Theoretical study of inception mechanism and growth of defect-induced damages in XLPE cable

We have investigated theoretically the inception mechanism and growth of the damage inside a cable in working conditions. We focused, in particular, our attention to the inception points originated from microscopic defects like voids. In order to clarify the implication of these defects with the failure and breakdown of cables, we have developed a theoretical model based on the theory of electrical breakdown solving numerically its basic equations. Calculations of the ionization rates of atmospheric gas filling the voids have been done as a function of the applied electric stress and void dimensions. Estimates of the energy release and local damages produced by hot electrons are given. A model of growth of damage is also proposed