FLAT PLATE CAPACITORS
NOTE: Some of you may have missed this message so I am re-posting it.
MC> Hi Richard,
MC> Another question for you again!
MC> I have been unable to find any source of 60 mil polyethylene
MC> film over here (the only place that is prepared to make some
MC> for me will only do it if I buy 500kg off them!) so I'm going
MC> to go with the flat plate capacitor described in one of your
MC> postings (similar to the plastic bag capacitor). I was just
MC> wondering how do you ensure a good bond between the plastic
MC> and the aluminium foil. mconway-at-deepthnk.kiwi.gen.nz
Generally the capacitor is held together by pressure. When placed
in the oil tank, use foam or other plastic material to compress the
capacitor. This is usually sufficient to prevent vibration and the
associated plate and dielectric shifting, it also cuts down on the
amounts of insulating oil required.
When using polyethylene (polythene in your part of the world) figure
on getting a dielectric K of 2. This is because it is not really
practical to get the tight plate/dielectric bonding you are thinking
of in a homemade cap.
... If all else fails... Throw another megavolt across it!