Defect tolerance of solid dielectric transmission class cable

This paper addresses the issue of determining the level of defect that is likely to cause the failure of solid dielectric transmission class cables. It also proposes methods for predicting the level of defect that is likely to cause failure and to provide a simple analytic approximation for doing so in the case of conducting spheroids aligned with the electric field. A common assumption is that conducting particles > 100 μm in length are likely to cause failure of extruded dielectric transmission cable. This analysis suggests that when the effects of operation at elevated temperature are included in the analysis, this is probably an appropriate criterion with a sound technical basis. For maximum background fields in the range of 15 kV/mm, as presently seen near the conductor shield of some transmission class cables, a worst-case particle length in the range of 0.1 mm is likely to be required to cause failure for the worst-case local polymer morphology in the range of the maximum operating temperature.