turck IM12-CD, Руководство по безопасности

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Appendix: Terms and Abbreviations
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7.3 Output relay – Load curve
Fig. 7: Output relay load curve
8 Appendix: Terms and Abbreviations
DC Diagnostic Coverage
FIT 1 FIT is 1 failure per 10E09 hours
FMEDA Failure Modes, Effects and Diagnostic Analysis
HFT Hardware failure tolerance
λ
AU
Undetected Annunciation failure rate (per hour)
Annunciation failures do not directly impact safety but impact the ability to detect a future
fault (such as a fault in diagnostic circuit).
λ
DD
Detected dangerous failure rate (per hour)
λ
DU
Undetected dangerous failure rate (per hour)
λ
SD
Detected safe failure rate (per hour)
λ
SU
Undetected safe failure rate (per hour)
MTTR Mean time to restoration (hour)
PFD
avg
Average probability of failure on demand
PFH Probability of dangerous failure per hour
SFF Safe Failure Fraction
SIL Safety Integrity Level
T1 Proof test interval (hour)
Type A “Non-complex” element (all failure modes are well defined); for details see 7.4.4.1.2 of
IEC 61508-2
Type B “Complex” element (using micro controlllers or programmable logic); for details see 7.4.4.1.3
of IEC 61508-2
A
10
0,1 0,5 1 2 5 20
V
50
100
200
300
400
10
DC
resistive load
AC
resistive load
for safety applications
Imax = 2 A