EN 61508-5:2010

Functional safety of electrical/electronic/programmable electronic safety-related systems - Part 5: Examples of methods for the determination of safety integrity levels

IEC 61508-5:2010 provides information on the 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 to be determined (see Annexes C, D, E, F and G). The method selected will depend upon the application sector and the specific circumstances under consideration. Annexes C, D, E, F and G illustrate quantitative and qualitative approaches and have been simplified in order to illustrate the underlying 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. This second edition cancels and replaces the first edition published in 1998. This edition constitutes a technical revision. It has been subject to a thorough review and incorporates many comments received at the various revision stages.
NEW! Also available:  IEC Standards+ 61508:2010, containing all parts, together with a commented Redline version. Changes made in this 2nd edition are highlighted and commented by a leading world expert.
This publication is of high relevance for Smart Grid.

Funktionale Sicherheit sicherheitsbezogener elektrischer/elektronischer/programmierbarer elektronischer Systeme - Teil 5: Beispiele zur Ermittlung der Stufe der Sicherheitsintegrität (safety integrety level)

Sécurité fonctionnelle des systèmes électriques/électroniques/électroniques programmables relatifs à la sécurité - Partie 5: Exemples de méthodes pour la détermination des niveaux d'intégrité de sécurité

La CEI 61508-5:2010 fournit des informations sur les concepts sous-jacents à la notion de risque et les liens entre le risque et l'intégrité de sécurité (voir Annexe A), un certain nombre de méthodes qui permettent de déterminer les niveaux d'intégrité de sécurité des systèmes E/E/PE relatifs à la sécurité (voir Annexes B, C, D et E). La méthode retenue dépend du secteur d'application et des conditions spécifiques à prendre en considération. Les Annexes C, D, E, F et G illustrent les approches quantitatives et qualitatives et ont été simplifiées dans le but d'illustrer les principes sous-jacents. Ces annexes ont été incluses pour illustrer les principes généraux d'un certain nombre de méthodes mais ne fournissent pas une interprétation figée. Il convient que les personnes souhaitant appliquer les méthodes indiquées dans ces annexes consultent les sources documentaires référencées. Cette deuxième édition annule et remplace la première édition publiée en 1998 dont elle constitue une révision technique. Elle a fait l'objet d'une révision approfondie et intègre de nombreux commentaires reçus lors des différentes phases de révision.

Funkcijska varnost električnih/elektronskih/elektronsko programirljivih varnostnih sistemov - 5. del: Primeri metod za ugotavljanje ravni celovite varnosti (IEC 61508-5:2010)

1.1 Ta del IEC 61508 podaja informacije o
– osnovnih konceptih tveganja in odnosu med tveganjem in celovito varnostjo (glej dodatek A);
– številnih metodah, ki omogočajo ugotavljanje ravni celovite varnosti za varnostne sisteme E/E/PE (glej dodatke C, D, E, F in G).
Izbrana metoda je odvisna od obravnavanega aplikacijskega sektorja in okoliščin. Dodatki C, D, E, F in G prikazujejo kvantitativne in kvalitativne pristope in so poenostavljeni, da ponazorijo osnovna načela. Ti dodatki so vključeni za ponazoritev splošnih načel številnih metod, vendar niso dokončni. Kdor namerava uporabiti metode, navedene v teh dodatkih, naj preveri referenčni izvorni material.
OPOMBA: Za več informacij o pristopih, prikazanih v dodatkih B in E, glej referenci [5] in [8] v bibliografiji. Za opis dodatnega pristopa glej tudi referenco [6] v bibliografiji.
1.2 IEC 61508-1, IEC 61508-2, IEC 61508-3 in IEC 61508-4 so osnovne varnostne objave, čeprav ta status ne velja v okviru nezapletenih varnostnih sistemov E/E/PE (glej točko 3.4.3 IEC 61508-4). Kot osnovne varnostne objave so namenjeni temu, da jih uporabljajo tehnični odbori pri pripravi standardov v skladu z načeli, opredeljenimi v Vodilu IEC 104 in Vodilu ISO/IEC 51. IEC 61508-1, IEC 61508-2, IEC 61508-3 in IEC 61508-4 se lahko tudi uporabijo kot samostojne objave. Horizontalno varnostno delovanje tega mednarodnega standarda ne velja za medicinsko opremo v skladu s serijo IEC 60601.
1.3 Ena od odgovornosti tehničnega odbora je, če je primerno, da uporabi temeljne varnostne objave pri pripravi svojih objav. V tem okviru zahteve, preskusne metode ali preskusni pogoji te temeljne varnostne objave ne veljajo, razen če se objave, ki so jih pripravili tehnični odbori, nanje izrecno sklicujejo ali jih vključujejo.
1.4 Slika 1 prikazuje celoten okvir serije IEC 61508 in nakazuje vlogo IEC 61508-5 pri doseganju funkcijske varnosti E/E/PE-varnostnih sistemov.

General Information

• Status: Published
• Publication Date: 27-May-2010
• Withdrawal Date: 30-Apr-2013
• ICS: 25.040.40 - Industrial process measurement and control
• Technical Committee: CLC/TC 65X - Industrial-process measurement, control and automation
• Drafting Committee: IEC/SC 65A - IEC_SC_65A
• Parallel Committee: IEC/SC 65A - IEC_SC_65A
• Current Stage: 6060 - Document made available - Publishing
• Start Date: 28-May-2010
• Completion Date: 28-May-2010
• Ref Project: SIST EN 61508-5:2011 - Functional safety of electrical/electronic/programmable electronic safety-related systems - Part 5: Examples of methods for the determination of safety integrity levels (IEC 61508-5:2010)

Relations

• Replaces: EN 61508-5:2001 - Functional safety of electrical/electronic/programmable electronic safety-related systems - Part 5: Examples of methods for the determination of safety integrity levels
• Effective Date: 28-Jan-2023

Standards Content (Sample)

SLOVENSKI STANDARD
01-maj-2011
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SIST EN 61508-5:2007
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Functional safety of electrical/electronic/programmable electronic safety-related systems
- Part 5: Examples of methods for the determination of safety integrity levels (IEC 61508-
5:2010)
Funktionale Sicherheit sicherheitsbezogener
elektrischer/elektronischer/programmierbarer elektronischer Systeme - Teil 5: Beispiele
zur Ermittlung der Stufe der Sicherheitsintegrität (safety integrety level) (IEC 61508-
5:2010)
Sécurité fonctionnelle des systèmes électriques/électroniques/électroniques
programmables relatifs à la sécurité - Partie 5: Exemples de méthodes pour la
détermination des niveaux d'intégrité de sécurité (IEC 61508-5:2010)
Ta slovenski standard je istoveten z: EN 61508-5:2010
ICS:
25.040.40 Merjenje in krmiljenje Industrial process
industrijskih postopkov measurement and control
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD
EN 61508-5
NORME EUROPÉENNE
May 2010
EUROPÄISCHE NORM
ICS 25.040.40 Supersedes EN 61508-5:2001

English version
Functional safety of electrical/electronic/programmable electronic safety-
related systems -
Part 5: Examples of methods for the determination of safety integrity
levels
(IEC 61508-5:2010)
Sécurité fonctionnelle des systèmes Funktionale Sicherheit sicherheitsbezogener
électriques/électroniques/électroniques elektrischer/elektronischer/programmierbarer
programmables relatifs à la sécurité - elektronischer Systeme -
Partie 5: Exemples de méthodes Teil 5: Beispiele zur Ermittlung der Stufe
pour la détermination des niveaux der Sicherheitsintegrität (safety integrety
d'intégrité de sécurité level)
(CEI 61508-5:2010) (IEC 61508-5:2010)

This European Standard was approved by CENELEC on 2010-05-01. CENELEC members are 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 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 same status as the official versions.

CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus,
the Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy,
Latvia, Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia,
Spain, Sweden, Switzerland and the United Kingdom.

CENELEC
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung

Management Centre: Avenue Marnix 17, B - 1000 Brussels

© 2010 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.
Ref. No. EN 61508-5:2010 E
Foreword
The text of document 65A/552/FDIS, future edition 2 of IEC 61508-5, prepared by SC 65A, System
aspects, of IEC TC 65, Industrial-process measurement, control and automation, was submitted to the
IEC-CENELEC parallel vote and was approved by CENELEC as EN 61508-5 on 2010-05-01.
This European Standard supersedes EN 61508-5:2001.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN and CENELEC shall not be held responsible for identifying any or all such patent
rights.
The following dates were fixed:
– latest date by which the EN has to be implemented
at national level by publication of an identical
national standard or by endorsement (dop) 2011-02-01
– latest date by which the national standards conflicting
with the EN have to be withdrawn (dow) 2013-05-01
Annex ZA has been added by CENELEC.
__________
Endorsement notice
The text of the International Standard IEC 61508-5:2010 was approved by CENELEC as a European
Standard without any modification.
In the official version, for Bibliography, the following notes have to be added for the standards indicated:
[1] IEC 61511 series NOTE  Harmonized in EN 61511 series (not modified).
[2] IEC 62061 NOTE  Harmonized as EN 62061.
[3] IEC 61800-5-2 NOTE  Harmonized as EN 61800-5-2.
[9] ISO/IEC 31010 NOTE  Harmonized as EN 31010.
[10] ISO 10418:2003 NOTE  Harmonized as EN 10418:2003 (not modified).
[12] ISO 13849-1:2006 NOTE  Harmonized as EN ISO 13849-1:2006 (not modified).
[13] IEC 60601 series NOTE  Harmonized in EN 60601 series (partially modified).
[14] IEC 61508-2 NOTE  Harmonized as EN 61508-2.
[15] IEC 61508-3 NOTE  Harmonized as EN 61508-3.
[16] IEC 61508-6 NOTE  Harmonized as EN 61508-6.
[17] IEC 61508-7 NOTE  Harmonized as EN 61508-7.
[18] IEC 61511-1 NOTE  Harmonized as EN 61511-1.
__________
- 3 - EN 61508-5:2010
Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications

The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.

NOTE  When an international publication has been modified by common modifications, indicated by (mod), the relevant EN/HD
applies.
Publication Year Title EN/HD Year

IEC 61508-1 2010 Functional safety of EN 61508-1 2010
electrical/electronic/programmable electronic
safety-related systems -
Part 1: General requirements
IEC 61508-4 2010 Functional safety of EN 61508-4 2010
electrical/electronic/programmable electronic
safety-related systems -
Part 4: Definitions and abbreviations

IEC 61508-5 ®
Edition 2.0 2010-04
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Functional safety of electrical/electronic/programmable electronic safety-related
systems –
Part 5: Examples of methods for the determination of safety integrity levels

Sécurité fonctionnelle des systèmes électriques/électroniques/électroniques
programmables relatifs à la sécurité –
Partie 5: Exemples de méthodes pour la détermination des niveaux d'intégrité
de sécurité
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
X
CODE PRIX
ICS 25.040.40 ISBN 978-2-88910-528-1
– 2 – 61508-5 © IEC:2010
CONTENTS
FOREWORD.3
INTRODUCTION.5
1 Scope.7
2 Normative references .9
3 Definitions and abbreviations.9
Annex A (informative) Risk and safety integrity – General concepts .10
Annex B (informative) Selection of methods for determining safety integrity level
requirements.21
Annex C (informative) ALARP and tolerable risk concepts .24
Annex D (informative) Determination of safety integrity levels – A quantitative method .27
Annex E (informative) Determination of safety integrity levels – Risk graph methods .30
Annex F (informative) Semi-quantitative method using layer of protection analysis
(LOPA) .38
Annex G (informative) Determination of safety integrity levels – A qualitative method –
hazardous event severity matrix.44
Bibliography.46

Figure 1 – Overall framework of the IEC 61508 series .8
Figure A.1 – Risk reduction – general concepts (low demand mode of operation) .14
Figure A.2 – Risk and safety integrity concept .14
Figure A.3 – Risk diagram for high demand applications .15
Figure A.4 – Risk diagram for continuous mode operation .16
Figure A.5 – Illustration of common cause failures (CCFs) of elements in the EUC
control system and elements in the E/E/PE safety-related system.17
Figure A.6 – Common cause between two E/E/PE safety-related systems .18
Figure A.7 – Allocation of safety requirements to the E/E/PE safety-related systems,
and other risk reduction measures .20
Figure C.1 – Tolerable risk and ALARP.25
Figure D.1 – Safety integrity allocation – example for safety-related protection system.29
Figure E.1 – Risk Graph: general scheme.33
Figure E.2 – Risk graph – example (illustrates general principles only) .34
Figure G.1 – Hazardous event severity matrix – example (illustrates general principles
only) .

Table C.1 – Example of risk classification of accidents .
Table C.2 – Interpretation of risk classes .26
Table E.1 – Example of data relating to risk graph (Figure E.2).35
Table E.2 – Example of calibration of the general purpose risk graph .36
Table F.1 – LOPA report .40

61508-5 © IEC:2010 – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
FUNCTIONAL SAFETY OF ELECTRICAL/ELECTRONIC/
PROGRAMMABLE ELECTRONIC SAFETY-RELATED SYSTEMS –

Part 5: Examples of methods for the determination
of safety integrity levels
FOREWORD
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