| With the opening of Qingzang-Tibet railway passenger train,China has plateau railway passenger trains that currently operate at the highest altitudes and have the longest routes in the world.Qingzang-Tibet railway passenger trains are the first passenger trains in the world suitable for all-weather operation on the "roof of the world".However,due to the special environment of the Qingzang-Tibet plateau,the poor insulation of the main electric power line has been troubling the vehicle operation department.During the period from November to March of the next year,condensed water will be produced on the surface of the insulating plate and pole of the power connector base of the running trains.This will result in reduced insulation of the mainline.When the condensed water phenomenon is serious,it is necessary to organize a large amount of labor force to decompose the electric connector seat and conduct blow-dry treatment to ensure the insulation of passenger trains to meet the quality requirements of outbound.This causes great inconvenience to the maintenance of vehicles,affects the train on time out of storage,resulting in hidden dangers in train operation.Therefore,a solution was urgently needed to solve the condensate water on the trains,to improve the poor seasonal insulation of trains and ensure the safety of operation of trains.This study took the DC600V power connector as the research object.The main methods and research results were as follows:(1)The condensation water generation mechanism of the connector of trains was studied.There was a temperature difference between the air temperature and the surface of the train end connector.The greater the temperature difference,the faster the water vapor in the air turned into water droplets.The power connector seat was installed on trains,the contact surface with the plug was exposed to the outside of the trains,and the wiring end was inside the trains.During the operation of Qingzang-Tibet passengers trains in winter,the heating device in the trains was always working.The temperature inside the trains was maintained at about 18℃,while the lowest temperature outside the trains reach-40℃.Due to the large temperature difference between the two ends of the connector seat,condensation water was easy to form.The higher the relative humidity of the air,the faster the water vapor in the air changed into water droplets.(2)The internal structure of the car end connector was improved.A new structure to prevent condensation water was adopted,and the improved waterproof core board and sleeve with higher sealing performance were replaced.These measures allowed the rod to be completely isolated from the insulating plate and shell in a separate space.That was,through good sealing of insulating materials,to insulate the condensate produced on the pole column and condensate produced on the insulation board,shell.(3)In order to completely isolate from the external environment,eliminate the convection of hot and cold air and ensure the tightness,an independent device was set to prevent condensation water.The device was a sealed box structure.In order to facilitate the disassembly and installation in the maintenance process,an independent installation flange structure was designed on the box body.In order to facilitate the inspection of the pressing of the power connector and the generation of condensed water in the process of using the vehicle,an observation window was designed on the back of the box.When installing the connector,first of all,the heat-shrinkable tube was sleeved into the cable and heated evenly with the hot air gun.The cable and the four protruding inlet holes are then wrapped and sealed;Finally,the condensate is sealed with a seal strip around it.(4)In order to verify the reliability of the device,this paper used ANSYS Workbench to analyze the static performance and modal performance of the device.Through the analysis,the maximum load of the structure was 26.194MPa,and the maximum deformation was 0.046392mm,which was within the allowable variation range.Through the modal analysis of the condensate prevention device,the frequency parameters of the sixth-order mode were obtained:The first-order natural frequency was 446.03 HZ;the second-order natural frequency was 453.39 HZ;the third-order natural frequency was 502.01 HZ;the fourth-order natural frequency was 516.8 HZ;the fifth-order natural frequency was 598.79 HZ;the sixth-order natural frequency was 653.62 HZ.The results showed that:the natural frequency of the sixth mode of the condensate prevention device was far greater than that of the Qingzang-Tibet railway passenger train,which can effectively avoid the harm caused by the resonance phenomenon in the driving process.(5)The test research on the low temperature,high temperature,salt spray corrosion,constant damp heat,temperature change,alternating damp-heat weather resistance of the connector preventing condensation water device after optimization design was carried out.The results showed that:the insulation resistance between connector jack and Jack and between Jack and shell was greater than 20 M Ω,meeting the insulation resistance requirements;The test voltage of 3580v and 50Hz could be borne between the connector jack and Jack and between the jack and the shell,and the flashover and breakdown phenomenon could be seen for 1min,meeting the dielectric strength requirements.(6)By simulating the DC600V power connector in the actual limit environment(external environment temperature of vehicle end-40℃,internal environment temperature of vehicle 18℃),the device was tested to prevent condensation water.The results showed that:under the simulated actual limit environment,there was no condensation water on the surface of the internal wiring terminal of the connector,and the insulation resistance between the connector jack and the jack,and between the jack and the shell is greater than 20 MΩ,which meted the insulation resistance requirements.The test voltage of 3580v and 50Hz could be borne between the connector jack and Jack and between the jack and the shell,and the flashover and breakdown phenomenon could be seen for 1min,meeting the dielectric strength requirements.It was of great significance to prevent the generation of condensation water and to improve the seasonal poor insulation of bus trunk lines.(7)The condensate prevention function verification test was carried out for 2 hours,and no condensation water was found to be condensed.By increasing the desiccant,it was theoretically possible to meet the maintenance requirements of a one-stage repair period.The device had been planned to carry out the loading verification of the shower trains modified by Qingzang-Tibet Company in 2019,and it was necessary to verify the actual effect after running a heating period. |
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