Locomotive Electric Circuit, Earth Fault Diagnosis System

With the further increased speed of electric locomotive and development of high-speed train, particularly the six times speedup of Chinese railway,it requires that each electric circuit of electric locomotive operate safely and reliably. When more than two grounding faults occur in a electrical circuit of locomotive, the locomotive will operate abnormally and even burn out. Therefore, reliable grounding fault detection device must be installed in every electric circuit of locomotive.This thesis is based on the research and development of primary grounding fault detection device. It can be applied to every electrical circuit of locomotive, and detects the grounding fault of each electric circuit real time. This device doesn't have the disadvantages such as bad reliability, heavy load on repairman which the grounding relay used to have. It adopts the method of passive detection, and realizes the electrical isolation among main circuit, auxiliary circuit and control circuit thus reduces EMI which the control circuit suffers and improves electric level of electric locomotive and reduce worker's load and the railway running cost.This thesis is based on the facts of locomotive, and introduces the characteristics and working mode of every electrical circuit. It also introduces the primary detection method briefly. According to different circuits, this thesis established simulation model for theoretical analysis. It can simulate different grounding fault waves and conclude the corresponding grounding fault judgment algorithms. Then the new diction method is compared to the primary one, it solves the blind spot of the primary one. The problem during applying is analyzed and solved.This grounding fault detection device is based on Siemens 200PLC, The detection method and operation theory is introduced in thesis; it also introduces the main software and hardware design and whole structure design in details. The samples have already passed the type test and industrialization has been realized on different locomotives. The running result shows it can be put into use safely and reliable,achieved the expected results.