大吨位压接式复合绝缘子长期运行的机械可靠性

Mechanical Reliability of Crimped Composite Insulators with High Specified Mechanical Load in Long-term Service

由于防污闪的需要,我国特高压交直流输电线路大量采用大吨位压接式复合绝缘子,这就需要对大吨位压接式复合绝缘子的机械可靠性提出更高的要求。为了研究此问题,对国内几个主要绝缘子生产厂家的大吨位压接式复合绝缘子进行了短时破坏强度试验和"机械强度-时间"特性试验研究。试验研究结果表明,国内目前大吨位压接式复合绝缘子的短时破坏强度分散性σ主要分布在2%～3%左右,长期蠕变斜率k一般小于4%,都远小于现行标准中规定的8%。根据我国目前大吨位压接式复合绝缘子的实际性能情况,对其提出了新的设计准则和比目前标准中更严格的试验要求,认为其型式试验中机械耐受的试验负荷应该由60%Mav提高到75%Mav(其中Mav为平均机械破坏负荷);应增加机械强度抽样试验,其试验方法为3支绝缘子产品在1.2MSML(其中MSML为标称的额定机械负荷)拉伸负荷作用下持续96h不发生破坏。

Composite insulators with high specified mechanical load（SML）have been largely used in the ultra high voltage（UHV）AC and DC projects in China in order to prevent pollution flashovers.This needs to put forward higher requirement for the mechanical reliability of crimped composite insulators with high SML.For this purpose,the time-load characteristics of crimped composite insulators from several manufactures with high SML were tested.The results showed that the relative standard deviationsσof crimping composite insulators failure loads mainly distributed around 2%～3%,and was far less than 8%.The creeping slopes k was generally less than 4%,and was also far less than 8%.Then a new design principle of mechanical properties of composite insulator was suggested,and a higher test requirement was also suggested at the same time.The test load of load-time test（type test）was suggested to be changed into 75% Mav.A new time-load test was also suggested as a new sample test,and the load was suggested to be 1.2 MSML.