Experimental Investigation Of Electrical Performance Simulation And Degradation Mechanisms For Contact Materials Used In Ac Contactor

AC contactor is an important low voltage apparatus for frequent switching long distance AC main circuit and large capacity control circuit.In recent years,the requirement of electronic control system to AC contactor electric life and reliability index.In order to define correlation between life length and contact material electrical property of AC contactor,the paper designed and developed a new AC contactor electrical performance simulation experiment system with contact material,on such basis,it researched electrical degradation phenomenon and physical mechanism of silver tin oxide contact material during the process of experiment.Firstly,taking CJT1-20 AC contactor as test object,it designed mechanical movement structure and electrical main circuit of simulation experiment system for electrical properties of contact materials,it further designed movement control,signal conditioning,hardware circuit and corresponding software calculation of data communication,realized some parameter tests and data analysis functions,such as contact static pressure,welding force,contact resistance,arc time,arc energy and so forth.It analyzed typical contact voltage,current and waveform of the processes of contact closing and breaking according to the example of AC1 leading condition,analyzed sensitive parameters during the process of electric life test,including degradation regularity and physical mechanism of contact static pressure,contact resistance,arc energy,welding force and so forth.Afterwards,it finished surface morphology analysis and element component analysis of silver tin oxide contact material after electrical life test through scanning electron microscope and X ray energy spectrum analyzer.Through comparing degradation feature of contact material at various stages during the process of life test,it discussed micro crack,pore,melt,accumulation on the surface of contact material and formulation mechanism and physical mechanism of arc erosion of some patterns.Finally,it proposed a kind of analytical method of contact material electrical performance parameter prediction on the basis of BP neural network.Using collected AC current contactor response time and cumulative arc energy during the process of electrical life experiment as learning sample for inputting scalar,feed established neural network prediction model after making sample data normalization processing.It acquired functional relation between second-order input tensor and residual electric life which is constituted by accumulative arc energy and response time.The research ca provide method for simulation and test assessment of AC contactor electrical properties of contact materials,while it can provide practical value for prediction and failure analysis of residual electric life of AC contactor as well.