turck IM12-CD, Руководство по безопасности

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V01.0 | 2019/04
5.3 FMEDA results
The following safety characteristic are the results of the FMEDA.
IMX12-CD01-2R-2U λ SD λ SU λ DD λ DU No effect DC SFF
SIL2 – [E1]  [A1] or [E2]  [A2]
0.0 134.97 0.0 18.07 235.76 0% 88.19%
SIL3 – [E1+E2]

[A1+A2] 0.0 134.97 0.0 18.07 235.76 0% 88.19%
SIL3 – [E3]

[A1+A2] 0.0 135.57 0.0 18.07 235.16 0% 88.24%
IM12-CD01-2R-1U λ SD λ SU λ DD λ DU No effect DC SFF
SIL2 - [E1]  [A1]
0.0 43.04 0.0 18.07 32.29 0% 70.4%
SIL3 - [E1]

[A1+A2] 0.0 43.04 0.0 18.07 32.29 0% 70.4%
The stated Safe Failure Fraction (SFF) is for reference only. The complete subsystem will need to
be evaluated to determine the overall SFF.
The failure rates used in this analysis are the basic failure rates from the Siemens standard
SN 29500 based on the average ambient temperature of components of 40 °C.
“No effect” is a failure mode of a component that plays part in implementing the safety func-
tion but is neither a safe nor a dangerous failure. According to IEC 62061, it would be possible
to classify the “No effect” failures as “Safe Undetected” failures. Not doing so represents the
worst-case.
5.4 Examples for using the results
5.4.1 Probability of dangerous failure per hour (High Demand mode)
The sum of the diagnostic test interval and the time to achieve the specified safe/alarm state
is less than 40ms. The ratio of the diagnostic test rate to the demand rate shall equal or exceed
100.
IMX12-CD01-2R-2U - safety functions PFH
SIL2 – [E1]

[A1] or [E2]

[A2] 1.807E-08 1/h
SIL3 – [E1+E2]

[A1+A2] 1.81E-09 1/h
SIL3 – [E3]

[A1+A2] 1.81E-09 1/h
IMX12-CD01-2R-2U - safety functions PFH
SIL2 - [E1]

[A1] 1.807E-08 1/h
SIL3 - [E1]  [A1+A2]
1.96E-09 1/h