Research On Electrical Life Test And Prediction Of Low-voltage Circuit Breaker Contacts

As an important switchgear in the power grid,low-voltage circuit breakers are widely used in various switch control cabinets of power plants and power distribution networks.They are responsible for the transmission and distribution of electric energy,as well as the protection and control of electrical equipment.The reliable on and off of low-voltage circuit breakers plays a very important role in the safety and stable operation of the power grid and the protection of electrical equipment.If the performance status of the low-voltage circuit breaker can be judged in time,and the maintenance or replacement of it before the end of the electrical life can be guaranteed Reliable operation of the power grid.Aiming at the degradation of the electrical life performance of low-voltage circuit breakers,the paper builds an electrical life test system.Through the test system,the automatic opening and closing of low-voltage circuit breakers can be realized,and parameters such as the breaking arc voltage and current can be monitored;Taking the CM3-100C circuit breaker as an example,the electrical life test was carried out.The relationship between contact resistance,contact bounce,contact erosion quality and electrical life was analyzed,and the failure of the low-voltage circuit breaker after the end of the electrical life was analyzed.The surface morphology and chemical composition of the contact were analyzed,and the results showed that the corrosion quality of the contact can more accurately reflect the electrical life performance status.In addition,through separate load opening and closing tests,the influence of the breaking and closing processes on the erosion of contact materials was quantitatively analyzed,and the results showed that the loss of contact materials mainly came from arc erosion during the breaking process;The separated electrode method was used to measure the arc stagnation and transfer time on the contact surface during the breaking process,and the influence of arc stagnation and transfer on the degradation of electrical life performance and the influence of the breaking current on the arc stagnation and transfer time were analyzed.A Wiener process-based low-voltage circuit breaker electrical life performance degradation model was established based on the cumulative erosion of the contacts at each stage.The maximum likelihood estimation method was used to solve the model parameters,and the point estimate and interval of the remaining electrical life of the low-voltage circuit breaker were calculated.estimated value.Finally,the Monte-Carlo method is used to simulate the electrical life performance degradation process of low-voltage circuit breakers,and the electrical life performance degradation model based on the Wiener process is established through the simulation data,and reliability evaluation and residual electrical life prediction are carried out.The maximum error between the predicted result and the actual value is Only 5.64%,the error result meets the actual needs of the project.