IEC TR 61000-1-1:2023

Electromagnetic compatibility (EMC) - Part 1-1: General - Application and interpretation of fundamental definitions and terms

IEC TR 61000-1-1:2023 which is a Technical Report, aims to describe and interpret various terms considered to be of basic importance to concepts and practical application in the design and evaluation of electromagnetically compatible equipment and systems. In addition, attention is drawn to the distinction between electromagnetic compatibility (EMC) tests carried out in a standardized set-up and those carried out at other locations, for example at premises where a device, equipment or system is manufactured or at the location where a device, equipment or system is installed (in situ tests or measurements). This second edition cancels and replaces the first edition published in 1992. This edition constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition:
a) the general description of the electromagnetic environment has been updated in accordance with IEC TR 61000-2-5;
b) the description of source, of potentially susceptible equipment/systems and of coupling mechanism has been updated,
c) elements from IEC TR 61000-2-3, that is intended to be withdrawn, as well as from IEC TR 61000-2-5, have been incorporated into this document.

General Information

• Status: Published
• Publication Date: 06-Feb-2023
• ICS: 33.100.01 - Electromagnetic compatibility in general
• Technical Committee: TC 77 - Electromagnetic compatibility
• Drafting Committee: WG 13 - TC 77/WG 13
• Current Stage: PPUB - Publication issued
• Start Date: 07-Feb-2023
• Completion Date: 09-Mar-2023

Standards Content (Sample)

IEC TR 61000-1-1 ®
Edition 2.0 2023-02
TECHNICAL
REPORT
colour
inside
BASIC EMC PUBLICATION
Electromagnetic compatibility (EMC) –
Part 1-1: General – Application and interpretation of fundamental definitions and
terms
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form
or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from
either IEC or IEC's member National Committee in the country of the requester. If you have any questions about IEC
copyright or have an enquiry about obtaining additional rights to this publication, please contact the address below or
your local IEC member National Committee for further information.

IEC Secretariat Tel.: [phone]
3, rue de Varembé [e-mail]
CH-1211 Geneva 20 www.iec.ch
Switzerland
About the IEC
The International Electrotechnical Commission (IEC) is the leading global organization that prepares and publishes
International Standards for all electrical, electronic and related technologies.

About IEC publications
The technical content of IEC publications is kept under constant review by the IEC. Please make sure that you have the
latest edition, a corrigendum or an amendment might have been published.

IEC publications search - webstore.iec.ch/advsearchform IEC Products & Services Portal - products.iec.ch
The advanced search enables to find IEC publications by a Discover our powerful search engine and read freely all the
variety of criteria (reference number, text, technical publications previews. With a subscription you will always have
committee, …). It also gives information on projects, replaced access to up to date content tailored to your needs.
and withdrawn publications.
Electropedia - www.electropedia.org
IEC Just Published - webstore.iec.ch/justpublished
The world's leading online dictionary on electrotechnology,
Stay up to date on all new IEC publications. Just Published
containing more than 22 300 terminological entries in English
details all new publications released. Available online and once
and French, with equivalent terms in 19 additional languages.
a month by email.
Also known as the International Electrotechnical Vocabulary

(IEV) online.
IEC Customer Service Centre - webstore.iec.ch/csc

If you wish to give us your feedback on this publication or need
further assistance, please contact the Customer Service
Centre: [e-mail].
IEC TR 61000-1-1 ®
Edition 2.0 2023-02
TECHNICAL
REPORT
colour
inside
BASIC EMC PUBLICATION
Electromagnetic compatibility (EMC) –

Part 1-1: General – Application and interpretation of fundamental definitions and

terms
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 33.100.01 ISBN 978-2-8322-6435-5

– 2 – IEC TR 61000-1-1:2023 © IEC 2023
CONTENTS
FOREWORD . 4
1 Scope . 7
2 Normative references . 7
3 Terms, definitions and abbreviated terms . 7
3.1 Terms and definitions . 7
3.2 Abbreviated terms . 10
4 The electromagnetic environment . 10
4.1 General . 10
4.2 Coupling between emitting and susceptible devices . 11
5 Application of EMC terms and definitions . 12
5.1 General . 12
5.2 Relation between various types of levels . 12
5.2.1 Emissions and immunity level (and limit). 12
5.2.2 Compatibility level . 13
5.2.3 Examples to illustrate the concepts of using levels and limits. 14
5.3 Probability aspects and margins . 16
5.3.1 Compatibility levels and uncertainties . 16
5.3.2 Standardized test. 17
5.3.3 In situ test – Superposition . 18
5.3.4 Lack of data . 20
6 Models and their limitations . 21
6.1 General . 21
6.2 Source models . 21
6.2.1 Conducted emissions . 21
6.2.2 Radiated emissions . 22
6.3 Coupling models . 23
6.3.1 General . 23
6.3.2 Common impedance coupling . 23
6.3.3 Coupling by induction . 24
6.3.4 Radiative coupling . 27
6.4 Susceptible device models . 27
Annex A (informative) Interpretation of EMC terms and definitions . 28
A.1 General . 28
A.2 Units and decibels . 28
A.3 Electromagnetic interference, compatibility and environment . 29
A.3.1 General . 29
A.3.2 Electromagnetic interference (EMI) . 29
A.3.3 Electromagnetic compatibility (EMC) . 30
A.3.4 The electromagnetic environment . 30
A.4 Susceptibility/immunity. 31
A.5 Level and limit . 31
A.6 Emission and immunity . 32
A.7 Compatibility level and margin . 34
Annex B (informative) Standardized and in situ tests . 37
Annex C (informative) Review of the historical assignment of radiated disturbance
degrees . 38

C.1 General . 38
C.2 Theoretical analysis of radiated disturbance degrees . 38
C.3 Detailed derivations . 40
C.3.1 Derivation of Formula (C.4). 40
C.3.2 Derivation of Formula (C.5). 41
Bibliography . 43

Figure 1 – Coupling paths between emitting and susceptible devices . 11
Figure 2 – Limits and levels for a single emitter and susceptible device as a function of
some independent variable (e.g., frequency) . 13
Figure 3 – Emission/immunity limits and compatibility levels, with an example of
emission/immunity levels for a single emitter and susceptible device as a function of
some independent variable (e.g., frequency) . 13
Figure 4 – Compatibility levels U for the odd harmonics in a public low-voltage
c
network and examples of associated emission and immunity limits . 15
Figure 5 – Limits, compatibility levels and margins, as a function of any independent
variable (e.g., frequency) . 17
Figure 6 – Example of the probability densities for an emission level and an immunity
level, at one single value of the independent variable . 18
Figure 7 – Example of superposition of disturbances . 20
Figure 8 – Example of probability densities for an ultimate disturbance level (the sum
of disturbance levels produced by various emitters) and the immunity levels of two
types of susceptible device . 20
Figure 9 – Source model for conducted emissions (source loaded by Z and Z ) . 22
L1 L2
Figure 10 – Electric and magnetic dipole elements . 23
Figure 11 – Capacitance per unit length as a function of conductor separation . 25
Figure 12 – Flux density from parallel conductors . 26
Figure A.1 – The basic form of an EMI problem . 29
Figure A.2 – Subdivision of EMC in its key aspects . 30
Figure A.3 – Overview of various EMC terms and measuring conditions . 34
Figure A.4 – Examples of probability densities p(D), p(I) and the resulting p(I – D) . 35
Figure C.1 – Problem geometry . 39

Table C.1 – Radiated disturbance degrees . 38

– 4 – IEC TR 61000-1-1:2023 © IEC 2023
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
ELECTROMAGNETIC COMPATIBILITY (EMC) –

Part 1-1: General – Application and interpretation
of fundamental definitions and terms

FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote international
co-operation on all questions concerning standardization in the electrical and electronic fields. To this end and
in addition to other activities, IEC publishes International Standards, Technical Specifications, Technical Reports,
Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC Publication(s)”). Their
preparation is entrusted to technical committees; any IEC National Committee interested in the subject dealt with
may participate in this preparatory work. International, governmental and non-governmental organizations liaising
with the IEC also participate in this preparation. IEC collaborates closely with the International Organization for
Standardization (ISO) in accordance with conditions determined by agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
consensus of opinion on the relevant subjects since each technical committee has representation from all
interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
misinterpretation by any end user.
4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
transparently to the maximum extent possible in their national and regional publications. Any divergence between
any IEC Publication and the corresponding national or regional publication shall be clearly indicated in the latter.
5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any
services carried out by independent certification bodies.
6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
members of its technical committees and IEC National Committees for any personal injury, property damage or
other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
Publications.
8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of patent
rights. IEC shall not be held responsible for identifying any or all such patent rights.
IEC TR 61000-1-1 has been prepared by IEC technical committee 77: Electromagnetic
compatibility. It is a Technical Report.
It forms Part 1-1 of IEC 61000. It has the status of a basic EMC publication in accordance with
IEC Guide 107.
This second edition cancels and replaces the first edition published in 1992. This edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) the general description of the electromagnetic environment has been updated in accordance
with IEC TR 61000-2-5;
b) the description of source, of potentially susceptible equipment/systems and of coupling
mechanism has been updated,
c) elements from IEC TR 61000-2-3, that is intended to be withdrawn, as well as from
IEC TR 61000-2-5, have been incorporated into this document.
The text of this Technical Report is based on the following documents:
Draft Report on voting
77/586/DTR 77/587/RVDTR
Full information on the voting for its approval can be found in the report on voting indicated in
the above table.
The language used for the development of this Technical Report is English.
This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in
accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement, available
at www.iec.ch/members_experts/refdocs. The main document types developed by IEC are
described in greater detail at www.iec.ch/publications.
A list of all parts in the IEC 61000 series, published under the general title Electromagnetic
compatibility (EMC), can be found on the IEC website.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under webstore.iec.ch in the data related to the
specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
IMPORTANT – The "colour inside" logo on the cover page of this document indicates
that it contains colours which are considered to be useful for the correct understanding
of its contents. Users should therefore print this document using a colour printer.

– 6 – IEC TR 61000-1-1:2023 © IEC 2023
INTRODUCTION
IEC 61000 is published in separate parts, according to the following structure:
Part 1: General
General considerations (introduction, fundamental principles)
Definitions, terminology
Part 2: Environment
Description of the environment
Classification of the environment
Compatibility levels
Part 3: Limits
Emission limits
Immunity limits (in so far as they do not fall under the responsibility of the product
committees)
Part 4: Testing and measurement techniques
Measurement techniques
Testing techniques
Part 5: Installation and mitigation guidelines
Installation guidelines
Mitigation methods and devices
Part 6: Generic standards
Part 9: Miscellaneous
Each part is further subdivided into several parts, published either as international standards
or as technical specifications or technical reports, some of which have already been published
as sections. Others will be published with the part number followed by a dash and a second
number identifying the subdivision (example: IEC 61000-6-1).

ELECTROMAGNETIC COMPATIBILITY (EMC) –

Part 1-1: General – Application and interpretation
of fundamental definitions and terms

1 Scope
This part of IEC 61000, which is a Technical Report, aims to describe and interpret various
terms considered to be of basic importance to concepts and practical application in the design
and evaluation of electromagnetically compatible equipment and systems.
In addition, attention is drawn to the distinction between electromagnetic compatibility (EMC)
tests carried out in a standardized set-up and those carried out at other locations, for example
at premises where a device, equipment or system is manufactured or at the location where a
device, equipment or system is installed (in situ tests or measurements).
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies.
For undated references, the latest edition of the referenced document (including any
amendments) applies.
IEC 60050-161:1990, International Electrotechnical Vocabulary (IEV) – Part 161:
Electromagnetic compatibility (available at www.electropedia.org)
3 Terms, definitions and abbreviated terms
3.1 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 60050-161 and the
following apply.
ISO and IEC maintain terminological databases for use in standardization at the following
addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
3.1.1
(electromagnetic) compatibility level
specified electromagnetic disturbance level used as a reference level for co-ordination in the
setting of emission and immunity limits
Note 1 to entry: By convention, the compatibility level is chosen so that there is only a small probability that it will
be exceeded by the actual disturbance level. However, electromagnetic compatibility is achieved only if emission
and immunity levels are controlled such that, at each location, the disturbance level resulting from the cumulative
emissions is lower than the immunity level for each device, equipment and system situated at this same location.
Note 2 to entry: The compatibility level may be phenomenon, time or location dependent.
[SOURCE: IEC 60050-161:1990, 161-03-10]

– 8 – IEC TR 61000-1-1:2023 © IEC 2023
3.1.2
(electromagnetic) compatibility margin
ratio of the immunity limit to the emission limit
Note 1 to entry: The compatibility margin is the product of the emission margin and the immunity margin
Note 2 to entry: If the levels are expressed in dB(. ), in the above margin definitions "difference” is used
instead of "ratio" and "sum" instead of "product".
[SOURCE: IEC 60050-161:1990, 161-03-17, modified – note 2 has been added.]
3.1.3
electromagnetic environment
totality of electromagnetic phenomena existing at a given location
Note 1 to entry: In general, this totality is time dependent and its description can need a statistical approach.
[SOURCE: IEC 60050-161:2018, 161-01-01]
3.1.4
electromagnetic disturbance
electromagnetic phenomenon that can degrade the performance of a device, equipment or
system, or adversely affect living or inert matter
Note 1 to entry: An electromagnetic disturbance may be an electromagnetic noise, an unwanted signal or a change
in the propagation medium itself
[SOURCE: IEC 60050-161:1990, 161-01-05]
3.1.5
electromagnetic interference
EMI
degradation in the performance of equipment or transmission channel or a system caused by
an electromagnetic disturbance
Note 1 to entry: Disturbance and interference are cause and effect, respectively.
Note 2 to entry: The English words “interference” and “disturbance” are often used indiscriminately.
[SOURCE: IEC 60050-161:2018, 161-01-06, modified – Note 1 and Note 2 have been revised.]
3.1.6
electromagnetic compatibility
EMC
ability of a device, equipment or system to function satisfactorily in its electromagnetic
environment without introducing intolerable electromagnetic disturbances to anything in that
environment
[SOURCE: IEC 60050-161:2018, 161-01-07, modified – the terms "device" and "equipment"
have been added to the definition.]
3.1.7
electromagnetic emission
phenomenon by which electromagnetic energy emanates from a source
[SOURCE: IEC 60050-161:2019, 161-01-08]

3.1.8
emission level (of a disturbing source)
level of a given electromagnetic disturbance emitted from a particular device, equipment or
system, measured in a specified way
[SOURCE: IEC 60050-161:1990, 161-03-11, modified – “measured in a specified way” has been
added.]
3.1.9
emission limit (from a disturbing source)
specified maximum emission level of a source of electromagnetic disturbance
[SOURCE: IEC 60050-161:1990, 161-03-12]
3.1.10
emission margin
ratio of the electromagnetic compatibility level to the emission limit
Note 1 to entry: If the levels are expressed in dB(. ), in the above margin definitions "difference” is used instead
of "ratio" and "sum" instead of "product".
[SOURCE: IEC 60050-161:1990, 161-03-13, modified – the note has been added.]
3.1.11
degradation (of performance)
undesired deviation in the operational performance of any device, equipment or system from its
intended performance
Note 1 to entry: The term “degradation” can apply to temporary or permanent failure
[SOURCE: IEC 60050-121:1990, 161-01-19]
3.1.12
disturbance level
level of an electromagnetic disturbance existing at a given location, which results from all
contributing disturbance sources
[SOURCE: IEC 60050-161:1990, 161-03-29]
3.1.13
immunity (to a disturbance)
ability of a device, equipment or system to perform without degradation in the presence of an
electromagnetic disturbance
[SOURCE: IEC 60050-161:1990, 161-01-20]
3.1.14
immunity level
maximum level of a given electromagnetic disturbance, incident in a specified way on a
particular device, equipment or system, at which no degradation of operation occurs
[SOURCE: IEC 60050-161:1990, 161-03-14]
3.1.15
immunity limit
minimum permissible immunity level

– 10 – IEC TR 61000-1-1:2023 © IEC 2023
Note 1 to entry: In some product/product family standards the term test level is used to express what is meant by
immunity limit.
3.1.16
immunity margin
ratio of the immunity limit to the electromagnetic compatibility level
Note 1 to entry: If the levels are expressed in dB(. ), in the above margin definitions "difference” is used instead
of "ratio" and "sum" instead of "product".
[SOURCE: IEC 60050-161:1990, 161-03-16, modified – the note has been added.]
3.1.17
level (of a time varying quantity)
magnitude value of a quantity, such as a power or a field quantity, measured and/or evaluated
in a specified manner during a specified time interval
Note 1 to entry: The level of a quantity can be expressed in logarithmic units, for example decibels with respect to
a reference value.
[SOURCE: IEC 60050-161:1990, 161-03-01]
3.1.18
(electromagnetic) susceptibility
inability of a device, equipment or system to perform without degradation in the presence of an
electromagnetic disturbance
Note 1 to entry: Susceptibility is a lack of immunity.
[SOURCE: IEC 60050-161:1990, 161-01-21]
3.2 Abbreviated terms
AC alternating current
DC direct current
EM electromagnetic
EMC electromagnetic compatibility
EMI electromagnetic interference
RF radio frequency
4 The electromagnetic environment
4.1 General
There are various approaches that can be used for describing the electromagnetic environment
at a considered location. Classification in terms of typical environmental locations such as
industrial, residential and commercial can have some meaning in that each of these tends to
imply some general characteristics of the electromagnetic environment on which compatibility
levels can be based. However, it is recognized that equipment not normally associated with a
particular environmental location class can indeed affect the electromagnetic environment at
any specific location.
For the above reason, the approach taken in this document is to indicate the electromagnetic
levels expected from particular sources or classes of sources. The level expected at a particular
location will be determined with reference to the sources existing at that location.
IEC TR 61000-2-5 provides a description of the electromagnetic environment with anticipated
disturbance levels for typical location classes.

At the same time, it is recognized that one cannot always identify all sources that can affect a
particular environment. Such is the case, for example, with conducted disturbances in a power
system generated at large distances, for example large distant nonlinear industrial loads or
unpredictable exceptionally severe lightning strokes. It is meaningful to make a distinction
between public supply and industrial or private networks.
The quality of the provided power supply at the point of common connection due to remote
users will depend upon the capacity of the network and the loads connected to it that an
individual consumer knows little about. Voltage fluctuations can be caused by load switching
as well as by system faults and lightning strokes. Within a consumer's system, residential or
industrial, the low frequency effects of local loads can be predicted. In general, one would
expect the remote sources to limit the quality of service delivered to a particular consumer
location, and that any given system needs to perform properly in the absence of local sources.
This is assuming that the quality of service is otherwise satisfactory. Local sources can be
expected to have more significant effects in possible system and device degradation.
4.2 Coupling between emitting and susceptible devices
The major reason for considering electromagnetic compatibility is the existence of devices
(equipment, systems) which show susceptibility to electromagnetic emission from other
devices.
Figure 1 – Coupling paths between emitting and susceptible devices
Emitting devices can have intentional emissions, such as a radio-frequency broadcasting signal,
or unintentional emissions. Through various coupling paths such emissions can reach the site
where a susceptible device is located as shown in Figure 1, thereby establishing the
electromagnetic environment for that device. The subdivisions shown in Figure 1 are important
for a description of the electromagnetic environment. Moreover, the technical possibilities
available to prevent or solve an interference problem are related to these subdivisions, as are
also the relevant EMC specifications.

– 12 – IEC TR 61000-1-1:2023 © IEC 2023
The susceptible device can be exposed to the electromagnetic environment via intentional
coupling paths, such as the aerial of a radio receiver, or via unintentional coupling paths such
as the recording head of a video tape recorder, a signal cable or a mains cable. Both types of
coupling paths, intentional and unintentional, can carry disturbances having frequency
components in the frequency band designated for the desired signal of the susceptible device,
and disturbances having components outside that band.
The disturbances received can be considered narrow band or broadband. For example, the
disturbance from a switched-mode power supply operating at 40 kHz and its harmonics is
narrow band when the bandwidth of the effected radio service is far broader than the bandwidth
of the disturbances.
5 Application of EMC terms and definitions
5.1 General
The definitions given in Clause 3 are basic conceptual definitions. When they are applied to
assign specific values to the levels in a particular case, several considerations are necessary.
A number of these are given in Clause 5, together with examples which will elucidate them. For
an interpretation of the various terms used, see Annex A and Annex B.
The basic devices or systems can be divided into two groups:
1) emitters – devices, equipment or systems which emit potentially disturbing voltages,
currents or fields, and
2) susceptible devices – devices, equipment or systems whose operation might be degraded
by those emissions.
Some devices can belong simultaneously to both groups.
5.2 Relation between various types of levels
5.2.1 Emissions and immunity level (and limit)
A possible combination of an emission level and an immunity level and their associated limits
as a function of some independent variable, for example the frequency, for a single type of
emitter and a single type of susceptible device, is illustrated in Figure 2.
In Figure 2, the emission level is always lower than its maximum permissible level (the emission
limit), and the immunity level is always higher than its minimum required level (the immunity
limit). In the illustrated scenario, the emitter and the susceptible device comply with their
specified limit. In addition, the immunity limit has been chosen to be higher than the emission
limit, and it has been assumed that the levels and limits are continuous functions of the
independent variable. These levels and limits can also be discrete functions of some
independent variable, see 5.2.3.1.
Further to the above, the following observations are noted:
a) By drawing the emission and immunity levels (and the associated limits) in one figure it is
assumed that only one particular disturbance is considered, unless it is clearly indicated
that different disturbances are considered and the relationship between the different
disturbances is also indicated.
b) Drawing the emission and immunity levels in one figure is only relevant when there is a good
interrelation between the specified way the emission level of the particular disturbance is
measured and the specified way that type of disturbance is incident on the equipment under
test. If this is the case, Figure 2 indicates an electromagnetically compatible situation.

Figure 2 – Limits and levels for a single emitter and susceptible device
as a function of some independent variable (e.g., frequency)
As shown in Figure 2, there is some margin between a measured level and its limit. This margin
might be called the "equipment design margin” and is an additional margin in the design to
ensure compliance with the limit if EMC testing is carried out. Although it is an important
consideration for manufacturers, this margin has neither been defined in IEC 60050-161 nor in
this document, as equipment design issues are the prerogative of the manufacturer. Emission
limits are often determined based on radio parameter considerations since radio coverage is
closely related to the noise that the radio receivers are able to cope with.
5.2.2 Compatibility level
The concept of compatibility level is illustrated in Figure 3. The solid blue lines indicate a
possible emission and immunity level for a single emitter and susceptible device. It is assumed
that only one particular disturbance is considered in Figure 3.

Figure 3 – Emission/immunity limits and compatibility levels, with an example of
emission/immunity levels for a single emitter and susceptible device as a function
of some independent variable (e.g., frequency)
Further to the above, the following observations are noted:

– 14 – IEC TR 61000-1-1:2023 © IEC 2023
a) The compatibility level, being a specified disturbance level, is expressed in the unit
corresponding to the emission limit. If the emission and immunity limits do not refer to the
same disturbance (see 5.2.3.2 below), the compatibility level can be expressed in the unit
corresponding to either the emission level or the immunity level.
b) If the electromagnetic environment is controllable, a compatibility level can be chosen first.
Following this, emission and immunity limits are derived from this level in order to ensure
an acceptable, high probability of EMC in that environment.
c) This consideration indicates that in a controllable environment, EMC can be achieved in the
most cost-effective way by initially choosing the compatibility level on financial and technical
grounds in order to realize appropriate emission and immunity limits for all equipment (to
be) installed in that environment.
d) If the electromagnetic environment is uncontrollable, the level is chosen on the basis of
existing or expected disturbance levels. However, emission and immunity limits have still to
be assessed, to ensure that the existing or expected disturbance levels will not increase
when new equipment is installed and that such equipment is sufficiently immune. If tests or
calculations indicate that an existing situation has to be improved because of the financial
and technical consequences of the chosen limits, the compatibility level has to be adjusted
and consequently, the emission and immunity limits. In the long run the adjusted
compatibility level will then result in a more cost-effective solution for the total system.
e) The determination of limits from the compatibility level is governed by probability consi-
derations, discussed in 5.3. In general, these limits are not at equal distances from the
compatibility level, see also 5.3. In Clause A.7, the compatibility level is determined for an
idealised situation, where the probability density functions are assumed to be known.
5.2.3 Examples to illustrate the concepts of using levels and limits
5.2.3.1 Emission and immunity levels and limits
Let one assume an immunity limit has to be determined with regard to disturbances at the
harmonics of the mains frequency, for equipment connected to the public low-voltage network.
In addition, let one assume that for the equipment under consideration the mains network only
serves as an energy supply (no mains signalling, etc.). As this example is only an illustration of
several aspects, the discussions will be limited to the odd harmonics.
The level of the harmonic disturbances in a public network is not readily controllable. Therefore,
, from IEC 61000-2-2. In
the discussions start by taking the compatibility level, U
c
IEC 61000-2-2, that level is given as a percentage of the rated voltage, and this approach is
followed here (see Figure 4).
To ensure an acceptable, high probability of EMC, two requirements have to be met:
a) At each frequency, the disturbance voltage level, U , in the network, i.e., the disturbance
d
voltage resulting from all disturbance sources connected to that network, is likely to have a
high probability of fulfilling the relation U < U at the locations where U is specified and
d c c
for most of the time.
b) At each frequency, there is a high probability that the immunity level U of each appliance
i
connected to the network fulfils the relation U > U .
i d
The first requirement is largely met by taking the compatibility levels from IEC 61000-2-2.

Figure 4 – Compatibility levels U for the odd harmonics in a public low-voltage
c
network and examples of associated emission and immunity limits
Also given in Figure 4 is an emission limit of a single disturbance source. If it is known how
many sources contribute to U and it is also known how the harmonic disturbances add, then
d
an estimate can be made of U in that network. This is of interest in cases where the levels are
d
controllable because this estimate leads to a first choice of U for that particular network. Of
c
course, the final choice is also determined by the immunity requirements.
The emission limit is also given to illustrate a problem. In IEC 61000-3-2:2018, Table 1, the
emission limit is given as the maximum permissible harmonic current in amperes. However, the
presentation in Figure 4 requires an emission limit expressed in a percentage of the rated
voltage. The latter limit can be derived from the first limit when the network impedance is known.
In this example it is simply assumed that this impedance is equal to the reference impedance,
given in IEC 61000-3-2. In line with the above reasoning, the maximum harmonic voltage ratios
given in IEC 61000-3-2:2018 and IEC 61000-3-2:2018/AMD1:2020, Annex A, are plotted in
Figure 4. Note that in IEC 61000-2-2, a distinction is made between the odd harmonics that are
a multiple of 3 and those that are not multiples of 3. In IEC 61000-3-2, this distinction is not
made for the emission limit.
The actual disturbance level strongly depends on the number of disturbance sources, i.e., on
the number of operating appliances connected to the network. In a public low-voltage network
the number of sources that may contribute significantly is generally much larger at the low-
frequency end than at the high-frequency end. Hence, the uncertainty about the actual
disturbance level at lower frequencies is much greater than that at higher frequencies. This is
reflected in Figure 4, where at the low-frequency end the distance between the emission limit
(for a single device) and the compatibility level (which takes the superposition of disturbances
into account) is much larger than the distance at the high-frequency end. This distance, i.e.,
the emission margin, will be discussed in 5.3.
To fulfil the second requirement a sufficiently strict immunity limit is needed, of which an
, i.e., an immunity margin, is
example is given in Figure 4. A distance between this limit and U
c
needed because:
– 16 – IEC TR 61000-1-1:2023 © IEC 2023
a) there is still a small probability that at a certain location and during a certain time interval
the disturbance level will be above the compatibility level; and
b) the internal impedance Z of the disturbance source used in the immunity test will not, in
i
general, be equal to the internal impedance of the actual network. (A discussion about the
value of Z to be used in the immunity test is beyond the scope of this document.)
i
It is possible to specify a continuous immunity limit as illustrated in Figure 4. This has the
advantage that the even harmonics, the inter-harmonics and all other disturbances in the given
frequency range can be considered. A continuous function could be chosen as it was assumed
at the beginning that the network served only as an energy supply, i.e., no mains signalling is
present. For test purposes there can be a need to convert the percentages in which the immunity
limit is given in Figure 4 to absolute values. An example for the derivation of disturbance
degrees and immunity limits for the phenomenon of high frequency radiated disturbances is
given in Annex C.
5.2.3.2 Compatibility level
There are cases where emission, compatibility and immunity levels and limits are expressed in
different units.
Let one consider the immunity to RF fields of equipment having dimensions that are small
compared to the wavelength of that RF field. It is well known that the equipment immunity is
determined largely by the immunity to common-mode currents induced in the leads connected
to that equipment. Hence, the interrelated radiated and conducted phenomena will be taken
into consideration when attempting to achieve EMC.
With regard to 5.2.1, as the relationship between the field strength and the e.m.f. has been
established in other studies, it is possible to express the emission level in Figure 2 as an electric
field strength (for example in dB (μV/m) and the immunity level as the e.m.f. (for example in
dB (μV)) of a disturbing source, for example, a test generator.
With regard to Figure 3 and the foregoing considerations, the compatibility level can now be
expressed in dB (μV/m) or in dB (μV). It is clear that this level depends on the chosen unit. In
addition, the choice of the compatibility level can also be determined by the susceptibility
properties of the susceptible device concerned. If the EMI problem to be prevented concerns
RF-field demodulation, the degradation is (in first order approximation) proportional to the
square of the RF disturbance level. Hence, the immunity margin may be chosen to be larger
than the emission margin.
5.3 Probability aspects and margins
5.3.1 Compatibility levels and uncertainties
If the emission and immunity tests have been designed in such a way that there is a good
correlation with the electromagnetic phenomena existing, the situation in Figure 5 represents
an electromagnetically compatible situation for the single emitter and susceptible device under
consideration.
---------------------- P
...