Re: Started winding today....

Hello,  I must say that I have lost several rolled polly caps :>(   I once
used (3) layers of 30 mill polly for one that I expected to work -at-15KVAC,
But My Resonator chowed on it for lunch. After rebuilding it I have derated
it to 9KVRMS!  At that level It seams quite reliable (yes, this was using a
very respected transformer oil, Shell diala). Not to be a pessimist, but
Tesla Coils will push beyond the envelope of rated values! So I would
suggest keeping DC breakdown values an order of magnitude from your
expected operation point. That is a significant exaggeration, but where do
you draw the line of reliability? I would suggest 90 mills of polly for
10KV, Minimum. It can be done at even 40 or 60 mills, but only with
commercially available equipment-materials, IMHO.


David Trimmell

At 01:47 PM 3/20/99 , you wrote:
>Original Poster: Esondrmn-at-aol-dot-com 
>In a message dated 3/19/99 2:36:00 AM Pacific Standard Time, tesla-at-pupman-dot-com
> - snip -
>>  My stacked plate PE cap is coming on well too, although I only have
>>  enough plastic (60 mils) for one layer at optimum value (10kV -at- 200mA /
>>  50Hz=> 0.06uF) and am wondering if I'm pushing my voltage ratings here -
>>  anyone who has experience with a similar setup, could you give me a
>>  hint?
>>  I also got my variac from Maplin (a UK co) and it looks good, rated for
>>  8A but I would think it should cope with about 10 (it's really heavy!).
>>  So, with a bit of luck, I should be ready for the UK Teslathon in May...
>>  phew, it's harder work than I'd imagined.... much more physical labour
>>  than that piddly microelectronics stuff!
>>  Alex Crow
>>  Happy Coiling All.........
>I have built two rolled poly caps and lost them both due to overvoltage.  I
>also used only one layer of .062 poly originally.  Two .030 layers would be
>much better and three .020 layers would be even better.  In my opinion .062
>poly is only good up to about 9 or 10 kv and will fail at 12 kv.  I think
>three layers of .030 for .090 total is good up to 12 kv (talking ac, rms here)
>and I think you need either four layers of .030 for 15 kv or perhaps six or
>more layers adding up to .090 total.
>What experience have others had in this area?
>Ed Sonderman