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Re: Success with PP Multi-Mini Cap
Hello Richard, all
>Original Poster: Richard Hull <rhull-at-richmond.infi-dot-net>
>
>In some of our very earliest video reports from back in 1989 and 90 we
>show how to make two different type of Tesla caps made up with
> series strings of smaller polypropylene units under oil.
>They work fine until you start throwing th' coals
>to things. Best for beginner systems under 2KW.
Regarding your last statement: Why? I noticed that you have mentioned
this a few times, but quite frankly, I donīt understand it and I canīt
say
I can agree with you.
How (general scheme) were your MMCs constructed and why did
you run them under oil? As I already pointed out to Ed Sonderman,
the oil does nothing to help the MMC survive. I canīt agree with
your last statement either (unless you used a single and very long
string). If you use many series strings in parallel, the total primary
current is divided up (pretty) evenly across all strings. Quick
example of what I mean: Letīs say you are running a single string
at 400W. Letīs further suppose the primary current is 40A. (Iīm
just using these values for convinience). Now, if I upgrade my
PSU to 4000W and design my MMC not as a single string, but
as a 10 string device, I still get (roughly) a current per string of
40A. So why should this MMC fail? I know the current wonīt go up
(from one xformer to another) in such a linear fashion, but the point
Iīm trying to make is another: If you keep the current PER series
string low, than it doesnīt matter if you use a 500VA or a 5kVA
xformer.
The MMC has another advantage that no other homebrew cap
has: It voltage versatility.
Example:
-------------
Xformer: 7.5kV
Needed cap: 10nF
Caps: 10nF-at-1kV each
Array: 10 strings of 10 caps each
Joules: 0.5*10606^2*10*10^-9=0.56J
Now letīs say I find a 15kV xformer. All I have to do is rearrange
the caps for 5 strings of 20 each. The total capacitance drops
to 1/4 of the original value. However, due to the square
function in the Joule equation, the Ws stay the same.
5 strings of 20 caps = 2.5nF.
Joules: 0.5*21213^2*2.5*10^-9=0.56J (same as above)
Of course, I COULD do the same thing with a rolled PE, but
I would have to build additional ones. The MMC setup allows
me to simply rearrange things, so that they fit. Meaning my
"work" is limited only to a re-wiring scheme (easy and
quick to do).
Coiler greets from germany,
Reinhard