Re: MMC warming

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

Original poster: "Malcolm Watts by way of Terry Fritz <twftesla-at-qwest-dot-net>" <m.j.watts-at-massey.ac.nz>

Hi Steven,

On 9 Jun 2002, at 22:47, Tesla list wrote:

> Original poster: "Steven Ward by way of Terry Fritz <twftesla-at-qwest-dot-net>"
<srward16-at-hotmail-dot-com>
> 
> Hi,
> 
> Im just wondering how warm do most MMC banks become.  Im looking for some 
> personal experience answers here.  I ask because my cap gets warm after a 
> bit of running.  I would say that my cap heats up to about 102 degrees(F).  
> Off hand i do not know how many degrees C that is.

About 44.  Conversion from C to F = ((F-32)*5)/9

  My GE caps are rated to 
> 85 C.  I have a feeling that they are not that hot.  Im running my TC with a 
> reconditioned NST(12/40).  My cap consists of one string of 8, GE .068uf for 
> a cap of .0079uf -at- 24kvdc.  I would have to say that my transformer primary 
> gets warmer than the cap, just to give you all an idea of the temperature.  
> I can hold my hand on the cap with absolutely no discomfort.  I hope that im 
> giving a good description of how warm they get.

One string is not enough in my book. I run about 40 - 50Apk/string at 
rep rates to 200 or so with just slight warming, mostly due I suspect 
to the connecting wire and a bit of heat conduction from the gap 
along it. The MMC I'm referring to has lasted well with repeated runs 
of a couple of minutes with variable length rest periods over the 
course of a day. I'm not saying you shouldn't do it, just that I 
wouldn't.

Regards,
Malcolm

> SOOOO... is this acceptable, or am i going to ruin these caps soon??  Ive 
> tried my next best cap configuration, 2 strings of 10 caps for a .0136 cap, 
> but this was much too big, and gave weak performance.
> 
> Also, I was wondering what my perfomance would be considered(good or bad).  
> Heres my specs:
> 
> 12000v ~40ma NST
> 9 gap static RQ type set at a tad bit over 12000v
> .0097 GE MMC
> Twin coil set up: pri, 3.5"inner/12"outer diameter, taped at 5 turns
>        Secondaries are 2.5"x 10" wound with 28g, 2"x12" toroids.
> 
> My best spark so far is 26" with a breakout point, and 22" without a 
> breakout point.  Unfortunately, i could not get my SRSG to work.
> 
> I would like to hear what you all think about my MMC getting warm like it 
> does, because i really would like it to last a while.
> 
> Steve Ward.
> 
> _
> 
> 
>