RE: Source of smoke found

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

Original poster: "Lau, Gary by way of Terry Fritz <twftesla-at-qwest-dot-net>" <Gary.Lau-at-hp-dot-com>

Hi Weasle:

I would keep the pig's case connected to the mains-ground, but definitely
connect the presently grounded HV terminal to RF ground instead.  You don't
want anything on the HV side to cause current to flow through the
mains-ground, and this is what happened.

Gary Lau
MA, USA


Original poster: "J. B. Weazle McCreath by way of Terry Fritz
<twftesla-at-qwest-dot-net>" <weazle-at-hurontel.on.ca>


Hello Coilers,

Further to my post about the primary to strike rail arcing, I did some
more sleuthing this morning and discovered the source of the smoke and
burning smell...my contactor box!  The entire inside of the box had a
black, sooty deposit all over it and there's a hole blown in the rear
of the receptacle that the variac plugs into.  Obviously a major short
with resulting carbon tracking, but what caused it?

My pig has one of its high voltage terminals grounded and hence I have
that lead connected to the inner end of the primary and one side of
the gap.  The other lead from the high voltage bushing connects to the
other side of the gap and to one terminal of the MMC.  The tap point
on the primary connects to the other MMC terminal, which completes the
primary circuit.  Because the one high voltage terminal is grounded to
the pig case, it's effectively connected to the ground (green) lead of
the power cord.

My secondary ground is a separate lead running to two ten foot rods in
the damp soil outside the shop.  The strike rail is connected to it as
well, meaning that the arc-over from the outer primary turn to the rail
was seeking ground via another path.  Should I connect the case ground
of the pig to the secondary ground and not use the green wire in the
power cord except for grounding Corcom filter case?

Any and all comments are welcome.  I don't want this happening again
to my rebuilt contactor box!

73, Weazle, VE3EAR/VE3WZL
G-1#1214

Listening: 147.030+ and 442.075+
E-mail:    weazle-at-hurontel.on.ca
           or ve3ear-at-rac.ca
Web site:  http://www.hurontel.on.ca/~weazle