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The influence of ozone surface treatment on surface flashover performance of epoxy resin/AhO3 microcomposites was investigated. Epoxy resin/AhO3 microcomposite samples with a diameter of 50 mm and a thickness of 1 mm were prepared and treated by ozone for various periods. Surface potential decay, surface conductivity, secondary electron emission coefficient, and surface flashover voltage in SF6 of...
Among all the carbon fillers, graphene has attracted tremendous research interest for its special two-dimensional and single-atom-thick structure. High electrical, mechanical and optical properties of graphene have been proved. By adding graphene as filler into polymer, it is possible to achieve a new composite with unique physical, electrical and thermal properties. In this paper, epoxy/graphene...
This paper focuses on the impulse and DC surface flashover performance of LDPE/TiO2 nanocomposites, which is beneficial to the improvement of electric discharge in power equipment. The results point out that both impulse and DC surface flashover voltages initially increase and then decrease with the increase of nanoparticle loading (DC flashover voltage is higher than that of impulse). Samples with...
It is known that nanocomposites may have better surface flashover properties, which are important to the use of dielectrics in electrical equipment. By changing the content of nanoparticles added into polymers, the surface flashover voltage of nanocomposites can be increased by 30 %. One reason is that the changing of nanoparticles makes a contribution to different trap characteristics. As the density...
Surface flashover phenomena under dc voltage greatly limit the improvement of insulating strength, which has been a key problem restricting the miniaturization and the practicality of high voltage dc power equipment. This paper investigated the influences of surface trap parameters for electrons on dc flashover in vacuum of epoxy composites. Pure epoxy resin, three kinds of epoxy nanocomposites and...
Because of the special surface energy of nanoparticles, the electrical, thermal and mechanical properties of nanocomposties may be improved. In general, emission of electrons at cathode leads to charging of the surface and thus results in surface flashover. Since flashover happens at the interface between dielectrics and atmosphere, different characteristics of atmosphere and dielectric may influence...
Surface flashover is one of the main factors leading to insulation failure. For example, epoxy insulator in Gas Insulated Switchgear (GIS) is the most vulnerable insulation components; the failure endangers the reliability of GIS and even leads to accidents and economic losses. Thus, developing advanced materials to be much more safely used in GIS is significant. Here we report the study on surface...
Deposited charges in dielectric material under electron-beam radiation have an important influence on dc vacuum surface flashover. This paper investigates the charge transport characteristics of polyimide under electron-beam radiation and dc voltage. Based on the actual size of electrodes and polyimide, a physical model of electron-beam radiation is proposed. Considered the processes of charge deposition...
Compared with breakdown strength of insulating material used in power equipments, insulator employed in power system is easy suffered from surface flashover in vacuum. So, surface flashover has become a mainly restricted factor for developing high voltage and efficiency power equipments in vacuum. Although many works have been done to investigate the characteristics of surface flashover in vacuum,...
In this paper, a new organic insulation structure was proposed and prepared to improve the surface flashover performance in vacuum by inserting multilayer high gradient organic composite between the electrode and the dielectric. The simulation technique was used to calculate and analyze the electric field distribution of this new insulation structure. On the basis of theory analysis, the samples of...
Some insulating structures of Mo/Al2O3 cermet - Al2O3 ceramic - Mo/Al2O3 cermet were prepared to improve surface flashover performance in vacuum through co-firing, where the volume amount of Mo was managed from 2 to 50 vol% and there could exist one or two layers with different Mo amount in Mo/Al2O3 cermet. The influences of Mo amount of Mo/Al2O3 cermet on the surface flashover voltage in vacuum of...
In this paper, a new organic three-layer A (carbon black semi-conductive master batch and PE)-B (polyethylene)-A insulation structure was proposed and prepared to improve the performance of vacuum surface flashover by adjusting the permittivity of the A layer dielectric. It is proved that the three-layer insulation structure could greatly improve the vacuum surface flashover performance.
In the paper, the influences of trap levels on both DC and impulse surface flashover voltage of semi-crystalline cross-linked polyethylene (XLPE) in vacuum were investigated. With different heat-treatment, the electrical properties and trap distribution of samples were studied. It is proposed that the trap levels are changed by heat treatment leading to the improvement of surface flashover properties...
In this paper, ZnO varistor+Al2O3 ceramic+ZnO varistor insulators were made, in which the conductivity and permittivity of ZnO varistors were controlled by changing its voltage gradient. Then the influences of conductivity and permittivity of ZnO varistors on the DC and pulsed surface flashover voltage in vacuum were experimentally investigated. The experimental results indicated that the DC and pulsed...
In this paper, A-B-A insulators were designed to improve the characteristics of surface flashover in vacuum by adjusting conductivity and permittivity of layer A. According to electric field theory of series dielectrics, the DC and pulsed field distributions of the insulators were calculated and the influences of conductivity and permittivity of Layer A on the electric field of vacuum-insulator-cathode...
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