Investigations on the Local Thermal Breakdown in Polymeric Insulation

The breakdown of cable insulation., is almost always preceded by a thermal runaway., which tends to initiate at some local spot., which may be the weakest link in the insulation matrix., owing to some impurity., defect or charge trapping. In this paper., the authors attempt to estimate the formation and propagation of local runaway spot and the temperature profile in low-density polyethylene (LDPE) films using thermal imaging., until breakdown., under a ramp-type DC voltage.