Functional Safety Management Eaton’s MTL FSM poster IEC 61508 & SAFETY LIFECYCLE CASS SCHEME Overall framework of the IEC 61508 series WHAT IS FUNCTIONAL SAFETY? In the process industries, safety can be defined as being protected from unacceptable risk of injury or damage to people, property or the environment. Functional Safety relates to the part of overall safety that depends upon the correct operation of an electrical/electronic/programmable electronic safety instrumented system, SIS. The requirements for such a SIS are defined in the IEC 61508 group of standards. Overall safety lifecycle Technical Requirements Part 0 Functional safety and IEC 61508 Other Requirements Part 1 Development of the overall safety requirements (concept, scope, definition, hazard and risk analysis) IEC 61508 Functional safety of E/E/PE safety-related systems Part 5 Example of methods for the determination of safety integrity levels 7.1 to 7.5 7.6 IEC 61511 Process industry sector IEC 61513 Nuclear power plants IEC 62061 Safety of machinery E/E/PES ISO 13849 Safety of simple machinery Part 1 Specification of the system safety requirements for the E/E/PE safety-related systems IEC 61800-5-2 Power Drives Part 2 Realisation phase for E/E/PE safetyrelated systems release the potential of E/E/PE technology to improve both safety and economic performance; enable technological developments to take place within an overall safety framework; provide a technically sound, system based approach, with sufficient flexibility for the future; provide a risk-based approach for determining the required performance of safety-related systems; provide requirements based on common underlying principles to facilitate: - improved efficiencies in the supply chain for suppliers of subsystems and components to various sectors - improvements in communication and requirements (i.e. to increase clarity of what needs to be specified), - the development of techniques and measures that could be used across all sectors, increasing available resources, - the development of conformity assessment services if required. IEC 61508 Part 1 Functional safety assessment Clause 8 E/E/PE system safety lifecycle (in realisation phase) A basic requirement of the standards is that all aspects of the safety lifecycle activities demonstrate Functional Safety Management. As well as concerns for equipment, this includes management of personnel competency, covering the end-user, contractors, suppliers and sub-contractors. 10.2 10 E/E/PE system safety validation planning One E/E/PE safety lifecycle for each E/E/PE safetyrelated system 10.3 E/E/PE system design & development including ASICs & software 10.4 E/E/PE system integration 10.6 E/E/PE system installation, commissioning, operation & maintenance procedures DEFINITION 61508:2010 IEC 61508:2010 safety integrity relating to random hardware failures in a • Hardware safety integrity; that part of IEC dangerous mode of failure. It may be necessary to use redundant architectures to achieve adequate hardware safety integrity. Safety Integrity Level (SIL) • Systematic safety integrity; that part of safety integrity relating to systematic failures in a dangerous mode of failure. Techniques such as redundant channels of identical hardware, which are very effective at controlling random hardware failures, are of little use in reducing systematic failures such as software errors. SIL Devices, elements and systems may be Type A or Type B. Type A is when the components required to perform a specified function meet all of the following: a) The failure modes of all components are well defined; and b) The behaviour of the device under fault conditions can be completely determined; and c) There is sufficient dependable failure data to show that the claimed failure rates for detected and undetected dangerous failures are met. 3 E/E/PE safety-related systems 11 Other risk reduction measures 4 4 3 ≥ 10-8 to < 10-7 2 1 ≥ 10-7 to < 10-6 ≥ 10-6 to < 10-5 www.61508.org 12 Overall installation and commissioning 13 Overall safety validation Component Assessment EN45011 Certification Bodies 14 Overall operation, maintenance and repair 16 Decommissioning or disposal 15 Clients Scope of IEC 61508-2 Software safety requirements Programmable electronic hardware Non-programmable hardware Software design & development Programmable electronics design & development Non-programmable hardware design & development A B < 60 % 60 % - < 90 % 90 % - < 99 % ≥ 99 % Hardware fault tolerance 0 1 2 SIL 1 SIL 2 SIL 3 SIL 3 SIL 2 SIL 3 SIL 4 SIL 4 SIL 3 SIL 4 SIL 4 SIL 4 Type B Safety System Safe failure fraction of an element < 60 % 60 % - < 90 % 90 % - < 99 % ≥ 99 % Safety Requirements Assessment Operations and Maintenance Assessment T4 T3 Technical Committees T1 T2 Sub-system Supplier T2a Engineering Function/System Integrator End user/ Operator Abbreviation AC/DC AIChE Full expression Alternating current/direct current American institute of chemical engineers Abbreviation LVL MooN ALARP ANSI ASIC BPCS CCF CPLD CCPS DC (E)EPLD As Low As Reasonably Practicable American National Standards Institute Application Specific Integrated Circuit Basic process control system Common Cause Failure Complex Programmable Logic Device Center for chemical process safety Diagnostic Coverage (Electrically) Erasable Programmable Logic Device Electrical/Electronic/Programmable Electronic Electrical/Electronic/Programmable Electronic System Electrically Erasable Programmable ReadOnly Memory Erasable Programmable Read-Only Memory Electro-magnetic compatibility Equipment Under Control Factory acceptance testing Field Programmable Gate Array Fixed program language Functional safety assessment Fault tree analysis Full variability language Generic Array Logic Hazard & risk assessment MooND MTBF MTTR MRT NP PAL PE PES PFD Full expression Limited variability language M out of N channel architecture (for example 1oo2 is 1 out of 2 architecture, where either of the two channels can perform the safety function) M out of N channel architecture with Diagnostics Mean Time Between Failures Mean Time To Repair Mean Repair Time Non-programmable Programmable Array Logic Programmable Electronic Programmable electronic system Probability of Dangerous Failure on Demand PFDavg Average Probability of dangerous Failure on Demand PFH Average frequency of dangerous failure [h-1] PLA Programmable Logic Array E/E/PE E/E/PE system integration Safe failure fraction of an element Integrated System Assessment Definitions and abbreviations Overall modification and retrofit E/E/PE system architecture Sub-system Assessment T5 TERMINOLOGIES & ABBREVIATIONS Back to appropriate overall safety lifecycle phase Hardware fault tolerance 0 1 2 Not Allowed SIL 1 SIL 2 SIL 3 SIL 1 SIL 2 SIL 3 SIL 4 SIL 2 SIL 3 SIL 4 SIL 4 While every effort has been made to ensure that the information contained within this document is accurate and up to date, Eaton makes no warranty, representation or undertaking whether expressed or implied, nor does it assume legal liability, whether direct or indirect, or responsibility for the accuracy, completeness, or usefulness of any information. Eaton Electric Limited, Great Marlings, Butterfield, Luton, Beds, LU2 8DL, UK. Tel: +44 (0)1582 723633 Fax: +44 (0)1582 422283 Functional Safety Management (FSM) UKAS Component Supplier www.iec.ch/functionalsafety www.cass.uk.net www.hse.gov.uk Technical Design Authority Relationship between CASS assessment types Test Houses Type A Safety System SIL for Low Demand Mode Safety Integrity Level Average probability of (SIL) a dangerous failure on demand of the safety function (PFDavg) 4 ≥ 10-5 to < 10-4 3 ≥ 10-4 to < 10-3 2 ≥ 10-3 to < 10-2 1 ≥ 10-2 to < 10-1 61508:2010 IEC 61508:2010 Type B isIEC simply when one or more of the components required to perform a specified function is not Type A. Governing Body E/E/PE (system) EEPROM Average frequency of a dangerous failure of the safety function [h-1] (PFH) ≥ 10-9 to < 10-8 Feedback Members Specification and Realisation To Box 14 in ‘Overall Safety Lifecycle’ SIL for High Demand Mode 2 10 Programmable electronics integration (hardware & software) SAFETY INTEGRITY LEVELS 1 E/E/PE system safety requirements specification Hardware safety requirements specification Scope of IEC 61508-3 E/E/PE system safety validation Certificate No. CASS 00015/01 Safety integrity is considered to be composed of the following two elements: 9 E/E/PE system design requirements specification To Box 12 in ‘Overall Safety Lifecycle’ SIL Overall safety requirements allocation E/E/PE system design requirements specification Approved Company SIL 5 The CASS Scheme Ltd Realisation C E RT I F I C AT I O N S E RV I C E SIL Overall safety requirements Relationship between & scope of IEC 61508-2 & IEC 61508-3 (see E/E/PE system safety lifecycle) 10.5 Note that a safety integrity level is a property of a safety function rather than of a system or any part of a system. 4 Accredited Certification for Safety Systems... to IEC 61508 and related standards E/E/PE safety-related systems 10.1 (In the UK see also guidance from HSE’ “Managing competence for safety-related systems”.) Safety integrity is the ability of the SIS to perform the required safety function as and when required. Four levels of safety integrity are defined, each corresponding to a range of target likelihood of failures of a safety function. Safety integrity level 4 (SIL4) is the highest level of safety integrity and safety integrity level 1 (SIL1) is the lowest level. Hazard and risk analysis 7.15 - 7.17 Functional Safety Management 011 3 (see E/E/PE system safety lifecycle) Part 1 Operation, maintenance, repair, modification and retrofit, decommissioning or disposal of E/E/PE safety-related systems Box 10 in ‘Overall Safety Lifecycle’ Functional Safety Overall scope definition Realisation commissioning planning 7.13 - 7.14 2 Overall safety validation planning Overall 8 installation and Part 7 Overview of techniques and measures Part 1 Installation, commissioning & safety validation of E/E/PE safetyrelated systems 7 Part 1 Management of functional safety Clause 6 Part 3 Realisation phase for safety-related software IEC 61508 aims to: • • • • • 6 Part 6 Guidelines for the application of Parts 2&3 7.10 Overall planning Overall operation and maintenance planning Concept RULES Part 1 Documentation Clause 5 & Annex A 1 IEC 61508 Part 1 Allocation of the safety requirements to the E/E/PE safety-related systems Part 4 Definitions & abbreviations CASS is a scheme for assessing the compliance of safety related systems with the requirements of IEC 61508 and associated standards. It provides a systematic approach to be used by certification bodies and others when assessing compliance at all stages from the specification of safety requirements through the design, development and manufacture of system components to integration, commissioning, operation and maintenance. EPROM EMC EUC FAT FPGA FPL FSA FTA FVL GAL H&RA HFT IEC IEV ISA ISO PLC SAT SC SFF SIF SIL SIS SRS UON ls or lsafe ld or ldangerous ldd Hardware Fault Tolerance ldu International Electrotechnical Commission lsu International Electrotechnical Vocabulary Instrumentation, Systems & Automation Society lsd International Organization for Standardization AUSTRALIA Tel: +61 1300 308 374 Fax: +61 1300 308 463 CHINA Tel: + 86 21 2899 3817 Fax: + 86 21 2899 3992 GERMANY Tel: +49 (0)22 73 98 12 - 0 Fax: +49 (0)22 73 98 12 - 2 00 ITALY Tel: +39 02 959501 Fax: +39 02 95950759 NORWAY Tel: +47 66 77 43 80 Fax: +47 66 84 55 33 SINGAPORE Tel: +65 6 645 9888 Fax: +65 6 487 7997 UNITED ARAB EMIRATES Tel: +971 2 44 66 840 Fax: +971 2 44 66 841 BeNeLux Tel: +31 (0)418 570290 Fax: +31 (0)418 541044 FRANCE Tel: +33 (0)4 37 46 16 53 Fax: +33 (0)4 37 46 17 20 INDIA Tel: +91 (0)44 24501660/24501857 Fax: +91 (0)44 24501463 JAPAN Tel: +81 (0)3 6430 3128 Fax: +81 (0)3 6430 3129 RUSSIA Tel: +7 (495) 981 3770 Fax: +7 (495) 981 3771 SOUTH KOREA Tel: +82 6380 4805 Fax: +82 6380 4839 UNITED KINGDOM Tel: +44 (0)1582 723633 Fax: +44 (0)1582 422283 AMERICAS Tel: +1 281-571-8065 Fax: +1 281-571-8069 Programmable logic controller Site acceptance test Systematic capability Safe failure fraction Safety instrumented function Safety integrity level Safety instrumented system Safety requirement specification Unless otherwise noted Failure rate of all safe failures Failure rate of all dangerous failures Failure rate of all dangerous detected failures Failure rate of all dangerous undetected failures Failure rate of all safe undetected failures Failure rate of all safe detected failures www.mtl-inst.com mtlenquiry@eaton.com For technical advice or further information call: +44 (0)1582 723633 ZL-P-FSM-EN-0916
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