JUMO Ex-i, Safety Manual

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6 Safety-related applications
28
6.15 Excerpt from FMEDA report
Normally open configurations C1-C4
Normally closed configurations C5-C8
Failure category IEC 61508:2010
Failure rates (in FIT)
C1
Normal
C2
Normal
C3
Inverted
C4
Inverted
Safe detected ( λ
SD
) 0 0 0 0
Safe undetected ( λ
SU
) 187 252 189 254
Dangerous detected ( λ
DD
) 6 6 6 6
Dangerous undetected ( λ
DU
) 48 83 51 86
No effect 104 104 106 106
Total failure rate (safety function) 241 341 246 346
SFF
a
a
The complete subsystem will need to be evaluated to determine the overall safe failure fraction. The
number listed is for reference only.
80 % 75 % 79 % 75 %
DC 9 % 7 % 9 % 6 %
SIL AC
b
b
SIL AC (architectural constraints) means that the calculated values are within the range for hardware
architectural constraints for the corresponding SIL but does not imply all related IEC 61508 require-
ments are fulfilled. In addition it must be shown that the device has a suitable systematic capability for
the required SIL and that the entire safety function can fulfill the required PFD / PFH values.
SIL 2 SIL 2 SIL 2 SIL 2
Failure category IEC 61508:2010
Failure rates (in FIT)
C5
Normal
C6
Normal
C7
Inverted
C8
Inverted
Safe detected ( λ
SD
) 0 0 0 0
Safe undetected ( λ
SU
) 177 232 179 234
Dangerous detected ( λ
DD
) 6 6 6 6
Dangerous undetected ( λ
DU
) 58 103 61 106
No effect 104 104 106 106
Total failure rate (safety function) 241 341 246 346
SFF
a
a
The complete subsystem will need to be evaluated to determine the overall safe failure fraction. The
number listed is for reference only.
75 % 69 % 75 % 69 %
DC 9 % 5 % 8 % 5 %
SIL AC
b
b
SIL AC (architectural constraints) means that the calculated values are within the range for hardware
architectural constraints for the corresponding SIL but does not imply all related IEC 61508 require-
ments are fulfilled. In addition it must be shown that the device has a suitable systematic capability for
the required SIL and that the entire safety function can fulfill the required PFD / PFH values.
SIL 2 SIL 2 SIL 2 SIL 2