Allen-Bradley 1734-OB8S - Add the POINT Guard I;O Module to the Controller Project

136 Rockwell Automation Publication 1734-UM013C-EN-P - August 2010
Appendix B Probability of Failure on Demand (PFD), Probability of Failure per Hour (PFH), and Mean Time Between Failure (MTBF) Data
Figure 23 - Calculated Values for Probability of Failure on Demand (PFD),
Probability of Failure per Hour (PFH), and Mean Time Between Failure (MTBF)
1.00E-07
1.00E-06
1.00E-05
1.00E-04
1.00E-03
1.00E-02
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21
1% of SIL 3 Limit
10% of SIL 3 Limit
PFD versus Proof Test Interval
Proof Test Interval (years)
PFD
Model Proof Test Interval
(Mission Time)
PFD (1/hour) PFH (1/hour) MTBF (hour)
Year Hour
1734-IB8S 1 8760 5.85E-07
1.34E-10 5.76E+06
2 17520 1.17E-06
5 43800 2.93E-06
10 87600 5.86E-06
20 175200 1.17E-05
1734-OB8S 1 8760 6.05E-07
1.38E-10 4.57E+06
2 17520 1.21E-06
5 43800 3.03E-06
10 87600 6.06E-06
20 175200 1.21E-05