Assessment of HV XLPE Cable Sheath Layer Modelling Approaches for EMT Studies

This paper presents the results of a study verifying the differences between various HV XLPE cable sheath modelling approaches used in EMT programs. Cable sheath is a compound layer, including two different conductive layers with a semi-conductive layer in between, but in EMT programs, it is modelled as a single solid conductive layer. In order to consider properties of the actual sheath layer, modifications in its representation are needed. For this purpose, several approaches are used but currently there is not sufficient information available to clarify what is the difference between them and how they affect simulation results. In this paper, frequency dependent sheath impedance characteristics are studied for single layer, equivalent single layer and double layer sheath approaches and simulation results are presented. It is shown that differences between various sheath modelling approaches exist and it is necessary to consider these in various system studies.