1 Scope
This Part provides safety requirements and guidance on the principles for the design and
integration of safety-related parts of control systems (SRP/CS), including the design of software. For these parts of SRP/CS, it specifies characteristics that include the performance level required for carrying out safety functions. It applies to SRP/CS, regardless of the type of technology and energy used (electrical, hydraulic, pneumatic, mechanical, etc.), for all kinds of machinery.
This Part does not specify the safety functions or performance levels that are to be used in a particular case.
This Part provides specific requirements for SRP/CS using programmable electronic systems.
This Part does not give specific requirements for the design of products which are parts of SRP/CS. Nevertheless, the principles given, such as categories or performance levels, can be used.
Note 1: Examples of products which are parts of SRP/CS: relays, solenoid valves, position switches, PLCs, motor control units, two-hand control devices, pressure sensitive equipment. For the design of such products, it is important to refer to the specifically applicable International Standards, e.g. GB/T 19671, GB/T 17454.1 and GB/T 17454.2.
Note 2: For the definition of required performance level, see 3.1.24.
Note 3: The requirements provided in this Part for programmable electronic systems are compatible with the methodology for the design and development of safety-related electrical, electronic and programmable electronic control systems for machinery given in IEC 62061.
Note 4: For safety-related embedded software for components with PLr = e see GB/T 20438.3-2007, Chapter 7.
Note 5: See also Table 1.
2 Normative References
Contents
Foreword III
Introduction V
1 Scope
2 Normative References
3 Terms, Definitions, Symbols and Abbreviated Terms
4 Design Considerations
4.1 Safety objectives in design
4.2 Strategy for risk reduction
4.3 Determination of required performance level (PLr)
4.4 Design of SRP/CS
4.5 Evaluation of the achieved performance level PL and relationship with SIL
4.6 Software safety requirements
4.7 Verification that achieved PL meets PLr
4.8 Ergonomic aspects of design
5 Safety Functions
5.1 Specification of safety functions
5.2 Details of safety functions
6 Categories and Their Relation to MTTFd of each channel, DCavg and CCF
6.1 General
6.2 Specifications of categories
6.3 Combination of SRP/CS to achieve overall PL
7 Fault Consideration, Fault Exclusion
7.1 General
7.2 Fault consideration
7.3 Fault exclusion
8 Validation
9 Maintenance
10 Technical Documentation
11 Information for Use
Appendix A (Informative) Determination of Required Performance Level (PLr)
Appendix B (Informative) Block Method and Safety-related Block Diagram
Appendix C (Informative) Calculating or Evaluating MTTFd Values for Single Components
Appendix D (Informative) Simplified Method for Estimating MTTFd for Each Channel
Appendix E (Informative) Estimates for Diagnostic Coverage (DC) for Functions and Modules
Appendix F (Informative) Estimates for Common Cause Failure (CCF)
Appendix G (Informative) Systematic Failure
Appendix H (Informative) Example of Combination of Several Safety-related Parts of the Control System
Appendix I (Informative) Examples
Appendix J (Informative) Software
Appendix K (Informative) Numerical Representation of Figure
Bibliography
