Effect of Graft Modification on Electrical Tree Growth in PP/POE Composite Insulation Cables

This paper focuses on the electrical tree growth characteristics of graft-modified polypropylene (PP) composite polyolefin elastomer (POE) insulation under the combined action of direct current and impulse voltages. The results show that the graft-modified specimens have shorter electrical tree lengths and smaller cumulative damage areas. At high temperatures, the cumulative damage area does not increase significantly, and the DC breakdown strength remains 75% of the original, which has excellent high-temperature stability. The results show that the hindered phenolic compounds grafted on PP/POE can not only inhibit the breakage of PP molecular chain and extension of the amorphous area by scavenging free radicals generated at high temperatures, but also make the mixing of PP and POE more homogeneous and reduce the physical defects of composite insulating materials, which prevents the occurrence of partial discharges, and thus inhibits the growth of electric dendrites.