EN 61508-4:2010

SLOVENSKI STANDARD
01-maj-2011
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Functional safety of electrical/electronic/programmable electronic safety-related systems
- Part 4: Definitions and abbreviations (IEC 61508-4:2010)
Funktionale Sicherheit sicherheitsbezogener
elektrischer/elektronischer/programmierbarer elektronischer Systeme - Teil 4: Begriffe
und Abkürzungen (IEC 61508-4:2010)
Sécurité fonctionnelle des systèmes électriques/électroniques/électroniques
programmables relatifs à la sécurité - Partie 4: Définitions et abréviations (CEI 61508-
4:2010)
Ta slovenski standard je istoveten z: EN 61508-4:2010
ICS:
01.040.25 Izdelavna tehnika (Slovarji) Manufacturing engineering
(Vocabularies)
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 61508-4
NORME EUROPÉENNE
May 2010
EUROPÄISCHE NORM
ICS 25.040.40; 29.020 Supersedes EN 61508-4:2001

English version
Functional safety of electrical/electronic/programmable electronic safety-
related systems -
Part 4: Definitions and abbreviations
(IEC 61508-4:2010)
Sécurité fonctionnelle des systèmes Funktionale Sicherheit sicherheitsbezogener
électriques/électroniques/électroniques elektrischer/elektronischer/programmierbarer
programmables relatifs à la sécurité - elektronischer Systeme -
Partie 4: Définitions et abréviations Teil 4: Begriffe und Abkürzungen
(CEI 61508-4:2010) (IEC 61508-4:2010)

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 61508-4:2010 E
Foreword
The text of document 65A/551/FDIS, future edition 2 of IEC 61508-4, 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 61508-4 on 2010-05-01.
This European Standard supersedes EN 61508-4:2001.
It has the status of a basic safety publication according to IEC Guide 104.
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 61508-4:2010 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 62061:2005 NOTE  Harmonized as EN 62061:2005 (not modified).
[3] IEC 61800-5-2 NOTE  Harmonized as EN 61800-5-2.
[4] IEC 61508-5:2010 NOTE  Harmonized as EN 61508-5:2010 (not modified).
[5] IEC 61508-6:2010 NOTE  Harmonized as EN 61508-6:2010 (not modified).
[6] IEC 61508-7:2010 NOTE  Harmonized as EN 61508-7:2010 (not modified).
[8] IEC 61131-3:2003 NOTE  Harmonized as EN 61131-3:2003 (not modified).
[10] ISO 8402:1994 NOTE  Harmonized as EN ISO 8402:1995 (not modified).
[11] IEC 60601 series NOTE  Harmonized in EN 60601 series (partially modified).
[14] IEC 61508-1:2010 NOTE  Harmonized as EN 61508-1:2010 (not modified).
[15] IEC 61508-2:2010 NOTE  Harmonized as EN 61508-2:2010 (not modified).
[16] IEC 61508-3:2010 NOTE  Harmonized as EN 61508-3:2010 (not modified).
[18] ISO 9000:2005 NOTE  Harmonized as EN ISO 9000:2005 (not modified).
__________
- 3 - EN 61508-4:2010
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 Guide 104 1997 The preparation of safety publications - -
and the use of basic safety publications and
group safety publications
ISO/IEC Guide 51 1999 Safety aspects - Guidelines - -
for their inclusion in standards

IEC 61508-4 ®
Edition 2.0 2010-04
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
BASIC SAFETY PUBLICATION
PUBLICATION FONDAMENTALE DE SÉCURITÉ
Functional safety of electrical/electronic/programmable electronic safety-related
systems –
Part 4: Definitions and abbreviations

Sécurité fonctionnelle des systèmes électriques/électroniques/électroniques
programmables relatifs à la sécurité –
Partie 4: Définitions et abréviations

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
V
CODE PRIX
ICS 25.040.40; 29.020 ISBN 978-2-88910-527-4
– 2 – 61508-4 © IEC:2010
CONTENTS
FOREWORD.3
INTRODUCTION.5
1 Scope.7
2 Normative references.9
3 Definitions and abbreviations .9
3.1 Safety terms .10
3.2 Equipment and devices.12
3.3 Systems – general aspects .15
3.4 Systems – safety-related aspects.17
3.5 Safety functions and safety integrity.19
3.6 Fault, failure and error (see Figure 4).22
3.7 Lifecycle activities.27
3.8 Confirmation of safety measures.28
Bibliography .32
Index .33

Figure 1 – Overall framework of the IEC 61508 series .8
Figure 2 – Programmable electronic system .16
Figure 3 – Electrical/electronic/programmable electronic system (E/E/PE system) –
structure and terminology.16
Figure 4 – Failure model .23

Table 1 – Abbreviations used in this standard.9

61508-4 © IEC:2010 – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
FUNCTIONAL SAFETY OF ELECTRICAL/ELECTRONIC/
PROGRAMMABLE ELECTRONIC SAFETY-RELATED SYSTEMS –

Part 4: Definitions and abbreviations

FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote
international co-operation on all questions concerning standardization in the electrical and electronic fields. To
this end and in addition to other activities, IEC publishes International Standards, Technical Specifications,
Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC
Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested
in the subject dealt with may participate in this preparatory work. International, governmental and non-
governmental organizations liaising with the IEC also participate in this preparation. IEC collaborates closely
with the International Organization for Standardization (ISO) in accordance with conditions determined by
agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
consensus of opinion on the relevant subjects since each technical committee has representation from all
interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
misinterpretation by any end user.
4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
transparently to the maximum extent possible in their national and regional publications. Any divergence
between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
the latter.
5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any
services carried out by independent certification bodies.
6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
members of its technical committees and IEC National Committees for any personal injury, property damage or
other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
Publications.
8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 61508-4 has been prepared by subcommittee 65A: System aspects,
of IEC technical committee 65: Industrial-process measurement, control and automation.
This second edition cancels and replaces the first edition published in 1998. This edition
constitutes a technical revision.
This edition has been subject to a thorough review and incorporates many comments received
at the various revision stages.
It has the status of a basic safety publication according to IEC Guide 104.

– 4 – 61508-4 © IEC:2010
The text of this standard is based on the following documents:
FDIS Report on voting
65A/551/FDIS 65A/575/RVD
Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2
A list of all parts of the IEC 61508 series, published under the general title Functional safety of
electrical / electronic / programmable electronic safety-related systems, can be found on the
IEC website.
The committee has decided that the contents of this publicat
...