A Method for Estimating Magnetic Shielding by 2-D-Thick Planar Plates for Distribution Systems Shielding

A simple method for calculating the magnetic shielding performance of long finite-width 2-D-thick planar shields made of imperfect material is presented. The source of the magnetic field can be any arbitrary number of line sources; therefore, the method can be applied to the shielding design in power transmission and distribution systems. Simple formulas for magnetic-field shielding by perfect conductor 2-D plates are extended to imperfect shields by using the simple near-field impedance method and the reflection coefficient of an infinite planar shield. The accuracy of the method has been validated in comparison to finite-element method solutions.