Mutual impedance of non‐parallel conductors with earth return

Abstract

AbstractThe calculation of currents and potentials along underground conductors (telecommunication and power cables, pipelines) occurs in many practical problems associated with interference from currents in power transmission lines or electrified railways lines. The knowledge of the mutual impedance between both earth‐return circuits is essential in case of inductive influence. The mutual impedances of long conductors may be derived using the Carson method. The formulas, however, apply only to parallel conductors. In case of non‐parallel conductors an approximation method overcomes this problem by segmenting the angled conductor along its length. In the paper the alternative approach is proposed, based on the linearization of the mutual impedance characteristic for 50 Hz. The use of the linear regression method leads to accurate results of calculation of potentials excited by the inductive effects of a transmission line on non‐parallel underground conductor.In the paper the method of determination of the mutual impedance of angled conductors with earth return is also developed for the case when one of the conductors is finite in the length. The formula for the mutual impedance contains an integral, which does not have an analytical solution. A numerical integration algorithm is developed. The exemplary calculations show that the use of the algorithm developed leads to results with considerably accuracy. Copyright © 2009 John Wiley & Sons, Ltd.