Experimental Study On Electrical Erosion Of Contact Materials Under Different Voltage,Current And Atmospheres

As one of the most critical parts of relay,electrical contacts are vulnerable to lose efficacy due to mechanical,arc and environmental erosion,in which the most obvious impact is electric erosion.However,electric erosion is a very complex subject,involving a lot of factors.Therefore,studying the anti-electric erosion property of contact materials and analyzing the influence of various parameters such as current,voltage and experimental atmosphere on the anti-electric erosion performance are of great significance to improve the arc erosion resistance of the contacts and enhance the reliability of the relay.Firstly,some improvements are made on the existing problems of the contact simulator to meet the experimental requirements.Then,the ablation experiment of AgNi and AgSnO2contacts under 20A,45A and 70A condition is carried out by using the improved device.The relationship between the current and the anti-corrosion performance is analyzed.The results showed that the two were positively correlated,and corrosion resistance of AgNi is better than that of AgSnO₂.The analysis may be due to the better thermal conductivity of Ni,which make it can quickly absorb contact heat.To investigate whether electrical erosion reisistance of AgNi is better than that of AgMeO,a series of AgNi and AgMeO contact ablation experiments are carried out under several kinds of current conditions,and no obvious regularity between the two electrical erosion resistance performance.Using scanning electron microscopy?SEM?and EDS analyses the typical morphology and composition of AgMeO and AgMe and verifies the causes of some of the contacts gaining weight.Secondly,due to the better ablation resistance of copper-based contacts than that of silver-based contacts,under the condition of 270V/270A,the ablation experiments of CuCr and CuW contact in Air are carried out to analyze their electrical erosion resistance.Then,keeping the experimental conditions unchanged,contacts ablation experiments in N₂ are carried out,and the results show that contact electrical erosion resistance in N₂ is better than in Air condition.Analyzing electrical properties of CuCr and CuW contacts under Air and N2 conditions by SEM and EDS approaches,and proves the above-mentioned conclusion.Finally,contacts ablation experiments are carried out under Air,N₂,CO₂ and O₂ four atmospheres with CuW70,which has relatively worse electrical erosion resistance,and we found that electrical erosion resistance still is the best in N₂ among the four kinds of atmosphere,whereas in O₂ contacts erode way too seriously than in other gases.