Accelerated aging study on 15 kV XLPE and EPR cables insulation caused by switching impulses

Cross-linked polyethylene (XLPE) and Ethylene Propylene Rubber (EPR) are the common polymeric materials used for power cable insulation in the USA. While in service, the main threats to the cable insulation include electrical stress, thermal stress, and mechanical stress. The electrical stress, from either operation voltages or abnormal over-voltages during transients, has negative impacts to the power cables insulation. The excessive electrical stress will trigger the aging of insulation materials, which will lead to the failures of cables, resulting in outages of power systems. The aging phenomena of polymeric power cables have been extensively studied during the past decades. Although the study of aging mechanisms was done on molded samples, little is known about the aging phenomena of the XLPE and EPR cables by switching impulses. In this experiment, the 15 kV XLPE and EPR cable samples were aged up to 10,000 switching impulses. The study helped to assess the reliability of the XLPE and EPR cables serving in electrical power systems.