Re: MMC or Maxwell? Which is better?

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

Original poster: "Robert Jones" <alwynj48-at-earthlink-dot-net> 

Hi,

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From: "Tesla list" <tesla-at-pupman-dot-com>
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Sent: Saturday, February 28, 2004 9:17 AM
Subject: Re: MMC or Maxwell? Which is better?


 > Original poster: Mark Broker <mbroker-at-thegeekgroup-dot-org>
 >
 > Actually, caps would have to be added in series as well....
 >
 > In my MMC and TC designing efforts in the past, I have found that smaller
 > NST coils tend to stress MMCs more with respect to instantaneous
 > current.  The larger TCs, particularly with higher break rates, tend to
 > have a lower peak current per string, but a higher RMS current per
 > string.  The official peak current rating of the 942C20P15K is 432A per
 > cap, which is fairly easily exceeded by a factor of 2 or 3 on an NST coil
 > (single string, low primary inductance).  On the other hand a 5kVA PDT
coil
 > will require maybe 5 strings, increasing the peak current rating to
2100A -
 > considerably higher than the peak current JavaTC gave me the last time I
 > "designed" a ~5kVA TC with it.

Are you suggesting that the pk current rating can be exceeded by a factor of
3 and still have reasonable TC life.

The pk current in a cap of a MMC is a function of the charge voltage and the
frequency.
So small coils (higher f) tend to have higher pk currents per cap.
The max frequency(423Apk) assuming 2000v is 230kHz.
If the 3 factor can be assumed that pushes the max f to cover most coils.

The rms current per cap is a function of the break rate, charge voltage and
k(inverse) and quench time.
Except at kHz break rates the rms of CD cap will not be exceeded.

I doubt that there would be a significant performance difference between CD
and Maxs.
Power loss in both cases is small compared to say gap losses.

Bob