In recent years,more and more high-voltage overhead transmission lines were built passing through the karst regions in southwestern China.This type of special landform seems to have an adverse effect on the aging of t...In recent years,more and more high-voltage overhead transmission lines were built passing through the karst regions in southwestern China.This type of special landform seems to have an adverse effect on the aging of the sheds of the line suspension composite insulators,which may lead to unexpected flashover and line tripping.In order to find out the particularity of the aging characteristics of insulators operating in the karst regions,samples in operation were selected from both the karst regions and the flatlands.Hydrophobicity,amount of surface contamination,and contaminant composition of the sheds were studied,then a comparison of performance between the two was made,and the possible influencing factors that cause such differences were discussed.The results show that the overall aging of the sheds of the composite insulators operating at the karst regions is more aggravated,which is caused by the combined influence of factors including the special topography,climate,and pollution in the area.The strong wind crossing the col will bring about the mutual scraping on the edges and stress concentration at the root of the sheds,leaving scratches and root cracks;the infiltration from these rupture of acid liquid,if any,will accelerate the aging and corroding of the internal silicone rubber material;moreover,the carbonates enriched on the surface of the sheds will gradually transform into more corrosive sulfates in an acidic environment,leading to further deterioration and chalking of the sheds of the insulators.The research work in this paper can provide guidance for the current operation and maintenance of composite insulators in the karst areas,as well as having important reference values for the layout design and insulation configuration of transmission lines to be built across karst landforms in the future.展开更多
Composite insulators have been widely used in transmission lines.After being removed from transmission lines,their housing silicone material cannot degrade naturally.To tackle this problem,this paper proposes an effec...Composite insulators have been widely used in transmission lines.After being removed from transmission lines,their housing silicone material cannot degrade naturally.To tackle this problem,this paper proposes an effective method to recycle waste insulators by pyrolysis to obtain mullite(3Al_(2)O_(3)·2SiO_(2))with high purity and compact structure.The recycling process studied will not generate toxic products.The thermal degradation process of housing material is investigated by analyzing its degradation products including the gas and residues in detail.The experimental results indicate that the colorant agent Fe2O3 inside the housing material is beneficial for the generation of mullite by decreasing the temperature of mullitization.Besides,since the transitional alumina generated by the dehydration of aluminum hydroxide(ATH)has a smaller diameter and can better dissolute into the silica phases,ATH is a better choice as the additional aluminum resource.By comparing the components,structure,and particle size of grains formed at different calcination temperatures,the proposed pyrolysis temperatures of the two stages are 1400◦C and 1600◦C,respectively.展开更多
Slow positron beam was applied to study the depth profile structure of the virgin and the aged high-temperature vulcanized silicone rubber(HTV). Scanning electron microscope(SEM) images show that the surface of virgin...Slow positron beam was applied to study the depth profile structure of the virgin and the aged high-temperature vulcanized silicone rubber(HTV). Scanning electron microscope(SEM) images show that the surface of virgin sample is smooth, while the outdoor aged samples are all rough. According to the S(E) curves obtained by slow positron beam, in a depth of more than 1 μm, the S parameter of the sample aged at low-potential side keeps the same value with the virgin one;while the S values of the highpotential side aged sample remain rather low in a depth of about 5 μm. Thermo gravimetric analysis(TGA) results show that the sample in high potential side contains more inorganic constituents than that of other samples. The results are attributed to the strong electric field induced corona aging at high potential side of the composite insulator.展开更多
This paper reviews the research progress on abnormal temperature rise(ATR)of composite insulators.The ATR of composite insulators can be divided into two types,point-form temperature rise(PFTR)and bar-form temperature...This paper reviews the research progress on abnormal temperature rise(ATR)of composite insulators.The ATR of composite insulators can be divided into two types,point-form temperature rise(PFTR)and bar-form temperature rise(BFTR).The composite insulators with PFTR only show significant temperature rise at high relative humidity(RH)(>70%),and the temperature rise is located in the area that is 20 cm above the metal end-fitting.In a low humidity environment(<30%),there is little temperature rise(<1.0 K).The polarization loss on the surface of the silicone rubber housing under an AC electric field after moisture absorption is the main heating source.Corona discharge in high RH causes surface degradation of the silicone rubber.The composite insulators with BFTR shows significant temperature rise at both high(>70%)and low(<30%)RH.The temperature rise could reach more than 10◦C and the temperature rise area is wider,extending from the high-voltage end to several shed units at the lowvoltage side.And the glass fiber reinforced plastic(GRP)core in the composite insulator is found to be corroded.The heating energy is supplied by both conductance loss and polarization loss of the corroded GRP core.The decay-like degradation of the GRP core is caused by the combination of damp conditions,high electric field,discharge,mechanical load,et al.and may evolve into a decay-like fracture of the composite insulator.The preventive methods concerning quality control,structure optimization,material modification and operational strategy are presented.It is suggested that when PFTR is detected on the composite insulator,the inspection period of the insulator should be properly shortened.The composite insulator should be replaced as soon as the BFTR was detected.展开更多
基金supported by Science and Technology Project of Southern Power Grid EHV Transmission Company of China(010700KK52190003).
文摘In recent years,more and more high-voltage overhead transmission lines were built passing through the karst regions in southwestern China.This type of special landform seems to have an adverse effect on the aging of the sheds of the line suspension composite insulators,which may lead to unexpected flashover and line tripping.In order to find out the particularity of the aging characteristics of insulators operating in the karst regions,samples in operation were selected from both the karst regions and the flatlands.Hydrophobicity,amount of surface contamination,and contaminant composition of the sheds were studied,then a comparison of performance between the two was made,and the possible influencing factors that cause such differences were discussed.The results show that the overall aging of the sheds of the composite insulators operating at the karst regions is more aggravated,which is caused by the combined influence of factors including the special topography,climate,and pollution in the area.The strong wind crossing the col will bring about the mutual scraping on the edges and stress concentration at the root of the sheds,leaving scratches and root cracks;the infiltration from these rupture of acid liquid,if any,will accelerate the aging and corroding of the internal silicone rubber material;moreover,the carbonates enriched on the surface of the sheds will gradually transform into more corrosive sulfates in an acidic environment,leading to further deterioration and chalking of the sheds of the insulators.The research work in this paper can provide guidance for the current operation and maintenance of composite insulators in the karst areas,as well as having important reference values for the layout design and insulation configuration of transmission lines to be built across karst landforms in the future.
基金supported by the National Natural Science Foundation of China(51977118).
文摘Composite insulators have been widely used in transmission lines.After being removed from transmission lines,their housing silicone material cannot degrade naturally.To tackle this problem,this paper proposes an effective method to recycle waste insulators by pyrolysis to obtain mullite(3Al_(2)O_(3)·2SiO_(2))with high purity and compact structure.The recycling process studied will not generate toxic products.The thermal degradation process of housing material is investigated by analyzing its degradation products including the gas and residues in detail.The experimental results indicate that the colorant agent Fe2O3 inside the housing material is beneficial for the generation of mullite by decreasing the temperature of mullitization.Besides,since the transitional alumina generated by the dehydration of aluminum hydroxide(ATH)has a smaller diameter and can better dissolute into the silica phases,ATH is a better choice as the additional aluminum resource.By comparing the components,structure,and particle size of grains formed at different calcination temperatures,the proposed pyrolysis temperatures of the two stages are 1400◦C and 1600◦C,respectively.
基金Funded by the National Natural Science Foundation of China(No.21174108)the Science and Technology Project of China Southern Power Grid Co,Ltd(No.GDKJQQ20161197)
文摘Slow positron beam was applied to study the depth profile structure of the virgin and the aged high-temperature vulcanized silicone rubber(HTV). Scanning electron microscope(SEM) images show that the surface of virgin sample is smooth, while the outdoor aged samples are all rough. According to the S(E) curves obtained by slow positron beam, in a depth of more than 1 μm, the S parameter of the sample aged at low-potential side keeps the same value with the virgin one;while the S values of the highpotential side aged sample remain rather low in a depth of about 5 μm. Thermo gravimetric analysis(TGA) results show that the sample in high potential side contains more inorganic constituents than that of other samples. The results are attributed to the strong electric field induced corona aging at high potential side of the composite insulator.
基金supported by the National Natural Science Foundation of China(51477072)。
文摘This paper reviews the research progress on abnormal temperature rise(ATR)of composite insulators.The ATR of composite insulators can be divided into two types,point-form temperature rise(PFTR)and bar-form temperature rise(BFTR).The composite insulators with PFTR only show significant temperature rise at high relative humidity(RH)(>70%),and the temperature rise is located in the area that is 20 cm above the metal end-fitting.In a low humidity environment(<30%),there is little temperature rise(<1.0 K).The polarization loss on the surface of the silicone rubber housing under an AC electric field after moisture absorption is the main heating source.Corona discharge in high RH causes surface degradation of the silicone rubber.The composite insulators with BFTR shows significant temperature rise at both high(>70%)and low(<30%)RH.The temperature rise could reach more than 10◦C and the temperature rise area is wider,extending from the high-voltage end to several shed units at the lowvoltage side.And the glass fiber reinforced plastic(GRP)core in the composite insulator is found to be corroded.The heating energy is supplied by both conductance loss and polarization loss of the corroded GRP core.The decay-like degradation of the GRP core is caused by the combination of damp conditions,high electric field,discharge,mechanical load,et al.and may evolve into a decay-like fracture of the composite insulator.The preventive methods concerning quality control,structure optimization,material modification and operational strategy are presented.It is suggested that when PFTR is detected on the composite insulator,the inspection period of the insulator should be properly shortened.The composite insulator should be replaced as soon as the BFTR was detected.
