poly cap death
I posted this about a year ago, but found this paper while running
through my old tesla stuff.
I constructed a poly cap rated at 20kv, .01uF under oil.
I placed this on a tesla coil system running 15kv, 60ma, and
ran them until they passed on. Here is what a noticed :
0:00 Start time, external temperature of PVC 72F, almost room temp.
5:15 Volume of spark gap decreases with simliar effects on spark output.
Drops from 15" to about 7". PVC temp 75F
13:15 Rupture of PVC sealant (RTV); small leak; PVC temp 90F
16:40 Some sort of presurized explosion taking off one endcap, spilling oil
everywhere. Temp off scale.
16:50-30:40 The coil runs with no oil in this cap. Noticable "burnt
30:40 Cap failure due to arc through, probably caused by corona.
For the temperature measurements, I used a fish tank monitor, a plastic
which tapes onto the outside of the glass (in this case PVC). I use one now
the caps I build, allowing me to monitor their temperatures. Usually ranges
I tried this out of curiousity and left over poly, I wouln't have expected
it to last
30 minutes anyway...