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EMU roof insulator is an important part of EMU equipment, but also to protect the EMU power supply safety and reliability of the key equipment. However, the increasing atmospheric pollution caused by environmental factors or equipment insulation aging are prone to EMU roof insulators flashover or other problems. If these faults cannot be ruled out in time, it will affect the safe operation of EMUs. In view of this, this article has designed EMU roof insulator leakage current detection system, can judge the insulation status of the roof insulator before rising bow. Taking into account that the normal operation of catenary voltage frequency of 50Hz, the system voltage is 0-60Hz adjustable frequency that can be used to simulate the contact network frequency fluctuations to meet the detection needs of different situations to achieve system flexibility. Also in order to facilitate the driver to observe and find problems in time, choose whether to raise bow, through the detection of hardware systems, software systems for analysis and judgment, the measurement system will be able to achieve intelligent and visualization. INTRODUCTION As the insulator runs under the conditions of strong electric field, mechanical stress, ultraviolet light, humidity, grime (acid, ozone, and dust) and the like for a long time, when the salt density on the surface reaches a certain level and the moisture is supplied, the insulation performance of the insulator will be reduced. 1, 3-5 We consider that we can have a more accurate judgment of the insulator state through detecting the leakage current. Because the leakage current is a dynamic indicator that is determined by the instantaneous actual creepage, weather and contamination levels. Leakage current is relatively easy to measure and is suitable for on-line testing, which contains enough information about the operating status of the insulator. 2 While designing the automotive high-voltage system of EMU, 25kV high-voltage electrical equipment is required to have sufficient high-voltage insulation performance to Yun ZHANG 1 Fu-Qiang TIAN 2* First author, Yun ZHANG, School of Electrical Engineering, Beijing Jiaotong University, Beijing, China Second author, Fu-Qiang TIAN, School of Electrical Engineering, Beijing Jiaotong University, Beijing, China Corresponding author: fqtian@bjtu.edu.cn

Study on Leakage Current Detection System of the Roof Insulators on the Electric Multiple Unit