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Re: Success with PP Multi-Mini Cap
Hello Reinhard and all,
You and many others on this list do seem to be getting very good results
using the MMC method. I was only thinking that the wire diameter of the
leads would be thin, unless you are paralleling many. With, potentially,
hundreds of amps going through these I would look for the weakest link. My
commercial Cap from Condenser Products Co. uses 5 or 6 (cant remember
which) individual caps in series, all are designed with extended foil for
low resistance. I also use a series string of Philips Polyprop caps for my
Tube coils, and they work very well. The real proof is in the performance,
though.
I would be interested in what power levels these MMC's have been used at,
anyone use them in a >2KW coil yet? Also a price comparison with available
commercial caps would be interesting. I seem to remember that a MMC of
around 0.02 uFd at, say 15KVAC, would cost around $130 to $160 USD, I
think? What is available on the commercial market for a pulse cap of like
ratings? My Condenser Products cap cost $160, but I understand they no
longer sell for Tesla coil use. My list of cap suppliers is out of date,
anyone got an updated one? Perhaps I could check price ranges.
Regards,
David Trimmell
At 09:56 PM 4/25/1999 , you wrote:
>Original Poster: "Reinhard Walter Buchner" <rw.buchner-at-verbund-dot-net>
>
>Hi Dave, all
>
>
>Dave wrote a loooong time ago:
>
>>Original Poster: David Trimmell <davidt-at-pond-dot-net>
>>I am far from a expert, but the use of MMC for large disruptive Tesla
>>coils, would I think, be more inefficient, due to resistive losses?
>
>Why do you think the MMC would be inefficient (resistive losses)
>in high powered DW-TCs? Most commercial pulse caps are not
>just a single unit (although they are in a single case), but rather
>a string of caps in series (being similar to the MMC construction).
>The really big pulse caps (ĩF range) are built exactly the same
>way the MMC is built (series/parallel configuration).
>
>What I think is most important, in constructing a MMC, is to use
>many (series) strings in parallel to keep the current per string
>low and use high quality caps that have a high dv/dt rating.
>
>My Philips MMC used MKP X2 caps (Series 336/2) rated for
>250Vac. I tried a two string configuration at a low 300W input
>power. I seriesed 35 caps, so the total voltage was well below
>the rated 250Vac (170v/cap). Yet, they died almost
>immediately, even though Philips claimed a 2000Vac/cap/2sec
>test rating. What I didnīt look at was the dv/dt. These caps had
>a very meager rating of only 200V/usec. Thatīs why they died.
>My ERO MMC is holding up quite well and I sure am not being
>kind to it.
>
>
>Coiler greets from germany,
>Reinhard
>