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RE: Stacked capacitor (fwd)

Subject: 
            RE: Stacked capacitor (fwd)
       Date: 
            Tue, 15 Apr 1997 08:15:09 +1200
       From: 
            "Malcolm Watts" <MALCOLM-at-directorate.wnp.ac.nz>
Organization: 
            Wellington Polytechnic, NZ
         To: 
            tesla-at-pupman-dot-com


Hi William,
            What you describe is the first configuration I came up 
with as a capacitor design for air operation. Using S shaped 
dielectric makes it a pig to roll. Also, you can't eliminate the
border at the edge of the plates as that halves the insulation 
thickness at that point.

>   From: 
>         "William Noble" <William_B_Noble-at-msn-dot-com>
>     To: 
>         "Tesla List" <tesla-at-pupman-dot-com>
> 
> 
> I've been thinking about making a similar capacitor - but it seems to me
> that 
> the insulating material can be placed in an "S" pattern between the
> plates so 
> that there is no need for a border on two of the sides (let * represent
> the 
> insulating dielectric):
> 
>                                                           *****
>   --------------------------------------------------- *
>  | *********************************************
>  | *-----------------------------------------------------|
>  | ********************************************   |
>  |---------------------------------------------------*   |
>    ********************************************
> and so on.  I havent tried this yet - but it seems to me that for a flat 
> capacitor it should be an improvement.  Further, I've been thinking that
> by 
> using copper plates you can solder bussbar to the plates giving them
> superior 
> current capacity over an aluminum equivalent.  I haven't quite convinced 
> myself that I know how to make a good connection to aluminum short of
> welding 
> another piece of aluminum to it.

In the end I used this configuration:

      ***************************
   -----------------------------*
      ***************************
         ***************************
         *------------------------------
         ***************************

with a stack of plates and rolled it up. They are reliable for 
moderate voltages but don't last as the ozone attacks the plastic. 
Oil-filled is the only way to go for longevity. Nine times out of ten 
they eventually fail at a plate edge where the strongest corona is 
formed. The caps are low-inductance but rather lossy.

Malcolm