Mitigation of Overhead Line Magnetic Field by U-shaped Grid Shield

The paper deals with the mitigation of a three-phase overhead line magnetic field by a U-shaped grid shield. The U-shaped grid shield is made of wires located in a vertical plane and two horizontal planes. All wires are connected in parallel. Shielding characteristics of four U-shaped grid shields and four U-shaped electromagnetic shields having equivalent quantity of metal are studied by numerical simulation. We found that the U-shaped grid shield is preferred because of its convenient and low cost erection. The length of arms is varied. Respectively the number of wires and their cross-sectional areas are varied for grid shields, and the thickness is varied for electromagnetic shields. The advisable length of arms and the advisable quantity of metal of the U-shaped grid shield are found out.