Calculation of Induction and Magnetic Field Effects of Three Phase Overhead Lines Above Homogeneous Earth

The paper addresses the problem of induction effects of a three phase transmission line on a parallel circuit, in the presence of homogeneous earth. It is based on the simple expression' ̄Z= ̄K ln(̄D"/D') of a mutual impedance (where ̄D" is complex) which approximates well earth return effects as calculated by Carson ². This expression is used to derive equations for the magnetic field intensity IT of a single phase line, and for both ̄Z and ̄H of three phase lines related to a parallel conductor with ground return.