The Experimental Investigation Of The Surface Discharge On Silicone Rubber Insulators

Compared with traditional porcelain and glass insulator, silicon rubber insulator has the advantages of light weight, strong hydrophobicity and convenient maintenance and so on. Therefore, in recent years it has developed rapidly in the world, especially in C hina. But due to the increasingly serious environmental pollution in our country, outdoor insulators will subject to dust, soot, industrial emissions and other pollution. Pollution layer will be formed on the surface of the insulator, which can greatly reduce the flashover voltage, lead to the occurrence of contamination flashover accident and seriously affect the safe operation of power system. So the surface discharge of polluted silicone rubber insulator is of great significance to research. In this paper, we use a needle-plate electrode model, make a series of experiments on the surface discharge of silicone rubber. Focus on the pressing state of electrode(contact angle), effects of pollution layer distribution and medium scratch on the discharge trigger state. And there are some results.Through the study about the influence of the contact angle of the electrode and the dielectric surface on the initiation form of the surface discharge, we found that there appear the "jumping corona" in the condition of positive contact angle. Then it will develop into the air corona or non-electrode surface discharge. The reason is that the silicon rubber is elastic, so the electrode will sink when it press on silicon rubber. Corona discharge trigger point move up, and the jumping corona appear. These findings provide a new experimental phenomenon for the study of the surface discharge on silicon rubber insulator.The effects of pollution layer on the flashover voltage are studied. It is found that when the pollution layer is granular, the pores among the particles make the discharge easy to develop. There is similar phenomenon on the porcelain insulator. The equivalent salt deposit density(ESDD) had significant influence on the flashover voltage.Studied on the influence of non- uniform distribution of pollution layer on surface discharge path, we observed the phenomenon that near the electrode, pollutio n layer make the discharge path more concentrated. It's due to the Joule heat caused by leakage current.We also studied on the effect of surface scratch on the discharge path. The result shows that silicone rubber has good ?self-healing? characteristics. Slight narrow scratches which perpendicular to the direction of the electric field have no effect on the discharge path, and slight narrow scratches along the direction of electric field have a weak effect. Severe wide scratches near the electrode will obs truct the discharge because of the discharge space reduced. And severe wide scratches along the direction of electric field make the discharge develop around the scratch for the reason of distorted electric field.With surface discharge experiments when there are sand grooves in sand layer, we found that the discharge develop around the sand groove. Similar with porcelain insulator, it's caused by the distorted electric field.These experimental phenomena observed are of great significance to our in-depth study of contaminated silicon rubber insulator surface discharge.