# A Network-Based Method to Analyze EMI Events of On-Board Signaling System in Railway
## 1 Introduction  
The electric multiple units (EMU) are becoming increasingly advanced and intelligent with the new technology applied in the world railway system, such as the new types of CR (Fuxing in China Railway) series in China in the last years. Risks from electromagnetic (EM) disturbance to the On-board Train Control System (OTCS) has been spotlighted and investigated in the railway industry [1; 2; 3; 4; 5], because it may cause serious fault or failure when the electric and electronic parts are subjected to them. To ensure the safe operation of the EMU, system-level EMC analysis of OTCS is essential and it is regarded as one tough work with the following features. The OTCS is a complex system that the subsystems and components are distributed throughout the EMU. During the continuous movement of EMU, interactions between high power sources (mainly from the traction power supply and drive system) and safety-critical systems (OTCS) will occur, and it is a different EM environment from other industries. Thus, EM modeling and test for every EMC problem of subsystem require large-scale computation and massive measurement. However, the traditional solutions facing such a system-level assessment are limited. Components and equipment in OTCS are required to fulfill the requirements of EMC regulations such as the IEC 62236 series before installation and application [6]. Therefore, there are no systems in OTCS that have not been qualified for EMC. Despite these numerous tests, the OTCS is still broke down possibly due to the special EM environment in high-speed railway. There is a disparity that leads to the EMC problems in OTCS between the tested EM environment in the laboratory and actual on-site conditions. In general, even if some measures have been taken for the EM interference problem of a particular subsystem, there may cause another problem in other subsystems in the limited space. To prevent EM disturbance generated by the traction power supply and drive system in EMU from interfering with the performance of OTCS, considerable research work has been done on this issue by manufacturers, researchers, and operators related to the railway domain. There are numerous sources of EM disturbances in the high-speed railway system. Through deep investigation and measurement of the EM environment in railway, it can be found that the sources derive from two major parts of the EMU. One is the traction power supply system and the other is the traction propulsion system [7; 8; 9; 10; 11; 12; 13]. The former mainly comes from the pantograph arcing at the offline moment from the pantograph and the contact wire due to the inevitable vibration. Reference [7] presented a measurement to investigate EM interference phenomena in pantograph arcing and the results showed a significant difference between the pantograph going up and down. Additionally, a foundation of the pantograph arcing process was formed by experimental analyses of pantograph arcing phenomena with the AC supply [8]. Because of the difficulty in calculating the radiated disturbance from pantograph arcing, a method that combines numerical modeling and reverberation chamber measurements was proposed in Reference [9]. Moreover, Reference [10] showed the radiated emission of a high-speed railway system by modeling and experimental measurements based on the multi-conductor transmission line theory. The latter parts including the transformer, converters, and motors export most of the sources with transient disturbance. References [11; 12] discussed the EM sources in the traction system by practical measurement. For the study and prediction of the EMC problems in the propulsion system, the high-frequency model containing converter and traction motor is developed in Reference [13].