More OLTC II Action

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

Original poster: "Steve Conner" <steve.conner-at-optosci-dot-com> 

Hi list

I have sorted out the power supply hassles on my OLTC II and done some more
runs. I found what was causing it to shut down seemingly at random. The
secondary was flashing over (round the back where I couldn't see it) and
that was triggering the crowbar protection circuit. Almost any arc to ground
triggers it, so that is something I still need to fix. But I think I know
what's causing it. Anyway, the power supply isn't breaking down any more. (I
scrapped the short circuit protection unit and rebuilt it using a different
type of IGBT, and a driver circuit with UVLO.)

http://www.scopeboy-dot-com/tesla/ladderarc.jpg
43" arc to a grounded ladder. ~850V, ~350bps. 6 second exposure, but
protection triggered ~1 sec into exposure.

http://www.scopeboy-dot-com/tesla/ladderstream.jpg
Streamers to air. One very dim one reaching towards the ground is ~53". I
can't even see it on this monitor :( 950V, 350bps. 6 second exposure,
protection triggered again this time.

For some alternative approaches to high power SSTCing, be sure to check out
the DRSSTC:
http://www.hot-streamer-dot-com/chunkyboy86/

And Gary Johnson's base-driven beast:
http://www.eece.ksu.edu/~gjohnson/

Which is best? You decide.

Steve Conner