Re: Reducing Self Resonance In Rolled Caps

To: tesla-at-pupman-dot-com
Subject: Re: Reducing Self Resonance In Rolled Caps
From: "Malcolm Watts" <malcolm.watts-at-wnp.ac.nz> (by way of Terry Fritz <twftesla-at-uswest-dot-net>)
Date: Thu, 17 Feb 2000 17:24:28 -0700
Approved: twftesla-at-uswest-dot-net
Delivered-To: fixup-tesla-at-pupman-dot-com-at-fixme

Hi Reinhard,

> Original Poster: "Reinhard Walter Buchner" <rw.buchner-at-verbund-dot-net> 
> 
> Hi Ruud, Bill,
> 
> Comments below.
> 
> > Original Poster: rdgraaf-at-ocenl.nl
> > Hello Bill,
> snip
> >
> > That's exactly the way I'am gone make my new cap's. I'am very
> > confident about this approach. The current will (if cap is connected
> > well) flow from both directions into the cap and will be almost
> > immediate on the right spot, so the inductance will be defined by
> > the lenght of the cap not by the length of te foil! I have a large
> > amount of ldpe of 0.125 mm (5 mil) and I will put the rolls into PVC
> > pipes and close them with massive metal discs with a screw-hole
> > in the middle of it (I need still to determine where to get these
> > complete and ready). I hope I do not have to use oil, by connecting
> > them serial.
> 
> I hate to blow your dreams, but been there, done that => doesn´t
> work for long. Building a rolled poly cap (whether it be extended
> foil design or not) and getting it to run w/o oil WON`T work. Period.

It can be made to work. I produced a design which increases the 
creepage distance between plates to as good as infinity. The design 
was published in Electronics World in 1995. However, air running 
gives the caps a limited lifetime which can be quantified quite 
accurately (I got about 40 minutes total runtime before the plastic 
gave up in each cap I built).  
         I agree that MMCs are the way to go however.

Regards,
Malcolm

> I went through many experimental stages of this design (you might
> want to search the archives) before I started designing (together
> with Terry) the MMC and it just doesn´t work out very well. You´ll
> be mighty surprised how far 7-15kV can creep along the surface
> of a dielectric (PE in this case). It is many fold the distance it will
> jump in free air. My advice: save your $$$ and jump on the MMC
> bandwagon. I don´t think anyone who has, has been dissatisfied
> with the results :o)) I will also agree (did some experimenting on
> this too) with Gary that the difference in TC output between the
> extended foil and *normal* design isn´t very high.... and the MMC
> has all the commercial pulse cap design already built in, w/o that
> huge price tag attached ;o))
> 
> dead rolled poly = heavy and messy doorstop
> dead MMC = easy to repair
> 
> Coiler greets from Germany,
> Reinhard
> 
> 
> 
> 
> 
> 
>