Reserch On The Insulation State Monitoring System Of Roof Insulator On High-Speed-Train

High speed railway is the inevitable trend of the development of electrified railway. By the end of 2014, the operation mileage of China’s investment in high-speed rail reached 16000 kilometers, mileage ranks first in the world, about 50% of the operation mileage of the word, "four vertical and four horizontal" rapid rail way network in the main framework has begun to take shape. Therefore, the high-speed-train as an important part of high-speed railway, its safe and reliable operation has an important significance.Roof insulator on high-speed-train as an important electrical component is installed between the roof and the pantograph, mainly plays a supporting and electrically insulation effect. However, because the train tail gas and haze contamination accumulation on the surface of the insulator, and when the contamination damp, the insulator may flashover under the working voltage, which influences the safety of train’s running.But so far, only in electric locomotive, a high voltage produced by the high voltage transformer on the locomotive loading on the high-pressure system, then by observation of two secondary side voltage to judge if the insulation is reliable. On the high-speed-train, insulation detecting device produces a high voltage loading on the high-pressure system to judge if the insulation is reliable. But both the two methods have some defects and can’t monitor the in sulation state of roof insulator on high-speed-train. Therefore, here study an insulation condition monitoring system of roof insulator on high-speed-train, which can monitor its insulation state on line. This paper mainly completed the following contents:First of all, this subject studies the mechanism of insulator flashover. This part mainly studies the four stages of development of insulator flashover, and analyzes several insulator discharge model, and it proves that the surface pollution resistance of the insulator and the leakage current through the surface have an inverse relationship. Selection of leakage current as the characterization of state of the insulator has certain theoretical basis. The voltage across the insulator, temperature and humidity of the environment and other factors will also affect the leakage current.Secondly, this paper completes the design of the hardware platform and software program of monitoring system for the roof insulator on the high-speed-train. According to the demand of the system, the hardware platform part mainly designs the overall scheme of the system, and then select and debug the sensor module, data acquisition and storage module, alarm module, power module and man-machine screen separately. Since B&R PLC uses time-division multi-task operating system, so the software adopts modular design, and design different program according different function, also it sets the task cycle time differently according to the importance degree of the different function. Then according to the data collected, this paper designs a man-machine screen interface. After debugging and verification, the monitoring system can satisfy the requirement.Finally, the monitoring system was used to carry out a high voltage test in laboratory. After the test, the paper obtained the leakage current threshold of three kinds of insulators with different contamination degree, under the voltage of 25kV. This method of this test can be used to the test of leakage current measurement of roof insulator on high-speed-train.