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Re: Halloween night, CP cap {con,de}struction

HI Chip,
          Congrats on an exciting run and commiserations on the cap 
failures.

> Original Poster: Chip Atkinson <chip-at-pupman-dot-com> 
> 
> Greetings all,
> 
> 
> Tonight was both the best and most expensive coiling night I've ever had. 
> I finished a 10" diameter coil a few weeks ago and got it running well
> enough that I can start to tinker with it.  In other words, it isn't going
> to self destruct in a few seconds.  
> 
> I put the coil and cap/gap box on top of my garage so that everyone could
> see it tonight.  After a minor hiccup, I was able to get the thing running
> well.  I even got some runs about as long as you see Richard Hull getting
> on his tapes.  After a particularly long run, I got that strange sound of
> the rotary gap firing but no output.  In about as much time as it takes to
> notice and wonder what's going on, I hear a loud BOOM and flames shoot out
> the sides of the box.  I shut down and climbed up to see what happened.
> 
> My Condenser Products 0.025uF/20,000V tesla coil cap blew up!  I'm glad it
> was on the roof because it could have really hurt someone.  
> 
> Luckily, I had another CP cap and decided to try it too, since the coil
> was going well and perhaps it was a fluke that it blew up.  Nope!  The
> second one blew, and even more violently than before.  
> 
> I disected the remains of the caps and it was very interesting.  They
> consist of four rolls of plastic and aluminum foil.  The ends of the plate
> stick out so that the ends of the roll has a sort of "fuzzy" look to it.
> The aluminum foil is very thin, much thinner than you can buy for food
> use.  The dielectric is probably polypropylene, but it is only plastic, no
> kraft paper.  The rolls were also interesting in that they were basically
> two caps in one.  They had two layers of plastic and three pieces of foil:
> 
>   ++++++++++++++++++++++++++ 
>     =====================
>   ++++++++++++++++++++++++++
> ==========     ==============
> 
> The ='s are foil, and the +'s are plastic.  Note how the ends of the lower
> part of the foil sticks out past the edge.  This is basically two caps in
> series.  Very interesting.  Also interesting is how there is nothing
> between the gap on the bottom plates.
> 
> In conclusion, the excitement of having the coil work well for once and
> for a long time has outweighed the loss of the caps.  I'm going to expand
> the under coil box to accomodate four home made rolled caps and am pretty
> well through with commercial caps.
> 
> BTW, I estimate that I was running at about 500 breaks/sec (6 electrodes
> turning at about 5000rpm, and somewhere between 10,500 and 11,500 volts,
> based on the variac settings.  (Didn't get to check on the voltage meter
> because of the excitement. :-)
> 
> Chip

Just for the record, CP stated on the outside of my units that they 
are rated for 120BPS max.

Malcolm