BERTHOLD TECHNOLOGIES LB 480 - Page 107

SENSseries LB 480 Level measurement
BERTHOLD TECHNOLOGIES GmbH & Co. KG
1 – 107
Volume 1 7 Functional Safety
1
7.12.2 Definition of Terms
SIL Safety Integrity Level
HFT Hardware Fault Tolerance
SFF Safe Failure Fraction
PFD
AVG
Average Probability of Dangerous Failure on Demand
PFH Average Probability of Dangerous Failure on Demand
FMEDA Failure Mode, Effects and Diagnostics Analysis
FIT Failure in Time (1 FIT = 1 failure/109h)
sd Rate for safe detected failure
su Rate for safe undetected failure
s s = sd + su
dd Rate for dangerous detected failure
du Rate for dangerous undetected failure
DC Diagnostic Coverage
T1 Proof Test Interval
MTBF Mean Time Between Failure
MTTR Mean Time To Repair
IBN Commissioning