Finite Element Simulation Research On Arc Erosion Of AgCuO And AgSnO₂ Electrical Contact Materials

Silver metal oxide(AgMeO)is an electrical contact material widely used in low-voltage electrical appliances.It plays an irreplaceable role in relays,household appliances and communication equipment.AgCdO electrical contact is known as"universal electrical contact"because of its excellent comprehensive performance in use.Because AgCdO electrical contact will evaporate toxic vapor in the process of use,EU issued ROHS directive to prohibit the use of AgCdO.In order to replace the toxic AgCdO electrical contact materials,people have studied the environmental friendly electrical contact materials such as AgSnO₂,AgCuO and AgZnO.However,these environmental friendly AgMeO,which are widely used in the market,can not completely replace AgCdO,especially in the aspect of arc erosion.In order to systematically clarify the influencing factors of arc erosion and splashing quality of AgCuO and AgSnO₂ electrical contacts,three models of single electrical contact,double contacts with positive and negative static electrodes and double contacts with positive and negative moving electrodes were established by using finite element method.Using different finite element models,the effects of oxide content,physical properties(density,constant pressure heat capacity and thermal conductivity)and external environment(breaking speed,ambient atmosphere and magnetic field intensity)on the arc erosion splash quality of the two AgMeO were measured at 18 V voltage and25 A current.The results are as follows:The effect of oxide content on the arc erosion and splash quality of AgCuO?AgSnO₂ electrical contact was studied by using a single electrical contact model.The results show that the arcing time range of solid phase to liquid phase transition at the center point of AgCuO electric contact is 0.8<T<1.2 ms.For AgCuO and AgSnO₂electrical contacts,with the increase of oxide content,the volume of molten pool increases and the splashing mass also increases;when CuO content is 2%,the volume of molten pool of AgCuO(2)electrical contact is smaller and the splashing mass of arc erosion is lower;when SnO₂ content is 10%,the volume of molten pool of AgSnO₂electrical contact is smaller and the splashing mass of arc erosion is lower.The effects of physical properties(density,constant pressure heat capacity and thermal conductivity)of oxides in AgCuO?AgSnO₂ electrical contacts on the quality of arc erosion and splashing were studied by using a single electrical contact model.Taking AgSnO₂ with 2%SnO₂ content as an example,the influence of density on the splash quality of AgSnO₂(2)electrical contact is not obvious,but with the decrease of thermal conductivity and constant pressure heat capacity,the splash quality of arc erosion increases,and the thermal conductivity has a greater influence on the splash quality of arc erosion.The effects of external environment(breaking speed,atmosphere and magnetic field intensity)on the quality of electric contact arc erosion and splashing were studied by using the static contact model and the moving contact model.Taking AgSnO₂ with SnO₂ content of 2%as an example,the results show that the quality of arc erosion splash of AgSnO₂ electric contact is smaller in nitrogen atmosphere than that in oxygen atmosphere.With the increase of magnetic field intensity and breaking speed,the quality of arc erosion splash decreases,and the magnetic field intensity has a great influence on the quality of arc erosion splash.By comparing the three finite element models,it is found that the splashing mass of the double contact model is the smallest.