Mitigation of magnetic field near power lines

The paper discusses in a tutorial manner the process of magnetic field mitigation achieved by use of an additional auxiliary loop placed near load carrying conductors of an existing power line. As an example mitigation of a 750kV class transmission line is presented. The auxiliary circuit is located (i) underneath two outer phases, (ii) above two outer phases, (iii) on ground, or (iv) two shield wires are used for mitigation. The interaction between the original field of the transmission line and that caused by current in the auxiliary loop is followed in detail and thereby an insight into the mitigating process is provided. The approach is best suited for situations where local reduction of the power line field is desired. Reduction of the existing field is possible not only at ground level, such as in the right-of-way, but also at elevated locations, such as at the wall of a building.