Re: Gap losses, was electrode holders

[FutureT-at-xxxxxxx (by way of Terry Fritz <twftesla-at-xxxxxxxxxx>)]

In a message dated 11/16/00 2:22:15 PM Eastern Standard Time, 
tesla-at-pupman-dot-com writes:

> Original poster: "sundog" <sundog-at-timeship-dot-net> 
>  
>  Hi all, David,
>  
>   Is there a website we all might find a picture of this unique gap?  It
>  sounds like a great idea, and I know where to obtain used grinders fairly
>  cheaply.
>  
>    I like the idea of running 2 discs, as your dissapation-per-gap will be
>  lower.  Gap spacing would be closer to keep the firing voltage consistant
>  and sane.

Shad,

Well even with one disc, the electrodes can usually be run pretty
close, esp if the tips are rounded a little to reduce the mechanical
dwell time.  I run my electrodes at 0.010" or so spacing.  Yes, the
dissipation per gap will be lower, and that's a plus.
>  
>    A question on gap losses, would the multiple gaps affect gap losses any?
>  Terry and others have shown that more gaps tend to quench better than a
>  single gap (lower dissapation per gap would decrease temp rise and local
>  ionisation, keeping a more consistant firing voltage vs a 2 electrode gap
>  where most of the losses are burned off in a single hotter spark.

More gaps quench better to a degree, but it's not clear if this will
really help the spark length, but the gaps will run cooler.  It seems to
depend on the system too.  I've compared 12 point rotaries, 8 point
rotaries, 4 point rotaries and 2 point rotaries, and I've seen no difference
in the spark length, and not much difference in the quench, but quench
is a little better with more points (series rotary gaps).
>  
>   A question on quenching, also.  On the first notch, the primary dumps a
>  goodly chunk of energy into the secondary, which resonates and makes a HV
>  spike.  I assume the presence of a streamer affects quenching by depleting
>  the energy in the secondary.  If the coil does not break out, or the
>  streamer load isn't that great (just a streamer, not a strike to an 
object),
>  more energy would be available to push back into the primary, inhibiting
>  quenching, right?

Yes, with no streamer, and no load, the energy keeps transfering 
back and forth between primary and secondary a lot more times,
which makes the quenching much worse.

John Freau

>                                           Caio
>                                               Sundog
>  -----Original Message-----