为了解决我国南部沿海地区110 k V双回架空线路试点应用的管型复合材料绝缘杆(简称"复合材料杆")所存在的接地引下线易短接杆身绝缘的问题,针对典型设计的110 k V双回线路复合材料杆的结构特点,分析了避雷线采用沿杆表面架设...为了解决我国南部沿海地区110 k V双回架空线路试点应用的管型复合材料绝缘杆(简称"复合材料杆")所存在的接地引下线易短接杆身绝缘的问题,针对典型设计的110 k V双回线路复合材料杆的结构特点,分析了避雷线采用沿杆表面架设接地引下线方式所面临电气问题的本质成因,提出了沿导线方向在两回线路中心线上竖直架设引下线的方式,定义为内侧竖直接地引下方式。该方式实现了将铁塔2项功能分离:复合材料杆起结构支撑作用、接地引下线起导电通流功能。通过真型杆头雷电冲击放电试验,证实了内侧竖直接地引下方式较沿杆表面接地引下方式的电气优势:沿杆表面和内侧竖直2种接地引下方式下的雷电冲击绝缘强度U50%分别为960 k V和1 230k V,后者较前者提高了28%;观察内侧竖直接地引下方式中雷电冲击放电路径,当垂直引下线离杆身距离大于0.60 m时,可避免沿杆表面接地引下时雷击闪络和工频续流电弧烧蚀复合材料横担,并可利用杆身绝缘性增加相对地爬距。结合雷电性能计算,获得了内侧竖直接地引下方式的雷电性能,与沿杆表面接地引下方式相比,反击耐雷水平提高了28%,雷击闪络跳闸率降低了54%。因此110 k V双回线路管型复合材料杆避雷线采用内侧竖直接地引下方式的雷电性能明显优于沿杆表面接地引下方式。展开更多
Dielectric strength testing of ceramics can be performed with various setups and parameters. Comparisons of results from different sources are often not meaningful, because the results are strongly dependent on the ac...Dielectric strength testing of ceramics can be performed with various setups and parameters. Comparisons of results from different sources are often not meaningful, because the results are strongly dependent on the actual testing procedure. The aim of this study is to quantify the influence of voltage ramp rate, electrode size, electrode conditioning, and sample thickness on the measured AC dielectric strength of a commercial alumina. Mean values, Weibull moduli, and failure probabilities determined in standardized short time tests are evaluated and related to withstand voltage tests. Dielectric strength values in the range from 21.6 to 33.2 kV·mm–1 were obtained for the same material using different testing procedures. Short time tests resulted in small standard deviations(< 2 kV·mm–1) and high Weibull moduli around 30, while withstand tests at voltage levels with low and virtual zero failure probability in short time tests resulted in large scatter of withstand time and Weibull moduli < 1. The strong decrease in Weibull moduli is attributed to progressive damage from partial discharge and depolarization during AC testing. These findings emphasize the necessity of a thorough documentation of testing procedure and highlight the importance of withstand voltage tests for a comprehensive material characterization.展开更多
文摘为了解决我国南部沿海地区110 k V双回架空线路试点应用的管型复合材料绝缘杆(简称"复合材料杆")所存在的接地引下线易短接杆身绝缘的问题,针对典型设计的110 k V双回线路复合材料杆的结构特点,分析了避雷线采用沿杆表面架设接地引下线方式所面临电气问题的本质成因,提出了沿导线方向在两回线路中心线上竖直架设引下线的方式,定义为内侧竖直接地引下方式。该方式实现了将铁塔2项功能分离:复合材料杆起结构支撑作用、接地引下线起导电通流功能。通过真型杆头雷电冲击放电试验,证实了内侧竖直接地引下方式较沿杆表面接地引下方式的电气优势:沿杆表面和内侧竖直2种接地引下方式下的雷电冲击绝缘强度U50%分别为960 k V和1 230k V,后者较前者提高了28%;观察内侧竖直接地引下方式中雷电冲击放电路径,当垂直引下线离杆身距离大于0.60 m时,可避免沿杆表面接地引下时雷击闪络和工频续流电弧烧蚀复合材料横担,并可利用杆身绝缘性增加相对地爬距。结合雷电性能计算,获得了内侧竖直接地引下方式的雷电性能,与沿杆表面接地引下方式相比,反击耐雷水平提高了28%,雷击闪络跳闸率降低了54%。因此110 k V双回线路管型复合材料杆避雷线采用内侧竖直接地引下方式的雷电性能明显优于沿杆表面接地引下方式。
文摘Dielectric strength testing of ceramics can be performed with various setups and parameters. Comparisons of results from different sources are often not meaningful, because the results are strongly dependent on the actual testing procedure. The aim of this study is to quantify the influence of voltage ramp rate, electrode size, electrode conditioning, and sample thickness on the measured AC dielectric strength of a commercial alumina. Mean values, Weibull moduli, and failure probabilities determined in standardized short time tests are evaluated and related to withstand voltage tests. Dielectric strength values in the range from 21.6 to 33.2 kV·mm–1 were obtained for the same material using different testing procedures. Short time tests resulted in small standard deviations(< 2 kV·mm–1) and high Weibull moduli around 30, while withstand tests at voltage levels with low and virtual zero failure probability in short time tests resulted in large scatter of withstand time and Weibull moduli < 1. The strong decrease in Weibull moduli is attributed to progressive damage from partial discharge and depolarization during AC testing. These findings emphasize the necessity of a thorough documentation of testing procedure and highlight the importance of withstand voltage tests for a comprehensive material characterization.
