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Re: Gap Dwell Times (formerly: Beating Solved)
Hi Skip and everyone,
> > I started from k approx dF/F, and ringup time = 1/2dF so you can see
> > how I derived that. The problem when cutting the gap off (if you
> > could) when Ip is maximum is that with k<1, most of the primary
> > energy is coupled to the primary. I tried doing exactly this with the
> > MOSFET gap and the spikes hit the roof. Virtually none of that energy
> > was coupled to the secondary. The spikes in a real gap would have re-
> > ignited it anyway. I wonder if they have actually tried doing this?
> > I found the ideal dwell to be when the secondary was fully rung-up
> > and the primary had virtually nothing left. Even then, quenching at a
> > primary zero-crossing is a no-no because of spike generation. I sent
> > some photos I took of this process to several people.
> >
> > Malcolm
>
>
> Hi Malcolm and all
>
> This is an extremely interesting thread. I am now getting confused.
> Exactly what do you mean when you say that the secondary was fully rung
> up? Is this when you believe that all of the energy is fully transferred
> to the secondary from the primary? If so, how can you tell?
The secondary amplitude reaches a maximum at the same time as the
primary reaches a minimum. You can see the secondary hit the peak by
monitoring its waveform alone. Being able to monitor both waveforms
simultaneously comfirmed it. If you have any of the Corum's notes you
will find the time domain oscillograms or drawings of them in there.
It definitely happens but you have to give it dwell time = 1/2kFr. Any
shorter and the process is not complete. Any later, and the process
has started to reverse (sec -> prim). To be more specific, the
secondary ends up with the energy at times (1+n)/2kFr where n is an
even number (0, 2, 4,.....) assuming no sparks. Each successive peak
is lower in amplitude than the last due to losses in both primary and
secondary but mostly primary. Typical secondary Q's are so high
relative to primary Q's that to all intents and purposes, Qp is the
determinant of overall system efficiency.
Malcolm