Reliability Analysis Of Vacuum Circuit Breaker Under Multiple Factors

Vacuum circuit breaker has higher capacity of arc extinguishing and insulation.It is small in size and easy to operate.It has less pollution,good operation effect,a long life.And high voltage equipment in operation can be controlled and protected.In addition,it is widely used in power grid construction,and plays the role of controlling and protecting high-voltage equipment in operation.In order to improve the power quality and reduce the unnecessary loss caused by high load power failure,it is particularly important to improve its reliability continuously.Compared with the traditional operating mechanism,the permanent magnet mechanism has no mechanical lock,less fault source,and is widely used in vacuum circuit breaker because of its simple structure and intelligence.As an important part of vacuum circuit breaker,its reliability can not be ignored.As a whole,equipment failure is often caused by many factors.Therefore,it is necessary to analyze the changes of equipment reliability under the action of multiple factors.In this paper,a series of tests have been carried out on a 12 k V indoor vacuum circuit breaker and its bistable double coil permanent magnet mechanism.This paper analyzes the influence of multiple factors on the reliability of circuit breaker and permanent magnet mechanism from different angles by using various analytical methods,which provides reference for equipment maintenance and equipment reliability improvement.First,mechanical life tests at room temperature are carried out on 4 bistable vacuum circuit breakers,and the failure life data and failure reasons of the circuit breakers are obtained.The parameter values are recorded and the parameters are divided into states according to the parameter range,and the reliability network model of vacuum circuit breaker is established according to the parameter relationship.Then,based on the imprecise Dirichlet method,the failure probability and reliability interval of the circuit breaker in the specific parameter state is analyzed.The results show that this method can effectively evaluate the reliability of circuit breakers.The mechanical life test at room temperature is carried out on 7 bistable permanent magnet mechanisms.The simulated load is installed and the mechanical characteristic parameters are recorded.The parameters with degradation characteristics are selected for degradation data fitting,and the fitting curve and degradation equation are obtained.By using covariance analysis to analyze the correlation between the parameters,the joint density function of the three factors is established,and the estimated reliability value of the permanent magnet mechanism at each moment is calculated.According to the relevant standards of circuit breakers,the breaking tests of capacitor voltage and ambient temperature are carried out for bistable permanent magnet mechanisms.The closing speed and opening speed are measured.Standard least square method is used for regression fitting and the order of influence of the two factors on the opening and closing speed and the predictive polynomial are obtained,respectively.The effect of capacitance voltage is higher than that of ambient temperature.A predictive polynomial expressing the relationship between factors is obtained and the predicted value is compared with the actual value.According to the mean square error root RMSE and fitting coefficient R2,the fitting effect is good and the error is within the acceptable range.