Safe Failure

failure of a safety system which tends to favour a given safety action

Note 1 to entry: The concept of safe failure is illustrated in Figure B.1.

Note 2 to entry: A failure is safe only with regard to a given safety function. This is a systemic failure in

relationship with a given safety action performed by the safety system. This concept is irrelevant for an

individual item on the shelves.

Note 3 to entry: The non-critical safe failures basically increase the probability of success of the safety function.

The critical safe failures initiate the related safety actions when this is not needed (see spurious failures).



Source: ISO/TR 12489:2013(E) Reliability modelling and calculation of safety systems. Global Standards

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