Określanie pokrycia diagnostycznego elementów i analiza ograniczeń architektonicznych podsystemów

Performing a safety related function by E/E/PE system requires proper operation of its subsystems. Its structure has to guarantee effective and fast detection of failure. The estimation of average probability of dangerous failure on demand (PFDavg) requires the knowledge concerning the value of diagnostic coverage (DC) for all elements and/or subsystems. It is preferable when subsystems are of type A. In such case the failure modes of all components and their behavior in case of some faults are well defined. This is the reason why the design of safety-related systems should use the devices adapted to execution of diagnostic tests to detect majority of failures that lead to serious consequences. In the article some theoretical and practical aspects of determining diagnostic coverage are outlined.