EN 62347:2007

SLOVENSKI STANDARD
01-januar-2008
Napotki za specifikacije sistemske zagotovljivosti (IEC 62347:2006)
Guidance on system dependability specifications
Anleitung zur Spezifikation der Zuverlässigkeit von Systemen
Lignes directrices pour les spécifications de sûreté de fonctionnement des systèmes
Ta slovenski standard je istoveten z: EN 62347:2007
ICS:
03.120.01 Kakovost na splošno Quality in general
21.020 =QDþLOQRVWLLQQDþUWRYDQMH Characteristics and design of
VWURMHYDSDUDWRYRSUHPH machines, apparatus,
equipment
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD
EN 62347
NORME EUROPÉENNE
March 2007
EUROPÄISCHE NORM
ICS 03.120.01
English version
Guidance on system dependability specifications
(IEC 62347:2006)
Lignes directrices  Anleitung zur Spezifikation
pour les spécifications de sûreté der Zuverlässigkeit von Systemen
de fonctionnement des systèmes (IEC 62347:2006)
(CEI 62347:2006)
This European Standard was approved by CENELEC on 2007-03-01. 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, 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

Central Secretariat: rue de Stassart 35, B - 1050 Brussels

© 2007 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.
Ref. No. EN 62347:2007 E
Foreword
The text of document 56/1138/FDIS, future edition 1 of IEC 62347, prepared by IEC TC 56,
Dependability, was submitted to the IEC-CENELEC parallel vote and was approved by CENELEC as
EN 62347 on 2007-03-01.
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) 2007-12-01
– latest date by which the national standards conflicting
with the EN have to be withdrawn (dow) 2010-03-01
Annex ZA has been added by CENELEC.
__________
Endorsement notice
The text of the International Standard IEC 62347:2006 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:
IEC 60300-1 NOTE  Harmonized as EN 60300-1:2003 (not modified).
IEC 60300-2 NOTE  Harmonized as EN 60300-2:2004 (not modified).
IEC 61069 NOTE  Harmonized in EN 61069 series (not modified).
IEC 61069-1 NOTE  Harmonized as EN 61069-1:1993 (not modified).
ISO 9000 NOTE  Harmonized as EN ISO 9000:2005 (not modified).
__________
- 3 - EN 62347:2007
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

1)
IEC 60050-191 - International Electrotechnical Vocabulary - -
(IEV) -
Chapter 191: Dependability and quality of
service
1)
ISO/IEC 15288 - Systems engineering - System life cycle - -
processes
1)
Undated reference.
NORME CEI
INTERNATIONALE
IEC
INTERNATIONAL
Première édition
STANDARD
First edition
2006-11
Lignes directrices pour les spécifications de
sûreté de fonctionnement des systèmes

Guidance on system dependability specifications
© IEC 2006 Droits de reproduction réservés ⎯ Copyright - all rights reserved
Aucune partie de cette publication ne peut être reproduite ni No part of this publication may be reproduced or utilized in any
utilisée sous quelque forme que ce soit et par aucun procédé, form or by any means, electronic or mechanical, including
électronique ou mécanique, y compris la photocopie et les photocopying and microfilm, without permission in writing from
microfilms, sans l'accord écrit de l'éditeur. the publisher.
International Electrotechnical Commission, 3, rue de Varembé, PO Box 131, CH-1211 Geneva 20, Switzerland
Telephone: +41 22 919 02 11 Telefax: +41 22 919 03 00 E-mail: inmail@iec.ch Web: www.iec.ch
CODE PRIX
V
PRICE CODE
Commission Electrotechnique Internationale
International Electrotechnical Commission
МеждународнаяЭлектротехническаяКомиссия
Pour prix, voir catalogue en vigueur
For price, see current catalogue

62347 © IEC:2006 – 3 –
CONTENTS
FOREWORD.5
INTRODUCTION.9

1 Scope.11
2 Normative references .11
3 Terms and definitions .11
4 Concepts dealing with system dependability.13
4.1 Understanding the system .13
4.2 System life cycle .17
4.3 System operation .21
4.4 System operating profile.21
4.5 Dependability requirements .23
5 Procedure for specifying system dependability .27
5.1 System specification process .27
5.2 System dependability specification process.27
5.3 Determining dependability values .29
5.4 Procedural steps for determining system dependability requirements .31

Annex A (informative) Evaluation of dependability characteristics .39
Annex B (informative) An example on developing a system dependability specification
– A home security system .53

Bibliography.69

Figure 1 – An example of system properties and related characteristics.15
Figure 2 – Overview of system life cycle stages .19
Figure 3 – Relationships of system operating profile and scenario in system operation .23
Figure 4 – Overview of system specification process .29
Figure 5 – Steps for determining system dependability requirements .33
Figure B.1 – System configuration for normal mode of operation.61
Figure B.2 – System configuration for panic mode of operation.63
Figure B.3 – System configuration for security service mode of operation .63

Table A.1 – Examples of influencing factors under each influencing condition.49
Table A.2 – Relationship of system properties with influencing conditions.51

62347 © IEC:2006 – 5 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
GUIDANCE ON SYSTEM DEPENDABILITY SPECIFICATIONS

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 provides no marking procedure to indicate its approval and cannot be rendered responsible for any
equipment declared to be in conformity with an IEC Publication.
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 62347 has been prepared by IEC technical committee 56:
Dependability.
The text of this standard is based on the following documents:
FDIS Report on voting
56/1138/FDIS 56/1161/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.

62347 © IEC:2006 – 7 –
The committee has decided that the contents of this publication will remain unchanged until
the maintenance result date indicated on the IEC web site under "http://webstore.iec.ch" in
the data related to the specific publication. At this date, the publication will be
• reconfirmed;
• withdrawn;
• replaced by a revised edition, or
• amended.
62347 © IEC:2006 – 9 –
INTRODUCTION
A system is a physical and/or virtual entity. It is necessary sometimes to define a system’s
boundary so that it can be distinguished or separated from other systems. A system interacts
with its surroundings or environment to fulfil a specific need or purpose, or to achieve a
defined objective. This is accomplished through the interaction of the system’s elements
representing the necessary functions designed to meet the intended objective. Determining
the functions needed to meet a specific objective represents the process of developing a
system specification. Detailed system design begins only after the functions have been
identified.
Systems may vary in their complexity structurally and functionally. A system can consist of
hardware, software, and human elements, or a com
...