Fail-safe design of a modern traction convertor compatible with railway track circuits

Compatibility as discussed by the author is treated by railway authorities as a safety issue. Consequentially the assessment of the proof offered by a traction manufacturer is a very careful and formal procedure and the proof he offers should be of a very high quality standard. A quality assurance system compliant with ISO 9001 at least is required to bring this procedure to a successful end. The author describes a concept which was pursued by Holec for the Class 323 EMU and focuses on safe design of the systems on the train themselves. He shows that modern traction systems require an unusual degree of filtering and design features to meet existing standards for track-circuit interference