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Re: BIG resonance! - thoughts...
" You "can" run the system in the resonant charging mode, but it
sounds
like you are now too far into the resonant region for this to be a good
idea.
A little resonance may not be too bad but if you are in the 6 to 8 times
region, you are risking a lot... You are very lucky that your "quick"
45 volt
input test did not blow something!!! When in doubt, it is far better to
turn
the variac DOWN, not up! :-)) The currents in this case are also much
higher
than expected causing even more problems. They also follow the resonant
rise
rule..."
Can't see anything wrong with operating at resonance, if the gap
spacing is safe. When the thing is sparking the transient responce of
the transformer is quite different from linear operation. I've run a
number of simulations in Electronics Work Bench which duplicate the
experimental results I've observed, and will assemble the waveforms into
a mailable form at some point. Depending on the breakdown voltage of
the capacitor and the actual capacitance value you can get all sorts of
interesting effects, particularly when you diddle the primary voltage
with a variac. As an example, I've observed a condition where, with
approximately resonant capacitance, at low voltage on the primary there
was one spark about every 8 cycles of the power line, and even lower
rates would probably be possible with careful adjustment. The
simulation shows the same effect. As voltage is applied it takes
several cycles for the secondary voltage to increase to the gap
breakdown voltage (after all, the Q is reasonably high); when the gap
breaks down the capacitor is discharged and the whole process starts
over again. With some gap settings and primary voltages chaotic
behavior is quite pronounced. For example, the gap may fire thre or
four times on one half cycles, one or two on the next, in a non-periodic
fashing.
Ed