Study On Insulation Performance Of Composite Silicone Rubber For Insulator Under High Voltage Environment

As an important component of insulators,composite silicone rubber plays an important role in a transmission line.Composite silicone rubber,also known as methyl vinyl silicone rubber,which has a helical molecular structure and relatively stable structure.However,under the influence of external environment for a long time,insulation aging of composite silicone rubber cannot be avoided.As a result,the cracks,hydrophobicity,and anti pollution flashover voltage of it will be greatly reduced,resulting in the internal breakdown and pollution flashover of the composite silicone rubber,which seriously affects the operation and maintenance of power grid lines.In this paper,the effects of temperature and high voltage on the insulation properties of composite silicone rubber were studied:(1)The change of molecular volume resistivity of composite silicone rubber affected by temperature was analyzed.it was found that the volume resistivity of composite silicone rubber decreased gradually with the increase of temperature,and the decreasing trend slowed down gradually,the change of molecular bond length of composite silicone rubber was revealed microscopically.(2)The change of bond length and bond angle with electric field strength of the microstructure atoms of the compound silicone rubber was analyzed,it is found that the internal temperature of composite silicone rubber increases first and then decreases,the molecular energy decreases towards the minimum,the chemical bond of the molecule shortens,the atoms in the molecule are close to each other,and the molecular motion is very violent and gradually reaches stability,the effect of electric field on the internal temperature of the composite silicone rubber was revealed.(3)The changes of molecular elastic properties of composite silicone rubber under temperature and pressure were analyzed,it was found that with the increase of pressure at the same temperature,the smaller the elastic modulus,the stronger the flexibility of the material;The Poisson's ratio increases with the increase of pressure,when the pressure is the same,at 500 K,the Poisson's ratio decreases with the increase of temperature,the reason is that the molecular state of the composite silicone rubber is in the rubber state,at 0.01 GPa,the pressure has a greater influence on the Poisson's ratio,which reveals the changes of temperature and pressure on the molecular elastic properties and Poisson's ratio of the composite silicone rubber.(4)The changes of the bond length and angle between the atoms of the molecular structure of the composite silicone rubber with the electric field strength were analyzed,it was found that with the increase of time steps,the MSD value increased gradually,and the movement of molecular chain showed a nonlinear trend.At the same temperature,the higher the pressure,the weaker the movement ability of molecular chain,under the same pressure,the higher the temperature is,the stronger the molecular motion ability is,at the same time,due to the expansion,the increase of molecular spacing,the internal volume of polymer increases,and the stronger the molecular chain motion ability is,the lower the mechanical properties are.By studying the effects of external electric field,temperature,and pressure on the insulation aging of composite silicone rubber,the variation rules of its molecular structure,chemical bond length,elastic modulus and other parameters were mastered,and the insulation breakdown mechanism of composite silicone rubber under high voltage was revealed.The research results provide a theoretical basis for understanding the change of insulation properties of composite silicone rubber under different temperature and high voltage environment,and have potential application value for diagnosing the insulation properties of composite silicone rubber.