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Re: correction factor for paper
From: Esondrmn-at-aol-dot-com[SMTP:Esondrmn-at-aol-dot-com]
Sent: Wednesday, July 30, 1997 6:21 AM
To: tesla-at-pupman-dot-com
Subject: Re: correction factor for paper
In a message dated 97-07-29 05:48:43 EDT, you write:
<< Hi all,
Does anyone know what factor to apply to the plate capacitor formula to
account for 30 lb kraft paper impregnated with oil between all layers of
the capacitor?
Or should I just add the dielectric constants of the paper to the
polyethylene in the fomula and adjust the distance between plates?
Something does not seem right about adding the paper constant to the poly
constant. They are in series with each other, but something tells me they
would not be additive.
It would be nice to know beforehand so I can design a value rather than
test (and run the compression frame down) as I go.
If the differences are insignificant, that would be nice to know too. Who
has experience with this?
Also, does anyone know the thickness of 30 lb kraft paper? I forgot to
bring a piece to work to measure.
Thanks in advance.
Michael Smith
md.smith-at-usa-dot-net
>>
Michael,
Since the paper will be oil impregnated, I doubt it will lower the dielectric
constant of the polyethylene. I would just add the paper thickness for
spacing and use a dielectric constant of 2 for the poly. For the caps that I
have built and measured, using a K of 2 makes the formula closely match the
finished product. I think this is really compensating for the fact that the
spacing between plates is something more than the measured thickness of the
poly. Probably due to all elements not being perfectly flat and in intimate
contact over their full surface area.
Ed Sonderman