Analysis of the Influence of 800kV Circuit Breaker Opening and Closing Action on the Electromagnetic-stress Distribution Characteristics of Closing Resistance and Its Suppression Measures

The Pre-insertion Resistors of the 800kV circuit breaker is mainly used to suppress the closing inrush current and operating overvoltage of the circuit breaker during the closing process. However, due to the special application environment of the circuit breaker, the abnormal rate of the closing resistance of the AC filter field is relatively high. The change of the internal field strength of the circuit breaker under several conditions of breakage of resistors in different positions and sizes, cracks inside and outside the resistors, and falling of fragments of the resistors are analyzed, and the stress changes of the resistors during the opening and closing process are also analyzed., combined with the analysis results, a vibration reduction measure of adding a pure aluminum transition sheet between each two resistor sheets is proposed. The research results show that when there is a crack on the inner ring surface of the resistor sheet (width about 1mm and length about 25mm), the electric field distribution around it The influence is very small. When there is a crack on the outer surface of the resistor sheet (width of about 1mm and length of about 25mm), it will have a certain influence on the distribution of the surrounding field strength, but the effect is limited and will not cause a significant change in the field strength; larger damaged fragments (length 50mm), the internal field strength will be distorted when dropped, especially the field strength around the falling debris is seriously distorted, up to 94kV/cm, which will lead to an abnormal increase in the local field strength and cause breakdown. At the same time, there are stress concentration points on the inner hole edge and outer edge of the resistor sheet, which are also weak points of force. The results of this paper can provide a reference for the operation and maintenance of 750kV circuit breakers to avoid failures during operation.