Transient enclosure voltage（TEV）,which is a phenomenon induced by the inner dielectric breakdown of SF_6 during disconnector operations in a gas-insulated switchgear（GIS）,may cause issues relating to shock hazard ...Transient enclosure voltage（TEV）,which is a phenomenon induced by the inner dielectric breakdown of SF_6 during disconnector operations in a gas-insulated switchgear（GIS）,may cause issues relating to shock hazard and electromagnetic interference to secondary equipment.This is a critical factor regarding the electromagnetic compatibility of ultra-high-voltage（UHV）substations.In this paper,the statistical characteristics of TEV at UHV level are collected from field experiments,and are analyzed and compared to those from a repeated strike process.The TEV waveforms during disconnector operations are recorded by a self-developed measurement system first.Then,statistical characteristics,such as the pulse number,duration of pulses,frequency components,magnitude and single pulse duration,are extracted.The transmission line theory is introduced to analyze the TEV and is validated by the experimental results.Finally,the relationship between the TEV and the repeated strike process is analyzed.This proves that the pulse voltage of the TEV is proportional to the corresponding breakdown voltage.The results contribute to the definition of the standard testing waveform of the TEV,and can aid the protection of electronic devices in substations by minimizing the threat of this phenomenon.展开更多
Long-term liquids diffusion tests were performed on glass fibre reinforced polymer(GFRP)used in high voltage composite insulator.The plate-shaped GFRP specimens were immersed in three types of liquids,which high volta...Long-term liquids diffusion tests were performed on glass fibre reinforced polymer(GFRP)used in high voltage composite insulator.The plate-shaped GFRP specimens were immersed in three types of liquids,which high voltage composite insulator would encounter in practice,including deionised water,NaCl solution and nitric acid solution for a period of 4000 h.Chemical reaction and physical dissolution complicated the diffusion processes,which could be divided into three types based on the features of diffusion curves.Fourier transform infrared spectroscopy,scanning electron microscopy and optical interferometry were employed to investigate the chemical property,two-dimensional(2D)and 3D surface morphologies of GFRP.The results revealed that the surface layer of GFRP was destroyed to some extent depending on the type and concentration of the liquid,the maximum of profile height deviation of GFRP surface was proposed to evaluate the extent of the corrosion of GFRP,the greater the profile height deviation,the more serious the corrosion of GFRP.The present work is helpful for a better understanding of the diffusion behaviour of liquids into GFRP used in high voltage composite insulator as well as in other industry applications.展开更多
High-temperature vulcanised(HTV)silicone rubber composite insulator has been widely used in extra-high and ultra-high transmission lines due to its excellent electrical and mechanical performance.In practice use,liqui...High-temperature vulcanised(HTV)silicone rubber composite insulator has been widely used in extra-high and ultra-high transmission lines due to its excellent electrical and mechanical performance.In practice use,liquids may encounter the composite insulator intermittently and can lead to the degradation and deterioration of silicone rubber.In the present research,the effects of liquids immersion and subsequent drying on the surface properties of HTV silicone rubber were investigated by means of the contact angle measurement and surface physical morphology measurement which was further analysed in terms of the discrete wavelet transform method,multiresolution signal decomposition algorithm,and three-dimensional fractal dimension calculation.Based on the experimental results,the mechanism of the loss and recovery of the hydrophobicity of HTV silicone rubber surface during the liquids immersion and subsequent drying processes were further explained by taking into consideration the embedded water molecules(and/or hydrated ions)on the HTV silicone rubber surface and the synergy of the increase in roughness/fractal dimension and low molecular weight siloxanes diffusion.This study is helpful for better understanding of the change of surface properties of HTV silicone rubber caused by environmental and electrical stresses.展开更多
基金supported by the National Basic Research Program of China(973 Program) under grant 2011CB209405
文摘Transient enclosure voltage（TEV）,which is a phenomenon induced by the inner dielectric breakdown of SF_6 during disconnector operations in a gas-insulated switchgear（GIS）,may cause issues relating to shock hazard and electromagnetic interference to secondary equipment.This is a critical factor regarding the electromagnetic compatibility of ultra-high-voltage（UHV）substations.In this paper,the statistical characteristics of TEV at UHV level are collected from field experiments,and are analyzed and compared to those from a repeated strike process.The TEV waveforms during disconnector operations are recorded by a self-developed measurement system first.Then,statistical characteristics,such as the pulse number,duration of pulses,frequency components,magnitude and single pulse duration,are extracted.The transmission line theory is introduced to analyze the TEV and is validated by the experimental results.Finally,the relationship between the TEV and the repeated strike process is analyzed.This proves that the pulse voltage of the TEV is proportional to the corresponding breakdown voltage.The results contribute to the definition of the standard testing waveform of the TEV,and can aid the protection of electronic devices in substations by minimizing the threat of this phenomenon.
文摘Long-term liquids diffusion tests were performed on glass fibre reinforced polymer(GFRP)used in high voltage composite insulator.The plate-shaped GFRP specimens were immersed in three types of liquids,which high voltage composite insulator would encounter in practice,including deionised water,NaCl solution and nitric acid solution for a period of 4000 h.Chemical reaction and physical dissolution complicated the diffusion processes,which could be divided into three types based on the features of diffusion curves.Fourier transform infrared spectroscopy,scanning electron microscopy and optical interferometry were employed to investigate the chemical property,two-dimensional(2D)and 3D surface morphologies of GFRP.The results revealed that the surface layer of GFRP was destroyed to some extent depending on the type and concentration of the liquid,the maximum of profile height deviation of GFRP surface was proposed to evaluate the extent of the corrosion of GFRP,the greater the profile height deviation,the more serious the corrosion of GFRP.The present work is helpful for a better understanding of the diffusion behaviour of liquids into GFRP used in high voltage composite insulator as well as in other industry applications.
文摘High-temperature vulcanised(HTV)silicone rubber composite insulator has been widely used in extra-high and ultra-high transmission lines due to its excellent electrical and mechanical performance.In practice use,liquids may encounter the composite insulator intermittently and can lead to the degradation and deterioration of silicone rubber.In the present research,the effects of liquids immersion and subsequent drying on the surface properties of HTV silicone rubber were investigated by means of the contact angle measurement and surface physical morphology measurement which was further analysed in terms of the discrete wavelet transform method,multiresolution signal decomposition algorithm,and three-dimensional fractal dimension calculation.Based on the experimental results,the mechanism of the loss and recovery of the hydrophobicity of HTV silicone rubber surface during the liquids immersion and subsequent drying processes were further explained by taking into consideration the embedded water molecules(and/or hydrated ions)on the HTV silicone rubber surface and the synergy of the increase in roughness/fractal dimension and low molecular weight siloxanes diffusion.This study is helpful for better understanding of the change of surface properties of HTV silicone rubber caused by environmental and electrical stresses.
