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Re: rolled caps, a new twist

Subject: 
           Re: rolled caps, a new twist
      Date: 
           Sun, 16 Mar 1997 05:10:46 GMT
      From: 
           jim.fosse-at-bdt-dot-com (Jim Fosse)
        To: 
           Tesla List <tesla-at-pupman-dot-com>
References: 
           1


On Fri, 14 Mar 1997 14:24:41 -0600, Tesla List <tesla-at-pupman-dot-com>, you
wrote:


>Kristian Ukkonen wrote:
>> 
>> Just to add - I haven't used any paper in my caps so I can't
>> really comment what the effects are but the idea sounds
>> logical. Someone posted the idea a while ago.
>> 


Chuck wrote:

>What I was envisionning was to use oil impregnated craft paper (only one
>layer thick) between the foil and the 
>plastic.  How does that strike you?
>
All,
        I tried this on 96/09/07.

        I used (about) 1.5" by 12" Aluminum plates with various
thickness of paper and paper-plastic between them all under shell
Diala-X transformer oil and a 2.2lb hammer to weight the construct
down. I measured the C and D with my Leader LCR-740 (unknown
calibration date;(


1 layer of 40lb "kraft paper"  C= 411 pf D=1.25 Breakdown at 2.2kV
2 layers                       C= 334 pf D=0.29 Breakdown at 2.6kV
4 layers                       C= 225 pf D=0.16 Breakdown at 5.95kV
8 layers                       C= 155 pf D=0.18 Breakdown at 14.2kV
12 layers                      C= 128 pf D=0.18 Breakdown at ~17.6kV
                               note: the plates were not overlapping
                                     this cap smoked on the third try
                                     at 18.2kV(ish) 40 LB kraft paper 
                                     measures about 0.005" thick.

                               Please note the nonlinearity in C with
different thicknesses. I think this is due to measurement error, but
I've not retried all the measurements.

On 96/09/27 I tried:

4 mill Polyethylene under oil.  C= 436 pf D= 0.07 Breakdown at 7.1kV

4 mill Poly and 1 40lb paper    C= 328 pF D= 0.07 Breakdown at 8.52kV

2X 4 mill Poly                  C= 234 pf D= 0.89 Breakdown at 17kV

1 layer 42# Cardboard stock (much heavier than kraft paper)  4.2kV
 Given the poor performance, I didn't try any more.

        (I still have a 200++lb tail-end roll of cardboard paper 4'
high by 2' diameter (and this is the left over from a cardboard
company;))


On 96/10/12 I built an 8' long 1 layer 42# kraft paper with 2 layers
of 4mill Polyethylene  Cair = 36nF d= 0.05.  Because of the poor
construction I never immersed it in oil or tested it for breakdown.

I started this testing because I was smoking 0.060" and 0.090" poly
caps at ~14.2kV. Since then I've built 2 0.120" poly caps and NOT
smoked them (yet;) (15 or 20 minutes total operation so far) I've not
pursued this method any further.


        Regards,

        jim