1/8th inch gap between the 
aluminum chalk
trays, less than 8 inches from the network port.  I hadn't heard of 
subsequent computer
problems in the building.  ;)

Mark Broker
Chief Engineer, The Geek Group

 >I've run at 1.5kW or so in a similar environment without losing a
 >transformer. I earther the secondary to what ever was firmly bolted
 >to the concrete (the mains ground also participated to some degree
 >which is why one or two other items with weak/old insulation
 >succumbed along the way ;) I stopped operating in the room I'd been
 >using when performance was increased to the point where sparks
 >threatened to connect with fluoro lights and smoke detectors in the
 >ceiling. The transformer has just a few inches of lead between its
 >secondary terminals and the main coil gap. No filters or any other
 >"protective" gear are included. How long were the leads between your
 >transformer and the gap?
 >
 >Regards,
 >malcolm
 >
 >