SIST EN 61511-1:2017
(Main)Functional safety - Safety instrumented systems for the process industry sector - Part 1: Framework, definitions, system, hardware and application programming Requirements (IEC 61511-1:2016 + COR1:2016)
Functional safety - Safety instrumented systems for the process industry sector - Part 1: Framework, definitions, system, hardware and application programming Requirements (IEC 61511-1:2016 + COR1:2016)
This part of IEC 61511 gives requirements for the specification, design, installation, operation
and maintenance of a safety instrumented system (SIS), so that it can be confidently
entrusted to achieve or maintain a safe state of the process. IEC 61511-1 has been
developed as a process sector implementation of IEC 61508:2010.
In particular, IEC 61511-1:
a) specifies the requirements for achieving functional safety but does not specify who is
responsible for implementing the requirements (e.g., designers, suppliers,
owner/operating company, contractor). This responsibility will be assigned to different
parties according to safety planning, project planning and management, and national
regulations;
b) applies when devices that meets the requirements of the IEC 61508 series published in
2010, or IEC 61511-1:2016 [11.5], is integrated into an overall system that is to be used
for a process sector application. It does not apply to manufacturers wishing to claim that
devices are suitable for use in SISs for the process sector (see IEC 61508-2:2010 and
IEC 61508-3:2010);
c) defines the relationship between IEC 61511 and IEC 61508 (see Figures 2 and 3);
d) applies when application programs are developed for systems having limited variability
language or when using fixed programming language devices, but does not apply to
manufacturers, SIS designers, integrators and users that develop embedded software
(system software) or use full variability languages (see IEC 61508-3:2010);
e) applies to a wide variety of industries within the process sector for example, chemicals, oil
and gas, pulp and paper, pharmaceuticals, food and beverage, and non-nuclear power
generation;
NOTE 1 Within the process sector some applications may have additional requirements that have to be
satisfied.
f) outlines the relationship between SIFs and other instrumented functions (see Figure 4);
g) results in the identification of the functional requirements and safety integrity requirements
for the SIF taking into account the risk reduction achieved by other methods;
h) specifies life-cycle requirements for system architecture and hardware configuration,
application programming, and system integration;
i) specifies requirements for application programming for users and integrators of SISs.
j) applies when functional safety is achieved using one or more SIFs for the protection of
personnel, protection of the general public or protection of the environment;
k) may be applied in non-safety applications for example asset protection;
l) defines requirements for implementing SIFs as a part of the overall arrangements for
achieving functional safety;
m) uses a SIS safety life-cycle (see Figure 7) and defines a list of activities which are
necessary to determine the functional requirements and the safety integrity requirements
for the SIS;
Funktionale Sicherheit - Sicherheitstechnische Systeme für die Prozessindustrie - Teil 1: Allgemeines, Begriffe, Anforderungen an Systeme, Hardware und Anwendungsprogrammierung (IEC 61511-1:2016 + COR1:2016)
Sécurité fonctionnelle - Systèmes instrumentés de sécurité pour le secteur des industries de transformation - Partie 1: Cadre, définitions, exigences pour le système, le matériel et la programmation d'application (IEC 61511-1:2016 + COR1:2016)
L'IEC 61511-1:2016 décrit les exigences relatives à la spécification, la conception, l'installation, au fonctionnement et à la maintenance d'un système instrumenté de sécurité (SIS, Safety Instrumented System) de manière à ce qu'il puisse être mis en oeuvre en toute confiance pour établir ou maintenir le processus dans un état de sécurité convenable. L'IEC 61511-1 a été conçue pour être une mise en oeuvre de l'IEC 61508:2010 dans le secteur des industries de transformation.
Funkcijska varnost - Sistemi z varnostnimi instrumenti za sektor procesne industrije - 1. del: Zahteve za ogrodja, definicije, zahteve za sistem ter strojno in programsko opremo (IEC 61511-1:2016 + COR1:2016)
Ta del standarda IEC 61511 določa zahteve za specifikacijo, zasnovo, namestitev, delovanje in vzdrževanje sistema z varnostnimi instrumenti (SIS), tako da mu je mogoče zaupati, da bo dosegel ali ohranjal varno stanje postopka. Standard IEC 61511-1 je bil zasnovan kot izvedba procesnega sektorja za standard IEC 61508:2010.
Standard IEC 61511-1:
a) določa zahteve za doseganje funkcionalne varnosti, vendar ne določa, kdo je odgovoren za izvajanje zahtev (npr. načrtovalci, dobavitelji, lastnik/operativna družba, pogodbenik). Ta odgovornost bo dodeljena različnim strankam v skladu z načrtovanjem varnosti, načrtovanjem in upravljanjem projekta ter nacionalnimi predpisi.
b) se uporablja, kadar so naprave, ki izpolnjujejo zahteve skupine standardov IEC 61508, objavljene leta 2010, ali v standardu IEC 61511-1:2016 [11.5], vgrajene v celoten sistem, ki je namenjen uporabi v procesnem sektorju. Ne uporablja se za proizvajalce, ki želijo trditi, da so naprave primerne za uporabo v sistemih z varnostnimi instrumenti za procesni sektor (glej standarda IEC 61508-2:2010 in IEC 61508-3:2010);
c) določa razmerje med standardoma IEC 61511 in IEC 61508 (glej sliki 2 in 3);
d) se uporablja, kadar so aplikacijski programi razviti za sisteme z jezikom z omejeno variabilnostjo ali pri uporabi naprav s fiksnim programskim jezikom, vendar se ne uporablja za proizvajalce, načrtovalce sistemov z varnostnimi instrumenti, integratorje in uporabnike, ki razvijajo vdelano programsko opremo (sistemska programska oprema) ali uporabljajo jezike s polno variabilnostjo (glej standard IEC 61508 -3:2010);
e) se uporablja za širok nabor panog v procesnem sektorju, npr. za kemikalije, nafto in plin, papirno kašo in papir, zdravila, hrano in pijačo ter nejedrsko proizvajanje energije;
OPOMBA 1: Nekatere aplikacije v procesnem sektorju imajo lahko dodatne zahteve, ki jih je treba izpolniti.
f) opredeljuje razmerje med funkcijami z varnostnimi instrumenti in drugimi funkcijami z instrumenti (glej sliko 4);
g) omogoča identifikacijo funkcionalnih zahtev in zahtev glede varnostne celovitosti za funkcije z varnostnimi instrumenti, pri čemer upošteva zmanjšanje tveganja zaradi drugih metod;
h) določa zahteve glede življenjskega cikla za sistemsko arhitekturo in strojno konfiguracijo, programiranje aplikacij in integracijo sistema;
i) določa zahteve za programiranje aplikacij za uporabnike in integratorje sistemov z varnostnimi instrumenti;
j) se uporablja, če se funkcionalna varnost doseže z uporabo ene ali več funkcij z varnostnimi instrumenti za zaščito osebja/splošne javnosti ali varstvo okolja;
k) se lahko uporabi za aplikacije, ki niso povezane z varnostjo, na primer za zaščito sredstev;
l) določa zahteve za implementacijo funkcij z varnostnimi instrumenti kot del celotnih dogovorov za dosego funkcionalne varnosti;
m) uporablja varnostni življenjski cikel sistemov z varnostnimi instrumenti (glej sliko 7) in opredeljuje seznam dejavnosti, ki so potrebne za določitev funkcionalnih zahtev in varnostne celovitosti za sisteme z varnostnimi instrumenti.
General Information
Relations
Related Packages
Standards Content (Sample)
SLOVENSKI STANDARD
SIST EN 61511-1:2017
01-september-2017
1DGRPHãþD
SIST EN 61511-1:2007
Funkcijska varnost - Sistemi z varnostnimi instrumenti za sektor procesne
industrije - 1. del: Zahteve za ogrodja, definicije, zahteve za sistem ter strojno in
programsko opremo (IEC 61511-1:2016 + COR1:2016)
Functional safety - Safety instrumented systems for the process industry sector - Part 1:
Framework, definitions, system, hardware and application programming Requirements
(IEC 61511-1:2016 + COR1:2016)
Funktionale Sicherheit - Sicherheitstechnische Systeme für die Prozessindustrie - Teil 1:
Allgemeines, Begriffe, Anforderungen an Systeme, Hardware und
Anwendungsprogrammierung (IEC 61511-1:2016 + COR1:2016)
Sécurité fonctionnelle - Systèmes instrumentés de sécurité pour le secteur des industries
de transformation - Partie 1: Cadre, définitions, exigences pour le système, le matériel et
la programmation d'application (IEC 61511-1:2016 + COR1:2016)
Ta slovenski standard je istoveten z: EN 61511-1:2017
ICS:
25.040.40 Merjenje in krmiljenje Industrial process
industrijskih postopkov measurement and control
SIST EN 61511-1:2017 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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SIST EN 61511-1:2017
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SIST EN 61511-1:2017
EUROPEAN STANDARD EN 61511-1
NORME EUROPÉENNE
EUROPÄISCHE NORM
April 2017
ICS 13.110; 25.040.01 Supersedes EN 61511-1:2004
English Version
Functional safety - Safety instrumented systems for the process
industry sector - Part 1: Framework, definitions, system,
hardware and application programming Requirements
(IEC 61511-1:2016 + COR1:2016)
Sécurité fonctionnelle - Systèmes instrumentés de sécurité Funktionale Sicherheit - Sicherheitstechnische Systeme für
pour le secteur des industries de transformation - die Prozessindustrie - Teil 1: Allgemeines, Begriffe,
Partie 1: Cadre, définitions, exigences pour le système, le Anforderungen an Systeme, Hardware und
matériel et la programmation d'application Anwendungsprogrammierung
(IEC 61511-1:2016 + COR1:2016) (IEC 61511-1:2016 + COR1:2016)
This European Standard was approved by CENELEC on 2016-03-30. 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 CEN-CENELEC
Management Centre 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 CEN-CENELEC Management Centre 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, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,
Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden,
Switzerland, Turkey and the United Kingdom.
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2017 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.
Ref. No. EN 61511-1:2017 E
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SIST EN 61511-1:2017
EN 61511-1:2017
European foreword
The text of document 65A/777/FDIS, future edition 2 of IEC 61511-1, 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 approved by CENELEC as EN 61511-1:2017.
The following dates are fixed:
(dop) 2017-10-21
• latest date by which the document has to be
implemented at national level by
publication of an identical national
standard or by endorsement
• latest date by which the national (dow) 2020-04-21
standards conflicting with the
document have to be withdrawn
This document supersedes EN 61511-1:2004.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CENELEC [and/or CEN] shall not be held responsible for identifying any or all such
patent rights.
Endorsement notice
The text of the International Standard IEC 61511-1:2016 + COR1:2016 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 60300-3-2:2004 NOTE Harmonized as EN 60300-3-2:2005 (not modified).
IEC 61025 NOTE Harmonized as EN 61025.
IEC 61131-3:2013 NOTE Harmonized as EN 61131-3:2013 (not modified).
IEC 61131-6:2012 NOTE Harmonized as EN 61131-6:2012 (not modified).
IEC 61508-4:2010 NOTE Harmonized as EN 61508-4:2010 (not modified).
IEC 61508-6:2010 NOTE Harmonized as EN 61508-6:2010 (not modified).
IEC 61511-2 NOTE Harmonized as EN 61511-2.
IEC 61511-3 NOTE Harmonized as EN 61511-3.
IEC 61784-3:2010 NOTE Harmonized as EN 61784-3:2010 (not modified).
IEC 62682:2014 NOTE Harmonized as EN 62682:2015 (not modified).
1)
ISO 9000:2005 NOTE Harmonized as EN ISO 9000:2005 (not modified).
2)
ISO 9001:2008 NOTE Harmonized as EN ISO 9001:2008 (not modified).
3)
ISO 13849-1:2006 NOTE Harmonized as EN ISO 13849-1:2006 (not modified).
ISO 13849-2:2012 NOTE Harmonized as EN ISO 13849-2:2012 (not modified).
ISO 14224:2006 NOTE Harmonized as EN ISO 14224:2006 (not modified).
1)
Superseded by EN ISO 9000:2015 (ISO 9000:2015).
2)
Superseded by EN ISO 9001:2015 (ISO 9001:2015).
3)
Superseded by EN ISO 13849-1:2015 (ISO 13849-1:2015).
2
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SIST EN 61511-1:2017
EN 61511-1:2017
Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications
The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including any amendments) applies.
NOTE 1 When an International Publication has been modified by common modifications, indicated by (mod), the relevant
EN/HD applies.
NOTE 2 Up-to-date information on the latest versions of the European Standards listed in this annex is available here:
www.cenelec.eu
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 61508-2 2010 Functional safety of EN 61508-2 2010
electrical/electronic/programmable
electronic safety-related systems -
Part 2: Requirements for
electrical/electronic/programmable
electronic safety-related systems
IEC 61508-3 2010 Functional safety of EN 61508-3 2010
electrical/electronic/programmable
electronic safety-related systems -
Part 3: Software requirements
3
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SIST EN 61511-1:2017
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SIST EN 61511-1:2017
IEC 61511-1
®
Edition 2.0 2016-02
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Functional safety – Safety instrumented systems for the process industry
sector –
Part 1: Framework, definitions, system, hardware and application programming
requirements
Sécurite fonctionnelle – Systèmes instrumentes de sécurité pour le secteur des
industries de transformation –
Partie 1: Cadre, définitions, exigences pour le système, le matériel et la
programmation d'application
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 13.110; 25.040.01 ISBN 978-2-8322-3159-3
Warning! Make sure that you obtained this publication from an authorized distributor.
Attention! Veuillez vous assurer que vous avez obtenu cette publication via un distributeur agréé.
® Registered trademark of the International Electrotechnical Commission
Marque déposée de la Commission Electrotechnique Internationale
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SIST EN 61511-1:2017
– 2 – IEC 61511-1:2016 IEC 2016
CONTENTS
FOREWORD . 5
INTRODUCTION . 7
1 Scope . 9
2 Normative references. 12
3 Terms, definitions and abbreviations . 13
3.1 Terms . 13
3.2 Terms and definitions . 13
3.3 Abbreviations . 31
4 Conformance to the IEC 61511-1:2016 . 33
5 Management of functional safety . 33
5.1 Objective . 33
5.2 Requirements . 33
5.2.1 General . 33
5.2.2 Organization and resources . 33
5.2.3 Risk evaluation and risk management . 34
5.2.4 Safety planning . 34
5.2.5 Implementing and monitoring . 34
5.2.6 Assessment, auditing and revisions . 35
5.2.7 SIS configuration management . 37
6 Safety life-cycle requirements . 37
6.1 Objectives . 37
6.2 Requirements . 38
6.3 Application program SIS safety life-cycle requirements . 40
7 Verification . 43
7.1 Objective . 43
7.2 Requirements . 43
8 Process H&RA . 45
8.1 Objectives . 45
8.2 Requirements . 45
9 Allocation of safety functions to protection layers . 46
9.1 Objectives . 46
9.2 Requirements of the allocation process . 46
9.3 Requirements on the basic process control system as a protection layer . 49
9.4 Requirements for preventing common cause, common mode and dependent
failures . 50
10 SIS safety requirements specification (SRS) . 50
10.1 Objective . 50
10.2 General requirements . 50
10.3 SIS safety requirements . 50
11 SIS design and engineering . 53
11.1 Objective . 53
11.2 General requirements . 53
11.3 Requirements for system behaviour on detection of a fault . 54
11.4 Hardware fault tolerance . 55
11.5 Requirements for selection of devices . 56
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SIST EN 61511-1:2017
IEC 61511-1:2016 IEC 2016 – 3 –
11.5.1 Objectives . 56
11.5.2 General requirements . 56
11.5.3 Requirements for the selection of devices based on prior use . 56
11.5.4 Requirements for selection of FPL programmable devices (e.g., field
devices) based on prior use . 57
11.5.5 Requirements for selection of LVL programmable devices based on
prior use . 58
11.5.6 Requirements for selection of FVL programmable devices . 59
11.6 Field devices . 59
11.7 Interfaces . 59
11.7.1 General . 59
11.7.2 Operator interface requirements . 59
11.7.3 Maintenance/engineering interface requirements . 60
11.7.4 Communication interface requirements . 60
11.8 Maintenance or testing design requirements . 61
11.9 Quantification of random failure . 61
12 SIS application program development . 63
12.1 Objective . 63
12.2 General requirements . 63
12.3 Application program design . 64
12.4 Application program implementation . 65
12.5 Requirements for application program verification (review and testing) . 66
12.6 Requirements for application program methodology and tools . 67
13 Factory acceptance test (FAT) . 68
13.1 Objective . 68
13.2 Recommendations. 68
14 SIS installation and commissioning . 69
14.1 Objectives . 69
14.2 Requirements . 69
15 SIS safety validation . 70
15.1 Objective . 70
15.2 Requirements . 70
16 SIS operation and maintenance . 73
16.1 Objectives . 73
16.2 Requirements . 73
16.3 Proof testing and inspection . 75
16.3.1 Proof testing . 75
16.3.2 Inspection . 76
16.3.3 Documentation of proof tests and inspection . 76
17 SIS modification . 76
17.1 Objectives . 76
17.2 Requirements . 77
18 SIS decommissioning . 77
18.1 Objectives . 77
18.2 Requirements . 78
19 Information and documentation requirements . 78
19.1 Objectives . 78
19.2 Requirements . 78
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SIST EN 61511-1:2017
– 4 – IEC 61511-1:2016 IEC 2016
Bibliography . 80
Figure 1 – Overall framework of the IEC 61511 series . 8
Figure 2 – Relationship between IEC 61511 and IEC 61508 . 10
Figure 3 – Detailed relationship between IEC 61511 and IEC 61508 . 11
Figure 4 – Relationship between safety instrumented functions and other functions . 12
Figure 5 – Programmable electronic system (PES): structure and terminology . 24
Figure 6 – Example of SIS architectures comprising three SIS subsystems . 27
Figure 7 – SIS safety life-cycle phases and FSA stages . 38
Figure 8 – Application program safety life-cycle and its relationship to the SIS safety
life-cycle . 41
Figure 9 – Typical protection layers and risk reduction means . 49
Table 1 – Abbreviations used in IEC 61511 . 32
Table 2 – SIS safety life-cycle overview (1 of 2). 39
Table 3 – Application program safety life-cycle: overview (1 of 2) . 42
Table 4 – Safety integrity requirements: PFD . 47
avg
Table 5 – Safety integrity requirements: average frequency of dangerous failures of the
SIF . 47
Table 6 – Minimum HFT requirements according to SIL . 55
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SIST EN 61511-1:2017
IEC 61511-1:2016 IEC 2016 – 5 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
FUNCTIONAL SAFETY –
SAFETY INSTRUMENTED SYSTEMS
FOR THE PROCESS INDUSTRY SECTOR –
Part 1: Framework, definitions, system,
hardware and application programming requirements
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 61511-1 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 2003. This edition
constitutes a technical revision. This edition includes the following significant technical
changes with respect to the previous edition:
• references and requirements to software replaced with references and requirements to
application programming;
• functional safety assessment requirements provided with more detail to improve
management of functional safety.
• management of change requirement added;
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SIST EN 61511-1:2017
– 6 – IEC 61511-1:2016 IEC 2016
• security risk assessment requirements added;.
• requirements expanded on the basic process control system as a protection layer;
• requirements for hardware fault tolerance modified and should be reviewed carefully to
understand user/integrator options.
The text of this standard is based on the following documents:
FDIS Report on voting
65A/777/FDIS 65A/784/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 in the IEC 61511 series, published under the general title Functional safety –
safety instrumented systems for the process industry sector, can be found on the IEC website.
The committee has decided that the contents of this publication will remain unchanged until
the stability date indicated on the IEC website 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.
The contents of the corrigendum of September 2016 have been included in this copy.
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SIST EN 61511-1:2017
IEC 61511-1:2016 IEC 2016 – 7 –
INTRODUCTION
Safety instrumented systems (SISs) have been used for many years to perform safety
instrumented functions (SIFs) in the process industries. If instrumentation is to be effectively
used for SIFs, it is essential that this instrumentation achieves certain minimum standards
and performance levels.
The IEC 61511 series addresses the application of SISs for the process industries. The
IEC 61511 series also addresses a process Hazard and Risk Assessment (H&RA) to be
carried out to enable the specification for SISs to be derived. Other safety systems'
contributions are only considered with respect to the performance requirements for the SIS.
The SIS includes all devices necessary to carry out each SIF from sensor(s) to final
element(s).
The IEC 61511 series has two concepts which are fundamental to its application: SIS safety
life-cycle and safety integrity levels (SILs).
The IEC 61511 series addresses SISs which are based on the use of
electrical/electronic/programmable electronic technology. Where other technologies are used
for logic solvers, the basic principles of the IEC 61511 series should be applied to ensure the
functional safety requirements are met. The IEC 61511 series also addresses the SIS sensors
and final elements regardless of the technology used. The IEC 61511 series is process
industry specific within the framework of the IEC 61508 series.
The IEC 61511 series sets out an approach for SIS safety life-cycle activities to achieve these
minimum principles. This approach has been adopted in order that a rational and consistent
technical policy is used.
In most situations, safety is best achieved by an inherently safe process design. However in
some instances this is not possible or not practical. If necessary, this may be combined with a
protective system or systems to address any residual identified risk. Protective systems can
rely on different technologies (chemical, mechanical, hydraulic, pneumatic, electrical,
electronic,
...
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