Misconception 3: Considering the Probability of a System Failure Is Sufficient with Regard to SIL
Quantifying the probability of failure of a protective device is not sufficient to fulfill a safety integrity level. Primary measures for the prevention and control of faults must be implemented to this end. The relevant standard requires, first and foremost, the application of a special quality management system (functional safety management).
In addition, failure control by means such as redundancy, fail-safe behavior, and fault detection (diagnostics) are mandatory. The extent to which these measures must be applied depends on the targeted SIL.