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BCU 580 · Edition 11.15l
130
Glossary
19 .14 Safe failure fraction SFF
Fraction of safe failures related to all failures, which are
assumed to appear
from EN 13611/A2:2011
19 .15 Probability of dangerous failure PFH
D
Value describing the likelihood of dangerous failure per
hour of a component for high demand mode or con-
tinuous mode. Unit: 1/h.
from EN 13611/A2:2011
19 .16 Mean time to dangerous failure
MTTF
d
Expectation of the mean time to dangerous failure
from EN ISO 13849-1:2008