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Re: rolled caps


From: 	Peter Electric[SMTP:elekessy-at-macquarie.matra-dot-com.au]
Reply To: 	elekessy-at-macquarie.matra-dot-com.au
Sent: 	Sunday, September 07, 1997 4:58 AM
To: 	Tesla List
Subject: 	Re: rolled caps

Tesla List wrote:

> From:   Mad Coiler[SMTP:tesla_coiler-at-hotmail-dot-com]
> Sent:   Saturday, September 06, 1997 3:22 PM
> To:     tesla-at-pupman-dot-com
> Subject:        Re: rolled caps
>
> >From:  Geoffrey Schecht[SMTP:geoffs-at-onr-dot-com]
> >Sent:  Saturday, September 06, 1997 9:46 AM
> >To:    Tesla List
> >Subject:       Re: rolled caps
> >
> >Answers to questions:
> >
> >1.) Having a PE-al-PE-al cap will give you about about half of the
> >capacitance of a PE-al-PE-PE-al cap since capacitance is directly
> inversely
> >to plate separation
>
> I think you meant double the capacitance.
>
> >(I think that I understood the question...maybe you
> >should repost with a layer scheme like the one I just used).
> >
>
> I dont think you eactly understood. The actual distance between plates
>
> should stay approximately the same - three thicknesses of 30 mill PE.
> I
> will attempt to show the two chioces I am facing:
> --     plate A
> O    PE 1
> O    PE 2
> O    PE 3
> --    plate B
>
> OR
>
> --     plate A
> O    PE 1
> --     AL (spacer)
> O    PE 2
> --     AL
> O    PE 3
> --    plate B
>
> Since the AL inbetween the PE layers is electricaly shorted from one
> side to another it shouldn't add to the total seperation of the
> plates.
> Another way to see this is that as the thickness or the dielectric
> increases the capacitance goes down. In both models the thicknes of
> the
> dielectric is constent - 90 mills. I just thought that having
> conductive
> plates between might improve the efficiency of energy storage. Having
> the extra plates would allow smaller charges to act on each other at
> closer distances, perhaps allowing it to be better at pulse type
> discharging? Hmmm, is that any clearer?
>

Dear Mad,

There is one problem with the PE,Al,PE,AL,PE type cap. If you get just
one weak point in your PE anywhere in the cap, the voltage will punch
through and wreck your cap. On the other hand, if you have several
layers of PE together, the chances of two weak spots coinciding is
extremely remote.

I think this outweighs any other advantages you might get with the idea.

Cheers,

Peter E.