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BCU 560, BCU 565 · Edition 02.16
129
Glossary
20 .13 Safe failure fraction SFF
Fraction of safe failures related to all failures, which are as-
sumed to appear
from EN 13611/A2:2011
20 .14 Probability of dangerous failure PFH
D
Value describing the likelihood of dangerous failure per hour
of a component for high demand mode or continuous mode.
Unit: 1/h.
from EN 13611/A2:2011
20 .15 Mean time to dangerous failure MTTF
d
Expectation of the mean time to dangerous failure
from EN ISO 13849-1:2008