Combination of probabilistic electro-thermal life model and discrete enlargement law for power cable accessories

摘要

In previous papers the authors have combined the electro-thermal Inverse Power Model-Arrhenius life model for electrical insulation with the volume enlargement law for coaxial cables, thereby attaining a comprehensive probabilistic life model that considers the effect of both electro-thermal stress and insulation volume on the breakdown behavior of cable insulation. The aim of this paper is enriching this model by including the effect of accessories - joints and terminations - so as to get even closer to the real behavior of cable systems. This is done under the Weibull hypothesis and according to the “weakest-link” representation of a cable system including cable lengths and accessories. The failure probability of the cable system is expressed as a function of the various involved independent variables, namely: electric field and temperature of cables and accessories; cable length; number of accessories; Arrhenius parameter and voltage endurance coefficient of cables and accessories. A preliminary sensitivity analysis of the model to these variables is carried out by following a parametric approach.