| Epoxy resin is widely used in electric power industry as an insulating material with excellent physical properties and processability.However,charge accumulation often occurs on the surface of epoxy resin under AC/DC electric field,which leads to local electric field distortion and surface flashover.Surface roughness is an important physical parameter of gas-solid interface,which can affect the surface flashover characteristics of materials by affecting arc development distance and charge transfer process.Therefore,this paper intends to study the influence of roughness modification on the surface insulation properties of epoxy resin.The DC flashover test is carried out on the roughness modified samples in different gas environments.The effects of surface roughness,rough surface position and texture orientation on the flashover voltage and its dispersion of epoxy resin are studied.It is found that in air,C4F7N/CO2 mixed gas and SF6,the maximum flashover voltage is achieved when the sample’s surface roughness is Ra=1.3 μm and its rough surface is at the center of the sample with out of order texture orientation.The flashover experiment under GIL electric field structure is carried out by using a scaled basin-type insulator model to verify the modification effect of the above parameter group.The AC flashover test on the roughness modified samples is carried out.It is found that in air,C4F7N/CO2 mixed gas and SF6,the AC surface flashover voltage of epoxy resin varies with the change trend of roughness modification parameters similar to the DC surface flashover voltage,the optimal parameter set is still that Ra=1.3 μm,the rough surface is at the center of the sample with out of order texture orientation.The flashover experiment based on the scaled basin-type insulator also shows that this set of parameters is effective for both AC and DC flashover voltage increase.The surface charge of sample after roughness modification is measured.The effects of surface roughness,rough surface position and texture orientation on surface charge accumulation and dissipation are investigated under positive and negative corona charging respectively.The results show that the sample with the most obvious flashover enhancement has the highest charge dissipation range and the lowest charge potential.The results show the correlation between flashover voltage and surface charge characteristics.In order to further illustrate the influence of surface charge on electric field and surface flashover,a coupling model of electrostatic field and diluted species field is established to simulate the charge behavior of gas-solid interface.The simulation results show that when the roughness is Ra=1.3 μm and the rough surface is at the center of the sample,the average surface charge density and maximum electric field modulus of the gas-solid interface are minimized,and the equivalent trap density is minimized.In this paper,the influence of roughness modification on surface insulation of epoxy resin is studied.An effective roughness modification scheme is obtained,which provided theoretical support for the surface structure design of insulators in different gases. |
