IEC 61557-15:2014
(Main)Electrical safety in low voltage distribution systems up to 1 000 V a.c. and 1 500 V d.c. - Equipment for testing, measuring or monitoring of protective measures - Part 15: Functional safety requirements for insulation monitoring devices in IT systems and equipment for insulation fault location in IT systems
Electrical safety in low voltage distribution systems up to 1 000 V a.c. and 1 500 V d.c. - Equipment for testing, measuring or monitoring of protective measures - Part 15: Functional safety requirements for insulation monitoring devices in IT systems and equipment for insulation fault location in IT systems
IEC 61557-15:2014 specifies requirements related to functional safety and is based on the IEC 61508 standard series for the realization of Insulation Monitoring Devices (IMD) as specified in IEC 61557-8 and for Insulation Fault Location Systems (IFLS) according to IEC 61557-9, according to phase 10 of the IEC 61508-1 lifecycle. These devices provide safety related functions for IT systems. This part of IEC 61557 is
- concerned only with functional safety requirements intended to reduce the functional risk during the use of IMDs and IFLSs;
- restricted to risks arising directly from the device itself or from several IMDs or IFLSs working together in a system; and
- intended to define the basic safety functions provided by the devices. This part of IEC 61557 does not
- deal with electrical safety according to IEC 61010-1 and the requirements of IEC 61557-8 and IEC 61557-9;
- cover the hazard and risk analysis of a particular use of the IMD or IFLS;
- identify all the safety functions for the application in which the IMD or IFLS is used; and
- cover the IMD or IFLS manufacturing process. Functional safety requirements depend on the application and should be considered as part of the overall risk assessment of the specific application. The supplier of IMDs and IFLSs is not responsible for the application. The application designer is responsible for the risk assessment and for specifying the overall functional safety requirements of the complete IT system and he should select the functional safety level (SIL) of the IMD and/or IFLS when their safety function is part of the functional safety assessment in the IT system.
This publication is to be read in conjunction with IEC 61557-8:2007 and IEC 61557-9:2009.
Sécurité électrique dans les réseaux de distribution basse tension de 1 000 V c.a. et 1 500 V c.c. - Dispositifs de contrôle, de mesure ou de surveillance de mesures de protection - Partie 15: Exigences de sécurité fonctionnelle pour les contrôleurs d'isolement de réseaux IT et les dispositifs de localisation de défauts d'isolement pour réseaux IT
L'IEC 61557-15:2014 spécifie les exigences relatives à la sécurité fonctionnelle; elle se fonde sur la série de normes CEI 61508 pour la réalisation de contrôleurs d'isolement (CPI) tels que spécifiés dans la CEI 61557-8 et de systèmes de localisation de défauts d'isolement (DLD) conformes à la CEI 61557-9 et à la phase 10 du cycle de vie de la CEI 61508-1. Ces dispositifs assurent des fonctions relatives à la sécurité pour des réseaux IT. La présente partie de la CEI 61557
- traite uniquement des exigences de sécurité fonctionnelle visant à réduire le risque fonctionnel lors de l'utilisation des CPI et des DLD;
- se limite aux risques résultant directement du dispositif proprement dit ou de plusieurs dispositifs CPI ou DLD collaborant au sein d'un réseau donné; et
- vise à définir les fonctions de sécurité de base assurées par les dispositifs. La présente partie de la CEI 61557
- ne traite pas de la sécurité électrique selon la CEI 61010-1 et des exigences des normes CEI 61557-8 et CEI 61557-9;
- ne couvre pas l'analyse des dangers et des risques d'un usage particulier de l'CPI ou de l'DLD;
- n'identifie pas toutes les fonctions de sécurité de l'application où l'CPI ou l'DLD est utilisé; et ne couvre pas le processus de fabrication de l'CPI ou de l'DLD. Les exigences de sécurité fonctionnelle dépendent de l'application et il convient d'en tenir compte dans le cadre de l'appréciation globale du risque de l'application spécifique. Le fournisseur des CPI et des DLD n'est pas responsable de l'application qui en est faite. Le concepteur de l'application est responsable de l'appréciation du risque et il lui incombe de spécifier les exigences globales de sécurité fonctionnelle de l'ensemble du réseau IT et il convient qu'il sélectionne le niveau de sécurité fonctionnelle (SIL) de l'CPI et/ou de l'DLD lorsque leur fonction de sécurité fait partie de l'évaluation de la sécurité fonctionnelle du réseau IT.
Cette publication doit être lue conjointement avec la CEI 61557-8:2007 et IEC 61557-9:2009
General Information
Overview
IEC 61557-15:2014 is an international standard that defines functional safety requirements for insulation monitoring devices (IMDs) and insulation fault location systems (IFLSs) used in IT electrical distribution systems. These systems operate in low voltage environments up to 1,000 V AC and 1,500 V DC. The standard ensures that devices tasked with monitoring or locating insulation faults in IT systems provide reliable safety-related functions, reducing functional risk during operation.
Based on the IEC 61508 series for functional safety, IEC 61557-15 specifically addresses risks arising directly from the devices themselves or from multiple devices working cooperatively. It complements related standards IEC 61557-8 and IEC 61557-9, which cover device-specific requirements for IMDs and IFLSs. IEC 61557-15 focuses narrowly on functional safety and does not cover electrical safety aspects per IEC 61010-1 or hazard analysis of specific applications.
Key Topics
- Functional Safety Requirements: Defines the safety functions embedded in IMDs and IFLSs, such as local and remote insulation warnings, insulation fault location warnings, remote enabling/disabling commands, and transformer monitoring warnings.
- Safety Lifecycle Management: Outlines management processes for functional safety during the development, realization, integration, and maintenance lifecycle phases based on phase 10 of the IEC 61508-1 lifecycle.
- Safety Integrity Levels (SIL): Establishes criteria for assigning and achieving SIL 1 or SIL 2 compliance in devices, including performance requirements, fault detection, failure probability, and diagnostic intervals.
- Design and Validation: Provides guidelines for device design, software and hardware requirements, safety integrity validation, fault detection approaches, and verification/validation planning.
- Modification and Proven-in-Use: Details procedures for managing device modifications, performing impact analyses, authorizations, and utilizing proven-in-use data for safety justification.
- Annexes: Informative guidance on risk analysis, SIL assignment methods, failure rate data, embedded software development best practices, and software verification/testing.
Applications
IEC 61557-15 is essential for manufacturers, system designers, and safety engineers working with IT (unearthed) low voltage distribution systems requiring insulation monitoring and fault location. Typical applications include:
- Electrical power distribution networks in commercial, industrial, and healthcare environments.
- Safety-critical IT systems where continuous insulation monitoring reduces risks of electric shock and fire.
- Development and commissioning of IMDs and IFLS devices ensuring compliance to functional safety standards.
- Integration of multiple monitoring devices to enhance fault detection without compromising overall system safety.
- Risk assessments and functional safety management during equipment design and maintenance phases.
By adhering to this standard, stakeholders can enhance operational reliability and protect personnel and equipment against electrical insulation faults.
Related Standards
- IEC 61557-8:2007 - Requirements for Insulation Monitoring Devices (IMDs) in IT systems.
- IEC 61557-9:2009 - Requirements for Equipment for Insulation Fault Location Systems (IFLS) in IT systems.
- IEC 61508 Series - Functional safety of electrical/electronic/programmable electronic safety-related systems, which forms the basis for the functional safety concepts in IEC 61557-15.
- IEC 61010-1 - General safety requirements for electrical equipment for measurement, control, and laboratory use (covers electrical safety but not functional safety).
Compliance with IEC 61557-15 ensures that insulation monitoring and fault location equipment meets robust functional safety expectations, aligning with international electrical safety and quality standards critical for modern low voltage IT electrical distribution systems.
Frequently Asked Questions
IEC 61557-15:2014 is a standard published by the International Electrotechnical Commission (IEC). Its full title is "Electrical safety in low voltage distribution systems up to 1 000 V a.c. and 1 500 V d.c. - Equipment for testing, measuring or monitoring of protective measures - Part 15: Functional safety requirements for insulation monitoring devices in IT systems and equipment for insulation fault location in IT systems". This standard covers: IEC 61557-15:2014 specifies requirements related to functional safety and is based on the IEC 61508 standard series for the realization of Insulation Monitoring Devices (IMD) as specified in IEC 61557-8 and for Insulation Fault Location Systems (IFLS) according to IEC 61557-9, according to phase 10 of the IEC 61508-1 lifecycle. These devices provide safety related functions for IT systems. This part of IEC 61557 is - concerned only with functional safety requirements intended to reduce the functional risk during the use of IMDs and IFLSs; - restricted to risks arising directly from the device itself or from several IMDs or IFLSs working together in a system; and - intended to define the basic safety functions provided by the devices. This part of IEC 61557 does not - deal with electrical safety according to IEC 61010-1 and the requirements of IEC 61557-8 and IEC 61557-9; - cover the hazard and risk analysis of a particular use of the IMD or IFLS; - identify all the safety functions for the application in which the IMD or IFLS is used; and - cover the IMD or IFLS manufacturing process. Functional safety requirements depend on the application and should be considered as part of the overall risk assessment of the specific application. The supplier of IMDs and IFLSs is not responsible for the application. The application designer is responsible for the risk assessment and for specifying the overall functional safety requirements of the complete IT system and he should select the functional safety level (SIL) of the IMD and/or IFLS when their safety function is part of the functional safety assessment in the IT system. This publication is to be read in conjunction with IEC 61557-8:2007 and IEC 61557-9:2009.
IEC 61557-15:2014 specifies requirements related to functional safety and is based on the IEC 61508 standard series for the realization of Insulation Monitoring Devices (IMD) as specified in IEC 61557-8 and for Insulation Fault Location Systems (IFLS) according to IEC 61557-9, according to phase 10 of the IEC 61508-1 lifecycle. These devices provide safety related functions for IT systems. This part of IEC 61557 is - concerned only with functional safety requirements intended to reduce the functional risk during the use of IMDs and IFLSs; - restricted to risks arising directly from the device itself or from several IMDs or IFLSs working together in a system; and - intended to define the basic safety functions provided by the devices. This part of IEC 61557 does not - deal with electrical safety according to IEC 61010-1 and the requirements of IEC 61557-8 and IEC 61557-9; - cover the hazard and risk analysis of a particular use of the IMD or IFLS; - identify all the safety functions for the application in which the IMD or IFLS is used; and - cover the IMD or IFLS manufacturing process. Functional safety requirements depend on the application and should be considered as part of the overall risk assessment of the specific application. The supplier of IMDs and IFLSs is not responsible for the application. The application designer is responsible for the risk assessment and for specifying the overall functional safety requirements of the complete IT system and he should select the functional safety level (SIL) of the IMD and/or IFLS when their safety function is part of the functional safety assessment in the IT system. This publication is to be read in conjunction with IEC 61557-8:2007 and IEC 61557-9:2009.
IEC 61557-15:2014 is classified under the following ICS (International Classification for Standards) categories: 17.220.20 - Measurement of electrical and magnetic quantities; 29.080.01 - Electrical insulation in general; 29.240.01 - Power transmission and distribution networks in general. The ICS classification helps identify the subject area and facilitates finding related standards.
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Standards Content (Sample)
IEC 61557-15 ®
Edition 1.0 2014-02
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Electrical safety in low voltage distribution systems up to 1 000 V a.c. and
1 500 V d.c. – Equipment for testing, measuring or monitoring of protective
measures –
Part 15: Functional safety requirements for insulation monitoring devices in IT
systems and equipment for insulation fault location in IT systems
Sécurité électrique dans les réseaux de distribution basse tension de
1 000 V c.a. et 1 500 V c.c. – Dispositifs de contrôle, de mesure ou de
surveillance de mesures de protection –
Partie 15: Exigences de sécurité fonctionnelle pour les contrôleurs d'isolement
de réseaux IT et les dispositifs de localisation de défauts d'isolement pour
réseaux IT
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IEC 61557-15 ®
Edition 1.0 2014-02
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Electrical safety in low voltage distribution systems up to 1 000 V a.c. and
1 500 V d.c. – Equipment for testing, measuring or monitoring of protective
measures –
Part 15: Functional safety requirements for insulation monitoring devices in IT
systems and equipment for insulation fault location in IT systems
Sécurité électrique dans les réseaux de distribution basse tension de
1 000 V c.a. et 1 500 V c.c. – Dispositifs de contrôle, de mesure ou de
surveillance de mesures de protection –
Partie 15: Exigences de sécurité fonctionnelle pour les contrôleurs d'isolement
de réseaux IT et les dispositifs de localisation de défauts d'isolement pour
réseaux IT
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
CODE PRIX XC
ICS 17.220.20, 29.080.01, 29.240.01 ISBN 978-2-8322-1406-0
– 2 – 61557-15 © IEC:2014
CONTENTS
FOREWORD . 6
INTRODUCTION . 8
1 Scope . 10
2 Normative references . 10
3 Terms, definitions and abbreviations . 11
3.1 Terms and definitions . 11
3.2 Abbreviations . 22
4 Definition of safety functions embedded in IMDs and IFLSs . 23
4.1 General . 23
4.2 Definition of safety functions . 23
4.2.1 Local insulation warning (LIW) . 23
4.2.2 Remote insulation warning (RIW) . 24
4.2.3 Local location warning (LLW) . 24
4.2.4 Remote location warning (RLW). 24
4.2.5 Remote enabling / disabling command (REDC) . 25
4.2.6 Local transformer monitoring warning (LTMW) . 25
5 Requirements on products implementing safety-related functions . 25
5.1 Requirement on non-safety-related functions . 25
5.2 Additional performance requirements for products implementing safety
functions . 26
5.2.1 General . 26
5.2.2 Additional performance requirements for IMDs complying with
SIL 1 or SIL 2 . 26
5.2.3 Additional performance requirements for IFLSs complying with
SIL 1 or SIL 2 . 26
6 Management of functional safety during the development lifecycle . 26
6.1 Management of functional safety for the IT system . 26
6.2 Use of IMDs and IFLSs in IT systems. 27
6.3 Safety lifecycle of IMDs and IFLSs in the realisation phase . 27
7 Management of functional safety during the realisation lifecycle of IMDs and
IFLSs. 28
7.1 General . 28
7.2 IMD and IFL design requirement specification (phase 10.1) . 29
7.2.1 Specification of functional safety requirements . 29
7.2.2 Provisions for the development of safety functions . 29
7.2.3 Verification plan for the development of safety functions . 30
7.2.4 Validation plan for the development of safety functions . 30
7.2.5 Planning of commissioning, installation and setting into
operation . 30
7.2.6 Planning of user documentation . 31
7.3 IMD and IFLS safety validation planning (phase 10.2) . 31
7.3.1 General . 31
7.3.2 Functional safety plan . 31
7.4 IMD and IFLS design and development (phase 10.3) . 32
7.4.1 General . 32
7.4.2 Design standards . 32
7.4.3 Realization . 32
61557-15 © IEC:2014 – 3 –
7.4.4 Safety integrity and fault detection . 32
7.4.5 Safety integrity level (SIL) assignment . 33
7.4.6 Hardware requirements . 33
7.4.7 Software requirements . 33
7.4.8 Review of requirements . 33
7.4.9 Requirements for the probability of dangerous failure on
demand (PFD) . 34
7.4.10 Failure rate data . 35
7.4.11 Diagnostic test interval . 35
7.4.12 Architectural constraints . 35
7.4.13 Estimation of safe failure fraction (SFF) . 37
7.4.14 Requirements for systematic safety integrity . 37
7.5 IMD and IFLS integration (phase 10.4) . 40
7.5.1 Hardware integration . 40
7.5.2 Software integration . 40
7.5.3 Modifications during integration . 40
7.5.4 Integration tests . 40
7.6 IMD and IFLS documentation related to installation, commissioning,
operation and maintenance procedures (phase 10.5) . 41
7.6.1 General . 41
7.6.2 Functional specification . 41
7.6.3 Compliance information . 41
7.6.4 Information for commissioning, installation, setting into
operation, operation and maintenance . 41
7.7 IMD and IFLS safety validation (phase 10.6) . 42
7.7.1 General . 42
7.7.2 Test . 42
7.7.3 Verification . 42
7.7.4 Validation . 43
7.7.5 EMC requirements . 43
8 Requirements for modifications. 44
8.1 General . 44
8.2 Modification request . 44
8.3 Impact analysis . 44
8.4 Authorization. 44
9 Proven in use approach . 44
Annex A (informative) Risk analysis and SIL assignment for IMDs and IFLSs . 45
A.1 General . 45
A.2 SIL assignment for IMDs and IFLSs . 47
A.3 Example of risk graph . 48
A.4 Alternative method of SIL assignment – quantitative method . 49
Annex B (informative) Examples for the determination of PFD, DC and SFF . 50
B.1 General . 50
B.2 Examples of IMD and IFLS architectures . 51
Annex C (informative) Failure rate databases . 52
C.1 General . 52
C.2 Failure rate references in current standards . 52
Annex D (informative) Guide to embedded software design and development . 53
D.1 General . 53
– 4 – 61557-15 © IEC:2014
D.2 Software element guidelines . 53
D.2.1 General . 53
D.2.2 Interface with system architecture. 53
D.2.3 Software specifications . 53
D.2.4 Pre-existent software . 54
D.2.5 Software design . 55
D.2.6 Coding . 55
D.3 Software development process guidelines . 55
D.3.1 Development process: software lifecycle . 55
D.3.2 Documentation: documentation management . 55
D.3.3 Configuration and software modification management . 56
D.3.4 Configuration and archiving management . 56
D.3.5 Software modifications management . 57
D.4 Development tools . 57
D.5 Reproduction of executable code production . 57
D.6 Software verification and validation . 57
D.7 General verification and validation guidelines . 57
D.8 Verification and validation review . 58
D.9 Software testing . 58
D.9.1 General validation . 58
D.9.2 Software specification verification: validation tests . 59
D.9.3 Software design verification: software integration tests . 59
D.9.4 Detailed design verification: module tests . 60
Annex E (informative) Information for the assessment of safety functions . 61
E.1 General . 61
E.2 Documentation management . 61
E.3 Documentation provided for conformity assessment . 61
E.4 Documentation of the development lifecycle. 63
E.5 Design documentation . 63
E.6 Documentation of verification and validation . 63
E.7 Test documentation . 63
E.8 Documentation of modifications . 63
E.9 Information for use . 63
Annex F (informative) Example of applications . 64
F.1 Overview. 64
F.2 Limitation in applications . 64
F.3 Typical applications covered by IEC 61557-15 . 64
F.3.1 General . 64
F.3.2 Local alarming . 64
F.3.3 Local transformer monitoring warning . 65
F.3.4 Alarming and processing of remote insulation warning and/or
remote location warning . 66
F.3.5 Automatic disconnection of the complete IT system in case of
a first insulation fault . 67
F.3.6 Automatic disconnection of an IT system sub-network . 69
F.3.7 Management of multiple source system (two incomers or of
incomer plus generator) . 71
F.3.8 Management of multiple source systems (two incomers or of
incomer plus generator – with a load shedder) . 72
Bibliography . 74
61557-15 © IEC:2014 – 5 –
Figure 1 – Relationship between IEC 61557-15 and related standards . 8
Figure 2 – Overall safety lifecycle applicable to an IT system . 27
Figure 3 – IMD and IFLS safety lifecycle (in realisation phase) . 28
Figure A.1 – Functional elements of an IT system and their relationship to the
definitions and abbreviations of the IEC 61508 series . 45
Figure A.2 – SIL assignment for IMDs and IFLSs . 47
Figure A.2 – Example of risk graph . 48
Figure B.1 – Flowchart for PFD, DC, SFF determination . 51
Figure F.1 – Local alarming, based on the systematic presence of one person and
based on a well-defined alarming management process. 65
Figure F.2 – Local transformer monitoring warning, based on the systematic presence
of a skilled person, and based on a well-defined alarming management process . 66
Figure F.3 – Alarming and processing of the remote insulation warning and/or the
remote location warning in a supervisory control system . 67
Figure F.4 – Disconnection of the complete IT system in case of insulation fault
detection . 68
Figure F.5 – Threshold 1 warning information and threshold 2 disconnection of the
complete IT system in case of an insulation fault detection . 69
Figure F.6 – Automatic disconnection of a faulty feeder via direct signal from the IFLS . 70
Figure F.7 – Automatic disconnection of a faulty feeder via a PLC . 71
Figure F.8 – Management of multiple source systems (two incomers or of one incomer
plus generator) . 72
Figure F.9 – Management of multiple source system (two incomers or of one incomer
plus generator, with a load shedder) . 73
Table 1 – Abbreviations with reference . 22
Table 2 – Safety integrity levels (SIL) and probability of a dangerous failure on
demand (PFD) of IMDs and IFLSs . 29
Table 3 – Hardware safety integrity: architectural constraints on type A and type B
safety-related subsystems . 37
Table A.1 – IT system risk analysis . 46
Table A.3 – Link between minimum risk reduction and SIL . 48
Table A.4 – Example of classifications according to risk graph Figure A.1 . 49
Table E.1 – Documentation to be provided . 62
– 6 – 61557-15 © IEC:2014
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
ELECTRICAL SAFETY IN LOW VOLTAGE DISTRIBUTION SYSTEMS UP TO
1 000 V AC AND 1 500 V DC – EQUIPMENT FOR TESTING, MEASURING OR
MONITORING OF PROTECTIVE MEASURES –
Part 15: Functional safety requirements for insulation monitoring devices
in IT systems and equipment for insulation fault location in IT systems
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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 61557-15 has been prepared by IEC technical committee 85:
Measuring equipment for electrical and electromagnetic quantities.
The text of this standard is based on the following documents:
FDIS Report on voting
85/465/FDIS 85/470/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.
61557-15 © IEC:2014 – 7 –
This part of IEC 61557 is to be used in conjunction with Part 8 and Part 9.
A list of all parts of the IEC 61557 series, published under the general title Electrical safety in
low voltage distribution systems up to 1 000 V a.c. and 1 500 V d.c. – Equipment for testing,
measuring or monitoring of protective measures, 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 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.
– 8 – 61557-15 © IEC:2014
INTRODUCTION
IEC 61508 deals with functional safety, this topic being of upmost importance for safety
related systems. Functional safety may be applicable to IT systems where safety is based on
insulation monitoring devices (IMD) and insulation fault location systems (IFLS), and also on
additional safety related measures (e.g. circuit-breakers).
Insulation monitoring devices and insulation fault location systems comprise electrical and
electronic components and can comprise embedded software.
Product requirements for these devices are defined in IEC 61557-8 and IEC 61557-9. These
standards include elementary requirements which need to be taken into account for the
functional safety approach according to IEC 61557-15, but do not cover the whole range of
requirements which shall be fulfilled for the assignment of a defined level of functional safety
and for the respective validation.
IEC 61508 series covers basic aspects to be considered when electrical and electronic
systems are used to carry out safety functions. One of the major objectives of this series of
standards is to facilitate the development of international application or equipment standards
by the responsible technical committee. This will allow the technical committee to take the
special requirements of their application fully into account.
It is recognized that there is a great variety of applications of insulation monitoring devices
and of insulation fault location systems in IT systems. This part of IEC 61557 defines basic
safety functions as well as their related levels of functional safety (SIL) and defines feasible
measures and principles to develop and validate these devices and systems under functional
safety aspects.
Figure 1 shows the link between IEC 61557-15 and the relevant product, safety and EMC
standards as well as the link to the IEC 61508 series.
IEC 61557-1
General requirements
IEC 61557-8
Insulation monitoring
devices (IMD) IEC 61326-3-1 IEC 61557-15 IEC 61508
series
EMC requirements Functional
(functional safety) safety Functional
to be used in requirements safety
combination with for IMDs basic standard
IEC 61326-2-4 and IFLSs
IEC 61557-9
Insulation fault location
systems (IFLS)
IEC 0440/14
Figure 1 – Relationship between IEC 61557-15 and related standards
This part of IEC 61557 does not cover phases 1 to 9 and 11 to 16 of IEC 61508-1 for the
complete IT systems. In particular, this standard does not cover the use of IMDs and IFLSs in
customer application.
61557-15 © IEC:2014 – 9 –
NOTE 1 An insulation fault location system (IFLS) can consist of several devices according to IEC 61557-9:
insulation fault locator (IFL), locating current injector (LCI), locating current sensor (LCS), insulation monitoring
device (IMD) according to IEC 61557-8.
IMDs and IFLSs are not protective devices in general, but they are part of the protective
measures in IT systems. IMDs and IFLSs function as permanent monitoring of the insulation
resistance of the unearthed IT system and the localization of insulation faults in any part of
the system can be seen as safety functions which are part of the protective measures in an IT
system.
This part of IEC 61557 only applies to IMDs and IFLSs implementing SIL 1 and SIL 2 related
safety functions. Higher SIL levels are not specified in this standard because those levels are
generally not required for IMDs and IFLSs in IT systems.
Conformance to this standard may be required for IMDs or IFLSs when functional safety is
requested in the respective application within IT systems. However, it does not generally
dictate that for these devices, a defined level of functional safety according to this standard is
required.
NOTE 2 Examples of applications where functional safety can be requested depending on the risk analysis are:
– chemistry,
– mines,
– marine,
– hospital,
– photovoltaic farms,
– railway signalling systems,
– control systems ( e.g. in nuclear power plants),
– etc.
Examples of typical applications are provided in Annex F.
– 10 – 61557-15 © IEC:2014
ELECTRICAL SAFETY IN LOW VOLTAGE DISTRIBUTION SYSTEMS UP TO
1 000 V AC AND 1 500 V DC – EQUIPMENT FOR TESTING, MEASURING OR
MONITORING OF PROTECTIVE MEASURES –
Part 15: Functional safety requirements for insulation monitoring devices
in IT systems and equipment for insulation fault location in IT systems
1 Scope
This part of IEC 61557 specifies requirements related to functional safety and is based on the
IEC 61508 standard series for the realization of insulation monitoring devices (IMD) as
specified in IEC 61557-8 and for insulation fault location systems (IFLS) according to
IEC 61557-9, according to phase 10 of the IEC 61508-1 lifecycle. These devices provide
safety related functions for IT systems.
This part of IEC 61557 is:
– concerned only with functional safety requirements intended to reduce the functional risk
during the use of IMDs and IFLSs;
– restricted to risks arising directly from the device itself or from several IMDs or IFLSs
working together in a system;
– intended to define the basic safety functions provided by the devices.
This part of IEC 61557 does not:
– deal with electrical safety according to IEC 61010-1 and the requirements of IEC 61557-8
and IEC 61557-9;
– cover the hazard and risk analysis of a particular use of the IMD or IFLS;
– identify all the safety functions for the application in which the IMD or IFLS is used;
– cover the IMD or IFLS manufacturing process.
Functional safety requirements depend on the application and should be considered as part of
the overall risk assessment of the specific application. The supplier of IMDs and IFLSs is not
responsible for the application. The application designer is responsible for the risk
assessment and for specifying the overall functional safety requirements of the complete IT
system and he should select the functional safety level (SIL) of the IMD and/or IFLS when
their safety function is part of the functional safety assessment in the IT system.
2 Normative references
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.
IEC 61508-1:2010, Functional safety of electrical/electronic/programmable electronic safety-
related systems – Part 1: General requirements
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
61557-15 © IEC:2014 – 11 –
IEC 61508-3:2010, Functional safety of electrical/electronic/programmable electronic safety-
related systems – Part 3: Software requirements
IEC 61508-4:2010, Functional safety of electrical/electronic/programmable electronic safety-
related systems – Part 4: Definitions and abbreviations
IEC 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 61508-6:2010, Functional safety of electrical/electronic/programmable electronic safety-
related systems – Part 6: Guidelines on the application of IEC 61508-2 and IEC 61508-3
IEC 61557-1, Electrical safety in low voltage distribution systems up to 1 000 V a.c. and
1 500 V d.c. – Equipment for testing, measuring or monitoring of protective measures – Part 1:
General requirements
IEC 61557-8, Electrical safety in low voltage distribution systems up to 1 000 V a.c. and
1 500 V d.c. – Equipment for testing, measuring or monitoring of protective measures – Part 8:
Insulation monitoring devices for IT systems
IEC 61557-9:2009, Electrical safety in low voltage distribution systems up to 1 000 V a.c. and
1 500 V d.c. – Equipment for testing, measuring or monitoring of protective measures – Part 9:
Equipment for insulation fault location in IT systems
IEC 61326-2-4:2012, Electrical equipment for measurement, control and laboratory use –
EMC requirements – Part 2-4: Particular requirements – Test configurations, operational
conditions and performance criteria for insulation monitoring devices according to
IEC 61557-8 and for equipment for insulation fault location according to IEC 61557-9
IEC 61326-3-1:2008, 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
3 Terms, definitions and abbreviations
3.1 Terms and definitions
For the purposes of this document, the definitions given in IEC 61557-1, IEC 61557-8 and
IEC 61557-9 and the following apply.
3.1.1
hazard
potential source of harm
Note 1 to entry: The term includes danger to persons arising within a short time scale (for example, fire and
explosion) and those that have a long-term effect on a person’s health (for example, release of a toxic substance).
[SOURCE: ISO/IEC Guide 51:1999, 3.5, modified – The note has been adapted.]
3.1.2
electrical hazard
potential source of harm when electric energy is present in an electrical installation or
equipment
[SOURCE: IEC 60050-651:1999, 651-01-30, modified – The note has been deleted.]
– 12 – 61557-15 © IEC:2014
3.1.3
hazardous situation
circumstance in which people, property or the environment are exposed to one or more
hazards
[SOURCE: IEC 61508-4:2010, 3.1.3]
3.1.4
hazardous event
event that may result in harm
Note 1 to entry: Whether or not a hazardous event results in harm depends on whether people, property or the
environment are exposed to the consequence of the hazardous event and, in the case of harm to people, whether
any such exposed people can escape the consequences of the event after it has occurred.
[SOURCE: IEC 61508-4:2010, 3.1.4]
3.1.5
harmful event
occurrence in which a hazardous situation or hazardous event results in harm
Note 1 to entry: Adapted from ISO/IEC Guide 51:1999, 3.4, to allow for a hazardous event.
[SOURCE: IEC 61508-4:2010, 3.1.5]
3.1.6
risk
combination of the probability of occurrence of harm and the severity of that harm
[SOURCE: ISO/IEC Guide 51:1999, 3.2]
3.1.7
tolerable risk
risk which is accepted in a given context based on the current values of society
Note 1 to entry: Tolerable risk is achieved by the iterative process of risk assessment (risk analysis and risk
evaluation) and risk reduction.
[SOURCE: ISO/IEC Guide 51:1999, 3.7, modified – Note 1 to entry has been added.]
3.1.8
residual risk
risk remaining after protective measures have been taken
[SOURCE: ISO/IEC Guide 51:1999, 3.9]
3.1.9
safety
freedom from unacceptable risk
[SOURCE: ISO/IEC Guide 51:1999, 3.1, modified – The note has been deleted.]
3.1.10
functional safety
part of the overall safety relating to the EUC and the EUC control system that depends on the
correct functioning of the E/E/PE safety related system and other risk reduction measures
[SOURCE: IEC 61508-4:2010, 3.1.12]
61557-15 © IEC:2014 – 13 –
3.1.11
safe state
state of the EUC when safety is achieved
Note 1 to entry: In going from a potentially hazardous condition to the final safe state, the EUC may have to go
through a number of intermediate safe states. For some situations a safe state exists only so long as the EUC is
continuously controlled. Such continuous control may be for a short or an indefinite period of time.
[SOURCE: IEC 61508-4:2010, 3.1.13]
3.1.12
reasonable foreseeable misuse
use of a product, process or service in a way not intended by the supplier, but which may
result from readily predictable human behaviour
[SOURCE: ISO/IEC Guide 51:1999, 3.14]
3.1.13
environment
all relevant parameters that can affect the achievement of functional safety in the specific
application under consideration and in any safety lifecycle phase
Note 1 to entry: This would include, for example, physical environment, operating environment, legal environment
and maintenance environment.
[SOURCE: IEC 61508-4:2010, 3.2.2]
3.1.14
fault
abnormal condition that may cause a reduction in, or a loss of, the capability of a functional
unit to perform a required function
[SOURCE: IEC 61508-4:2010, 3.6.1; based on ISO/IEC 2382-14:1997, 14-01-10]
3.1.15
fault avoidance
use of techniques and procedures that aim to avoid the introduction of faults during any phase
of the safety lifecycle of the safety related system
[SOURCE: IEC 61508-4:2010, 3.6.2]
3.1.16
fault tolerance
ability of a functional unit to continue to perform a required function in the presence of faults
or errors
Note 1 to entry: The definition in IEC 60050-191-15-05 refers
...
IEC 61557-15：2014は、1000Vの交流および1500Vの直流までの低圧配電システムにおける電気安全性に関する要件を定めた規格です。この規格は、IEC 61557-8に指定された絶縁監視装置（IMD）とIEC 61557-9に基づく絶縁故障位置決定システム（IFLS）の実現に関連する機能的安全性要件に基づいており、IEC 61508シリーズに基づいています。これらの装置は、ITシステムの安全関連機能を提供します。このIEC 61557の一部は、次のことに関連しています： - IMDおよびIFLSの使用中の機能的リスクを軽減するための機能的安全性要件に関連しています。 - 装置自体またはシステム内で複数のIMDまたはIFLSが連動して発生するリスクに制限されます。 - 装置が提供する基本的な安全機能を定義することを意図しています。ただし、IEC 61010-1およびIEC 61557-8およびIEC 61557-9に関連する電気安全性には言及していません。 - 特定のIMDまたはIFLSのハザードおよびリスク分析をカバーしていません。 - IMDまたはIFLSが使用される特定の応用プログラムにおけるすべての安全機能を識別しません。 - IMDまたはIFLSの製造プロセスをカバーしていません。 機能的安全性要件は、応用プログラムによって異なり、特定の応用プログラムの全体的なリスク評価の一環として考慮されるべきです。IMDおよびIFLSの供給業者は、応用プログラムに対する責任を負いません。応用プログラムの設計者は、リスク評価を担当し、完全なITシステムの機能的安全性要件を指定し、IMDおよび/またはIFLSの機能的安全性レベル（SIL）を選択する必要があります。この規格はIEC 61557-8：2007およびIEC 61557-9：2009とともに参照する必要があります。
記事のタイトル：IEC 61557-15：2014 - 1,000V a.c.および1,500V d.c.までの低電圧配電システムにおける電気安全性 - 保護措置の試験、測定、監視のための装置 - 第15部：ITシステムにおける絶縁監視装置の機能的安全要件およびITシステムの絶縁故障位置のための装置 記事の内容：IEC 61557-15：2014は、機能的な安全要件に関連する要件を規定しており、IEC 61557-8で指定された絶縁監視装置（IMD）およびIEC 61557-9で指定された絶縁故障位置システム（IFLS）の実現に基づいています。この規格は、ITシステムの安全関連機能を提供するこれらの装置に関連する機能的なリスクを低減することを目的としています。IEC 61557-15の範囲は次のとおりです。 - IMDおよびIFLSの使用中に直接的に発生する装置自体からまたは複数のIMDまたはIFLSがシステムで連携して発生するリスクに限定されます。 - 装置が提供する基本的な安全機能を定義することを意図しています。 - IEC 61010-1およびIEC 61557-8およびIEC 61557-9に基づく電気安全性に対応していません。 - 特定のIMDまたはIFLSのハザードおよびリスク分析をカバーしていません。 - 使用されるIMDまたはIFLSのすべての安全機能を特定しません。 - IMDまたはIFLSの製造プロセスは対象としていません。 機能的安全要件は、使用状況に依存し、特定のアプリケーションの全体的なリスク評価の一部として考慮されるべきです。IMDおよびIFLSの供給業者はアプリケーションに対する責任を持っておらず、アプリケーションのデザイナーはリスク評価を担当し、完全なITシステムの機能的安全要件を指定する役割を果たすべきです。ITシステムの機能的安全評価においてIMDおよび/またはIFLSの機能的安全レベル（SIL）を選択する必要があります。 この記事はIEC 61557-8：2007およびIEC 61557-9：2009と併せて読む必要があります。
The article discusses the requirements set by the IEC 61557-15:2014 standard for insulation monitoring devices (IMDs) and insulation fault location systems (IFLSs) used in IT systems. The standard is based on the IEC 61508 series and focuses on functional safety requirements to reduce the risks associated with IMDs and IFLSs. It does not cover electrical safety or the hazard and risk analysis of specific applications. The responsibility for risk assessment and specifying functional safety requirements lies with the application designer, while the supplier is responsible for meeting the specified requirements. The article suggests reading the IEC 61557-8:2007 and IEC 61557-9:2009 standards in conjunction with IEC 61557-15:2014.
기사 제목: IEC 61557-15:2014 - 1,000V a.c. 및 1,500V d.c. 이하의 저압 배전 시스템에서의 전기적 안전 - 보호 조치를 테스팅, 측정 또는 모니터링하는 장비 - 부품 15: IT 시스템에서의 절연 모니터링 장치와 장비에 대한 기능적 안전 요구 사항 기사 내용: IEC 61557-15:2014는 기능적 안전 요구 사항과 관련된 규정을 명시하며, IEC 61557-8에서 명시된 절연 모니터링 장치(IMD) 및 IEC 61557-9에서 명시된 절연 결함 위치 시스템(IFLS)의 실현을 위해 IEC 61508 표준 시리즈에 기초합니다. 이러한 장치들은 IT 시스템에 대한 안전 관련 기능을 제공합니다. 이 IEC 61557 시리즈의 일부인 IEC 61557-15은 다음과 같은 내용을 다룹니다. - IMDs와 IFLSs 사용 시 사용 중 발생 가능한 기능적 위험을 줄이기 위한 기능적 안전 요구 사항에 대한 내용에만 관여합니다. - 단독으로 나타나는 장치 자체 또는 여러 IMDs 또는 IFLSs가 시스템에서 함께 작동할 때 발생하는 위험에 제한됩니다. - 장치가 제공하는 기본적인 안전 기능을 정의하는 것을 목적으로합니다. - IEC 61010-1의 전기적 안전 및 IEC 61557-8 및 IEC 61557-9의 요구 사항과는 무관합니다. - 특정 IMD 또는 IFLS의 위험성 및 위험 분석을 다루지 않습니다. - IMD 또는 IFLS가 사용되는 응용 분야에서 제공되는 모든 안전 기능을 식별하지 않습니다. - IMD 또는 IFLS의 제조 공정에 관여하지 않습니다. 기능적 안전 요구 사항은 응용 분야에 따라 다르며, 특정 응용 프로그램의 총 위험 평가의 일환으로 고려되어야합니다. IMD 및 IFLS의 공급자는 응용 분야에 대한 책임이 없으며, 응용 프로그램 디자이너는 위험 평가를 담당하고 완전한 IT 시스템의 기능적 안전 요구 사항을 지정하는 역할을 합니다. 그리고 IT 시스템의 기능적 안전 평가에서 IMD 및/또는 IFLS의 기능 안전 레벨(SIL)을 선택해야합니다. 이 기사는 IEC 61557-8:2007 및 IEC 61557-9:2009를 함께 읽어야합니다.
IEC 61557-15:2014는 저압 분배 시스템에서 사용되는 전기적 안전성에 대한 규정을 제시한다. 이 문서는 절연 모니터링 장치(IMD) 및 절연 경로 위치 시스템(IFLS)의 기능적 안전 요구 사항에 관련되며, IEC 61508 표준 시리즈를 기반으로 한다. 이 장비들은 IT 시스템에서 안전 관련 기능을 제공한다. 이 부분은 다음과 관련이 있다: - IMD 및 IFLS를 사용함으로써 발생하는 기능적 위험을 감소시키기 위한 기능적 안전 요구 사항에만 관련된다. - 단독으로 장비로부터 발생하는 위험, 또는 여러 IMD 또는 IFLS가 시스템에서 함께 작동함으로써 발생하는 위험에만 제한된다. - 장치가 제공하는 기본적인 안전 기능을 정의하는 것을 목적으로 한다. 이 부분은 다음을 포함하지 않는다: - IEC 61010-1에 따른 전기적 안전 및 IEC 61557-8 및 IEC 61557-9의 요구 사항 - 특정 IMD 또는 IFLS의 위험 및 위험 분석 - IMD 또는 IFLS 사용에서의 모든 안전 기능 식별 - IMD 또는 IFLS의 제조 공정 기능적 안전 요구 사항은 응용 프로그램에 따라 다르며 특정 응용 프로그램의 전반적인 위험 평가의 일환으로 고려되어야 한다. IMD 및 IFLS 공급업체는 응용 프로그램에 대한 책임이 없다. 응용 프로그램 개발자는 위험 평가를 담당하고 전체 IT 시스템의 기능적 안전 요구 사항을 지정하며, 기능적 안전 수준(SIL)을 선택해야 한다. 이 표준은 IEC 61557-8:2007 및 IEC 61557-9:2009와 함께 읽어야 한다.
IEC 61557-15:2014 is a standard that specifies functional safety requirements for Insulation Monitoring Devices (IMD) and Insulation Fault Location Systems (IFLS) used in IT systems. The standard is based on the IEC 61508 series and aims to reduce the functional risk of these devices. It only covers risks directly related to the devices themselves or their interaction in a system. The standard does not address electrical safety, specific hazard and risk analysis, all safety functions for specific applications, or the manufacturing process of IMDs and IFLSs. The responsibility for risk assessment and specifying functional safety requirements lies with the application designer. The standard should be read in conjunction with IEC 61557-8:2007 and IEC 61557-9:2009.
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