Re: Measuring Capacitance (fwd)
---------- Forwarded message ----------
Date: Fri, 24 Apr 1998 23:10:48 +0000
From: "Patrick J. Gustafson" <gustafpj-at-uwec.edu>
To: Tesla List <tesla-at-pupman-dot-com>
Subject: Re: Measuring Capacitance (fwd)
> To calculate the capacitance of a rolled poly cap, use the formula:
> C(pf) = .224 K A / d. Area is in square inches, K is the dielectric constant
> and d is the dielectric thickness in inches. Then multiply the answer by two.
> I have built several rolled poly caps and find this formula agrees with
> measured values within a few percent if I use 2.0 for K instead of 2.2.
> We have had the oil discussion here a few times recently - using different
> oils, when the primary dielectric thickness is accounted for by the LDPE, will
> only change the resulting capacitance by a small amount.
> Ed Sonderman
I have several programs that quickly calculate the capacitance. The problem that
I have is in finding an accurate (and reliable) method of measuring the "actual"
capacitance, not theoretical.