Re: Series capacitance and how it affects a tank capacitor.

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: Terry Fritz <teslalist-at-twfpowerelectronics-dot-com>

Hi,

At 09:09 AM 2/23/2004, you wrote:
>I've been doing alot of research on the capacitors used in a primary tesla 
>circuit, and even built a  rolled capacitor and a saltwater bottle 
>capacitor. Although I cant see myself dishing out big bucks for an MMC for 
>my first tesla coil, I was doing some reading about homemade capacitors 
>and corona. It never occured to me but when placed in series each 
>capacitor sees a reduced voltage across its dielectric. If I took 4 
>capacitors and placed them in series with a 10 kilavolt 60 hz AC charging 
>current would each one only see 2.5 kilavolts, thus eliminating corona 
>almost altogether.

Yes!  There may be a little corrona at the ends to air just do to the high 
voltage, but adding many caps in series does get ride of that blue plate glow.

>The only problem I can see with this is the series resistance of 
>capacitors. How does this affect MMCs, and how would it affect several 
>homemade capacitors in series?
>

Series resistance will not normally affect the coil's operation.  But it 
can seriously heat up the caps causing failure.  Big high-current 
polypropylene caps are usually fine.  If the caps get hot, they will 
fail.  Peak current of say a thousand amps will destroy full metal film 
caps too.  So we suggest "foil" type caps that have heavy foil in them for 
electrodes instead of the super thin metal film.

Cheers,

         Terry