沿海地区与内陆地区复合支柱绝缘子直流污闪特性比较

Comparison of DC Flashover Performances of Polluted Composite Post Insulators in Coastal Areas and Inland Areas

根据沿海地区绝缘子积污测量调研的结果,以不同盐灰比模拟沿海地区和内陆地区的复合支柱绝缘子积污特性,首先测量了两类试品在试验雾室内表面电阻随时间的变化趋势,然后在昆明特高压国家工程实验室进行直流人工污秽试验,试验过程中,用紫外放电仪对两类试品的局部放电现象进行观测,统计了紫外放电光子数,同时利用高速摄像机观察试品临闪电弧的发展情况。结果表明:灰密含量高的内陆地区试品表面电阻相对沿海地区试品低;在同盐密条件下,沿海地区试品的污闪电压高于内陆地区,且随着盐密的增加,两者差异越大;灰密大的内陆试品易产生局部电弧而出现干区,出现干区后,强吸水性使干区快速再次湿润,如此反复最后闪络,因此其污闪电压低;随着试验盐密的增加,不仅进一步降低试品表面电阻,还会使灰密高的内陆试品电弧桥接现象更明显,甚至出现电弧跨接现象,爬距利用率大幅降低,造成两者污闪电压值的差异更大。

According to the survey results of natural pollution of insulators in coastal areas, different ratios of equivalent salt deposit density （ESDD） to non-soluble deposit density （NSDD） are used to represent the accumulated pollution characteristics of composite post insulators located in coastal areas and inland areas. Firstly, the changing tendency of the upside shed surface resistances of the two sorts of specimens were measured in the fog chamber; then the DC artificial pollution tests were performed in National Engineering Laboratory for Ultra High Voltage Engineering Technology （Kunming） and the pollution flashover voltage U50% was determined by the Up-and-Down method. During the tests the partial discharge of the two sorts of specimens was observed by ultra violet camera and the statistics of ultraviolet photons was carried out, meanwhile the high-speed camera Phantom 12.1 was used to observe the partial discharge and the development of partial arcs on the insulator surfaces of the two sorts of specimens, which were assumed to be located in coastal areas or inland areas. Test results show that the surface resistances of specimens in inland areas with higher NSDD is lower than that in coastal areas; under the same ESDD the U50% of composite post insulators in coastal areas is higher than that in inland areas, and with the increase of ESDD the difference of the Usovo between them is greater; on the specimens with higher NSDD for inland areas the partial arc is easy to occur and it causes the dry-bands on the surfaces of insulators, when dry-band appears, its strong water absorbability makes the dry-band moist once again immediately, and the repeated reoccurrence of this phenomena makes the insulator surface flashover and the Usovo is lower than that of composite post insulators in coastal areas; with the increase of test ESDD, not only the surface resistances of the specimens decrease fiarther, but also the arcing-bridge of sheds on inland area specimens with higher NSDD becomes more obvious, it decreases the availability of creepage distance evidently and make the greater difference between the U50% of composite post insulators in the inland areas and that in the coastal areas.