Safety Integrity Levels Model for Safety-Related Systems with Automatic Diagnoses

摘要

It is often misunderstood that the automatic diagnoses reduce the frequency of the hazardous event down to the negligible degree compared to those caused by undetected-failures. However, the result obtained here indicates it is not always true. There are cases where frequencies of the hazardous events brought about by detected-failures exceed those caused by undetected-failures, as far as EUC is not shut down after the detection of failures. This fact becomes clear with the increasing demand rate and the diagnostic coverage. Thus, the new model proposed here is important for those systems.