MMC Caps

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

Original poster: "Rob Judd by way of Terry Fritz <twftesla-at-qwest-dot-net>" <canska-at-a5-dot-com>

I'm looking to build an MMC and The Geek Group caps look like a good deal to
me. The caps are Cornell Dubilier 942C20P15K, 0.150uF +-10%, 2kV each. See
http://www.cornell-dubilier-dot-com/misc/h942.htm and
http://www.cornell-dubilier-dot-com/film/9422000.htm for more details on the
caps.

I've got 3 NSTs, each 15kv 30ma. So for 15kv 90ma the resonant tank cap
would be 0.0159uF. In theory, one string of 10 of these caps should do it.
The actual capacitance would be .0150 and should take 10 caps * 2kv = 20kv
max (assuming the DC volt rating is acceptable as the AC rating for tesla
coil use). But the peak voltage of a 15kv RMS transformer should be
something like 19kv. Is this pushing the caps to the limit? Is there any way
to guestimate the life expectancy of a string of these caps used this way?

I realize I could use longer strings to tolerate more voltage and add more
strings until reaching the desired capacitance, and also reduce the current
on each string. But I'm not rich, so if just one string of 10 will work for
a reasonable lifetime, I'm inclined to go with that!

Any help at all is appreciated!
Rob Judd - rob-at-a5-dot-com - canska-at-a5-dot-com