Abstract
Since concerns have been expressed regarding the environmental effects of ELF (Extremely Low Frequency) magnetic fields, it is important to establish a method for mitigation of the magnetic fields around electric power facilities. We previously reported a method to reduce the magnetic field generated from underground cables using cylindrical shielding materials. In this paper, to gain a more practical understanding of shielding phenomena, we investigated magnetic field reduction mainly by means of numerical and analytical calculations. At first, a numerical calculation method and an approximate formula for magnetic shielding effectiveness were applied to the cylindrical shielding materials and their validity was verified. Then, the relationship between several parameters of shielding materials that affect the shielding effectiveness was clarified. A design guideline for the magnetic shielding was also proposed.
