Probabilistic Metric for random Hardware Failures

T Top Failure Metrics (Probabilistic Metric for Random Hardware Failure, PMHF)... 

The top failure metrics officially called PMHF (Probabilistic Metric for random Hardware Failures) in ISO 26262. It represents a comparable metric such as PFH (Probabilistic Failure per Hour) of lEC 61508. The top failure metrics of ISO 26262 focuses on failure probabilities, with which a safety goal could be violated, whereas PFH according to lEC 61508 is all about the probability of a danger through the system. Both target values of the metrics are specified in failure per hour (failure in time, FIT = lOE-9 h). Also in this case we assume an exponential distribution of the basis failure rate. The key difference between PFH and PMHF is that the PMHF is per safety goal and PFH for a safety-related system. The PFH considers mainly the probability that the system reaches in case of failure a de-energized safe state. 

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