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Silicone rubber is widely used in power equipment such as cable joint. In order to get better performance of insulator, it is significant to evaluate the insulation condition of aged silicone rubber insulators. Thus in this paper, surface potential decay measurement has been applied to investigate the performance of pristine and aged silicone rubber. Pristine and aged silicone rubber samples are charged...
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...
Epoxy resin (EP) is widely used as an insulating material in power equipment. Its dielectric relaxation and carrier transport properties are important factors affecting breakdown and surface flashover performance. The dielectric relaxation and carrier transport properties of EP based alumina (Al2O3) microcomposite were investigated through broadband dielectric spectroscopy. The glass transition temperature...
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...
Considering the response of free charges to high frequency alternating current (AC) electric field and multiemission and capture processes of weakly bound charges, dielectric relaxation effect of free carriers are proposed in this paper. According to this model, free charges and bound charges are regarded as the same except for the difference in transport distance, which is defined by the frequency...
Space charge characteristics of double-layer dielectric, which consists of low density polyethylene (LDPE) and nano-titania filled LDPE (named TiO2-LDPE), have been tested by pulsed electro acoustic (PEA) method under different high voltage direct current (HVDC) electric fields. The TiO2-LDPE material is fabricated by doping nano-TiO2 into free additive LDPE with different weight proportions of 0...
Compared with the conventional microcomposites, incorporating nanoparticles into polymeric matrix can better improve breakdown performance. Much works have been done to investigate the electrical properties of nanodielectrics since the first experimental results published. It is acknowledged that the interface between nanoparticle and polymeric matrix play a dominant role in the electric properties...
ZnO varistors are used extensively as the surge suppressor in the form of surge arresters in the power protection against lightning, temporary over-voltages, switching surges, transients, etc. In this research, DC degradation process at 50 mA/cm2 for 115 hours and restorability by heat-treatment at 800 oC for 24 hours for ZnO varistors were performed. The breakdown field E1mA (electric field at 1...
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,...
Basing on the range theory of European Space Agency (ESA) and Touzin's charge deposition theories, a 1-D internal charging model has been employed in simulating the effects of incident electron flux (IEF) and irradiation time on deep dielectric charging (DDC). It is calculated that the distribution of electric field, conductivity and space charge under both different IEF and time. The results indicate...
In this paper, a computer numerical simulation of one-dimensional deep dielectric charging (DDC) of spacecrafts induced by temperature and energetic electrons has been developed. It provides a method for spacecraft engineers to analyze the phenomena of DDC in spacecrafts and then to predict whether or when electrostatic discharging (ESD) will occur. The simulation code is developed to analyze the...
Recently, universal power law becomes widely used. In this paper, it was used to study the ZnO/Bi2O3 ceramics. Bi2O3 is the only additive of ZnO here in order to directly study the effect of Bi2O3 in ZnO. ZnO samples with different content of Bi2O3 were made by the traditional ceramic technique. Then the microstructure of the acid erosion surface was observed by polarized optical microscope, the dielectric...
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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