[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: MMC Design and Wiring

Original poster: Terry Fritz <vardin@xxxxxxxxxxxxxxxxxxxxxxx>

Hi Mark,

At 03:21 PM 12/19/2005, you wrote:


All:

Should an MMC be wired so that the current flows in opposite directions
in adjacent capacitors in a series string(to reduce inductance in the
primary circuit)?
Seems to me this was discussed before, but I can't find the reference.
Any idea how significant this inductance(from the capacitors) is?
Yes, that does help reduce the 'stray" inductance of the capacitor string. I would make a wild guess at like 0.5 to 1 uF per foot. I have never really worried at all about it. The wiring between the caps, primary coil, and gap is probably much more significant. For my DRSSTC the primary is a little too small, so the 12 added feet of primary wiring to the caps and H-bridge sure helps ;-)) I would guess about 7uH... 



My Primary has ~25uH inductance and my tank cap ~40 nF.

I am planning to use the CDE 942C2 series.  For me I will need (3)
strings of (10) in series for a 20KV rating to handle my DC based MOT
power supply with charging reactor.  Can I place the strings in close
proximity to one another without danger of arc over between strings?
I would be real careful of that!!! The casing of the caps (just a little tape) is virtually worthless at big voltages. Of course, the voltage should be uniform up the strings too... I never felt real "lucky" about that stuff though... 


Adjacent capacitors in the next string would theoretically be at the
same potential.

If I build it with extra unused strings(for future use) then I have
danger of arc over to the unused string if I don't leave clearance,
right?  Any idea how much clearance I need?


At least one inch.



With all the abuse us homemade cap guys are getting, I figure I'd try an
MMC to find out what all the hype is about.  My parallel plate mylar and
aluminum caps have worked great so far, but if you guys are right, I'll
eventually destroy them.


I will look forward to hearing of how well they compare!

Cheers,

        Terry



Mark Dunn