Internal Impedance of Two-Layer Cylindrical Conductors

Abstract

Computation of the internal impedance per unit length of solid and tubular cylindrical conductors, energized by time-harmonic current, needs to take into account the skin effect. Computation algorithm involves direct numerical manipulations with Bessel functions. These functions are defined by infinite series, which yield unstable and often erroneous results, particularly for large magnitudes of the function argument at high frequencies. Therefore, different approximate formulas are used in order to alleviate this problem. In this paper, exact formulas, with scaled Bessel and Neumann functions and scaled coefficients, for internal impedance of two-layer cylindrical conductors are presented. In two numerical examples presented, results for internal impedances per unit length of two-layer conductors computed by exact formulas are compared with results based on Amos subroutines, which are used in program package MATLAB

Slavko Vujević

Professor Emeritus

An expert in electrical engineering, particularly known for his contributions to numerical modeling of electromagnetic phenomena, lightning protection, and grounding. Throughout his career, he was a key member of the Faculty of Electrical Engineering, Mechanical Engineering, and Naval Architecture in Split, where he taught, mentored students, and actively participated in scientific research and international professional organizations.

Tonći Modrić

Associate Professor | Department of Electrical Intallations and Systems

Researcher and Full Professor at the Faculty of Electrical Engineering, Mechanical Engineering, and Naval Architecture in Split. His research focus is numerical modeling and calculation of the electric and magnetic fields in power systems and transmission lines, with an emphasis on the development of advanced models for interpreting geoelectrical ground survey data. Additionally, he is involved in the analysis of electromagnetic transients in systems with a high share of renewable energy sources, using finite element techniques.