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V2.0 | 2018/01
10 Appendix: Designations and abbreviations
Abbreviation
Meaning
DC
Diagnostic Coverage
E/E/PE-system
Electrical/electronic/programmable electronic system
HFT
Hardware failure tolerance
MTTF
d
Mean Time To Failure Dangerous
PFD
Probability of dangerous failure on demand
PFH
Average frequency of dangerous failure per hour
PL
Performance Level
SIL
Safety Integrity Level
11 Appendix: Function tests
Ensure that the function test is only carried out by qualified personnel.
A suggested function test consists of the following steps:
Step
Action
1
Switch every safety related input at least once a year.
2
Control the switching behavior by monitoring the output circuits.
3
Observe the maximum duty cycle and the total operation time depending on the select-
ed PFD value.
4
If the maximum duty cycle is reached: request the shutdown function in order to check
the function of the safety system
Once the test has been completed, document and archive the results.
12 Appendix: Document history
Version
Date
Modifications
1.0
2016-06-30
First version
2.0
2018-01-17
– Safety characteristic data updated
– Connection examples extended
