Simulation Analysis And Experimental Study On Contact Erosion Model Of High-power DC Relay

In recent years,with the continuous development of aerospace,marine,and distributed power generation technologies,the application of high voltage,high power,long life and miniaturization relays in the field of switching electrical appliances has become more widespread.Relay electrical contact is one of the most critical parts in electrical products.The arc generated during the static and dynamic contact breaking process will cause surface erosion,which will affect the reliability and life of the relay product.Up to now,few studies in the world have involved the simulation calculation of contact erosion of high voltage and high-power DC relays by various factors?contact material,ambient atmosphere,transverse magnetic field,separation speed,etc.?,which can not provide accurate theoretical basis for contact anti-erosion design and optimization.In this paper,the temperature field distribution of the contact pool is calculated based on the traditional heat transfer model and the fluid dynamics heat transfer model.The improved sputter function is used to calculate the sputter erosion of the contact model and the different contact materials are studied.The influence of the anode and cathode,voltage and current conditions,atmospheric conditions,transverse magnetic field and separation speed on the erosion amount is studied,and the comparison between the experimental results and the simulation results is verified.The time-varying diagram of the temperature field of the molten pool,the phase change diagram of silver material,the temperature change curve of the center point,the radial temperature curve of the upper surface at the highest temperature moment and the axial temperature curve at the highest temperature moment are obtained,and the width,depth and volume of the molten pool are extracted.The parameters of molten pool can provide data for the calculation of sputter erosion.Based on the improved probabilistic statistical sputter model and Borkowski arc cathode and anode energy power expression,the temperature field of 4 pure metal contacts?Ag,Cu,W,Cr?and 6 alloys?CuCr40,CuCr45,CuCr50,CuW60,CuW70,CuW90?are simulated and calculated.The order of the volume,width,depth and amount of the molten pool change with time as follows:Ag>Cu>W>Cr,CuCr50>CuCr45>CuCr40,CuW90>CuW70>CuW60.CuCr series materials have better overall erosion resistance than CuW series.Principal component regression analysis shows that the order of influence of three physical parameters on the sputter erosion of contact materials:thermal conductivity>density>specific heat capacity.Corrosion calculations are carried out on CuCr,CuW and silver-based contact cathodes and anodes,and the erosion of the anode is calculated to be much larger than that of the cathode.The simulation results of Ag-based contacts show that the amount of anodic erosion of Ag-based contacts is generally larger than that of cathodes,and the order of erosion of cathode and anode contacts is:AgCuO10>AgZnO10>AgNi10.The CuW70,AgW60 and Cu contacts are simulated in the Air,N₂ and O₂ atmospheres.The CuW70 and AgW60 contacts are the most eroded in O₂,the least in N₂,the Air was centered,and the Cu contacts have the best effect in the Air and the least amount of erosion.The erosion results of CuW70 anode contacts under different magnetic fields of 300V/60A and 300V/100A are simulated and calculated.For the same voltage and current condition,the order of sputter erosion in different magnetic fields is:80mT>65mT>50mT.The erosion results of CuW70 anode contacts at different separation speed of 300V/60A,300V/100A and 300V/140A are calculated.For the same external circuit voltage and current condition,the other parameters are unchanged,the order of erosion amount at different separation speed is:70mm/s>85mm/s>100mm/s.Considering the fluidity of molten pool,a comprehensive model system of dynamic and static contacts is established.With the help of moving grid technology,the moving process of dynamic contacts in arc time is considered,and the melting and fluidity of anode and cathode in molten pool are described by finite volume method.Based on the Borkowski model and the improved probabilistic statistical sputter model,the erosion of anode and cathode contacts is calculated and analyzed,including the influence of material,ambient atmosphere,transverse magnetic field and so on.The influence of material,ambient atmosphere,transverse magnetic field and separation speed to the sputter erosion of cathode and anode erosion contacts is consistent with the law obtained by traditional heat transfer model.Finally,a series of experiments on arc erosion are carried out and compared with the simulation results of 2 models.The morphology analysis and energy spectrum analysis of some contact materials are carried out.The CuW and CuCr series arc erosion experiments are carried out under the condition of 270VDC/100A to analyze the corrosion resistance of different Cu-based materials.Under the conditions of 200-500VDC/40-150A,in the Air,N₂,O₂ and CO₂ atmospheres,the CuW70 contact arc erosion experiment is carried out.Under the condition of 200-500VDC/40-150A,the AgW60 and Cu contact arc erosion experiments are carried out for Air,N₂ and other 4 atmospheres to analyze the influence of different atmospheres on the contact erosion.Under the condition of 200-500VDC/40-150A,arc erosion experiment of the CuW70 contact is carried out for different transverse magnetic field conditions and average separation speed conditions,and the influence of transverse magnetic field and separation speed on the corrosion of CuW70 contact is analyzed.Analyzing and comparing the experimental results under the corresponding conditions and the simulated calculation of the anodic erosion results,there is a good consistency between the two laws.The final calculated erosion amount of the model considering the fluidity of the molten pool is less than that of the traditional heat transfer model under the corresponding condition,which is closer to the actual erosion amount.