IEC 61326-3-1:2008

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

IEC 61326-1 applies to this part of IEC 61326 but is limited to systems and equipment for industrial applications intended to perform safety functions as defined in IEC 61508 with SIL 1-3. The electromagnetic environments encompassed by this product family standard are industrial, both indoor and outdoor, as described for industrial locations in IEC 61000-6-2 or defined in 3.7 of IEC 61326-1. Equipment and systems intended for use in other electromagnetic environments, for example, in the process industry or in environments with potentially explosive atmospheres, are excluded from the scope of this product family standard, IEC 61326-3-1. The contents of the corrigendum of September 2008 have been included in this copy.

Matériel électrique de mesure, de commande et de laboratoire - Exigences relatives à la CEM - Partie 3-1: Exigences d'immunité pour les systèmes relatifs à la sécurité et pour les matériels destinés à réaliser des fonctions relatives à la sécurité (sécurité fonctionnelle) - Applications industrielles générales

La CEI 61326-1 est applicable à la présente partie de la CEI 61326, mais elle est limitée aux systèmes et matériels pour applications industrielles destinés à réaliser des fonctions de sécurité telles que définies dans la CEI 61508, avec un niveau d'intégrité de sécurité (SIL) 1-3. Les environnements électromagnétiques considérés par cette famille de normes produit sont des environnements industriels, en bâtiment et en extérieur, tels que décrits pour les emplacements industriels dans la CEI 61000-6-2 ou définis en 3.7 de la CEI 61326-1. Les matériels et les systèmes pour une utilisation dans d'autres environnements électromagnétiques, par exemple dans l'industrie de processus ou dans des environnements avec des atmosphères potentiellement explosives sont exclus du domaine d'application de la norme CEI 61326-3-1, qui est une norme de famille de produits. Le contenu du corrigendum de septembre 2008 a été pris en considération dans cet exemplaire.

General Information

• Status: Published
• Publication Date: 29-Jan-2008
• ICS: 25.040.40 - Industrial process measurement and control
• ICS: 33.100.20 - Immunity
• Technical Committee: SC 65A - System aspects
• Drafting Committee: WG 4 - TC 65/SC 65A/WG 4
• Current Stage: DELPUB - Deleted Publication
• Start Date: 16-May-2017
• Completion Date: 26-Oct-2025

Relations

• Replaces: IEC 61326:2002 - Electrical equipment for measurement, control and laboratory use - EMC requirements
• Effective Date: 05-Sep-2023
• Replaces: IEC 61326:2002/COR1:2002 - Corrigendum 1 - Electrical equipment for measurement, control and laboratory use - EMC requirements
• Effective Date: 05-Sep-2023
• Corrected By: IEC 61326-3-1:2008/COR1:2008 - Corrigendum 1 - 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
• Effective Date: 05-Sep-2023
• Revised: IEC 61326-3-1:2017 - 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
• Effective Date: 05-Sep-2023

Overview

IEC 61326-3-1:2008 is an international standard developed by the International Electrotechnical Commission (IEC). It focuses on electromagnetic compatibility (EMC) immunity requirements for electrical equipment used in measurement, control, and laboratory applications that perform safety-related functions. This part of the IEC 61326 series applies specifically to general industrial environments where equipment operates to support functional safety in accordance with IEC 61508, covering Safety Integrity Levels (SIL) 1 to 3.

The standard defines the immunity requirements to ensure that safety-related systems and equipment can reliably operate without malfunction due to electromagnetic disturbances in typical industrial settings. It excludes equipment used in explosive atmospheres or specialized process industries, maintaining a scope focused on industrial, indoor and outdoor electromagnetic environments.

Key Topics

• Scope and Application
  IEC 61326-3-1 is derived from IEC 61326-1 and tailored for systems performing safety functions per IEC 61508 requirements. It addresses immunity testing in line with environments defined under IEC 61000-6-2 for industrial locations.

• Immunity Requirements
  The standard outlines immunity levels and testing methodologies intended to safeguard electrical equipment from various electromagnetic phenomena, such as:

  • Electrostatic discharge (ESD)
  • Radiated and conducted radio-frequency electromagnetic fields
  • Electrical fast transients and surges
  • Conducted disturbances along supply lines and control ports

• Performance Criteria
  IEC 61326-3-1 specifies distinct performance criteria to evaluate equipment behavior under test conditions, including the special criterion FS related to functional safety. This ensures that safety functions are preserved despite EMC disturbances.

• Test Setup and Philosophy
  Detailed test plan guidance specifies equipment configuration, operation modes, cabling, and grounding during EMC immunity tests. The document covers testing approaches for both standalone safety equipment and integrated safety-related systems.

• Documentation and Reporting
  Requirements for compiling test reports and interpreting test results aim to facilitate compliance verification and support certification processes.

Applications

IEC 61326-3-1 serves as a critical standard for manufacturers, engineers, and safety professionals involved in:

• Industrial Control Systems
  Ensuring controllers, sensors, and actuators responsible for safety functions maintain integrity against electromagnetic interference in factories and production lines.

• Functional Safety Equipment
  Devices used in emergency shutdown systems, safety interlocks, and protective relays operating under SIL 1-3 classifications.

• Laboratory and Measurement Instruments
  Equipment used for safety monitoring or control in industrial laboratory environments requiring EMC robustness.

• System Integrators and Test Labs
  Designing EMC test programs that comply with international safety standards, supporting product certification and market access.

Related Standards

• IEC 61508
  Fundamental standard specifying functional safety requirements for electrical, electronic, and programmable electronic safety-related systems.

• IEC 61326-1
  General EMC requirements for electrical equipment used in measurement, control, and laboratory applications.

• IEC 61000-6-2
  Generic standards for EMC immunity applicable to industrial environments, defining typical electromagnetic conditions.

• IEC 61326-2-X series
  Specialized EMC requirements for equipment in particular industries or applications.

---

Keywords: IEC 61326-3-1, functional safety, EMC immunity requirements, safety-related systems, industrial applications, IEC 61508, electromagnetic compatibility, SIL 1-3, industrial control systems, electrical equipment standard, immunity testing, safety functions.

Standards Content (Sample)

IEC 61326-3-1
Edition 1.0 2008-01
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
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
Matériel électrique de mesure, de commande et de laboratoire – Exigences
relatives à la CEM –
Partie 3-1: Exigences d'immunité pour les systèmes relatifs à la sécurité et pour
les matériels destinés à réaliser des fonctions relatives à la sécurité (sécurité
fonctionnelle) – Applications industrielles générales

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IEC 61326-3-1
Edition 1.0 2008-01
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
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
Matériel électrique de mesure, de commande et de laboratoire – Exigences
relatives à la CEM –
Partie 3-1: Exigences d'immunité pour les systèmes relatifs à la sécurité et pour
les matériels destinés à réaliser des fonctions relatives à la sécurité (sécurité
fonctionnelle) – Applications industrielles générales

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
W
CODE PRIX
ICS 25.040.40; 33.100.20 ISBN 2-8318-9509-X

– 2 – 61326-3-1 © IEC:2008
CONTENTS
FOREWORD.4
INTRODUCTION.6

1 Scope.9
2 Normative references .9
3 Terms and definitions .11
4 General .13
5 EMC test plan.13
5.1 General .13
5.2 Configuration of EUT during testing.14
5.2.1 General .14
5.2.2 Composition of EUT.14
5.2.3 Assembly of EUT.14
5.2.4 I/O ports .14
5.2.5 Auxiliary equipment .14
5.2.6 Cabling and earthing (grounding).14
5.3 Operation conditions of EUT during testing.14
5.3.1 Operation modes .14
5.3.2 Environmental conditions.14
5.3.3 EUT software during test .15
5.4 Specification of performance criteria .15
5.5 Test description.15
6 Performance criteria .15
6.1 Performance criteria A, B and C .15
6.2 Performance criterion FS.15
6.3 Application of the performance criterion FS .16
7 Immunity requirements .16
8 Test set-up and test philosophy for EUTs with functions intended for safety
applications .22
8.1 Testing of safety-related systems and equipment intended to be used in
safety-related systems .22
8.2 Test philosophy for equipment intended for use in safety-related systems.23
8.3 Test philosophy for safety-related systems .24
8.4 Test configuration.24
8.5 Monitoring .24
9 Test results and test report.25

Annex A (informative) Evaluation of electromagnetic phenomena .29
Annex B (informative) Allowed effects during immunity tests.33

Bibliography.38

Figure 1 – Correlation between the standards IEC 61326-1, IEC 61326-2-X,
IEC 61326-3-1 and IEC 61326-3-2 .8
Figure 2 – Typical test set-up for equipment intended for use in a safety-related system
integrated into a representative safety-related system during test .26

61326-3-1 © IEC:2008 – 3 –
Figure 3 – Typical test set-up for equipment intended for use in safety-related system
tested stand-alone .27
Figure 4 – Typical test set-up for a safety-related system .28
Figure A.1 – Emission/immunity levels and compatibility level, with an example of
emission/immunity levels for a single emitter and susceptor, as a function of some
independent variables (see IEC 61000-1-1) .30

Table 1a – Immunity test requirements for equipment intended for use in industrial
locations – Enclosure port.17
Table 1b – Immunity test requirements for equipment intended for use in industrial
locations – Input and output a.c. power ports .18
Table 1c – Immunity test requirements for equipment intended for use in industrial
locations – Input and output d.c. power ports .19
Table 1d – Immunity test requirements for equipment intended for use in industrial
locations – I/O signal/control ports .20
Table 1e – Immunity test requirements for equipment intended for use in industrial
locations – I/O signal/control ports connected direct to power supply networks .21
Table 1f – Immunity test requirements for equipment intended for use in industrial
locations – Functional earth port .21
Table 2 – Selected frequencies for electromagnetic field tests .22
Table 3 – Selected frequencies for conducted r.f. tests .22
Table 4 – Applicable performance criteria and observed behaviour during test for
equipment intended for use in safety-related systems .23
Table A.1 – Exemplary considerations on electromagnetic phenomena and test levels
with regard to functional safety in industrial applications.32
Table B.1 – Allowed effects during immunity tests on functions of equipment.34
Table B.2 – Allowed effects during immunity tests on functions of a system .36

– 4 – 61326-3-1 © IEC:2008
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
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

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
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5) IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for any
equipment declared to be in conformity with an IEC Publication.
6) All users should ensure that they have the latest edition of this publication.
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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 61326-3-1 has been prepared by subcommittee 65A: System
aspects, of IEC technical committee 65: Industrial-process measurement and control.
The IEC 61326 series cancels and replaces IEC 61326:2002 and constitutes a technical
revision.
IEC 61326-3-1 is to be read in conjunction with IEC 61326-1.

61326-3-1 © IEC:2008 – 5 –
The text of this standard is based on the following documents:
FDIS Report on voting
65A/500/FDIS 65A/505/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 the parts of the IEC 61326 series, under the general title Electrical equipment for
measurement, control and laboratory use – EMC requirements, can be found on the IEC
website.
The committee has decided that the contents of this publication will remain unchanged until
the maintenance result date indicated on the IEC web site under "http://webstore.iec.ch" in
the data related to the specific publication. At this date, the publication will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
The contents of the corrigendum of September 2008 have been included in this copy.

– 6 – 61326-3-1 © IEC:2008
INTRODUCTION
Functional safety is that part of the overall safety relating to the equipment under control
(EUC) and the EUC control system which depends on the correct functioning of the electrical
safety-related systems. To achieve this all items of equipment of the safety-related system
which are involved in the performance of the safety functions must behave in a specified
manner under all relevant conditions.
The IEC basic safety publication for functional safety of electrical/electronic/programmable
electronic safety-related systems is IEC 61508. It sets the overall requirements to achieve
functional safety. Sufficient immunity to electromagnetic disturbances is one of those
requirements.
The concept of IEC 61508 distinguishes between the consideration of the application and the
design of safety-related electrical and electronic systems. The interface between both is the
safety requirements specification (SRS). It specifies all relevant requirements of the intended
application, as follows.
a) Definition of the safety function, based on a risk assessment of the intended
application (which function is intended to reduce risk).
b) Appropriate safety integrity level (SIL) for each safety-function based on a risk
assessment of the intended application.
c) Definition of the environment in which the system is intended to work including the
electromagnetic environment as required by IEC 61508-2.
Hence, with regard to immunity against electromagnetic phenomena, the essential starting
point is that the electromagnetic environment and its phenomena are considered in the SRS,
as required by IEC 61508. The safety-related system intended to implement the specified
safety function has to fulfil the SRS, and, from it, corresponding immunity requirements have
to be derived for the items of equipment, which results in an equipment requirement
specification. With respect to the electromagnetic environment, the SRS and the equipment
requirement specification should be based on a competent assessment of the foreseeable
electromagnetic threats in the real environment over the whole operational life of the
equipment. Hence, immunity requirements for the equipment depend on the characteristics of
the electromagnetic environment in which the equipment is intended to be used.
The equipment manufacturer, therefore, has to prove that the equipment fulfils the equipment
requirement specification and the system integrator must prove that the system fulfils the
SRS. Evidence has to be produced by application of appropriate methods. They do not need
to consider any other aspects of the application, for example, risk of the application
associated to any failure of the safety-related system. The objective is for all equipment in the
system to comply with particular performance criteria taking into account functional safety
aspects (for example, the performance criterion FS) up to levels specified in the SRS
independent of the required safety integrity level (SIL).
There are basically two approaches on how to deal with the electromagnetic environments
and to conclude on immunity requirements.
(A) To consider a general electromagnetic environment with no specific restrictions, for
example, an industrial environment, and to take into account all the electromagnetic
phenomena that can occur as well as their maximum amplitudes when deriving
appropriate immunity levels for the system and the equipment. This approach has
been used to determine the levels specified within this part of IEC 61326 leading to
increased immunity levels for some electromagnetic phenomena compared to
immunity levels which are derived without functional safety considerations.
(B) To control the electromagnetic environment, for example, by the application of
particular installation and mitigation practices, in such a way that electromagnetic
phenomena and their amplitudes could occur only to a certain extent. These
phenomena and restricted amplitudes are then taken into account by appropriate

61326-3-1 © IEC:2008 – 7 –
immunity levels. These levels are not necessarily higher than those derived without
functional safety considerations because it is ensured by corresponding means that
higher amplitudes are not normally expected. This approach is considered in
IEC 61326-3-2.
Applying approach (A) with regard to a general industrial environment requires appropriate
knowledge of the electromagnetic phenomena and the amplitudes to be expected there. For
this purpose and as it is also requested by IEC 61508, electromagnetic environment data of
IEC 61000-2-5 are to be used. This IEC publication gives information about electromagnetic
phenomena to be expected and describes their amplitudes in terms of compatibility levels.
Since they can be considered as disturbance levels at which an acceptable electromagnetic
compatibility should exist, these levels are used as the basis for normal immunity
requirements as given in non-safety-related standards such as IEC 61326-1, IEC 61326-2-X
or the generic standard IEC 61000-6-2. This normal approach applied to achieve
electromagnetic compatibility is based on a technical/economical compromise allowing a
certain amount of harmful interference cases. This approach, however, is not sufficient in the
case of safety-related systems and the equipment used in them. Immunity levels have to be
determined which take into account all electromagnetic phenomena and the maximum levels
to be expected in the electromagnetic environment under consideration and hence for many
electromagnetic phenomena these levels are increased compared to the normal ones.
Following approach (A), IEC 61326-3-1 gives specific electromagnetic immunity requirements
that apply to safety-related systems and equipment intended to be used in safety-related
systems. These requirements supplement certain requirements of IEC 61326-1, and the
selected electromagnetic phenomena and defined immunity test levels are expected to match
with the environmental conditions of most industrial applications.
The correlation between the standards IEC 61326-1, IEC 61326-2-X, IEC 61326-3-1 and
IEC 61326-3-2 is described in the diagram of Figure 1.
The increased specified test levels in this standard are derived from the highest levels to be
expected in the environment of most industrial applications. These increased test levels are
related to the electromagnetic environment (that can occur). They cannot be related in an
analytical way to the SIL required for the safety-related system because there is no practically
provable relationship between test level and probability of failure during use. The influences
of electromagnetic phenomena are considered as systematic effects and by their nature often
result in common cause events.
Design features of equipment must take into account the required SIL and must be designed
to avoid dangerous systematic failures. Sufficient immunity against electromagnetic
disturbances can only be ensured by design, mitigation and construction techniques which
take into account electromagnetic aspects, which, however, are not within the scope of this
standard.
It is therefore recommended that the approach to achieve the capability for the required SIL
should be through the adoption of design features on the one hand and through appropriate
test performance parameters in order to increase the level of confidence in the test results on
the other hand.
– 8 –                  61326-3-1 IEC:2008
©
IEC  2338/07
Figure 1 – Correlation between the standards IEC 61326-1, IEC 61326-2-X,
IEC 61326-3-1 and IEC 61326-3-2

61326-3-1 © IEC:2008 – 9 –
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

1 Scope
The scope of IEC 61326-1 applies to this part of IEC 61326 but is limited to systems and
equipment for industrial applications intended to perform safety functions as defined in
IEC 61508 with SIL 1-3.
The electromagnetic environments encompassed by this product family standard are
industrial, both indoor and outdoor, as described for industrial locations in IEC 61000-6-2 or
defined in 3.7 of IEC 61326-1. Equipment and systems intended for use in other
electromagnetic environments, for example, in the process industry or in environments with
potentially explosive atmospheres, are excluded from the scope of this product family
standard, IEC 61326-3-1.
Equipment and systems considered as “proven-in-use” according to IEC 61508 or IEC 61511
are excluded from the scope of IEC 61326-3-1.
Fire alarm systems and security alarm systems intended for protection of buildings are
excluded from the scope of IEC 61326-3-1.
2 Normative references
The following referenced documents are indispensable for the application of this standard. For
dated references, only the edition cited applies. For undated references, the latest edition of
the referenced document (including any amendments) applies.
IEC 60050-161, International Electrotechnical Vocabulary – Chapter 161: Electromagnetic
compatibility
IEC 61000-4-2:2001, Electromagnetic compatibility (EMC) – Part 4-2: Testing and
measurement techniques – Electrostatic discharge immunity test
IEC 61000-4-3:2006, Electromagnetic compatibility (EMC) – Part 4-3: Testing and
measurement techniques – Radiated, radio-frequency, electromagnetic field immunity test
IEC 61000-4-4:2004, Electromagnetic compatibility (EMC) – Part 4-4: Testing and
measurement techniques – Electrical fast transient/burst immunity test
IEC 61000-4-5:2005, Electromagnetic compatibility (EMC) – Part 4-5: Testing and
measurement techniques – Surge immunity test
IEC 61000-4-6:2004, Electromagnetic compatibility (EMC) – Part 4-6: Testing and
measurement techniques – Immunity to conducted disturbances, induced by radio-frequency
fields
– 10 – 61326-3-1 © IEC:2008
IEC 61000-4-8:1993, Electromagnetic compatibility (EMC) – Part 4-8: Testing and
measurement techniques – Power frequency magnetic field immunity test
Amendment 1 (2000)
IEC 61000-4-11:2004, Electromagnetic compatibility (EMC) – Part 4-11: Testing and
measurement techniques –Voltage dips, short interruptions and voltage variations immunity
tests
IEC 61000-4-16:1998, Electromagnetic compatibility (EMC) – Part 4-16: Testing and
measurement techniques – Test for immunity to conducted, common mode disturbances in
the frequency range 0 Hz to 150 kHz
Amendment 1 (2001)
IEC 61000-4-29:2000, Electromagnetic compatibility (EMC) – Part 4-29: Testing and
measurement techniques – Voltage dips, short interruptions and voltage variations on d.c.
input power port immunity tests
IEC 61000-6-2:2005, Electromagnetic compatibility (EMC) – Part 6-2: Generic standards –
Immunity for industrial environments
IEC 61326-1:2005, Electrical equipment for measurement, control and laboratory use – EMC
requirements – Part 1: General requirements
IEC 61326-2-1:2005, Electrical equipment for measurement, control and laboratory use –
EMC requirements – Part 2-1: Particular requirements – Test configurations, operational
conditions and performance criteria for sensitive test and measurement equipment for EMC
unprotected applications
IEC 61326-2-2:2005, Electrical equipment for measurement, control and laboratory use –
EMC requirements – Part 2-2: Particular requirements – Test configurations, operational
conditions and performance criteria for portable test, measuring and monitoring equipment
used in low-voltage distribution systems
IEC 61326-2-3:2006, Electrical equipment for measurement, control and laboratory use –
EMC requirements – Part 2-3: Particular requirements – Test configurations, operational
conditions and performance criteria for transducers with integrated or remote signal
conditioning
IEC 61326-2-4:2006, 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 61326-2-5:2006, Electrical equipment for measurement, control and laboratory use –
EMC requirements – Part 2-5: Particular requirements – Test configurations, operational
conditions and performance criteria for field devices with interfaces according to IEC 61784-1,
CP 3/2
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 EM environment
———————
There exists a consolidated edition 1.1 (2001) that includes edition 1.0 and its amendment.

61326-3-1 © IEC:2008 – 11 –
IEC 61508-2:2000, Functional safety of electrical/electronic/programmable electronic safety-
related systems – Part 2: Requirements for electrical/electronic/programmable electronic
safety-related systems
ISO/IEC Guide 51:1999, Safety aspects – Guidelines for their inclusion in standards
3 Terms and definitions
For the purposes of this document, the terms and definitions of IEC 61326-1 and IEC 60050-
161, as well as the following, apply.
NOTE Other definitions, not included in IEC 60050-161 and in this standard, but nevertheless necessary for the
application of the different tests, are given in the EMC basic publications of the IEC 61000 series.
3.1
dangerous failure
failure which has the potential to put the safety-related system in a hazardous or fail-to-
function state
NOTE Whether or not the potential is realised may depend on the channel architecture of the system; in systems
with multiple channels to improve safety, a dangerous hardware failure is less likely to lead to the overall
dangerous or fail-to-function state.
[IEC 61508-4, 3.6.7]
3.2
equipment
the term equipment as used in this document is extremely general and is applied to a wide
variety of possible subsystems, apparatus, appliances and other assemblies of products
3.3
equipment under control (EUC)
equipment, machinery, apparatus or plant used for manufacturing, process, transportation,
medical or other activities
NOTE The EUC control system is separate and distinct from the EUC.
3.4
functional safety
part of the overall safety relating to the EUC and the EUC control system which depends on
the correct functioning of the E/E/PE safety-related systems, other technology safety-related
systems and external risk reduction facilities
[IEC 61508-4, 3.1.9]
3.5
harm
physical injury or damage to the health of people, or damage to property or the environment
[ISO/IEC Guide 51, 3.3]
3.6
hazard
potential source of harm
NOTE The term includes danger to persons arising within a short time scale (for example, fire and explosion) and
also those that have a long-term effect on a person’s health (for example, release of a toxic substance).
[ISO/IEC Guide 51, 3.5, modified]

– 12 – 61326-3-1 © IEC:2008
3.7
safe failure
failure which does not have the potential to put the safety-related system in a hazardous or
fail-to-function state
NOTE Whether or not the potential is realised may depend on the channel architecture of the system; in systems
with multiple channels to improve safety, a safe hardware failure is less likely to result in an erroneous shut-down.
[IEC 61508-4, 3.6.8]
3.8
safety function
function to be implemented by an E/E/PE safety-related system, other technology safety-
related system or external risk reduction facilities, which is intended to achieve or maintain a
safe state for the EUC, in respect of a specific hazardous event (see 3.4.1)
[IEC 61508-4, 3.5.1]
3.9
programmable electronic (PE)
based on computer technology which may be comprised of hardware, software and of input
and/or output units
NOTE This term covers microelectronic devices based on one or more central processing units (CPUs) together
with associated memories, etc.
EXAMPLE The following are all programmable electronic devices:
– microprocessors;
– micro-controllers;
– programmable controllers;
– application specific integrated circuits (ASICs);
– programmable logic controllers (PLCs);
– other computer-based devices (for example, smart sensors, transmitters, actuators).
[IEC 61508-4, 3.2.5]
3.10
electrical/electronic/programmable electronic (E/E/PE)
based on electrical (E) and/or electronic (E) and/or programmable electronic (PE) technology
NOTE The term is intended to cover any and all devices or systems operating on electrical principles.
EXAMPLE: Electrical/electronic/programmable electronic devices include
– electro-mechanical devices (electrical);
– solid-state non-programmable electronic devices (electronic);
– electronic devices based on computer technology (programmable electronic); see 3.2.5 (of IEC 61326-1).
[IEC 61508-4, 3.2.6]
3.11
d.c. distribution network
local d.c. electricity supply network in the infrastructure of a certain site or building intended
for connection of any type of equipment
NOTE Connection to a local or remote battery is not regarded as a d.c. distribution network if such a link
comprises only the power supply for a single piece of equipment.
3.12
system (in the context of this document)
combination of apparatus and/or active components constituting a single functional unit and
intended to be installed and operated to perform (a) specific task(s)

61326-3-1 © IEC:2008 – 13 –
NOTE "Safety-related systems" are specifically "designed" equipment that both
– implement the required safety functions necessary to achieve or maintain a safe state for a controlled
equipment;
– are intended to achieve on their own or with other safety-related equipment or external risk reduction facilities,
the necessary safety integrity for the safety requirements.
[IEC 61508-4, 3.4.1, modified]
3.13
EUT
the equipment (devices, appliances and systems) subjected to immunity tests
3.14
auxiliary equipment (AE)
equipment necessary to provide the equipment under test (EUT) with the signals required for
normal operation and equipment to verify the performance of the EUT
4 General
In addition to the requirements in IEC 61326-1, this standard specifies additional
requirements for systems and equipment for industrial applications intended to perform safety
functions according to IEC 61508. These additional requirements do not apply to the non-
safety-related functions of the equipment or systems.
NOTE 1 The overall design process and the necessary design features to achieve functional safety of electrical
and electronic systems are defined in IEC 61508. This includes requirements for design features that make the
system tolerant (IEC 61508-2:2000, 7.4.5.1) of electromagnetic disturbances.
The immunity requirements in IEC 61326-1 have been selected to ensure an adequate level of
immunity for equipment used in non-safety-related applications, but the required immunity
levels do not cover extreme cases that may occur at any location but with an extremely low
probability of occurrence.
The possibility of occurrence of higher disturbance levels is not considered in IEC 61326-1
and it is also not considered on a statistical basis. Therefore, increased immunity test levels
are defined as a systematic measure intended to avoid dangerous failures caused by
electromagnetic phenomena. Consequently, it is not necessary to take into account the effect
of electromagnetic phenomena in the quantification of hardware safety integrity, for example,
probability of failure on demand. Increased immunity test levels are defined phenomenon by
phenomenon where necessary.
Increased immunity test levels are related to functional safety aspects only, they are not
applicable for the assessment of reliability and availability aspects. The increased immunity
test levels apply only to the safety-related functions having a specific performance criterion
for functional safety (performance criterion FS). The increased immunity test levels set the
limits for the maximum test values. Further tests with higher values are not required for
compliance with this standard.
NOTE 2 The safety-related system intended to implement the specified function should fulfil the SRS as required
in IEC 61508. The SRS specifies all relevant requirements of the intended application. Equipment intended for use
in that system has to fulfil the relevant requirements derived from the SRS.
5 EMC test plan
5.1 General
An EMC test plan shall be established prior to testing. It shall contain as a minimum the
elements given in 5.2 to 5.5.
– 14 – 61326-3-1 © IEC:2008
It may be determined from consideration of the electrical characteristics and usage of a
particular apparatus that some tests are inappropriate and therefore unnecessary. In such
cases the decision not to test shall be recorded in the EMC test plan.
5.2 Configuration of EUT during testing
5.2.1 General
Measurement, control and laboratory equipment often consists of systems with no fixed
configuration. The kind, number and installation of different subassemblies within the equip-
ment may vary from system to system.
To simulate EMC conditions realistically the equipment assembly shall represent a typical
installation as specified by the manufacturer. EMC tests shall be carried out as type tests
under normal conditions as specified by the manufacturer.
5.2.2 Composition of EUT
All devices, racks, modules, boards, etc. which are potentially relevant to EMC and belonging
to the EUT shall be documented.
5.2.3 Assembly of EUT
If an EUT has a variety of internal or external configurations, the type tests shall be made with
the most susceptible configuration, as expected by the manufacturer. All types of modules
shall be tested at least once. The rationale for this selection shall be documented in the EMC
test plan. The possibility of any electromagnetic interactions between items of equipment shall
be taken into account when building up the most susceptible configuration.
5.2.4 I/O ports
Where there are multiple I/O ports all of the same type and function, connecting a cable to
just one of those ports is sufficient, provided that it can be shown that the additional cables
would not affect the results significantly. The rationale for this selection shall be documented
in the EMC test plan.
5.2.5 Auxiliary equipment
When a variety of items of auxiliary equipment are provided for use with the EUT, at least one
of each type of item of auxiliary equipment shall be selected to simulate actual operating
conditions. Auxiliary equipment can be simulated.
5.2.6 Cabling and earthing (grounding)
The cables and earth (ground) shall be connected to the EUT in accordance with the
manufacturer's specifications. There shall be no additional earth connections.
5.3 Operation conditions of EUT during testing
5.3.1 Operation modes
A selection of representative operation modes shall be made, taking into account that not all
functions, but only the most typical functions of the equipment can be tested. The estimated
worst-case operating modes for the intended application shall be selected.
5.3.2 Environmental conditions
The tests shall be carried out within the manufacturer’s specified environmental operating
range (for example, ambient temperature, humidity, atmospheric pressure), and within the

61326-3-1 © IEC:2008 – 15 –
rated ranges of supply voltage and frequency, except where the test requirements state
otherwise.
5.3.3 EUT software during test
The software used for simulating the different modes of operation shall be documented. This
software shall represent the estimated worst-case operating mode for the intended
application.
5.4 Specification of performance criteria
Performance criteria for each port and test shall be specified, where possible, as quantitative
values.
5.5 Test description
Each test to be applied shall be specified in the EMC test plan. The description of the tests,
the test methods, the characteristics of the tests, and the test set-ups are given in the basic
standards, which are referred to in Table 1. The contents of these basic standards need not
be reproduced in the test plan; however, additional information needed for the practical
implementation of the tests is given in this standard. In some cases, the EMC test plan shall
specify the application in detail.
NOTE Not all known disturbance phenomena have been specified for testing purposes in this standard, but only
those which are considered as critical. For further information, see Annex A.
6 Performance criteria
Performance criteria are used to describe and to assess the reaction of the equipment under
test when being exposed to electromagnetic phenomena. With regard to functional safety
purposes, a particular performance criterion FS shall be considered.
6.1 Performance criteria A, B and C
Performance criterion A: During testing, normal performance within the specification limits.
Performance criterion B: During testing, temporary degradation, or loss of function or
performance which is self-recovering.
Pe
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