Re: Racing sparks

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: Bart Anderson <classi6-at-classictesla-dot-com> 

Hi Tom, Gerry,

I don't completely understand each mechanism either, but I view the racing 
sparks incident due a couple situations:

1) The voltage stress somewhere along the length of the coil is high enough 
to breakout before the charge on the top terminal is capable.

2) There must be node(s) or areas along the length of the secondary which 
are pronounced enough to cause the initial breakout a direct path down the 
secondary. And with that, the further the arc creeps down the secondary, 
the greater the difference in potential becomes. This why I think most 
racing sparks will typically run the full the length of the coil. However, 
I don't think this will occur each and everytime. The arc may make an 
abrubt turn outward part way down.

I believe "any situation" which might cause stresses in unwanted areas of 
the coil are capable of producing the same affect. Tuning, coupling, and 
topload affects on current distribution along the length of the coil are 
three areas of adjustment to reduce these stresses in both 1 and 2 above.

Someone else may have a better theory.
Take care,
Bart

Tesla list wrote:

>Original poster: "Gerry Reynolds" <gerryreynolds-at-earthlink-dot-net>
>
>Hi Tom,
>
>You might want to make sure the coil is in tune.  I got racing sparks on my
>3.5 inch coil when I went from a 6k/30 to 12k/30 and had to hafve the
>capacitance.  I ran out of primary turns to compensate and got racing
>sparks.  Added more copper and retuned the coil and racing sparks
>disappeared.  I have heard that out of tuned coils can cause this, but I
>don't think I can explain why.  Maybe someone else can.
>
>Gerry R
>
> > Original poster: "Tom Luttrell" <tom-at-pwrcom-dot-com.au>
> >
> > Unfortunately it's too good. After about 5 to 10 seconds of operation I
> > start to see racing sparks on the secondary.
> >
> >
>
>
>
>