Re: Capacitance Between a Power Line and a Conducting Sphere

In article
<fc5d36ce-19c7-4d37-9048-3d145dbefb6f@xxxxxxxxxxxxxxxxxxxxxxxxxxx>,
Wimpie <wimabctel@xxxxxxxxx> wrote:

Hello Don,

You right, there is no radial symmetry. When assuming: power line
very large with respect to the sphere's diameter and distance between
power line large with respect to sphere's diameter, most of int(E*ds)
is close to the sphere.

Close to the sphere there is reasonable radial symmetry. So as a first
estimate, you can use the capacitance for a sphere, where diameter of
outer sphere goes to infinity.

When requiring better accuracy, you need to do the math, and also
taking into account mutual capacitances via other structures.

There is an example given in Ramo and Whinnery's "Fields and Waves in
Modern Radio." The same techniqu can be extended to cover this case.

The potential for a sphere in the presence of other conductors is going
to be a sum of spherical harmonics of unknown coefficients. This sum has
to equal the potential on the sphere and the cylindrical wire. There
should be sufficient symmetry to set some of the harmonics to zero
amplitude. Matching potentials at 1000 points will give a linear
equation set. Even modest computers these days can handle the solution
of such equations.

I am not saying that it would be easy but it is certainly feasible.

Bill

--
Most people go to college to get their missing high school education.
.

Relevant Pages

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