Re: Oil Filled Capacitors

Craig Sawyers <c.sawyers@...>

Corona discharge would be pretty hard to induce at 200 Vac. You would have
to hit frequency around cap's resonance
That reminds me of another failure mechanism - acoustic. Try the following
experiment. Make a simple power amp for square waves with a couple of
transistors or FETS, driving +/- 30V (say). Connect capacitor from output
to low impedance load to get a reasonable current flowing. Now sweep an
audio generator.

Many capacitors howl like a banshee at particular frequencies where the
internal mechanics resonate. These are usually ones where the windings
inside are relatively "loose". Very tightly wound capacitors are very
quiet - but there are some real shocks out there when you try the experiment
(like some respected 10kV polypropylene which were more like a loudspeaker
than a capacitor).

Needless to say, such mechanical vibration does nothing to help the
reliability of the capacitor.


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