Re: Triggered gaps vs Sync rotary

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

Original poster: "Jim Lux by way of Terry Fritz <twftesla-at-qwest-dot-net>" <jimlux-at-earthlink-dot-net>

> >
> > One wonders why the SRSG seems to have better performance?  What aspect
of
> > the triggered gap is the problem? On-resistance? Quenching?
>
> I got the same spark length with a triggered gap and with a
> SRSG on my TT-42 TC, at about 700 watts.  I suspect that
> at higher powers, the triggered gaps have poor quenching,
> or may heat up and misfire, etc., unless they have some
> sort of cooling/quenching airblast, such as a typical static
> gap would probably require.
>

I was thinking that while an air blast can fix the quenching and cooling,
with a triggered gap, you're still looking at a longer arc path (since it
has to be long enough to hold off the primary voltage before firing).  A
rotary can have a very short gap for the time while the arc is burning (and,
in fact, probably actually gets shorter during the arc, as the electrodes
come closer to each other).

A few extra hundred volts drop in the gap could have a very large effect on
overall efficiency, particularly for a high powered coil where the primary
current is high.  In a 1000A arc, the voltage drop is something along the
lines of 10kV/meter (or 100 V/cm), and for the probably much lower currents
in a TC, the drop is probably higher.