# Re: Now, How does a coil really work??

```In a message dated 1/26/99 5:22:19 PM Pacific Standard Time, tesla-at-pupman-dot-com
writes:

> "Bert,
>  I agree, it was a good question and a good answer. So many times I've
>  seen
>  coilers using static gaps but they always assume 120bps (60hz) or
>  100(50Hz). Most
>  really don't know and assume this. I'm curious how often we can fire the
>  gap
>  during a cycle? Is there a major limitation beyond electrical or
>  mechanical
>  stresses? My first thought at this I came up with 4 x main freq., but
>  the
>  more I
>  think about this, I bet the gap could be fired quite a few times during
>  a
>  cycle.
>
>  Bart"
>
>  	Not sure what you mean by "how often can we fire the gap....", but the
>  answer is many times per half-cycle of the line frequency if you set the
>  gap small enough. On the other hand, if you set the gap wide enough (and
>  your transformer doesn't short), or if you reduce the primary voltage to
>  your transformer, you can get the gap to fire once every few cycles if
>  the capacitor is series resonant with the transformer leakage
>  inductance.  (This is sometimes called "the matched capacitor".  You can
>  get all sorts of chaoatic behavior too.
>
>  	I've run a number of simulations which produce results which agree very
>  well with my observations, considering the simplifications involved.
>  Should collect some of the predicted waveforms and have them ready to
>  send to anyone who is interested.
>
>  Ed
Another consideration is quenching.  If you start out with say 12 kv at 60 ma
for a power supply, then steadily add increased current capacity, you will get
to a point where a static gap will fire at a higher and higher rate (bps) and
then will not quench - it will stay fired.  Then you can add vacuum or air
blast and go up to a new higher current limit and finally that gap will not
quench either.  Then you finally will need to go to a rotary gap.  And, if you
continue this saga, I suppose the rotary will need to get larger (contact size
and wheel size) as more current yet is added.

Ed Sonderman

```