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Calculated Values of PFD and PFH Appendix 2
Appendix 2: Calculated Values of PFD and PFH
Calculated values of PFD and PFH of the DST1-series Safety I/O Terminals are given in the following tables.
These values must be calculated for the overall devices within the system to comply with the SIL level required
for application.
A-2-1 Calculated PFD Values
IMPORTANT The proof test interval of the DST1-MRD08SL-1 must not exceed 0.5 years because the mainte-
nance interval for the relay contacts must not exceed a period of 6 month to satisfy safety cate-
gory 4 in accordance with EN 954-1.
A-2-2 Calculated PFH Values
Model Proof test interval (years) PFD
DST1-ID12SL-1 0.25 2.21E-07
0.5 4.39E-07
1 8.76E-07
2 1.76E-06
DST1-MD16SL-1 0.25 2.22E-07
0.5 4.40E-07
1 8.77E-07
2 1.76E-06
DST1-MRD08SL-1 0.25 4.70E-06
0.5 9.54E-06
DST1-XD0808SL-1 0.25 2.22E-07
0.5 4.40E-07
1 8.77E-07
2 1.76E-06
Model PFH
DST1-ID12SL-1 2.00E-10
DST1-MD16SL-1 2.00E-10
DST1-MRD08SL-1 4.20E-09
DST1-XD0808SL-1 2.00E-10
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