Analysis of Extremely-Low Frequency Magnetic Field Shielding Effect Using a Cylindrical Shielding Model

To shield magnetic fields in the extremely low frequency(60Hz) band generated from transmission lines and power equipment, the magnetic field shielding effect was analyzed using Faraday 3D. The analysis model was in the form of a cylindrical shielding material surrounding a wire carrying a single-phase current. The shielding material had a single-layer structure of a high-permeability magnetic layer or a highly conductive metal layer, or a multilayer structure consisting of a magnetic layer/conductive metal layer. The analysis was performed by changing physical properties such as relative magnetic permeability, electrical conductivity and the layer thickness. In the case of single-layer shielding, it was difficult to obtain high enough shielding rate with thickness less than 1mm. In the case of double-layer shielding, however, high shielding rate of 85.3% was achieved when the magnetic permeability of the primary layer was 100 and the conductivity of the secondary layer was 1.0×10SUP5/SUP(S/m) at 0.2mm thickness of each layer. In multilayer structures consisting of three or more layers, the shielding effect was saturated.