| Un-uniform pollution of insulators on running transmission lines is a commonphenomenon and one of the causes of flashover accident. So far, a lot of researchesabout un-uniform pollution have been taken at home and abroad. Their study is mainlyabout the uneven distribution of contamination along the top and bottom surface ofinsulators or the insulator strings, while study on un-uniform pollution along windwardsurface and leeward surface of insulator is very few.Based on the existing research results at home and abroad, this paper selected4types of typical porcelain and glass insulators as samples, and a lot of laboratoryinvestigations on the DC flashover performances of sample insulator strings werecarried out in the artificial fog room at Key Laboratory of Chongqing University, themain work and conclusion for this paper is as follow:①Use XP-70，XWP2-70，LXY-70and LXY4-160as tested insulator, study theDC flashover performance under condition of sectoral non-uniform contaminationbased on average salt deposit density(SDD). The results show that the characteristicexponent (a) characterizing the influence of SDD on Ufis basically not affected bysectoral non-uniform pollution. Both Y/B and K have impact on Uf. With the increasingof Y/B and K, the value of Ufwill decrease, and the influence of Y/B on Ufis moreobvious than that of K.②According to the results of the test, analyzed the impact of structure and type ofinsulators and sectoral un-uniform pollution on valid coefficient of creepage distance.As the results show, in the condition of uniform pollution, the valid coefficient ofcreepage distance of insulators are different because of the different structure and type.In the condition of sectoral un-uniform pollution, under light contamination, the validcoefficient of creepage distance will firstly increase and then decrease with theincreasing of Y/B, and increase all the time with the increasing of K; while uder heavycontamination, the valid coefficient of creepage distance will increase with theincreasing of Y/B and K.③By using XP-70insulator as tested sample, measured the leakage current andanalyzed the impact of sectoral un-uniform pollution on the critical flashover currentIcr.The results show: the critical flashover current will increase with the increase of SDD,and more serious the sectoral un-uniform pollution is, less obvious the influence of SDD on Icrwill be; Y/B and K have impact on Icrtoo, and the value of Icrwill increase withthe increase of Y/B and K.④By using cameral, the DC pollution flashover process can be described as fourphases: Corona discharge, the forming of filamentous small local arc, the developing ofbig local arc and flashover of insulator. The more serious sectoral un-uniform pollutionis, floating arc phenomenon is more obvious, and therefore the lower the flashovervoltage.⑤Taking LXY4-160insulator as example, this paper analyzed the influence ofsectoral un-uniform pollution on the choice of out-doot insulation on transmission lines.The results show that, under sectoral un-uniform pollution, the number of insulatorsneeded on transmission lines will increase. |
