THE REDUCTION OF MAGNETIC FIELD OF UNDERGROUND CABLE LINE IN ESSENTIAL AREAS BY MEANS OF FINITE-LENGTH COMPOSITE MAGNETIC SHIELDS

Abstract

In the article, the numerical calculation and analysis of three-dimensional magnetic field of underground power cable line with finite-length magnetic shields used to reduce the level of this field on the ground are carried out. Both fill-up soil and filling soil containing magnetic particles and then having effective magnetic properties (=1÷1000) are proposed to used as magnetic shields. The shielding efficiency is studied for underground 330 kV cable line depending on the dimensions and effective magnetic permeability () of the shields. As shown, the use of filling soil with magnetic properties gives a possibility to reduce the field on the ground five times. This type of shielding is more efficient as compared to magnetic fill-up soil. The computed results reveal the non-monotonic variation of magnetic field on the ground above the soil edge zones. The longitudinal size of these zones is in the order of the depth of the cables. References 16, figures 9.