Line composite insulators are widely used in 35-500 kV AC and DC lines nationwide because of their advantages such as light weight, high mechanical strength, strong surface hydrophobicity, strong resistance to pollution flashover, zero test value, and convenient manufacturing and maintenance. Taiyuan Power Grid first tried 110 kV composite insulators (a total of 6 pieces) developed by the Department of Electrical Engineering of Tsinghua University in April 1988. So far, the longest running time has reached 17 years. With the increase of the number of composite insulators connected to the grid and the increase in the number of operating years, the number of accidents with composite insulators has also increased, mainly in the areas of lightning flashover, pollution flashover, bird damage, and decreased mechanical strength. This leaves hidden dangers to the safe operation of the power grid.
1 Operation of composite insulators After the successful development of domestic composite insulators, due to the lack of operational experience, Taiyuan Power Grid only operated on the heavily polluted 110 kV Ersheng Line 6 # and Yexi Line 33 # to test its anti-pollution performance. Large-scale use of composite insulators has been used since 1991, mainly for heavily polluted areas and difficult-to-traffic pole towers. As of June 2006, there are a total of 8 454 composite insulators used by Taiyuan Power Grid on 110 kV and above lines, which are installed on all linear pole towers of 110 kV and above lines. String of insulators.
2 Analysis and preventive measures of flashover failure of composite insulators Summary of the nearly 20 years of operating experience of composite insulators in Taiyuan Power Grid, it can be said that they have withstood the test of long-term harsh natural environment and maintained a good operating record, such as in March 1990 and Snow and fog continued in November 1994 and no line trip occurred. However, some failures have also occurred. Table 1 shows the statistics of composite insulator failures in Taiyuan Power Grid as of the end of 2005. It can be seen from Table 1 that the composite insulator failure caused by bird damage is 1 time, the composite insulator failure caused by fog flash is 1 time, and the composite insulator failure caused by lightning is 9 times. All faults occurred are external insulation flash