Peak Primary currents (was Re: MMC bleed resistors)

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

Original poster: Mark Broker <mbroker-at-thegeekgroup-dot-org> 

Actually, if there are more strings of MMCs and the same overall 
capacitance is maintained then the current is shared more or less equally 
amongst the strings.  So two strings will have half the current of a single 
string.

A TC with a freq of ~200kHz and driven by a single 12/60 NST with an LTR 
static gap coil using the Geek MMC "recommended design" of 1 string of 8 
caps gives a peak primary current, according to JavaTC, of 430A.  That's 
*right* at the spec sheet's limit of 432A!  Using a secondary with a higher 
resonant frequency will only increase the current beyond the rated limit.

This is why I stated last week that I feel smaller TCs tend to be more 
stressful on the MMC, with respect to peak current, than larger 
TCs.  Although the peak currents do go up with larger TCs, the MMC 
generally has more strings to share the higher current.

Regards,

Mark Broker
Chief Engineer, The Geek Group



On Sat, 13 Mar 2004 12:16:10 -0700, Tesla list <tesla-at-pupman-dot-com> wrote:

>Original poster: "Robert Jones" <alwynj48-at-earthlink-dot-net> Hi,
>
>  > Original poster: "Virtualgod" <mike.marcum-at-zoomtown-dot-com>
>  >
>  > that's only a few microns thick, unless it's some tiny coil running with
>low
>  > pulse current (might work with a 4/20 nst with a high primary L, but I
>would
>  > expect no more than 4-5" with ceramic caps). They make nice multiplier or
>  > filter caps though.
>  >
>
>Yes its easy to imagine a small coil has a lower peak current per cap.
>Actually the peak current in a cap of an MMC  is proportional to charge
>voltage on that cap and frequency of the primary.  So in general because
>small coils have a higher frequency than big ones a small coil will have a
>high peak current.  For the same reason doubling the number of strings does
>not reduce the peak current in any of the caps.  The peak current can only
>be reduced by reducing the charge voltage and or frequency.
>
>Bob