The electrical aging life of polypropylene(PP)insulation,a new environmentally friendly material,and its nano-SiO2 composites were investigated to provide theoretical support for the reliability of PP-insulated cables in later applications.Based on the electric aging life formula-inverse power method,the life model parameters of PP insulation and SiO2/PP composites were estimated by constant voltage accelerated aging test,and then the reliabi-lity of life index n was evaluated by stepwise accelerated aging test.The SiO2/PP composites were also structurally characterized and performance tested.The results show that the lifetime index n of SiO2/PP6 is 14.61,which is en-hanced by 16.51％compared with that of PP6 of 12.54.It is found in the experimental stage that the doping of SiO2 has a significant effect on the enhancement of PP6's time to failure at lower aging field strengths,and it is predicted that the long-term electrical aging lifetime of SiO2/PP6 is more than five times that of PP6 below the aging field strength of 25 kV·mm-1.Meanwhile,the doping of nano-SiO2 reduced the industrial frequency dielectric loss factor and lowered the loss peak height of PP insulation.Based on the electrical aging cavity theory,it is proposed that SiO2 enhances the electrical aging life of PP insulation by limiting the chain segment breakage by consuming hot electron energy.
polypropylene insulationelectric aging lifenano SiO2accelerated electrical aging testcomposite material
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