A proposal for performance evaluation of low frequency shielding efficiency

The present work aims to propose a methodology for evaluating the performance of low-frequency magnetic shields used for the shielding of complex sources such as MV/LV substations. Today there is no standard procedure for testing shields based on the use of a single-coil for generating artificial MF (MF: Magnetic Field) as is the case for high-frequency anechoic chambers. In the case of shielding for industrial frequency sources, these are generally open shields with sources of various types: 3D transformers, switch-gear, and power lines. These kinds of sources and shields are better checked if the artificial MF has all three components in space. The work proposes a methodology based on the use of a tri-axial source, capable of generating a rotating magnetic field. The supports of the coils are made using a 3D printing process. The paper presents the design steps, the analytical evaluation of the performance of the source and as an application a test of a magnetic shielding plate was presented.