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Re: Blown Rolled "Hull" Capacitor Discussion


On Wed, 6 Mar 1996 tesla-at-grendel.objinc-dot-com wrote:

> I have just scored 20 litres of good quality transformer oil from a 
> local power company. Not only did they give it to me ("paperwork's
> worth more the the oil") but ran it through their test tank while I

Good luck. They ask 2usd/liter here at local company..

> was watching. I'm not sure whether they were using AC or DC in the
> tank (and interestingly enough, the guy who did the testing didn't
> know either - duh? :( , but the best holdup measured was 39kV across
> a 3mm gap with 15mm balls. It looks just the goods - great insulation
> and reasonably runny to boot. Amazing what can happen when you ask.

An idea: one should be able to test mineral-oil (or any other
oil) before using it for capasitor.. Just a spark-gap immersed
to that oil with a known gap and voltage - a neon xformer for
example.. This will do for a quick-and-dirty test, I'd guess!

A simple apparatus for testing: a plastic container with two
door knobs (brass) attached to base with, say, 2 mm distance.
Oil is poured to container so that electrodes are immersed
to it and voltage between electrodes raised via variac until breakdown - 
if it will undergo breakdown..


   X                   X
   X                   X
   X      VVV   VVV    X
   X     VVVVV VVVVV   X
   X      VVV   VVV    X
   X       V     V     X
   X       V     V     X
   XXXXXXXXVXXXXXVXXXXXX
           V     V
           N     H

where X container, V electrode, N neutral, H hot - x volts..
Of course, gap between electrodes should be accurately measured,
like with the devive used for car spark-gaps..


Kristian Ukkonen.