Performance Analyzes On The Flashover Voltage Characteristic Of Insulator Strings Under Polluted Conditions

Contamination flashover of insulator strings is one of the most serious natural disasters, and it is also one of the most important pacing factors for determining insulation coordination of power system. A large number of researches about the influence of the equivalent salt deposit density(PESDD)on AC flashover voltage(Uf)of polluted insulators have been done home and abroad, but the research on the influence of the non-soluble deposit density(PNSDD)on Uf is few. And the relationship among Uf, PESDD and PNSDD has never been found. For each insulator shape, flashover occurring on the insulator surface has been determined with no surface pollution, uniform surface pollution and also partial surface pollution. For partial pollution, it has few cases been studied, the relationship between AC flashover voltages of contaminated insulators and the different sections of the insulator surface are polluted must be further researched.Base on measurement results of some out-door insulators, the strings under lower pollution severity had higher prosperity to flashover. Transmission line routes are located in different geographical environments, different weather conditions and different grades pollution. In this paper, a lot of laboratory experiments were carried out on artificially polluted XP-4.5 insulator strings in accordance with the standards IEC 60507:1991< Artificial pollution tests on high-voltage insulators to be used on a.c systems >. The article based on the result of pollution test, analyze on the flashover voltage characteristic of insulator string. Summing up the conclusion, the flashover voltages of single-chip insulator in contrast with the size of polluted surface. The voltage distribution of multi-string insulators relative to the shape of pulluted surface.The temperature and humidity also can make it changed. The results of study can be used to enrich the insulator strings flashover mechanism of frequency voltage transmission line, conform to the way of installation for the safe operation of the circuit and provide some guidance for the structural optimization of insulator and the connection fittings. It can also used to design the voltage-sharing measures for improving the voltage distribution. With the aim of benefiting the advanced study for setting up the effective standards of pollution severity.