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Re: Cap Failure
Re"
"Well boys and girls, I believe I know why they blow. Run out to you
garage, shop or lab and look closely at the printing on the cap casing.
Yep, the pvc casing is only rated at 10 kvac. I may assure you that
the inner rolls are intimately in contact with the inside of the
casing. When I closely examined my casing there were several small
black carbonized tracks in the casing. Under magnification they appear
to be arc tracks through the pvc wall. As pointed out earlier, these
caps are sealed with the specifications of a bomb. And, with our
resonances and kickback I'm sure the 10 kvac case rating is handily
exceeded."
How did the carbon track form? Was the capacitor sitting
on something or did it just start to grow along the casing from
one end? Can't see how the casing could be rated at 10 (kV) from
end to end. Was the breakdown from capacitor section to capacitor
section (started between them, I mean)????? Tell us more. This
is an interesting and important topic, since I bought a couple of
the things and have been looking forward to using them. Wonder if
there were bubbles or the like in there, and breakdown started
within the bubbles? Standing them on end (for a significant period
of time) might help that, but that arrangement would sure be
unhandy......
A little more dope, please. Hate to think of getting involved
in the icky, oily mess you describe - either on the top of my table
or in a deliberate rebuild.......
Ed Phillips