Consideration of skin effect in high-voltage coaxial systems under transient and steady-state conditions, and its impact on steep travelling waves

TLDR: In this paper, the use of a ferromagnetic coating applied to the busbars of an SF6 busduct as a means of controlling disconnect transients is discussed and a software travelling wave model is described.

Abstract: The paper discusses the use of a ferromagnetic coating applied to the busbars of an SF6 busduct as a means of controlling disconnect transients. A software travelling wave model is described. The model is based on a frequency-domain characterisation of the busbars in the system. The model accounts for the skin effect in coated materials, and incorporates the effect of discontinuities in the system. The influence of the various coating attributes are noted. The model is shown to perform accurately as a travelling-wave analysis tool. Consideration is also given to the transient skin effect, which is shown to increase the attenuation of transients. Results recorded in a laboratory system with and without ferromagnetic busbars are presented. Ferromagnetics are shown to introduce marked risetime lengthening, as well as an envelope attentuation to disconnect transients.