JUMO 701150 14597 safetyM STB/STW - Safety Temperature Limiter and Safety Temperature Monitor Operating Manual - Manual (Page 56)

6 Safety Manual 2014-05-01 56
6.12 Evaluating the achieved Performance Level PL and the relationship to the SIL
For application in this part of DIN EN ISO 13849, the capability of safety-related parts to perform a safety function is expressed
through the determination of a Performance Level.
The PL must be assessed for each selected SRP/CS and/or SRP/CS combination that performs a safety function. The PL of
the SRP/CS must be determined by assessing the following aspects:
-
The MTTF c
value of individual components (see Appendices C and D)
- The DC (see Appendix E)
- The CCF (see Appendix F)
- The structure (see section 6)
- The behavior of the safety function under failure conditions (see section 6)
- Safety-related software (see 4.6 and Appendix J)
- Systematic failures (see Appendix G)
- The capability to perform a safety function under predictable ambient conditions
The following diagram depicts the procedure for selecting the categories in combination with MTTF d for each channel and the
DC avg to achieve the required PL for each safety function.