Computation of Cable Impedances Based on Subdivision of Conductors

The frequency-dependent resistances and inductances of cables can either be found from analyt ical formulas, or with numerical methods based on finite elements or subdivision of conductors. While analytical formulas are limited to coaxial configurations, numerical methods can be used for non-concentric configurations as well. This paper discusses the method of subdivision into subconductors of circular, square or elemental shape, and compares the results for the case of a coaxial cable, where exact solutions are available from analytical formulas. The inclusion of ground return impedances is discussed next. The method is then applied to the calculation of impedances of pipe-type cables with magnetic pipe material, and of internal impedances of stranded conductors in the power line carrier frequency range.