Study On The Electrical Properties Of Silicone Rubber Insulating Material At Low Temperature

Silicone rubber has the unique Si-O bond.The primary bond energy is high.it has good chemical stability and weak intermolecular interactions,and its heat resistance and cold resistance is excellent.Because of the ozone resistance,corona resistance,good electrical insulation performance and surface hydrophobicity,the mechanical properties of silicone rubber can be kept stable in different environments,and it has become the main material for the production of composite insulators.The crystallization ability of silicone rubber molecules will enhance and the crystallinity will increase in low temperature environment,which has a great impact on the performance of silicone rubber.The period of low temperature lasts long for the high altitudes of the Northwest China,Northern Europe,Russia and some other high-latitude regions,operation of power facilities puts forward higher requirements for the performance of insulating silicone rubber material,so it is important to research the electrical properties changes of insulating silicone rubber material in low temperature environment.The four properties of insulating silicone rubber material which contains hydrophobicity,dielectric loss,surface flashover and power frequency breakdown has been studied in this paper,it provide some references for evaluating the electrical properties of silicone rubber material in low temperature environment.In this paper,the static contact angle method is used to evaluate the hydrophobicity change of silicone rubber material in low temperature environment.The silicone rubber material for composite insulators has been carried out low temperature freezing treatment with constant-temperature test chamber at first.Then the static contact angle of silicone rubber samples were obtained by contact angle measuring instrument JC2000 DM.The change trend of hydrophobicity for silicone rubber materials was found at different temperatures.And the mechanism of hydrophobicity change for silicone rubber were analyzed.The research results show that the average static contact angle of silicone rubber samples with different temperature treatments is higher than that of the normal temperature.In addition,with the extension of low temperature treatment time,the static contact angle of the silicone rubber samples showed a significant increasing trend,it increases at first and then stabilizes.The circular plate-plate electrode system is used to press round silicone rubber samples,and the dielectric loss of silicone rubber materials is obtained by dielectric loss measuring instrument at low temperature,it is founded that the dielectric loss increases at first and then decreases when the temperature drops.Considering the effect of environmental temperature and aluminum hydroxide content on the properties of silicone rubber,the surface flashover voltage and power frequency breakdown voltage of siliconerubber materials is measured in low temperature environment.It is obvious that the change curve of surface flashover voltage and power frequency breakdown voltage is obtained about silicone rubber in non-uniform electric field at low temperature.The analysis of the regularity of characteristics has been completed,and The electric field distribution about different electrodes was simulated and verified by COMSOL software.