Reliability assessment of permanent magnetic actuator for vacuum circuit breaker

In recent years, the permanent magnetic actuator (PMA) is wildly applied in vacuum circuit breaker. The reliability of PMA is becoming more and more important with the development of vacuum circuit breaker. To enhance the reliability of PMA, the operation characteristics have been simulated and investigated in many papers. But only few of them are related to the reliability assessment of PMA. In order to assess the reliability of PMA of vacuum circuit breaker, demagnetization test of single steady-state permanent magnetic actuator (SSPMA) and life test are investigated in this paper. The results show that the permanent magnet can be demagnetized by opening coil current. The closing retention force decreases with the increase of the tripping current. Moreover, the SSPMA reliability decreases correspondingly. Based on the information of PMA life test, the reliability model is established applying Weibull distribution. With the help of the reliability model of permanent magnetic actuator, the reliability of PMA can be analyzed systematically, which is beneficial for the design of PMA.