Research On Temperature Rise Characteristics Of The Static Electrical Contact For The Current Collector And Conductor Rail System

Current collector and conductor rail system is one of the main current collection modes of urban rail trains.Current collector and conductor rail system is a typical electric contact system,which transmits electric energy through the interaction between collector shoe and conductor rail.When the electric train stops,the internal equipment on the train needs to maintain normal operation,current collector and conductor rail remain relatively static,the current flows from the conductor rail to the collector shoe through the contact surface of the collector shoe and the conductor rail,and the Joule heat generated by the contact resistance accumulates on the contact surface,resulting in temperature rise.If the temperature rise is too high,it may damage the collector shoe and the conductor rail,and affect the quality of power supply.Therefore,it is necessary to study the temperature rise characteristics of the static electrical contact for the current collector and conductor rail system.In this paper,the temperature rise characteristics of static electric contact between the current collector and the conductor rail are studied by the method of theoretical derivation and experiment.Firstly,the fractal contact model of the collector shoe and the conductor rail is established from the micro point of view based on M-B fractal theory.Then,the contact resistance equivalent model and the temperature rise model of the contact surface between the collector shoe and the conductor rail are established,and the calculation formula of the contact resistance and the temperature rise of the contact surface is obtained based on the electric contact theory and heat conduction theory.Then,the temperature on the surface of the collector shoe is measured by setting up a static electric contact temperature rise test bed in the laboratory.Finally,the temperature data measured by the test and the temperature rise formula derived from the theory are verified mutually,and the applicability of the temperature rise formula is analyzed.The results show that the higher the current is,the higher the temperature rise on the collector shoe surface,the smaller the current,the smaller the fluctuation of the temperature rise curve and the easy to reach the steady state.And when the current exceeds 80 A,the temperature rise curve will fluctuate greatly and the stable state is not achieved for a long time,which is due to the change of contact resistance caused by the large temperature rise.On the whole,the average temperature rise of the contact surface between the collector shoe and the conductor rail decreases with the increase of the static contact force,and the change of the static contact force will change the distribution of the conductive spots on the contact surface,so that the temperature rise trend of each point on the contact surface is different,but there is a mutual restriction relationship.The test results show that the static electric contact performance of the current collector and conductor rail system is the best when the temperature of the contact surface is within 65℃,and the current is the main factor affecting the temperature rise.If only the temperature rise is considered,the static current should not exceed80 A.At the same time,increasing the static contact force appropriately can also reduce the temperature rise,such as ambient temperature,mechanical wear of shoe rail,etc.,the final value is determined.At the same time,increasing the static contact force can also reduce the temperature rise,in actual operation,the final value should be determined according to the actual situation of the site,such as environmental temperature,mechanical wear of current collector and conductor rail,etc.It is verified by actual measurement that the temperature rise model is consistent with the measured value when the current is less than 80 A,and the larger the static contact force is,the closer the measured value is to the theoretical value when the temperature rise reaches the steady state.When the current is above 80 A and the temperature rise is large,the theoretical temperature rise calculated by the temperature rise model is quite different from the measured value due to the material softening of the contact surface and the problem of heat dissipation in practice.