SIST EN 61131-6:2013
(Main)Programmable controllers - Part 6: Functional safety (IEC 61131-6:2012)
Programmable controllers - Part 6: Functional safety (IEC 61131-6:2012)
This Part of the IEC 61131 series specifies requirements for programmable controllers (PLCs) and their associated peripherals, as defined in Part 1, which are intended to be used as the logic subsystem of an electrical/electronic/programmable electronic (E/E/PE) safety-related system. A programmable controller and its associated peripherals complying with the requirements of this part is considered suitable for use in an E/E/PE safety-related system and is identified as a functional safety programmable logic controller (FS-PLC). An FS-PLC is generally a hardware (HW) / software (SW) subsystem. An FS-PLC may also include software elements, for example predefined function blocks. An E/E/PE safety-related system generally consists of sensors, actuators, software and a logic subsystem. This part is a product specific implementation of the requirements of the IEC 61508 series and conformity to this part fulfils all of the applicable requirements of the IEC 61508 series related to FS-PLCs. While the IEC 61508 series is a system standard, this part provides product specific requirements for the application of the principles of the IEC 61508 series to FS-PLC. This Part of the IEC 61131 series addresses only the functional safety and safety integrity requirements of an FS-PLC when used as part of an E/E/PE safety-related system. The definition of the functional safety requirements of the overall E/E/PE safety-related system and the functional safety requirements of the ultimate application of the E/E/PE safety-related system are outside the scope of this part, but they are inputs for this part. For application specific information the reader is referred to standards such as the IEC 61511 series, IEC 62061, and the ISO 13849 series. This part does not cover general safety requirements for an FS-PLC such as requirements related to electric shock and fire hazards specified in IEC 61131-2. This part applies to an FS-PLC with a Safety Integrity Level (SIL) capability not greater than SIL 3. The objective of this part is: - to establish and describe the safety life-cycle elements of an FS-PLC, in harmony with the general safety life-cycle identified in IEC 61508-1, -2 and -3; • to establish and describe the requirements for FS-PLC HW and SW that relate to the functional safety and safety integrity requirements of a E/E/PE safety-related system; - to establish evaluation methods for a FS-PLC to this part for the following parameters/criteria: - a Safety Integrity Level (SIL) claim for which the FS-PLC is capable, - a Probability of Failure on Demand (PFD) value, - an average frequency of dangerous failure per hour value (PFH), - a value for the safe failure fraction (SFF), - a value for the hardware fault tolerance (HFT), - a diagnostic coverage (DC) value, - a verification that the specified FS-PLC manufacturer’s safety lifecycle processes are in place, - the defined safe state, - the measures and techniques for the prevention and control of systematic faults, and - for each failure mode addressed in this part, the functional behaviour in the failed state; - to establish the definitions and identify the principal characteristics relevant to the selection and application of FS-PLCs and their associated peripherals. This part is primarily intended for FS-PLC manufacturers. It also includes the critical role of FS-PLC users through the user documentation requirements. Some user guidelines for FSPLCs may be found in IEC 61131-4. The requirements of ISO/IEC Guide 51 and IEC Guide 104, as they relate to this part, are incorporated herein.
Speicherprogrammierbare Steuerungen - Teil 6: Funktionale Sicherheit (IEC 61131-6:2012)
Automates programmables - Partie 6: Sécurité fonctionnelle (CEI 61131-6:2012)
La CEI 61131-6:2012 spécifie les exigences pour les automates programmables (PLC) et leurs périphériques associés, comme défini dans la Partie 1, visant à être utilisés comme sous-système logique d'un système électrique/électronique/électronique programmable relatif à la sécurité. Un automate programmable et ses périphériques associés, conformes aux exigences de cette partie, sont considérés comme appropriés dans un système électrique/électronique/électronique programmable relatif à la sécurité et sont identifiés comme un automate programmable de sécurité fonctionnelle (FS-PLC). Un FS-PLC est généralement un sous-système matériel ou logiciel. Un FS-PLC peut également inclure des éléments logiciels, par exemple des blocs fonctionnels prédéfinis.
Programirljivi krmilniki - 6. del: Funkcionalna varnost (IEC 61131-6:2012)
Ta del skupine standardov IEC 61131 določa zahteve za programirljive krmilnike (PLC) in pripadajoče periferne naprave, kot so opredeljene v 1. delu in se uporabljajo kot logični podsistem električnega/elektronskega/elektronsko programirljivega (E/E/PE) varnostnega sistema. Programirljivi krmilniki in pripadajoče periferne naprave, ki izpolnjujejo zahteve iz tega dela, so primerni za uporabo v električnem/elektronskem/elektronsko programirljivem varnostnem sistemu in opredeljeni kot funkcionalno varni programirljivi logični krmilniki (FS-PLC). Funkcionalno varni programirljivi logični krmilniki so običajno podsistem strojne (HW)/programske (SW) opreme. Funkcionalno varni programirljivi logični krmilniki lahko vključujejo tudi elemente programske opreme, na primer predprogramirane funkcijske bloke. Električni/elektronski/elektronsko programirljivi varnostni sistem je na splošno sestavljen iz senzorjev, stikal, programske opreme in logičnega podsistema. Ta del je namenjen izvajanju posebnih zahtev za izdelke iz skupine standardov IEC 61508, zato izdelki, ki so v skladu s tem delom, izpolnjujejo vse veljavne zahteve iz skupine standardov IEC 61508 v zvezi s funkcionalno varnimi programirljivimi logičnimi krmilniki. Skupina standardov IEC 61508 je sistemski standard, ta del pa določa posebne zahteve za izdelke glede uporabe načel skupine standardov IEC 61508 pri funkcionalno varnih programirljivih logičnih krmilnikih. Ta del skupine standardov IEC 61131 obravnava samo zahteve glede funkcionalne varnosti in varnostne celovitosti funkcionalno varnih programirljivih logičnih krmilnikov, kadar so del električnega/elektronskega/elektronsko programirljivega varnostnega sistema. Opredelitev zahtev funkcionalne varnosti za celotni električni/elektronski/elektronsko programirljivi varnostni sistem in zahteve funkcionalne varnosti za končno uporabo električnega/elektronskega/elektronsko programirljivega varnostnega sistema ne spadajo na področje uporabe tega dela, vendar so podlaga zanj. Informacije, specifične za uporabo, so navedene v standardih, kot je skupina standardov IEC 61511, standard IEC 62061 in skupina standardov ISO 13849. Ta del ne zajema splošnih varnostnih zahtev za funkcionalno varne programirljive logične krmilnike, kot so zahteve v zvezi z nevarnostjo električnega udara in požara, ki so navedene v standardu IEC 61131-2. Ta del se uporablja za funkcionalno varne programirljive logične krmilnike, ki lahko dosežejo največ 3. stopnjo varnostne celovitosti (SIL).
General Information
Standards Content (Sample)
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Programirljivi krmilniki - 6. del: Funkcionalna varnost (IEC 61131-6:2012)Speicherprogrammierbare Steuerungen - Teil 6: Funktionale Sicherheit (IEC 61131-6:2012)Automates programmables - Partie 6: Sécurité fonctionnelle (CEI 61131-6:2012)Programmable controllers - Part 6: Functional safety (IEC 61131-6:2012)35.240.50Uporabniške rešitve IT v industrijiIT applications in industry25.040.40Merjenje in krmiljenje industrijskih postopkovIndustrial process measurement and controlICS:Ta slovenski standard je istoveten z:EN 61131-6:2012SIST EN 61131-6:2013en01-februar-2013SIST EN 61131-6:2013SLOVENSKI
STANDARD
SIST EN 61131-6:2013
EUROPEAN STANDARD EN 61131-6 NORME EUROPÉENNE
EUROPÄISCHE NORM November 2012
CENELEC European Committee for Electrotechnical Standardization Comité Européen de Normalisation Electrotechnique Europäisches Komitee für Elektrotechnische Normung
Management Centre: Avenue Marnix 17, B - 1000 Brussels
© 2012 CENELEC -
All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.
Ref. No. EN 61131-6:2012 E
ICS 25.040.40; 35.240.50
English version
Programmable controllers -
Part 6: Functional safety (IEC 61131-6:2012)
Automates programmables -
Partie 6: Sécurité fonctionnelle (CEI 61131-6:2012)
Speicherprogrammierbare Steuerungen – Teil 6: Funktionale Sicherheit
(IEC 61131-6:2012)
This European Standard was approved by CENELEC on 2012-11-06. 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, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom.
SIST EN 61131-6:2013
EN 61131-6:2012 - 2 - Foreword The text of document 65B/831/FDIS, future edition 1 of IEC 61131-6, prepared by SC 65B, "Devices & process analysis", of IEC TC 65, "Industrial-process measurement, control and automation" was submitted to the IEC-CENELEC parallel vote and approved by CENELEC as EN 61131-6:2012. The following dates are fixed: • latest date by which the document has to be implemented at national level by publication of an identical national standard or by endorsement (dop) 2013-08-06 • latest date by which the national standards conflicting with the document have to be withdrawn (dow) 2015-11-06
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 61131-6:2012 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 61000 series IEC 61025:2006 IEC 61069-7:1999 IEC 61078:2006 IEC 61131-3:2003 IEC 61165:2006 IEC 61496-1:2004 + A1:2007 IEC 61496-3:2008 IEC 61508 series IEC 61508-4:2010 IEC 61508-5:2010 IEC 61508-7:2010 IEC 61511-1:2003 IEC 61511-2:2003 IEC 61511-3:2003 NOTE
Harmonized in EN 61000 series (not modified). NOTE
Harmonized as EN 61025:2007 (not modified). NOTE
Harmonized as EN 61069-7:1999 (not modified). NOTE
Harmonized as EN 61078:2006 (not modified). NOTE
Harmonized as EN 61131-3:2003 (not modified). NOTE
Harmonized as EN 61165:2006 (not modified). NOTE
Harmonized as EN 61496-1:2004 (modified) + A1:2008 (not modified).
NOTE
Harmonized as CLC/TS 61496-3:2008 (not modified). NOTE
Harmonized in EN 61508 series (not modified). NOTE
Harmonized as EN 61508-4:2010 (not modified). NOTE
Harmonized as EN 61508-5:2010 (not modified). NOTE
Harmonized as EN 61508-7:2010 (not modified). NOTE
Harmonized as EN 61511-1:2004 (not modified). NOTE
Harmonized as EN 61511-2:2004 (not modified). NOTE
Harmonized as EN 61511-3:2004 (not modified). SIST EN 61131-6:2013
- 3 - EN 61131-6:2012 IEC 62061:2005 IEC 62079:2001 CISPR 11:2009 ISO 8402:1994 ISO 9000-3:1997 ISO 9001:2008 ISO 13849-1:2006 ISO 13849-2:2003 ISO 14224:2006 NOTE
Harmonized as EN 62061:2005 (not modified). NOTE
Harmonized as EN 62079:2001 (not modified). NOTE
Harmonized as EN 55011:2009 (modified). NOTE
Harmonized as EN ISO 8402:1995 (not modified). NOTE
Harmonized as EN ISO 9000-3:1997 (not modified). NOTE
Harmonized as EN ISO 9001:2008 (not modified). NOTE
Harmonized as EN ISO 13849-1:2008 (not modified). NOTE
Harmonized as EN ISO 13849-2:2003 (not modified). NOTE
Harmonized as EN ISO 14224:2006 (not modified).
SIST EN 61131-6:2013
EN 61131-6:2012 - 4 - 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
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 60947-5-1 2003 Low-voltage switchgear and controlgear -
Part 5-1: Control circuit devices and switching elements - Electromechanical control circuit devices EN 60947-5-1 + corr. July
2004 2005
IEC/TS 61000-1-2 2008 Electromagnetic compatibility (EMC) -
Part 1-2: General - Methodology for the achievement of functional safety of electrical and electronic systems including equipment with regard to electromagnetic phenomena - -
IEC 61000-4-2 2008 Electromagnetic compatibility (EMC) -
Part 4-2: Testing and measurement techniques - Electrostatic discharge immunity test EN 61000-4-2 2009
IEC 61000-4-3 2006 Electromagnetic compatibility (EMC) -
Part 4-3: Testing and measurement techniques - Radiated, radio-frequency, electromagnetic field immunity test EN 61000-4-3 2006
IEC 61000-4-4 2012 Electromagnetic compatibility (EMC) -
Part 4-4: Testing and measurement techniques - Electrical fast transient/burst immunity test EN 61000-4-4 2012
IEC 61000-4-5 + corr. October
2005 2009 Electromagnetic compatibility (EMC) -
Part 4-5: Testing and measurement techniques - Surge immunity test EN 61000-4-5 2006
IEC 61000-4-6 2008 Electromagnetic compatibility (EMC) -
Part 4-6: Testing and measurement techniques - Immunity to conducted disturbances, induced by radio-frequency fields EN 61000-4-6 2009
IEC 61000-4-8 2009 Electromagnetic compatibility (EMC) -
Part 4-8: Testing and measurement techniques - Power frequency magnetic field immunity test EN 61000-4-8 2010
IEC 61131-1 2003 Programmable controllers -
Part 1: General information EN 61131-1 2003
IEC 61131-2 2007 Programmable controllers -
Part 2: Equipment requirements and tests EN 61131-2 2007
IEC/TR 61131-4 2004 Programmable controllers -
Part 4: User guidelines - -
SIST EN 61131-6:2013
- 5 - EN 61131-6:2012 Publication Year Title EN/HD Year IEC 61326-3-1 + corr. August
2008 2008 Electrical equipment for measurement, control and laboratory use - EMC requirements -
Part 3-1: Immunity requirements for safety-related systems and for equipment intended to perform safety-related functions (functional safety) - General industrial applications EN 61326-3-1 2008
IEC 61326-3-2 2008 Electrical equipment for measurement, control and laboratory use - EMC requirements -
Part 3-2: Immunity requirements for safety-related systems and for equipment intended to perform safety-related functions (functional safety) - Industrial applications with specified electromagnetic environment EN 61326-3-2 2008
IEC 61508-1 2010 Functional safety of electrical/electronic/programmable electronic safety-related systems -
Part 1: General requirements EN 61508-1 2010
IEC 61508-2 2010 Functional safety of electrical/electronic/programmable electronic safety-related systems -
Part 2: Requirements for electrical/electronic/programmable electronic safety-related systems EN 61508-2 2010
IEC 61508-3 2010 Functional safety of electrical/electronic/programmable electronic safety-related systems -
Part 3: Software requirements EN 61508-3 2010
IEC 61508-6 2010 Functional safety of electrical/electronic/programmable electronic safety-related systems -
Part 6: Guidelines on the application of IEC 61508-2 and IEC 61508-3 EN 61508-6 2010
IEC 61784-3 2010 Industrial communication networks -
Profiles –
Part 3: Functional safety fieldbuses - General rules and profile definitions EN 61784-3 2010
IEC 62443 Series Security for industrial process measurement and control - Network and system security - -
IEC Guide 104 2010 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 - -
EN 50205 2002 Relays with forcibly guided (mechanically linked) contacts - -
SIST EN 61131-6:2013
SIST EN 61131-6:2013
IEC 61131-6 Edition 1.0 2012-10 INTERNATIONAL STANDARD NORME INTERNATIONALE Programmable controllers –
Part 6: Functional safety
Automates programmables –
Partie 6: Sécurité fonctionnelle
INTERNATIONAL ELECTROTECHNICAL COMMISSION COMMISSION ELECTROTECHNIQUE INTERNATIONALE XD ICS 25.040.40;
35.240.50 PRICE CODE CODE PRIX ISBN 978-2-83220-402-3
® Registered trademark of the International Electrotechnical Commission
Marque déposée de la Commission Electrotechnique Internationale ®
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. SIST EN 61131-6:2013
– 2 – 61131-6 © IEC:2012 CONTENTS FOREWORD . 6 INTRODUCTION . 8 1 Scope . 10 2 Normative references . 11 3 Terms and definitions . 12 4 Conformance to this standard . 25 5 FS-PLC safety lifecycle . 25 5.1 General . 25 5.2 FS-PLC functional safety SIL capability requirements . 27 5.2.1 General . 27 5.2.2 Data security . 28 5.3 Quality management system . 28 5.4 Management of FS-PLC safety lifecycle . 29 5.4.1 Objectives . 29 5.4.2 Requirements and procedures . 29 5.4.3 Execution and monitoring . 33 5.4.4 Management of functional safety . 33 6 FS-PLC design requirements specification. 33 6.1 General . 33 6.2 Design requirements specification contents . 34 6.3 Target failure rate . 35 7 FS-PLC design, development and validation plan . 36 7.1 General . 36 7.2 Segmenting requirements . 36 8 FS-PLC architecture . 37 8.1 General . 37 8.2 Architectures and subsystems . 38 8.3 Data communication . 38 9 HW design, development and validation planning . 38 9.1 HW general requirements . 38 9.2 HW functional safety requirements specification . 38 9.3 HW safety validation planning . 38 9.4 HW design and development . 39 9.4.1 General . 39 9.4.2 Requirements for FS-PLC behaviour on detection of a fault . 39 9.4.3 HW safety integrity . 40 9.4.4 Random HW failures . 48 9.4.5 HW requirements for the avoidance of systematic failures . 53 9.4.6 HW requirements for the control of systematic faults . 53 9.4.7 HW classification of faults . 54 9.4.8 HW implementation . 55 9.4.9 De-rating of components. 56 9.4.10 ASIC design and development . 56 9.4.11 Techniques and measures to prevent the introduction of faults in ASICs . 56 SIST EN 61131-6:2013
61131-6 © IEC:2012 – 3 – 9.5 HW and embedded SW and FS-PLC integration . 56 9.6 HW operation and maintenance procedures . 57 9.6.1 Objective . 57 9.6.2 Requirements . 57 9.7 HW safety validation . 58 9.7.1 General . 58 9.7.2 Requirements . 58 9.8 HW verification . 59 9.8.1 Objective . 59 9.8.2 Requirements . 59 10 FS-PLC SW design and development . 60 10.1 General . 60 10.2 Requirements . 61 10.3 Classification of engineering tools . 61 10.4 SW safety validation planning . 62 11 FS-PLC safety validation . 62 12 FS-PLC type tests . 62 12.1 General . 62 12.2 Type test requirements . 62 12.3 Climatic test requirements . 65 12.4 Mechanical test requirements . 65 12.5 EMC test requirements . 65 12.5.1 General . 65 12.5.2 General EMC environment . 65 12.5.3 Specified EMC environment . 67 13 FS-PLC verification . 69 13.1 Verification plan . 69 13.2 Fault insertion test requirements . 70 13.3 As qualified versus as shipped . 71 14 Functional safety assessment . 71 14.1 Objective . 71 14.2 Assessment requirements . 72 14.2.1 Assessment evidence and documentation . 72 14.2.2 Assessment method . 72 14.3 FS-PLC assessment information. 74 14.4 Independence. 74 15 FS-PLC operation, maintenance and modification procedures . 75 15.1 Objective . 75 15.2 FS-PLC modification. 75 16 Information to be provided by the FS-PLC manufacturer for the user . 76 16.1 General . 76 16.2 Information on conformance to this standard . 76 16.3 Information on type and content of documentation . 76 16.4 Information on catalogues and/or datasheets . 76 16.5 Safety manual . 76 16.5.1 General . 76 16.5.2 Safety manual contents . 76 Annex A (informative)
Reliability calculations . 79 SIST EN 61131-6:2013
– 4 – 61131-6 © IEC:2012 Annex B (informative)
Typical FS-PLC Architectures . 80 Annex C (informative)
Energise to trip applications of FS-PLC . 86 Annex D (informative)
Available failure rate databases . 88 Annex E (informative)
Methodology for the estimation of common cause failure rates in a multiple channel FS-PLC . 90 Bibliography . 92
Figure 1 – FS-PLC in the overall E/E/PE safety-related system safety lifecycle phases . 9 Figure 2 – Failure model . 16 Figure 3 – FS-PLC safety lifecycle (in realization phase) . 26 Figure 4 – Relevant parts of a safety function . 35 Figure 5 – FS-PLC to engineering tools relationship . 37 Figure 6 – HW subsystem decomposition . 43 Figure 7 – Example: determination of the maximum SIL for specified architecture . 45 Figure 8 – Example of limitation on hardware safety integrity for a multiple-channel safety function . 47 Figure 9 – Fault classification and FS-PLC behaviour . 54 Figure 10 – ASIC development lifecycle (V-Model) . 56 Figure 11 – Model of FS-PLC and engineering tools layers . 60 Figure B.1 – Single FS-PLC with single I/O and external watchdog (1oo1D) . 81 Figure B.2 – Dual PE with single I/O and external watchdogs (1oo1D) . 81 Figure B.3 – Dual PE with dual I/O, no inter-processor communication, and 1oo2 shutdown logic . 82 Figure B.4 – Dual PE with dual I/O, inter-processor communication, and 1oo2D shutdown logic . 83 Figure B.5 – Dual PE with dual I/O, no inter-processor communication, external watchdogs, and 2oo2 shutdown logic . 83 Figure B.6 – Dual PE with dual I/O, inter-processor communication, external watchdogs, and 2oo2D shutdown logic . 84 Figure B.7 – Triple PE with triple I/O, inter-processor communication, and 2oo3D shutdown logic . 85
Table 1 – Safety integrity levels for low demand mode of operation . 35 Table 2 – Safety integrity levels for high demand or continuous mode of operation . 36 Table 3 – Faults to be detected and notified (alarmed) to the application program . 40 Table 4 – Hardware safety integrity – low complexity (type A) subsystem . 41 Table 5 – Hardware safety integrity – high complexity (type B) subsystem . 41 Table 6 – Faults or failures to be assumed when quantifying the effect of random hardware failures or to be taken into account in the derivation of safe failure fraction . 50 Table 7 – Examples of tool classification . 61 Table 8 – Performance criteria . 64 Table 9 – Immunity test levels for enclosure port tests in general EMC environment . 66 Table 10 – Immunity test levels in general EMC environment . 67 Table 11 – Immunity test levels for enclosure port tests in specified EMC environment . 68 Table 12 – Immunity test levels in specified EMC environment . 69 Table 13 – Fault tolerance test, required effectiveness . 71 SIST EN 61131-6:2013
61131-6 © IEC:2012 – 5 – Table 14 – Functional safety assessment Information . 74 Table 15 – Minimum levels of independence of those carrying out functional safety assessment . 75 Table E.1 – Criteria for estimation of common cause failure . 90 Table E.2 – Estimation of common cause failure factor . 91
SIST EN 61131-6:2013
– 6 – 61131-6 © IEC:2012 INTERNATIONAL ELECTROTECHNICAL COMMISSION ____________
PROGRAMMABLE CONTROLLERS –
Part 6: Functional safety
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.
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