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1、Licensed Copy: Institute Of Technology Tallaght, Institute of Technology, Mon Jun 11 16:16:33 GMT+00:00 2007, Uncontrolled Copy, (c) BSIBRITISH STANDARD BS EN61508-5:2002Incorporating Amendment No.1 to BS IEC 61508-5:1998 (renumbers theBS IEC asBS EN 61508-5:2002)Functional safety ofelectrical/elect
2、ronic/ programmable electronicsafety-related systems Part 5: Example of methods for the determination of safety integrity levelsThe European Standard EN 61508-5:2001 has the status of aBritish StandardICS 25.040.40; 29.020 BS EN 61508-5:2002National forewordThis British Standard is the official Engl
3、ish language version ofEN 61508-5:2001. It is identical with IEC 61508-5:1999 including corrigendumApril 1999.The UK participation in its preparation was entrusted to Technical Committee GEL/65, Measurement and control, to Subcommittee GEL/65/1, System considerations, which has the responsibility to
4、:aid enquirers to understand the text;present to the responsible international/European committee any enquiries on the interpretation, or proposals for change, and keep the UK interests informed;monitor related international and European developments and promulgate them in the UK.A list of organizat
5、ions represented on this committee can be obtained on request to its secretary.Cross-referencesThe British Standards which implement international or European publications referred to in this document may be found in the BSI Standards Catalogue under the section entitled “International Standards Cor
6、respondence Index”, or by using the “Find” facility of the BSI Standards Electronic Catalogue.A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application.Compliance with a British Standard does no
7、t of itself confer immunity from legal obligations.Licensed Copy: Institute Of Technology Tallaght, Institute of Technology, Mon Jun 11 16:16:33 GMT+00:00 2007, Uncontrolled Copy, (c) BSIThis British Standard, having been prepared under the direction of the Electrotechnical Sector Committee, was pub
8、lished under the authority of the Standards Committee and comes into effecton 15 July 1999 BSI 15 March 2002ISBN 0 580 32728 0Summary of pagesThis document comprises a front cover, an inside front cover, the EN title page, pages 2 to 29 and a back cover.The BSI copyright date displayed in this docum
9、ent indicates when the document was last issued.Amd. No.DateComments1378315 March 2002Implementation of the European Standard and correction of the front cover to remove reference to corrigendumAmendments issued since publicationEUROPEAN STANDARDEN 61508-5NORME EUROPENNEEUROPISCHE NORMDecember 2001I
10、CS 25.040.40English versionFunctional safety of electrical/electronic/programmable electronic safety-related systemsPart 5: Examples of methods for the determination of safety integrity levels(IEC 61508-5:1998 + corrigendum 1999)Scurit fonctionnelle des systmes lectriques/lectroniques/lectroniques p
11、rogrammables relatifs la scurit Partie 5: Exemples de mthodes de dtermination des niveaux dintgritde scurit(CEI 61508-5:1998 + corrigendum 1999)Funktionale Sicherheit sicherheitsbezogener elektrischer/ elektronischer/programmierbarer elektronischer SystemeTeil 5: Beispiele zur Ermittlung der Stufe d
12、er Sicherheitsintegritt (safety integrity level)(IEC 61508-5:1998 + Corrigendum 1999)Licensed Copy: Institute Of Technology Tallaght, Institute of Technology, Mon Jun 11 16:16:33 GMT+00:00 2007, Uncontrolled Copy, (c) BSIThis European Standard was approved by CENELEC on 2001-07-03. CENELEC members a
13、re bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration.Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to
14、the Central Secretariat or to any CENELEC member.This European Standard exists in three official versions (English, French, German). A version in any other language made by translation under the responsibility of a CENELEC member into its own language and notified to the Central Secretariat has the
15、same status as the official versions.CENELEC members are the national electrotechnical committees of Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Malta, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom.C
16、ENELECEuropean Committee for Electrotechnical Standardization Comit Europen de Normalisation Electrotechnique Europisches Komitee fr Elektrotechnische NormungCentral Secretariat: rue de Stassart 35, B - 1050 Brussels 2001 CENELEC - All rights of exploitation in any form and by any means reserved wor
17、ldwide for CENELEC members.Ref. No. EN 61508-5:2001 EPage 29EN 615085:2001Licensed Copy: Institute Of Technology Tallaght, Institute of Technology, Mon Jun 11 16:16:33 GMT+00:00 2007, Uncontrolled Copy, (c) BSIForewordThe text of the International Standard IEC 61508-5:1998 including its corrigendum
18、April 1999, prepared by SC 65A, System aspects, of IEC TC 65, Industrial-process measurement and control, was submitted to the Unique Acceptance Procedure and was approved by CENELEC as EN 61508-5 on 2001-07-03 without any modification.The following dates were fixed: latest date by which the EN has
19、to be implemented at national level by publication of an identicalnational standard or by endorsement(dop) 2002-08-01 latest date by which the national standards conflictingwith the EN have to be withdrawn(dow) 2004-08-01Annexes designated normative are part of the body of the standard. Annexes desi
20、gnated informative are given for information only.In this standard, annex ZA is normative and annexes A, B, C, D, E and F are informative.Annex ZA has been added by CENELEC.IEC 61508 is a basic safety publication covering the functional safety of electrical, electronic and programmable electronic sa
21、fety-related systems. The scope states:This International Standard covers those aspects to be considered when electrical/electronic/ programmable electronic systems (E/E/PESs) are used to carry out safety functions. A major objective of this standard is to facilitate the development of application s
22、ector international standards by the technical committees responsible for the application sector. This will allow all the relevant factors associated with the application, to be fully taken into account and thereby meet the specific needs of the application sector. A dual objective of this standard
23、is to enable the development of electrical/electronic/ programmable electronic (E/E/PE) safety-related systems where application sector international standards may not exist.The CENELEC Report R0BT-004, ratified by 103 BT (March 2000) accepts that some IEC standards, which today are either published
24、 or under development, are sector implementations of IEC 61508. For example: IEC 61511, Functional safety - Safety instrumented systems for the process industry sector; IEC 62061, Safety of machinery Functional safety of electrical, electronic and programmable electronic control systems; IEC 61513,
25、Nuclear power plants Instrumentation and control for systems important to safety General requirements for systems.The railways sector has also developed a set of European Standards (EN 50126; EN 50128 and prEN 50129).NOTE EN 50126 and EN 50128 were based on earlier drafts of IEC 61508. prEN 50129 is
26、 based on the principles of the latest version of IEC 61508.This list does not preclude other sector implementations of IEC 61508 which could be currently under development or published within IEC or CENELEC.Licensed Copy: Institute Of Technology Tallaght, Institute of Technology, Mon Jun 11 16:16:3
27、3 GMT+00:00 2007, Uncontrolled Copy, (c) BSICONTENTSPageINTRODUCTION .4Clause1Scope .62Normative references .83Definitions and abbreviations .8AnnexesARisk and safety integrity General concepts. .9BALARP and tolerable risk concepts .15CDetermination of safety integrity levels: a quantitative method
28、.18DDetermination of safety integrity levels A qualitative method: risk graph .21EDetermination of safety integrity levels A qualitative method:hazardous event severity matrix .26FBibliography .28Annex ZA (normative) Normative references to international publications with theircorresponding European
29、 publications . 29Figures1Overall framework of this standard. .7A.1Risk reduction: general concepts .12A.2Risk and safety integrity concepts .12A.3Allocation of safety requirements to the E/E/PE safety-related systems,other technology safety-related systems and external risk reduction facilities .14
30、B.1Tolerable risk and ALARP .16C.1Safety integrity allocation: example for safety-related protection system .20D.1Risk graph: general scheme .23D.2Risk graph: example (illustrates general principles only) .24E.1Hazardous event severity matrix: example (illustrates general principles only) .27TablesB
31、.1Risk classification of accidents .17B.2Interpretation of risk classes .17D.1Example data relating to example risk graph (figure D.2) .25Licensed Copy: Institute Of Technology Tallaght, Institute of Technology, Mon Jun 11 16:16:33 GMT+00:00 2007, Uncontrolled Copy, (c) BSIINTRODUCTIONSystems compri
32、sed of electrical and/or electronic components have been used for many years to perform safety functions in most application sectors. Computer-based systems (generically referred to as programmable electronic systems (PESs) are being used in all application sectors to perform non-safety functions an
33、d, increasingly, to perform safety functions. If computer system technology is to be effectively and safely exploited, it is essential that those responsible for making decisions have sufficient guidance on the safety aspects on which to make those decisions.This International Standard sets out a ge
34、neric approach for all safety lifecycle activities for systems comprised of electrical and/or electronic and/or programmable electronic components (electrical/electronic/ programmable electronic systems (E/E/PESs) that are used to perform safety functions. This unified approach has been adopted in o
35、rder that a rational and consistent technical policy be developed for all electrically-based safety-related systems. A major objective is to facilitate the development of application sector standards.In most situations, safety is achieved by a number of protective systems which rely on many technolo
36、gies(forexamplemechanical,hydraulic,pneumatic,electrical,electronic, programmable electronic). Any safety strategy must therefore consider not only all the elements within an individual system (for example sensors, controlling devices and actuators) but also all the safety-related systems making up
37、the total combination of safety-related systems. Therefore, while this International Standard is concerned with electrical/elec- tronic/programmable electronic (E/E/PE) safety-related systems, it may also provide a framework within which safety-related systems based on other technologies may be cons
38、idered.It is recognised that there is a great variety of E/E/PES applications in a variety of application sectors and covering a wide range of complexity, hazard and risk potentials. In any particular application, the required safety measures will be dependent on many factors specific to the applica
39、tion. This Standard, by being generic, will enable such measures to be formulated in future application sector international standards.This International Standard:considers all relevant overall, E/E/PES and software safety lifecycle phases (for example, from initial concept, through design, implemen
40、tation, operation and maintenance to decommissioning) when E/E/PESs are used to perform safety functions;has been conceived with a rapidly developing technology in mind; the framework is sufficiently robust and comprehensive to cater for future developments;enables application sector international s
41、tandards, dealing with safety-related E/E/PESs, to be developed; the development of application sector international standards, within the framework of this International Standard, should lead to a high level of consistency (for example, of underlying principles, terminology etc.) both within applic
42、ation sectors and across application sectors; this will have both safety and economic benefits;provides a method for the development of the safety requirements specification necessary to achieve the required functional safety for E/E/PE safety-related systems;Licensed Copy: Institute Of Technology T
43、allaght, Institute of Technology, Mon Jun 11 16:16:33 GMT+00:00 2007, Uncontrolled Copy, (c) BSIuses safety integrity levels for specifying the target level of safety integrity for the safety functions to be implemented by the E/E/PE safety-related systems;adopts a risk-based approach for the determ
44、ination of the safety integrity level requirements;sets numerical target failure measures for E/E/PE safety-related systems which are linked to the safety integrity levels;sets a lower limit on the target failure measures, in a dangerous mode of failure, that can be claimed for a single E/E/PE safet
45、y-related system; for E/E/PE safety-related systems operating in:a low demand mode of operation, the lower limit is set at an average probability of failure of 105 to perform its design function on demand;a high demand or continuous mode of operation, the lower limit is set at a probability of a dan
46、gerous failure of 109 per hour;NOTE A single E/E/PE safety-related system does not necessarily mean a single-channel architecture.adopts a broad range of principles, techniques and measures to achieve functional safety for E/E/PE safety-related systems, but does not use the concept of fail safe whic
47、h may be of value when the failure modes are well defined and the level of complexity is relatively low. The concept of fail safe was considered inappropriate because of the full range of complexity of E/E/PE safety-related systems that are within the scope of the standard.Licensed Copy: Institute O
48、f Technology Tallaght, Institute of Technology, Mon Jun 11 16:16:33 GMT+00:00 2007, Uncontrolled Copy, (c) BSIFUNCTIONAL SAFETY OF ELECTRICAL/ELECTRONIC/PROGRAMMABLE ELECTRONIC SAFETY-RELATED SYSTEMS Part 5: Examples of methods for the determination of safety integrity levels1Scope1.1This part of IE
49、C 61508 provides information onthe underlying concepts of risk and the relationship of risk to safety integrity (see annex A);a number of methods that will enable the safety integrity levels for the E/E/PE safety-related systems, other technology safety-related systems and external risk reduction fa
50、cilities to be determined (see annexes B, C, D and E).1.2The method selected will depend upon the application sector and the specific circumstances under consideration. Annexes B, C, D and E illustrate quantitative and qualitative approaches and have been simplified in order to illustrate the underl
51、ying principles. These annexes have been included to illustrate the general principles of a number of methods but do not provide a definitive account. Those intending to apply the methods indicated in these annexes should consult the source material referenced.NOTE For more information on the approa
52、ches illustrated in annexes B, D and E, see references 4, 2 and 3respectively in annex F. See also reference 5 in annex F for a description of an additional approach.1.3Parts 1, 2, 3 and 4 of this standard are basic safety publications, although this status does not apply in the context of low compl
53、exity E/E/PE safety-related systems (see 3.4.4 of part 4). As basic safety publications, they are intended for use by technical committees in the preparation of standards in accordance with the principles contained in IEC Guide 104 and ISO/IEC Guide 51. Parts 1, 2, 3, and 4 are also intended for use
54、 as stand-alone publications.One of the responsibilities of a technical committee is, wherever applicable, to make use of basic safety publications in the preparation of its publications. In this context, the requirements, test methods or test conditions of this basic safety publication will not app
55、ly unless specifically referred to or included in the publications prepared by those technical committees.NOTE In the USA and Canada, until the proposed process sector implementation of IEC 61508 (i.e. IEC 61511) is published as an international standard in the USA and Canada, existing national proc
56、ess safety standards based on IEC 61508 (i.e. ANSI/ISA S84.01-1996) can be applied to the process sector instead of IEC 61508.1.4Figure 1 shows the overall framework for parts 1 to 7 of IEC 61508 and indicates the role that IEC 61508-5 plays in the achievement of functional safety for E/E/PE safety-
57、related systems.PART 1Development of the overall safety requirements (concept, scope definition, hazard and risk analysis)(E/E/PE safety-related systems, other technology safety-related systems and external risk reduction facilities)7.1 to 7.5Technical requirementsPART 5Risk based approaches to the development of the safety integrity requirementsP
【BS英國標(biāo)準(zhǔn)】BS EN 61508-5-2002 Functional safety of electricalelectronic programmable electronic safety-related systems — Part 5 Example of methods for the determination of safety integrity levels.doc
