Effect Of Nano-Coating On Surface Charge Dynamic Behavior And Flashover Of Epoxy Nanocomposites

Epoxy nanocomposites have been widely used in the power equipment as the insulation material,for the excellent comprehensive properties.However,the problem of surface charge accumulation has become an important reason to induce flashover and reduce the insulation performance of nanocomposite materials.After summarizing the methods about surface charge regulation in recent years,the method of nano-coating which is tightly attached with nanocomposite through natural deposition was proposed in this paper,to suppress surface charge accumulation and enhance flashover voltage.The charging experiments under DC voltage were carried out for the sample coated and uncoated,after which,the effects of content of filler,coating thickness and temperature were all investigated in this paper.The surface conductivity and flashover voltage were measured after the charge accumulation,meanwhile,the influence of surface charge on the electric field along the center line were measured by the method of simulation.The main work is as follows:1.The EP/Al₂O₃ composite and EP/SiC coating,EP/?SiC+GO?coating were all prepared by using mechanical mixing method,the former coating was obtained by adding the nano-size SiC into EP,the later coating was obtained by adding both the SiC and GO into EP together.Scanning electron microscopy?SEM?observation was employed to analyze the morphology of sample structure.2.A pair of plane to plane electrode structure was employed to charge the samples coated and uncoated,after which,the effects of coating on suppressing the charge accumulation were investigated.The results indicate that for the EP/SiC coating,surface charge density decreases with the increasing of SiC content;The charge density increases with the increasing of coating thickness and temperature.For the EP/?SiC+GO?coating,surface charge density increases with the rising content of SiC,when the GO content remain unchanged;The charge density increases with the increasing of coating thickness and temperature.The Isothermal Surface potential decay?ISPD?were adopted to measure the changes of trap energy and trap density,according to the trap theory of polymer,the mechanism of the experimental phenomenon was obtained in this paper.3.After the surface charge accumulation,the relationship between surface potential and decay time was obtained to measure the surface conductivity of samples.Meanwhile,the influences and mechanisms of both filler content and temperature are analysed in this paper.The flashover voltage was measured immediately after surface charge accumulated,and the variation of electric field along the center line were measured by the method of simulation.The results indicated that electric field was increased,causing the decline of flashover voltage.Nano-coating can suppress the charge accumulation,improve the electric field distribution and advance the flashover voltage.