Re: [TCML] Baffle tally (was Secondary Troubles)

[Quarkster <quarkster@xxxxxxx>]

Gary -
   
  Compiling real data about list member's experiences with secondary internal arcing will be interesting and informative. However, I'm not sure if it will "prove" anything about the usefulness of internal baffles.
   
  In my own experience, one of my very first secondaries failed due to internal arcing. The windings were not brought inside the coilform, but the top-load attachment to the coilform was not hermetically sealed. Of course at that time I was very ignorant about the subtleties of good high-voltage construction techniques (cleanliness, surface tracking, corona generation at sharp points and edges, etc, etc).
   
  Later,  I personally saw at least two other secondaries fail due to internal arcing (a friend's coil, and one at a So Cal teslathon). Both were 6" or 8" dia PVC pipe secondaries. I don't recall all the construction details, but the end results were very similar: slowly decreasing spark length, until it was realized that something was very wrong. Both secondaries had rather extensive internal charring and carbon-tracking.
   
  So, I began using baffles in all my secondaries as cheap "insurance" against catastrophic failure, and have never again had one of my secondaries suffer an internal arc. Would they have failed without the baffles? Who knows? However, in Tesla coils that generate arcs longer than the secondary length, I think it's just good design practice to include one or more internal baffles. Theoretically, if the winding nevers passes through the wall of the coilform, and the top of the form is sealed with a cap or plug of some sort, then internal arcing is extremely remote.
   
  I might add that a second reason that I use baffles is that in all my later secondaries I run the top of the winding into the coilform for esthetic reasons, and to mechanically isolate the winding from the connection to the topload. I position one baffle a few inches down from the top of the coilform, and terminate the magnet wire to a standoff insulator firmly bolted to the baffle with nylon screws. Then, another wire is run up through a removable upper baffle, which is what the topload is bolted to. This assures that I'll never break the magnet wire at the top of the coil, even if some disaster befalls the topload or its attachment to the secondary.
   
  I'll send additional details directly to you.
   
  Regards,
  Herr Zapp
   
  

"Lau, Gary" <Gary.Lau@xxxxxx> wrote:
  Realize also that the vast majority of coilers use NO baffles whatsoever, and have never seen an internal flashover (under?). I believe the dire predictions for not following one persons coiling edicts are significantly overstated.

I say this with no hard data before me beyond my own experiences and the general sentiment expressed on this List, but I have to wonder for those that have experienced internal secondary flashover - did the wire enter the interior of the form, or was there some other identifiable cause for the flashover?

Let's take a tally and get some data. I'll volunteer to tabulate and report the results.

For each coiler, please reply and report:

1) Number of secondary coils you have ever built and used WITH baffles, and how many of these had internal flashovers.

2) Number of secondary coils you have ever built and used WITHOUT baffles, and how many of these had internal flashovers.

3) For all flashovers, please indicate if there was any identifiable cause.

Regards, Gary Lau
MA, USA


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