Analysis on natural contamination characteristics of UHV AC post porcelain insulator

In order to study the natural contamination characteristics of UHV post porcelain insulator, we tested pollution severity of post insulator for three years which operated in 1000kV Jindongnan UHV AC substation. According to ESDD and NSDD measurement and pollution composition analysis results, a series influence factor of comparative analysis on natural contamination characteristics were performed on post insulators. Such influence factors include the top surface to bottom surface of insulator shed, the windward side to leeward side of insulator shed, average diameter, long time contamination depositing and etc. The results are as follows: 1) The distribution of pollution matter for 1000kV post porcelain insulator is very uneven. The ESDD ratio of high-voltage end of insulator is 3.4 times severe than other part, and The NSDD ratio is 2.3; 2) The pollution severity measurement value of insulator top surface is higher than bottom surface generally. The ESDD ratio of top surface to bottom surface of insulator(T/B) is 1.8, and the NSDD ratio of top surface to bottom surface of insulator (T/B) is 1.6; 3) The pollution severity measurement value of insulator leeward side is higher than windward side generally. The ESDD ratio of the windward side to leeward side of insulator (W/L) is 0.64, and the NSDD ratio of the windward side to leeward side of insulator (W/L) is 0.55; 4) The saturated ESDD is not proportional to continuous deposition time, but the saturated NSDD is basically proportional to continuous deposition time; 5) The pollution level of insulator has descend trend along with the increase of average diameter; 6) the CaSO
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content of pollution matter is 68%. This work can provide some important references for UHV project external insulation design, product manufacturing, operation and maintenance.