Abstract
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.
Highlights
Under DC voltages, when there is a strong normal electric field, the surface charge accumulates to a significant extent and the spacer will suffer from a degraded insulating performance
Seeböck used polyimide films in the form of dielectric barrier discharge (DBD) discharge in air, and the results showed that plasma, as an efficient method, could effectively promote the wettability, surface oxidation, and roughness of samples
By changing the O2 flow rate in Ar, the results showed that the etching rate of Ar–O2 mixed gas treated LDPE was higher than that of pure Ar, but their electrical properties were not mentioned in this research
Summary
The growth of energy consumption has promoted the use of a gas insulated transmission line (GIL) in power grids, as they have a large transmission capacity, good operational stability, and a low capacitance load and are less influenced by their geographical environment. As a significant component of GIL, the spacer will accumulate charge on its surface during long term operation. In particular, under DC voltages, when there is a strong normal electric field, the surface charge accumulates to a significant extent and the spacer will suffer from a degraded insulating performance. In addition, the tangential electric field has a significant influence on the surface charge accumulation in the presence of a temperature gradient field. Excessive charge accumulation on the spacer surface will cause distortion of the surrounding electric field, partial discharge, and even the surface flashover of the spacer, seriously threatening the stable operation of the equipment. from the perspective of improving the surface conductivity of insulating materials and reducing surface charge accumulation, researchers have conducted much research into the modification of spacers. Seeböck used polyimide films in the form of DBD discharge in air, and the results showed that plasma, as an efficient method, could effectively promote the wettability, surface oxidation, and roughness of samples.. By measuring the physical morphology and chemical characteristics of the modified samples and applying DC voltages to the modified samples in SF6 gas to test the surface flashover effect, a plasma modification method of epoxy resin suitable for SF6 gas has been proposed. The original oxygen and other impurities in the air were brought out by the first introduced Ar. After applying the voltage, the atoms were ionized and the inert gas was mainly at the excited state, which hit the surface of the sample to open chemical bonds. CF4 offered both active particles and free radicals in the reaction and reacted with the chemical bonds opened on the surface of the sample
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