Study On On-line Monitoring System Application Of Vacuum Degree Of Circuit Breaker

Vacuum circuit breaker has the advantages of large open capacity, long service life and low maintenance workload, so they get wide application in distribution network. Taking Baoding as an example, almost all breakers applied in distribution network are vacuum circuit breakers. Because of various reasons, the vacuum degree of the arc chamber is gradually destroyed under working condition, leading to the failure of the vacuum circuit breaker to open the current, and even the explosion. In order to solve this problem, an on-line monitoring system for vacuum degree of circuit breaker is designed in this paper to realize the real-time monitoring of the vacuum degree of circuit breaker, and to decrease the power failure caused by the vacuum arc extinguishing chamber.Firstly, structure, parameters and working principle of vacuum circuit breaker are introduced in this paper and common vacuum degree on-line monitoring method are introduced. The equivalent capacitance model is established for the potential change detection method and the coupling capacitance method and the advantages of these two detection methods are analyzed. Method of monitoring the vacuum degree of the electric field and the discharge pulse signal in the shield is introduced in this paper.Then the design process of the vacuum circuit breaker on line monitoring system is detailed introduced and in the data communication subsystem CRC checksum is introduced to confirm and guarantee the accuracy of the received code. The steady state interference signal is tested in a substation in Hebei Province and the main frequency is 50Hz and the digital filter is designed based on zero and pole assignment method.In the end, the on-line monitoring system of vacuum degree is verified in the laboratory environment and change of the electric field of the sensor is analyzed.