Experience with microprocessor-based railway signalling equipment in an electrically noisy environment

Summary form only given. British Rail Research have been monitoring the performance of microprocessor-based railway signalling equipment installed in trackside locations adjacent to an electrified railway. In some locations there has been a higher than expected incidence of equipment malfunction and consequential failure to a safe (more restrictive) state. The author presents the results of investigations which have shown a high degree of correlation between these malfunctions and the presence of severe electromagnetic interference at the particular locations. In the course of these investigations the author has attempted to characterise the nature of the electrical environment in selected locations which contain the particular microprocessor equipment. This is to enable `standard´ tests generated by proprietary high-voltage transient testing equipment to be applied to the equipment under laboratory conditions. This procedure greatly facilitating systematic investigation of improvements to the performance of the equipment