5. Glossary

Aussi bon que neuf; as good as new (AGAN)

Calculation assumption used in the standard IEC 61508-6 . After each periodic test, PFD(t) is assumed to return to its initial value.

Danger; hazard

Potential source of damage ( EC 61511 :2016 ).

Risk; risk

Combination of the probability of damage and its severity ( IEC 61511 :2016 ).

Safe failure fraction (SFF)

Proportion of a device's overall rate of random hardware failures that results in a safety failure or a detected unsafe failure (