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 Carson2. 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.