Research On The Contact Performance Of Power Connectors Based On Low Melting Point Alloys

Power connectors are commonly used connection devices in power transmission systems,and inevitably there are some latent failures.According to statistics,power connector failures account for more than half of transmission and transmission line failures.Power failures caused by connector failures cause a large amount of economic loss,and faulty power connectors are often accompanied by abnormal heating,which causes a large amount of energy loss.Serious accidents even lead to safety accidents,which seriously violates the guidelines for safe production of power systems.For the first time,this paper proposes to apply low-melting alloys to power connectors to replace the currently used power composite greases and reduce the failure rate of power connectors.In this paper,two series of low melting point Sn-Zn-Cu-Bi quaternary alloy and normal temperature liquid Sn-Ga-Zn-Bi quaternary alloy are studied to analyze whether the two series of alloys are suitable for power connectors..The main research contents and conclusions are as follows:(1)Firstly,through the analysis of the electrical contact theory,the factors affecting the contact resistance of the power connector are obtained.Then,the two-dimensional contact model of the rough surface and the two-dimensional contact model of the rough surface coated with the low melting point alloy are established,which is simulated by finite element method.The current line shrinkage diagram and the potential contour map of the two models were obtained,which verified the positive effect of coating the low melting point alloy on improving the contact performance of the power connector.(2)Adding Bi element to the Sn-0.7Cu-Zn alloy to form a Sn-Cu-Zn-Bi quaternary alloy,for alloys with a Bi content of 0.5%,1%,1.5%,and 2%,respectively.The test was conducted;the interface wettability was the main evaluation index,and the alloy with the mass fraction of Bi element of 1% was selected as the best.The reliability,mechanical properties,corrosion resistance and thermal stability of the power connector coated with a low melting point alloy with a mass fraction of 1% Bi were investigated.The results show that the Sn-0.7Cu-Zn-1Bi low melting point alloy can be used.It is applied to power connectors and can achieve better results.(3)The Sn-50Ga-10Zn-20 Bi alloy with normal temperature is applied to the power connector.Firstly,the contact resistance test scheme is designed.The coating is applied under different bolt fastening forces,different surface roughness and coating thickness.Comparison of power connectors covering Sn-50Ga-10Zn-20 Bi alloy and coated power composite grease.The results show that the power connector coated with Sn-50Ga-10Zn-20 Bi has a smaller contact resistance;then the electro-thermal coupling simulation and temperature rise test are designed.The results show that the power of Sn-50Ga-10Zn-20 Bi is coated.The connector has a small temperature rise,which verifies that the Sn-50Ga-10Zn-20 Bi has a positive effect on reducing the power connector.