Re: [femm] Shielding effectiveness

[David Meeker <dmeeker@xxxxxxxxxxxxxxxxx>]

Emiliano wrote:

> My goal is to calculate the reduction of B around the shield, in the
> external region.
> In this situation is importan to calculate the currents induced on the
> shield.
> ... But the currents depends on the lenght of the wire and the shield ....
> So, is correct adjust the sigma of the shield in rtelation of its lenght ?
> For example for 10 mt: sigma_alluminium=sigma_alluminium/10.

You shouldn't have to "fix" the shield conductivity. Also, you might want to
take a look at the example from a few weeks ago about eddy currents induced in a
pipe at http://members.aol.com/_ht_a/gmagnetics/tube/tube.htm . This is pretty
much the same problem you are looking at.

Dave Meeker


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