Original poster: "resonance" <resonance@xxxxxxxxxxxx>Efficient HV cap design is accomplished at 250 Volts / mil. We use this factor in our commercial HV caps.
Hand contaminants such as hand oils, ie, conductive sodium based, can be a big problem.
Another problem is that PP, PE, or PS is almost impossible to handle by hand as it easily generates static electric charge that will attract all kinds of dust, lint particles, hair, or anything else in the air that's nearby. A small particle between the dielectric and plate material will produce a corona inclusion (small void) in the insulating oil. The difference between the two dielectric values will produce damaging corona in the small voids which at RF frequencies leads to RF surface tracking and heating of the dielectric.
This eventually produces a failure --- the time required for failure is a function of the size of the contaminant particle and the size of the void (bubble) formed.
Dr. Resonance
PE can rate from 450V/mil to 1200V/mil. How pure (absence of contaminants) PE is will determine it's puncture voltage. It's hard to know just buying PE roll stock. It's best to test it. If you have a means of varying the voltage on a hv supply (such as a variac), you can then do the test yourself. Take several samples along the roll and get a decent average of "that rolls" puncture voltage. Also, the dielectric constant of PE is 2.2 to 2.3.This is really the only way to be sure. Anything else is a guess and may not apply to the PE you purchase.Take care, Bart Tesla list wrote:Original poster: jhowson4@xxxxxxxxxxxHey guys how many volts can 4 mil of polyethylene withstand. I am making a cap and am trying to figure out how thick I need the dielectric to be. I have 4 mil sheets.Many Thanks