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Re: More RSG/cap queries
Hi Richie,
Thanks for the clearity. Sorry to reply late, but I've been on
business in NY this past week. I understand your statement of a
41% voltage increase as based on the allowed voltage between each
presentation.
for example:
The voltage at the gap is governed by electrode spacing, charge
time, and rotational presentation time. This will set the bang
size and voltage at the gap assuming the supply is adequate. If
the charge time of the cap greatly exceeds the presentation time,
then the voltage at the gap will be lower, and as a result, the
gap spacing will be narrower to allow firing. Then if a
presentation is missed, the voltage at the gap (assuming we fired
on the next presentation) would be 41% higher than the allowed
voltage between each presentation.
Bart
Tesla List wrote:
> Original Poster: "R.E.Burnett" <R.E.Burnett-at-newcastle.ac.uk>
>
> Bart, and sync-gap tesla coilers,
>
> I while back, when discussing sync rotary behaviour, and
> particularly the result of a missed firing, I suggested
> that the voltage rose to 41% higher than normal at the
> next firing.
>
> This figure was chosen to illustrate what happens for
> two reasons:-
>
> 1) It was very close to what I saw when doing a simulation
> of a missed firing on a particular rotary gap, with a
> particular capacitor, and supply etc.. I really forget
> what the actual components were, but the 41% "extra"
> voltage was fairly typical for that 100 BPS design.
>
> 2) I was trying to make the point that the energy pumped
> into the capacitor leading up to the missed presentation
> is preserved, and is released at the next firing.
>
> If each bang occurs when the cap voltage is V volts, then
> the bang energy will be 0.5 x C x V x V. At the bang
> immediately following a missed presentation I said the
> voltage was 1.41 x V. Since 1.41 is the square root of
> 2 this bang contains 0.5 x C x V x V x 2 energy, which
> is twice the normal energy. ie. It contains the sum of
> the energy supplied leading up to the missed firing and
> the energy supplied for one normal bang.
>
> The actual process is slightly more complex than what I have
> explained above, since a missed firing does lead to some
> variations in bang energies over the following 5 or 6 bangs.
> A missed firing essentially "upsets" the system, but it
> quickly recovers due to regular electrode presentations, if
> the gap is set correctly.
>
> In a sync gap, the TIMING of the rotary dictates the TIMING
> of the bang. Because the charging circuit is resonant,
> each bang energy is a complex function of many, many
> parameters including supply volts, supply amps, capacitor
> size, and THE TIME SINCE THE LAST BANG.
>
> If all is running smoothly then all of these parameters are
> "constant" and the peak capacitor voltage will be even over
> time. If a firing is missed the capacitor has twice as long
> to charge.
>
> The 41% rise was offered because it has been observed in
> simulations and makes the explanation a bit easier (Not much!)
> (I have seen less than 41% and also much more, depending
> on capacitor size, supply current and break rate.)
>
> Also I would like to point out that all this assumes that
> a safety gap doesn't "cut in" before the voltage rises too
> high. And we all use safety gaps in case the phase
> is set incorrectly, or in case there are several adjacent
> missed presentations !
>
> I hope this is a bit clearer, since my previous reply was
> somewhat rushed, (typed while at work !)
>
> - Richie
>
> - In sunny Newcastle