Page 71 - 捷運技術 第43期

捷運技術半年刊 第43 期 65

apportioned to a functional level (system functions).

h Starting from system and subsystems architectures (as highlighted in the fault Tree Analyses)
it is possible to identify which subsystem and then which equipment is responsible for a

particular safety function.

h The THR for a function is then translated to a SIL for the subsystem involved using the SIL
correspondence (Table 2). Safety Integrity Levels (SIL) are so defined at this functional level

for the sub-systems implementing the functionality.

Figure 4cSIL Definition