Analysis and modeling of EMC problems in railway detector system

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Analysis and modeling of EMC problems in railway detector system

Niska, S. / Ekman, J.

Current trends in railway transportation is towards heavier loads and increasing speed of train sets. This require improved control security systems and communication services to maintain a high security level. This development is putting higher demands on the electromagnetic compatibility (EMC) of each electronic system placed near the railway. EMC applied to railway traction systems covers a wide range of phenomena, such as inductive noise in parallel communication lines, impulse noise from lightning and traction transients, production of hazardous voltages under step and touch conditions and the appearance of stray current. This paper details electromagnetic modeling and analysis of detector systems used in the Swedish railway system. The partial element equivalent circuit method has been used to recreate transient waveforms, captured by a measurement system, and to evaluate possible coupling paths to the detector system. Further, several important conclusions are drawn concerning current detector installations. Using the computational model, the magnitude of the rail disturbances recorded by measurements could be determined. To prevent crosstalk, the correct use of ground is very important. A separate ground for the electronic equipment and the communication signals will prevent crosstalk from high power sources. The shield of the cables must be grounded to protect low voltages signals. The cables must be grounded to the shed coating where it is penetrated into the shed. It is also important to be aware of the EM topology when constructing the detector system and use appropriate barriers at each zone border.