Partial Discharge Erosion of Polypropylene/Elastomer Blends Characterized with Multi-Sensors under AC Voltage

Polypropylene (PP) has been considered as a promising insulation material for power cable in both AC and DC systems because of its excellent insulation performance and recyclability. The exposure to partial discharge gives rise to the deterioration of the material that threatens the safe operation of cable. Therefore, it is of great significance to understand the mechanism of partial discharge of PP and its blends subjected to AC voltage. In this work, PP/elastomer blends with thickness of $150 \mu \mathrm{m}$ were prepared as samples. A needle-plane electrode system was employed to introduce partial discharge by applying an AC voltage with 5 kV rms for 2 hours. The erosion behavior was characterized through multi-sensors system, including high frequency current transformer (HFCT), optical recorder and gas sensor. To better understand the erosion mechanism, isothermal surface potential decay (ISPD) method was used to analyze trap characteristics. The results showed that the trap center became shallower with the increase of elastomer content for both ethylene-octene copolymer elastomer (EOC) and polypropylene based elastomer (PBE). Compared with pure PP, the addition of elastomer improved the resistance of partial discharge and PP with 20 wt% loading percent of EOC presented better resistance to partial discharge compared with PP with 20 wt% loading percent of PBE.