Reliabilty Theory And Experimental Study On Electrical Contact Of A Circuit Breaker With Movableand Static Contacts Under A Dynamic Load

With the rapid development of low voltage circuit breakers,the requirements for the performance and reliability of low voltage circuit breakers are becoming higher and higher.The utilization rate of low voltage circuit breakers on vehicles,high-speed railways and ships is also improving rapidly,and its reliability is directly related to people's life and property safety.At present,the reliability research of circuit breaker is mainly static,and there is little research on the reliability of vibration and shock environment for highway,railway,marine transportation and so on,so it is necessary to build reliability test of low voltage circuit breaker under dynamic load.This paper mainly through the research on the reliability test of circuit breaker contact mechanism and movement method,based on the high speed and variable load under the condition of circuit breaker reliability test system and simulation platform of compound vibration,fill blank in low-voltage electrical reliability test under load.The main work of this article is as follows:(1)Based on the "ES-60WLS3-445" electric vibration platform,the reliability test platform of the circuit breaker is developed in this paper.The platform mainly includes X,Y,Z axis 3D sliding platform positioning mechanism based on PLC control,circuit breaker contact breaking detection system and stratified data acquisition system.In this paper,vibration test platform is built for 3VT8 moulded case circuit breaker and 3WT8 frame circuit breaker.The frame breaker is separated from the circuit breaker's dynamic contact by lever principle because of its complex shape.(2)The manipulator as a tensile mechanism that separates the static and dynamic contacts of the circuit breaker needs sufficient strength,and it will not be stimulated in theexperimental process,and the degree of deformation should meet the experimental requirements.This paper uses ANSYS Workbench structure static analysis of the manipulator,it was found that the maximum is 0.1812 mm,the maximum equivalent stress is 132.59 MPa,the manipulator deformation on the influence is very small and the strength to meet the requirements;modal analysis found that manipulator six order vibration frequency is more than 120 Hz,will not be excited during the experiment.The random vibration analysis shows that the 3? stress of the manipulator meets the material strengthrequirements,and the 3? deformation of the three directions of X,Y and Z meet therequirements of the experiment.(3)Based on the mechanical modeling and analysis of the failure of the low voltage circuit breaker under the vibration excitation,the mechanical characteristic model of the low voltage circuit breaker under the dynamic load is established.The mechanical system of low voltage circuit breaker under vibration environment is simplified to the inverted pendulum system.Its vibration environment is provided by the shaking table,the shaking table is simplified into a car,and the dynamic contact of the circuit breaker is simplified to the inverted pendulum.Based on the analysis results,the reliability testing technology of low voltage circuit breaker is studied.Through this method,we can get the vibration response and characteristics of low voltage circuit breaker under the harmonic excitation(sinusoidal vibration)load.(4)The constant frequency sinusoidal vibration test of the 3VT8 plastic case circuit breaker is carried out,and the critical acceleration of the separation of the dynamic contact of the circuit breaker is obtained from 5Hz to 100 Hz.The piecewise linear interpolation is used to draw the corresponding fitting curve of the critical acceleration of the circuit breaker,and the change rule of the critical acceleration of the breaker's static and dynamic contacts is found with the increase of frequency.In addition,the experimental results are checked with the mechanical characteristic model of the circuit breaker.It is found that the theoretical simulation and the experimental results are basically consistent.The random vibration test of 3WT8 frame breaker,studied under different reserve force ?F,the critical power circuit breaker contact separation density.