Effect of Mechanical Stress on Space Charge Behaviors of PP Insulation Materials

Abstract

Polypropylene (PP) blended with polyolefin elastomer (POE) has been considered as a potential choice to replace cross-linked polyethylene (XLPE) as HVDC cable insulating material, which shows excellent performance in electrical, mechanical and thermal properties. The space charge accumulation, formed under dc electric field in PP/POE blend, would distort the local electric field, and furtherly lead to partial discharge or premature breakdown. During the processes of fabrication, installation and operation, the cable insulating material may be exposed to mechanical stress. In order to study the influence of mechanical stretching on space charge behaviors, PP/POE blends were prepared and stretched to different ratios of 1, 1.1, 1.2, 1.3 and 1.4, and the space charge behaviors during polarization and depolarization processes were measured and analyzed by PEA method. Besides, the effect of mechanical stretching on surface and internal morphology were analyzed by SEM test, and the relationship between the surface and internal morphology and space charge characteristics is obtained in this chapter.