Modelling Of The Ac Contactor Conta CT Resistance And Application

AC contactor is an important switching device in power system,and it is the key to ensure reliable operation of power system.Therefore,it is necessary to study the method of improving its working reliability.Contact resistance is not only the key factor of AC contactor performance and reliability,but also an important basis for measuring contact failure and life prediction.Therefore it is important to model and study contact resistance of AC contactor.In this paper,the surface contact problem is briefly reviewed,and the research status of rough contact surface model and contact resistance are summarized.We study and model the problems of rough surface characterization.The roughness surface is extracted by statistical sampling and fractal function respectively.By comparing the two methods,fractal representation is more general than statistical method.Therefore,we select W-M function fractal representation to analyze the rough surface.Then,in order to simplify the contact modeling,considering the contact deformation,two rough contact surfaces of the deformable contact is simplified as a surface with roughness which equal to two surfaces equivalent roughness and an ideal smooth plane contact.We analyze the force and deformation of convex body as the smallest analysis unit,then calculate the contact press and contact area of actual points.At the end of this paper,by combining the fractal characterization of rough surface model,the mathematical model of contact resistance was established.Some suggestions for reducing the contact resistance are put forward:(1)If the roughness of the contact surface is reduced,the contact surface become more smooth,and the actual area of the current conduction is greater,and the contact resistance is smaller.(2)For specific material and contact surface,which means fractal parameters D and G is fixed,suitable contact load can be calculated.(3)Selecting the appropriate material can reduce the contact resistance,such as mentioned in this article,silver tin oxide added 500 nmBi as a material improve the electrical conductivity and hardness,which can optimize the performance.The above three methods can reduce the contact resistance,then optimize the performance of AC contactors and meet the market demand.