Anexo B - Definiciones De Conceptos - Siemens SITRANS LG240 Manual Del Usuario

Abreviaturas
SITRANS LG240, LG250, LG260 and LG270 - Safety Manual
8 Anexo B - Definiciones de conceptos
SIL Safety Integrity Level (SIL1, SIL2, SIL3, SIL4)
SC Systematic Capability (SC1, SC2, SC3, SC4)
HFT Hardware Fault Tolerance
SFF Safe Failure Fraction
PFD Average Probability of dangerous Failure on Demand
AVG
PFH Average frequency of a dangerous failure per hour (Ed.2)
FMEDA Failure Mode, Effects and Diagnostics Analysis
FIT Failure In Time (1 FIT = 1 failure/10
λ Rate for safe detected failure
SD
λ Rate for safe undetected failure
SU
λ λ = λ + λ
S S SD SU
λ Rate for dangerous detected failure
DD
λ Rate for dangerous undetected failure
DU
λ Rate for failure, who causes a high output current (> 21 mA)
H
λ Rate for failure, who causes a low output current (≤ 3.6 mA)
L
λ Rate for diagnostic failure (detected)
AD
λ Rate for diagnostic failure (undetected)
AU
DC Diagnostic Coverage
PTC Proof Test Coverage
T1 Proof Test Interval
LT Useful Life Time
MTBF Mean Time Between Failure
MTTF Mean Time To Failure
MTTR Mean Time To Restoration (Ed.2)
MTTF Mean Time To dangerous Failure (ISO 13849-1)
d
PL Performance Level (ISO 13849-1)
h)
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