21
UK
15 Terms and abbreviations
CCF
Common Cause Failure
DC
Diagnostic Coverage
MTTF
D
Mean Time To Dangerous
Failure
OSSD
Output Signal Switching Device
PFH
Probability of Failure per Hour
PL
Performance Level
PL to EN ISO 13849-1
SIL
Safety Integrity Level
SIL 1-4 to IEC 61508� The higher the SIL the
lower the probability that a safety function
will fail�
SIL
cl
Safety Integrity Level
Claim Limit
to IEC 62061
T
M
Mission Time
Lifetime
(= max� service life)