Surface Charge Dissipation Characteristics of Al₂O₃ Silicone Rubber Composites

Silicone rubber composite insulators represent a crucial component in the outdoor insulation of high-voltage equipment. However, the influence of DC electric field might lead to the accumulation of surface charge on insulators, potentially resulting in insulation failure. To enhance the dissipation rate of surface charge on silicone rubber composite insulators, this paper employs a needle-plate electrode to inject surface charges into silicone rubber, then the surface potential decay properties of nano- and micro-scale Al ₂ O ₃ /silicone rubber composites at concentrations of 10 wt%, 20 wt%, and 30 wt% are measured by using an electrostatic capacitance probe. The results show that the addition of nano- and micro-scale Al ₂ O ₃ introduces new shallow traps in silicone rubber, thereby enhancing the dissipation rate of surface charge. Al ₂ O ₃ /silicone rubber composites with different concentrations reduce the time required to achieve a 30% decline in the average surface charge density, falling within the range of 25.41% - 30.53%. While the addition of Al ₂ O ₃ enhances the dissipation rate of surface charge, it concurrently results in a reduction of the surface flashover voltage. The negative DC surface flashover voltage of charged samples with pure silicone rubber, nano-scale Al ₂ O ₃ /silicone rubber composite, and micro-scale Al ₂ O ₃ /silicone rubber composite can be recovered to 89.44%, 97.41%, and 95.78% of uncharged samples, respectively.