IEC 61326-3-2:2008

IEC 61326-3-2
Edition 1.0 2008-01
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
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

Matériel électrique de mesure, de commande et de laboratoire – Exigences
relatives à la CEM –
Partie 3-2: 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 dont l’environnement
électromagnétique est spécifié
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IEC 61326-3-2
Edition 1.0 2008-01
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
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

Matériel électrique de mesure, de commande et de laboratoire – Exigences
relatives à la CEM –
Partie 3-2: 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 dont l’environnement
électromagnétique est spécifié
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
V
CODE PRIX
ICS 25.040.40; 33.100.20 ISBN 2-8318-9510-3

SC 65A/Publication 61326-3-2 (2008), First edition/I-SH 01
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
INTERPRETATION SHEET 1
This interpretation sheet has been prepared by subcommittee 65A: System aspects, of IEC
technical committee 65.
The text of this interpretation sheet is based on the following documents:
ISH Report on voting
65A/632/ISH 65A/644/RVD
Full information on the voting for the approval of this interpretation sheet can be found in the
report on voting indicated in the above table.
___________
Introduction
equipment intended to perform safety-related functions (functional safety) in industrial
applications with specified electromagnetic environment. The actual immunity levels, test
parameters and applicable basic standards are listed in Table 1a to Table 1f of that standard.
In case of the phenomenon “Conducted r.f.” the basic standard IEC 61000-4-6:2004 shall be
applied. The frequency range under consideration in IEC 61326-3-2:2008 is from 10 kHz to 80
MHz though the basic standard IEC 61000-4-6:2004 lists calibration parameters for the
frequency range from 150 kHz to 80 MHz only. This lack in having some information
concerning the calibration was the reason for having introduced footnote c in Table 1b (and
for the identical footnotes regarding this phenomenon in the other tables).
However, footnote c in Table 1b leaves some space for interpretation as it is not entirely clear
whether it applies to the entire calibration situation for all types of injection methods or to that
one of CDNs only, as in the first case some information would be missing for the situation of
testing via clamp injection.
Interpretation:
Footnote c in Table 1b shall be interpreted as follows:
The basic standard IEC 61000-4-6:2004 allows different injection methods, and their selection
shall be done according to the rules for selecting injection methods and test points (see 7.1 of
IEC 61000-4-6:2004).
June 2013 ICS 25.040.40; 33.100.20

In case the CDN injection method is applied the impedance of the CDN in the frequency range
10 kHz up to 150 kHz has to comply with the asymmetric impedance requirements of
IEC 61000-4-6:2004 at 150 kHz. Calibration shall be performed in accordance with
IEC 61000-4-6:2004. Sufficient decoupling can be demonstrated if the impedance criterion is
met both with the AE port short-circuited and then open-circuited.
In case the clamp injection is applied the procedures of 7.3 or 7.4 of the basic standard
IEC 61000-4-6:2004 are applicable in the frequency range from 10 kHz to 150 kHz as well.

_____________
June 2013 ICS 25.040.40; 33.100.20

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

1 Scope.9
2 Normative references .10
3 Terms and definitions .11
4 General .13
5 EMC test plan.14
5.1 General .14
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 .15
5.2.5 Auxiliary equipment .15
5.2.6 Cabling and earthing (grounding).15
5.3 Operation conditions of EUT during testing.15
5.3.1 Operation modes .15
5.3.2 Environmental conditions.15
5.3.3 EUT software during test .15
5.4 Specification of performance criteria .15
5.5 Test description.15
6 Performance criteria .16
6.1 Performance criteria A, B and C .16
6.2 Performance criterion FS.16
6.3 Application of the performance criterion FS .16
7 Immunity requirements .16
8 Test set-up and test philosophy for EUT with functions intended for safety
applications .19
8.1 Testing of safety-related systems and equipment intended to be used in
safety-related systems .19
8.2 Test philosophy for equipment intended for use in safety-related systems.20
8.3 Test philosophy for safety-related systems .20
8.4 Test configuration.20
8.5 Monitoring .21
9 Test results and test report.21

Annex A (informative) Evaluation of electromagnetic phenomena .25
Annex B (informative) Details of the specified electromagnetic environment .27
Annex C (informative) Example of immunity levels in the process industry.31

Bibliography.32

Figure 1 – Correlation between the standards IEC 61326-1, IEC 61326-2-X,
IEC 61326-3-1 and IEC 61326-3-2 .8

61326-3-2 © IEC:2008 – 3 –
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 .22
Figure 3 – Typical test set-up for equipment intended for use in a safety-related system
tested stand-alone .23
Figure 4 – Test set-up for a safety-related system .24
Figure B.1 – Recommended cable layouts for different categories .28

Table 1a – Immunity test requirements for equipment intended for use in industrial
locations with specified electromagnetic environment – Enclosure port.17
Table 1b – Immunity test requirements for equipment intended for use in industrial
locations with specified electromagnetic environment – Input and output a.c. power
ports .17
Table 1c – Immunity test requirements for equipment intended for use in industrial
locations with specified electromagnetic environment – Input and output d.c. power
ports .18
Table 1d – Immunity test requirements for equipment intended for use in industrial
locations with specified electromagnetic environment – I/O signal/control ports .18
Table 1e – Immunity test requirements for equipment intended for use in industrial
locations with specified electromagnetic environment – I/O signal/control ports
connected directly to power supply networks .19
Table 1f – Immunity test requirements for equipment intended for use in industrial
locations with specified electromagnetic environment – Functional earth port .19
Table A.1 – General considerations for the application of electromagnetic phenomena
for functional safety in industrial applications with specified electromagnetic environment
(examples).26
Table C.1 – Immunity test requirements for equipment intended for use in industrial
locations with a specified electromagnetic environment according to NE 21.31

– 4 – 61326-3-2 © IEC:2008
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
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
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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Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested
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with the International Organization for Standardization (ISO) in accordance with conditions determined by
agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
consensus of opinion on the relevant subjects since each technical committee has representation from all
interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
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4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
transparently to the maximum extent possible in their national and regional publications. Any divergence
between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
the latter.
5) IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for any
equipment declared to be in conformity with an IEC Publication.
6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
members of its technical committees and IEC National Committees for any personal injury, property damage or
other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
Publications.
8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 61326-3-2 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 61326-3-2 is to be read in conjunction with IEC 61326-1.

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– 6 – 61326-3-2 © 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 integrated 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; this 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 IEC 61326-3-1 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

61326-3-2 © 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
no higher amplitudes as normally are to be expected. This approach is considered in
this part of IEC 61326.
Applying approach (B) results in the fact that there is a specified electromagnetic environment
due to the strict observation of particular installation and mitigation practices. In addition,
however, appropriate knowledge is required concerning the electromagnetic phenomena and
the amplitudes to be expected in this specified electromagnetic environment. This has been
achieved by taking into account statistical data on faults in safety applications of the process
industry. For this evaluation more than 20 000 units in safety applications are annually
analysed on the occurrence of failures; from this data it has been shown that the failure rates
meet the requirements connected to the safety integrity level (SIL). These units are in
compliance with particular EMC requirements of the process industry.
Following approach (B), IEC 61326-3-2 gives specific electromagnetic immunity requirements
that apply to safety-related systems and equipment intended to be used in safety-related
systems. These requirements supplement some requirements of IEC 61326-1 (or of
comparable EMC requirements of the process industry) and the selected electromagnetic
phenomena and defined immunity test levels are expected to match with the environmental
conditions of the specified industrial applications as defined in the scope of this standard.
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 specified test levels in this standard are derived from the highest levels to be expected in
the specified environment of industrial applications. These test levels are related to the
electromagnetic environment (what 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 –                 61326-3-2 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

61326-3-2 © IEC:2008 – 9 –
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
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 within a specified electromagnetic environment and
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 they can be found in industrial applications with an
electromagnetic environment having specified characteristics (for example, process industry).
The difference between the electromagnetic environment covered by this standard compared
to the general industrial environment (see IEC 61326-3-1) is due to the mitigation measures
employed against electromagnetic phenomena leading to a specified electromagnetic
environment.
The environment of industrial application with a specified electromagnetic environment
typically includes the following characteristics:
– industrial area with limited access;
– limited use of mobile transmitter;
– dedicated cables for power supply and control, signal or communication lines;
– separation between power supply and control, signal or communication cables;
– factory building mostly consisting of metal construction;
– overvoltage/lightning protection by appropriate measures (for example, metal construction
of the building or use of protection devices);
– pipe heating systems driven by a.c. main power may be present;
– no high-voltage substation close to sensitive areas;
– presence of CISPR 11 Group 2 ISM equipment using ISM frequencies only with low
power;
– competent staff;
– periodical maintenance of equipment and systems;
– mounting and installation guidelines for equipment and systems.
A more detailed description of the above-mentioned typical characteristics is given in
Annex B.
Equipment and systems considered as “proven-in-use” according to IEC 61508 or IEC 61511
are excluded from the scope of IEC 61326-3-2.
Fire alarm systems and security alarm systems intended for protection of buildings are
excluded from the scope of IEC 61326-3-2.

– 10 – 61326-3-2 © IEC:2008
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
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 61000-4-29:2000, 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
—————————
There exists a consolidated edition 1.1 (2001) that includes edition 1.0 and its amendment.

61326-3-2 © IEC:2008 – 11 –
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 61326-3-1:2008, 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 functions (functional safety) – General industrial
applications
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
IEC 61508-4:1998, Functional safety of electrical/electronic/programmable electronic safety-
related systems – Part 4: Definitions and abbreviations
IEC 61511-1:2003, Functional safety – Safety instrumented systems for the process industry
sector – Part 1: Framework, definitions, system, hardware and software requirements
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 sub-systems, 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
– 12 – 61326-3-2 © IEC:2008
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]
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).

61326-3-2 © IEC:2008 – 13 –
[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 DC 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)
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
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 with a specified
electromagnetic environment intended to perform safety functions as defined in IEC 61508.
These additional requirements do not apply to the normal (non-safety-related) functions of the
equipment and/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 (61508-2:2000, 7.4.5.1) of electromagnetic disturbances.

– 14 – 61326-3-2 © IEC:2008
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 is also not considered on a statistical basis. Therefore, it is needed to control the
environment (for example, defining installation requirements, limited use of mobile
transmitters) or to generally increase immunity test levels 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.
In addition to the immunity requirements of IEC 61326-1 the experience with this type of
electromagnetic environment is used to specify adequate levels of immunity and adequate
performance criteria.
NOTE 2 For the determination of adequate levels and performance criteria, data related to the occurrence of
faults have been collected and analysed. For the evaluation, more than 20 000 units in safety applications are
analysed annually on the occurrence of failures whereas it has been shown that the failure rates meet the SIL
requirements. These units are in compliance with specified EMC requirements applicable for their normal functions
within the process industry (see Annex C).
NOTE 3 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.
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 t
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