Accelerated electrical aging of medium voltage EPR cables energized by elevated AC voltage with switching impulses superimposed

Aging of polymer insulated power cables has been a significant subject of investigation during the last several decades. Despite the great achievements in single-stress aging mechanism, much less is known about the multi-stress aging and the associated phenomena. The cables will suffer from the electrical stress, thermal stress, mechanical stress, and other aging factors during the operation, which will initiate the unwanted aging of the cables. In the study, the accelerated electrical aging of Ethylene Propylene Rubber (EPR) cables was carried out. The 15 kV EPR cables were stressed by 3V₀ (26 kV) ac voltage with switching impulses superimposed. The ac current of ampacity (226 A) was applied to simulate the thermal stress at full load. The major objective of the study is to obtain a comprehensive understanding of the accelerated aging phenomena of EPR cable insulation and the impacts from different aging factors.