Subsystem hazard analysis system description

This example will develop a hardware FMEA for a proposed system that is well into the design phase of the product life cycle. For informational purposes, it is assumed that a preliminary hazard analysis was previously performed during the early stages of the design phase of this system. The information from the PHA will be used to assist in the development of the hardware FMEA. It should also be noted that the nature of a FMEA requires evaluation of subsystems, subassemblies, and/or components. For this reason, more detailed and specific descriptive information is provided here than that supplied for previous examples discussed in this text. 

ABSTRACT This paper is focused on the safety analysis of an analogue transceiver located in the BTM, a subsystem of the European Railway Traffic Management System (ERTMS). Balise detection is the transceiver safety related function and the ERTMS specifications define it as a SIL2, setting a maximiun tolerable hazard rate of 10 failures per hour. By means of FTA and FMEA analyses, and failure rate calculation, this paper demonstrates that a bIsT topology is suitable to accomplish safety requirements. The description of the topology and the diagrams of both analyses are also exposed. To conclude, the comparison between the values obtained for both architectures are shown and the safety improvement is e)q)lained. 

---