Research on diagnostic method of plasma caused by corona discharge on top of composite insulator under atmosphere conditions

When a high voltage composite insulator is running online, there occurs corona discharge on both ends of it, which makes electricity particles accumulated on the top of the insulator. As the result, plasma is produced by corona discharge. With the incessant deterioration of running conditions, it is possible to make the plasma parameters change constantly to shorten part of creep distance, which is an important step during the whole flashover process. Therefore, it is undoubtedly significant to diagnose the plasma parameters for flashover mechanism research of contaminated composite insulators. Based on this, a composite insulator artificial contaminated test was designed and completed. The running conditions of insulator were simulated by adjusting the running parameters of the artificial contaminated lab, and the plasma parameters at certain running status were diagnosed by both Langmuir probe method and emission spectrum method. The test shows both of the two methods are valid for plasma diagnostic caused by corona discharge on the top of composite insulator, and the diagnostic results obtained by the two methods are accordant. The plasma parameters caused by corona discharge are in accordance with insulator´s running status in trend.