Epoxy resin is the main material of spacer in a gas insulated transmission line and other gas-insulated equipment. During long-term operation, the charge accumulates on the surface of the epoxy resin, which will distort the electric field and thus accelerate the failure of the insulation. In this paper, the surface of the epoxy resin was fluorinated by dielectric barrier discharge at different times. The surface physical, chemical, and flashover properties of the samples before and after modification were measured. The results show that the method used in this paper can graft fluorine on the surface of the sample, change the surface roughness, and make the electron trap shallower and the hole trap deeper. The appropriate modification time can reduce the charge accumulation on the surface, hinder the formation of flashover channels, and improve the surface flashover voltage, showing potential for use in the improvement of the insulating performance of insulating materials.
Free metal particle is one of the main defects affecting the safe and stable operation of GIS equipment. In order to further analyze the characteristics of partial discharge produced by metal particles, an independent sealed test model which can simulate real defects is designed in this paper. By adjusting applied voltage, particle size and number of particles, PRPD and n-φ pattern of partial discharge caused by particle defects are characterized. Analysis of the causes of formation of features, especially in the light of particle motion patterns, the transfer and neutralization of charges carried by particles at various stages are elaborated, which provides a reference for the follow-up research and field detection work.
Considering the consumption of time and energy for the traditional heat treatment process, a new heat treatment method with high speed and low energy consumption has always been the direction of researchers. The microstructure and mechanical properties of engineering 316L stainless steel were measured under electropulsing treatment within 400 ns and annealing treatment for 2 h. Compared with the original cold-rolled state, it was found that the yield strength after 3.8 × 103 A/mm2 electropulsing treatment was reduced by 26.2% and that after 800 °C heat treatment was reduced by 27.7%. The nucleation after electropulsing treatment is mainly concentrated at one end of the lamellar grain and finally grows into the square or rhombic grain with an average grain size of 1.5 µm. After annealing, the nucleation is mainly concentrated at the grain boundaries of the lamellae and finally grows into equiaxed grains with an average grain size of 1.8 µm. Under the action of electronic wind, the recrystallization nucleation after electropulsing is mainly dominated by the mechanism of subgrain nucleation and growth. However, under the action of a uniform thermal field, the recrystallization nucleation after annealing is mainly based on the grain boundary bow-out mechanism.
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