EN 61000-4-31:2017

SLOVENSKI STANDARD
01-april-2017
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Electromagnetic Compatibility (EMC) - Part 4-31: Testing and measurement techniques -
AC mains ports broadband conducted disturbance immunity test
Compatibilité électromagnétique (CEM) - Partie 4-31: Techniques d'essai et de mesure -
Essai d'immunité aux perturbations conduites à large bande sur les accès d'alimentation
secteur en courant alternatif
Ta slovenski standard je istoveten z: EN 61000-4-31:2017
ICS:
33.100.20 Imunost Immunity
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD EN 61000-4-31

NORME EUROPÉENNE
EUROPÄISCHE NORM
February 2017
ICS 33.100.20
English Version
Electromagnetic compatibility (EMC) -
Part 4-31: Testing and measurement techniques - AC mains
ports broadband conducted disturbance immunity test
(IEC 61000-4-31:2016)
Compatibilité électromagnétique (CEM) -  Elektromagnetische Verträglichkeit (EMV) -
Partie 4-31: Techniques d'essai et de mesure - Essai Teil 4-31: Prüf- und Messverfahren - Prüfung der
d'immunité aux perturbations conduites à large bande sur Störfestigkeit gegen leitungsgeführte breitbandige
les accès d'alimentation secteur en courant alternative Störgrößen an Wechselstrom-Netzanschlüssen
(IEC 61000-4-31:2016) (IEC 61000-4-31:2016)
This European Standard was approved by CENELEC on 2016-09-01. CENELEC members are bound to comply with the CEN/CENELEC
Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration.
Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN-CENELEC
Management Centre or to any CENELEC member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by translation
under the responsibility of a CENELEC member into its own language and notified to the CEN-CENELEC Management Centre has the
same status as the official versions.
CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus, the Czech Republic,
Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,
Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden,
Switzerland, Turkey and the United Kingdom.

European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2017 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.
Ref. No. EN 61000-4-31:2017 E
European foreword
The text of document 77B/758/FDIS, future edition 1 of IEC 61000-4-31, prepared by SC 77B “High
frequency phenomena” of IEC/TC 77 “Electromagnetic compatibility" was submitted to the
IEC-CENELEC parallel vote and approved by CENELEC as EN 61000-4-31:2017.

The following dates are fixed:
(dop) 2017-08-24
• latest date by which the document has to be
implemented at national level by
publication of an identical national
standard or by endorsement
• latest date by which the national (dow) 2020-02-24
standards conflicting with the
document have to be withdrawn
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CENELEC [and/or CEN] shall not be held responsible for identifying any or all such
patent rights.
Endorsement notice
The text of the International Standard IEC 61000-4-31:2016 was approved by CENELEC as a
European Standard without any modification.
In the official version, for Bibliography, the following note has to be added for the standard indicated:

CISPR 16-1-2 NOTE Harmonized as EN 55016-1-2.
Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications

The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including any amendments) applies.

NOTE 1 When an International Publication has been modified by common modifications, indicated by (mod), the relevant
EN/HD applies.
NOTE 2 Up-to-date information on the latest versions of the European Standards listed in this annex is available here:
www.cenelec.eu
Publication Year Title EN/HD Year

IEC 60050-161 -  International Electrotechnical Vocabulary - -
(IEV) -
Chapter 161: Electromagnetic compatibility
IEC 61000-4-6 2013 Electromagnetic compatibility (EMC) - EN 61000-4-6 2014
Part 4-6: Testing and measurement
techniques - Immunity to conducted
disturbances, induced by radio-frequency
fields
IEC 61000-4-31 ®
Edition 1.0 2016-07
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
BASIC EMC PUBLICATION
PUBLICATION FONDAMENTALE EN CEM

Electromagnetic compatibility (EMC) –

Part 4-31: Testing and measurement techniques – AC mains ports broadband

conducted disturbance immunity test

Compatibilité électromagnétique (CEM) –

Partie 4-31: Techniques d'essai et de mesure – Essai d'immunité aux

perturbations conduites à large bande sur les accès d'alimentation secteur en

courant alternatif
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 33.100.20 ISBN 978-2-8322-3564-5

– 2 – IEC 61000-4-31:2016 © IEC 2016
CONTENTS
FOREWORD . 5
INTRODUCTION . 7
1 Scope and object . 8
2 Normative references. 8
3 Terms and definitions . 8
4 General . 10
5 Test levels . 11
6 Test equipment and level setting procedures . 13
6.1 Test generator . 13
6.2 Coupling and decoupling devices . 14
6.2.1 General . 14
6.2.2 CDND for the port under test . 15
6.2.3 Coupling/decoupling networks (CDNs) for cables that are not under test . 15
6.3 Verification of the test systems . 17
6.3.1 General . 17
6.3.2 Verification procedure of test generator flatness . 17
6.3.3 Verification procedure of the insertion loss of the CDND using
transformer jigs . 18
6.3.4 Insertion loss of the injection coupling system . 20
6.4 Test level setting procedure . 21
6.4.1 General . 21
6.4.2 Setting of the output level at the EUT port of the CDND . 21
7 Test set-up and injection methods . 22
7.1 Test set-up. 22
7.2 EUT comprised of a single unit . 22
7.3 EUT comprised of several units . 23
7.4 CDN and CDND termination application . 25
8 Test procedure . 26
9 Evaluation of the test results . 27
10 Test report. 27
Annex A (informative) Measurement uncertainty of the power spectral density test
level . 29
A.1 General . 29
A.2 Uncertainty budgets for test methods . 29
A.2.1 General symbols . 29
A.2.2 Definition of the measurand . 29
A.2.3 MU contributors of the measurand . 29
A.2.4 Input quantities and calculation examples for expanded uncertainty . 30
A.3 Expression of the calculated measurement uncertainty and its application . 31
Annex B (informative) Rationale for the selection of the preferred broadband source –
Information on test signal generation . 33
B.1 General . 33
B.2 Principles of band-limited broadband signal generation . 33
B.2.1 General . 33
B.2.2 (True) random noise generation. 33

IEC 61000-4-31:2016 © IEC 2016 – 3 –
B.2.3 Pseudo-random noise sequence . 34
B.2.4 Impulse . 38
B.2.5 OFDM scheme . 40
B.3 Selection of the preferred broadband source . 42
Bibliography . 43

Figure 1 – Immunity test to broadband conducted disturbances . 11
Figure 2 – Example of voltage spectrum of a broadband test signal measured with a
120 kHz resolution bandwidth . 13
Figure 3 – Principle of the test generator . 14
Figure 4 – Example of simplified diagram for the circuit of CDND . 15
Figure 5 – Example of coupling and decoupling network for power ports other than AC
mains . 16
Figure 6 – Test set-up regarding test generator flatness and typical test signal . 18
Figure 7 – Typical circuit diagram of the transformer jig showing 50 Ω side and 100 Ω
side of the transformer and 2 pcs 0,1 µF coupling capacitors . 18
Figure 8 – Transformer jig specifications . 20
Figure 9 – Example of the set-up geometry to verify the insertion loss of the injection
coupling system . 20
Figure 10 – Set-up for the evaluation of the total insertion loss of the injection
coupling system . 21
Figure 11 – Set-up for level setting . 22
Figure 12 – Example of test set-up for an EUT comprised of a single unit (top view) . 23
Figure 13 – Example of a test set-up for an EUT comprised of several units (top view) . 24
Figure 14 – Immunity test to a 2-port EUT (when only CDNDs can be used) . 26
Figure A.1 – Example of influences upon the power spectral density test level using a
CDND . 30
Figure B.1 – White noise source . 34
Figure B.2 – Principle of band-limited broadband signal generation with an arbitrary
waveform generator . 35
Figure B.3 – Signal spectrum of a band-limited pseudo-random noise signal (measured
with a 120 kHz resolution bandwidth) . 36
Figure B.4 – Extract of the band-limited pseudo noise signal in time domain (measured
with an oscilloscope) . 37
Figure B.5 – Signal spectrum of the band-limited pseudo noise signal without an anti-
alias filter . 37
Figure B.6 – Extract of the signal spectrum of a band-limited pseudo noise signal
(measured with a 200 Hz resolution bandwidth) . 38
Figure B.7 – Signal spectrum of a band-limited impulse signal (measured with a
120 kHz resolution bandwidth) . 39
Figure B.8 – Extract of the band-limited impulse signal in time domain (measured with
an oscilloscope) . 39
Figure B.9 – Extract of the signal spectrum of a band-limited impulse signal
(measured with a 200 Hz resolution bandwidth) . 40
Figure B.10 – Signal spectrum of an OFDM signal (measured with a 120 kHz
resolution bandwidth) . 41
Figure B.11 – Extract of the signal spectrum of an OFDM signal (measured with a
200 Hz resolution bandwidth) . 41

– 4 – IEC 61000-4-31:2016 © IEC 2016
Figure B.12 – Signal spectrum of an OFDM signal with an amplitude step at 30 MHz
(measured with a 120 kHz resolution bandwidth) . 42

Table 1 – Test levels . 12
Table 2 – Characteristics of the test generator . 14
Table 3 – Specification of the main parameters of the CDND for current ≤ 16 A . 15
Table 4 – Usage of CDNs. 16
Table A.1 – CDND level setting process . 31
Table B.1 – Comparison of white noise signal generation methods . 42

IEC 61000-4-31:2016 © IEC 2016 – 5 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
ELECTROMAGNETIC COMPATIBILITY (EMC) –

Part 4-31: Testing and measurement techniques –
AC mains ports broadband conducted disturbance immunity test

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.
International Standard IEC 61000-4-31 has been prepared by subcommittee 77B: High-
frequency phenomena, of IEC technical committee 77: Electromagnetic compatibility.
This standard forms Part 4-31 of the IEC 61000 series. It has the status of a basic EMC
publication in accordance with IEC Guide 107.
The text of this standard is based on the following documents:
FDIS Report on voting
77B/758/FDIS 77B/760/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.

– 6 – IEC 61000-4-31:2016 © IEC 2016
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 publication will remain unchanged until
the stability date indicated on the IEC website 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.
IMPORTANT – The 'colour inside' logo on the cover page of this publication 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.
IEC 61000-4-31:2016 © IEC 2016 – 7 –
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).
This part is an International Standard which gives immunity requirements and test procedure
related to conducted broadband disturbances.

– 8 – IEC 61000-4-31:2016 © IEC 2016
ELECTROMAGNETIC COMPATIBILITY (EMC) –

Part 4-31: Testing and measurement techniques –
AC mains ports broadband conducted disturbance immunity test

1 Scope and object
This part of IEC 61000 relates to the conducted immunity of electrical and electronic
equipment to electromagnetic disturbances coming from intended and/or unintended
broadband signal sources in the frequency range 150 kHz up to 80 MHz.
The object of this standard is to establish a common reference to evaluate the immunity of
electrical and electronic equipment when subjected to conducted disturbances caused by
intended and/or unintended broadband signal sources on AC mains ports. The test method
documented in this standard describes a consistent method to assess the immunity of an
equipment or system against a defined phenomenon.
Equipment not having at least one AC mains port is excluded. The power ports not intended
to be connected to AC mains distribution networks are not considered as “AC mains ports”
and therefore are excluded.
This standard is applicable only to single phase equipment having rated input current ≤ 16 A;
the application of the broadband disturbance to multiple phase equipment and/or equipment
with rated input current > 16 A is under consideration.
NOTE As described in IEC Guide 107, this standard is a basic EMC publication for use by product committees of
the IEC. As also stated in Guide 107, the IEC product committees are responsible for determining whether this
immunity test standard is to be applied or not, and if applied, they are responsible for determining the appropriate
test levels and performance criteria. TC 77 and its sub-committees are prepared to co-operate with product
committees in the evaluation of the value of particular immunity tests for their products.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and
are indispensable for its application. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any
amendments) applies.
IEC 60050-161, International Electrotechnical Vocabulary (IEV) – Part 161: Electromagnetic
compatibility (available at www.electropedia.org)
IEC 61000-4-6:2013, Electromagnetic compatibility (EMC) – Part 4-6: Testing and
measurement techniques – Immunity to conducted disturbances, induced by radio-frequency
fields
3 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 60050-161 as well
as the following apply.
3.1
artificial hand
electrical network simulating the impedance of the human body under average operational
conditions between a hand-held electrical appliance and earth

IEC 61000-4-31:2016 © IEC 2016 – 9 –
Note 1 to entry: The construction should be in accordance with CISPR 16-1-2.
[SOURCE: IEC 60050-161:1990, 161-04-27, modified – A note to entry has been added.]
3.2
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
3.3
common mode impedance
asymmetrical mode impedance between a cable attached to a port and the reference ground
plane (RGP)
Note 1 to entry: This note applies to the French language only.
3.4
coupling network
electrical circuit for transferring energy from one circuit to another with a defined impedance
Note 1 to entry: Coupling and decoupling devices can be integrated into one box (coupling/decoupling network
(CDN)) or they can be in separate networks.
3.5
coupling/decoupling network
CDN
electrical circuit incorporating the functions of both the coupling and decoupling networks
3.6
coupling/decoupling network for differential mode coupling
CDND
electrical circuit incorporating the functions of both the coupling and decoupling networks that
injects the signal primarily in differential mode
3.7
decoupling network
decoupling device
electrical circuit for preventing test signals applied to the EUT from affecting other devices,
equipment or systems that are not under test
3.8
differential mode impedance
symmetrical mode impedance between L and N of an AC mains port
3.9
longitudinal conversion loss
LCL
measure, in a one- or two-port network, of the degree of unwanted transverse (symmetric
mode) signal produced at the terminals of the network due to the presence of a longitudinal
(asymmetric mode) signal on the connecting leads
Note 1 to entry: LCL is a ratio expressed in dB.
[SOURCE: ITU-T O.9:1999, 4.1, modified – The definition has been rephrased and the
parentheses have been added.]
– 10 – IEC 61000-4-31:2016 © IEC 2016
3.10
orthogonal frequency-division multiplexing
OFDM
digital multi-carrier modulation scheme, which uses a large number of closely-spaced
orthogonal sub-carriers
Note 1 to entry: See ITU-R BT.1306-7:2015.
Note 2 to entry: This note applies to the French language only.
3.11
test generator
generator capable of generating the required test signal
Note 1 to entry: The generator may include the following: white noise source, modulation source, attenuators,
broadband power amplifier and filters.
Note 2 to entry: See Figure 3.
3.12
voltage standing wave ratio
VSWR
ratio of a maximum to an adjacent minimum voltage magnitude along the line
4 General
The source of disturbance covered by this standard is basically an intended and/or
unintended conducted broadband disturbance superimposed on the mains line to the AC
mains port of the EUT.
For example, the signals generated by PLT systems are intentionally-generated broadband
disturbances, whereas other electrical and electronic equipment connected to the AC mains
network may emit unintentional broadband disturbances.
NOTE Power line telecommunications (PLT) is also known as broadband power line (BPL) and as power line
communication (PLC).
Even when the broadband signal is intended to be differential, the unbalance of the mains
converts part of it into a common mode signal. To take this phenomenon into account, the
disturbance signal is injected through a coupling/decoupling network for differential mode
coupling (CDND) having a longitudinal conversion loss (LCL) similar to a typical mains
distribution network (see Figure 1).
The characteristics of the CDND are given in 6.2.

IEC 61000-4-31:2016 © IEC 2016 – 11 –
Test
L
L
generator
A2
AE T EUT
CDN CDND
RGP
h ≥ 30 mm h ≥ 30 mm
0,1 m ± 0,05 m support
IEC
Key
A2 optional power attenuator
L 0,1 m ≤ L ≤ 0,3 m
T termination 50 Ω
CDND coupling and decoupling network for injection of the test signal primarily in differential mode
CDN coupling and decoupling network as prescribed in IEC 61000-4-6
Figure 1 – Immunity test to broadband conducted disturbances
With the EUT connected to the CDND, a power attenuator (A2 in Figure 1) of 3 dB or larger
shall be inserted between the test generator and the CDND, unless it can be shown that the
voltage standing wave ratio (VSWR) due to the mismatch between the test generator and the
CDND is ≤ 2.
5 Test levels
The level of the broadband test signal to be applied to the AC power ports under test over the
selected frequency range of interest is defined by its power spectral density (PSD) expressed
in dBm/Hz and shall be selected from column 2 of Table 1.
For convenience, the test levels are also given for the whole frequency range from 150 kHz to
80 MHz in equivalent voltage spectrum expressed in dB (µV)/100 kHz (see column 3 of
Table 1), and in total forward power expressed in dBm (see column 4 of Table 1).
These values were derived in a 50 Ω system using Formula (1) and need to be recalculated if
a different or reduced frequency range is selected for the test.
For more details regarding the verification of test levels see also Figure 11.

– 12 – IEC 61000-4-31:2016 © IEC 2016
Table 1 – Test levels
Frequency range 150 kHz to 80 MHz
Level Power spectral density Equivalent voltage Total forward power
spectrum density
dBm/Hz dBm
dB (µV)/100 kHz
1 –60 97 19
2 –50 107 29
3 –40 117 39
a
x Special Special Special
NOTE The requirements are in column 2; columns 3 and 4 are added for convenience.
a
"x" can be any level, above, below or in between the others. The level has to be specified in the dedicated
equipment specification.
An example of a broadband test signal is shown in Figure 2.
In particular cases of intentional broadband disturbances, product committees may specify a
suitable limited frequency range for testing the EUT.
The total forward power for a given power spectral density and selected frequency range can
be calculated using Formula (1).
f − f (1)
stop start
P = P + 10log( )
T F SD
1 Hz
where
P is the total forward power, in dBm;
TF
P is the power spectral density, in dBm/Hz;
SD
f is the upper frequency of the test frequency band, in Hz; and
stop
f is the lower frequency of the test frequency band, in Hz.
start
The setting procedure of the test levels at the EUT port of the coupling device (CDND) is
described in 6.4.
IEC 61000-4-31:2016 © IEC 2016 – 13 –
0 10 20 30 40 50 60 70 80 90 100
Frequency (MHz)
IEC
Figure 2 – Example of voltage spectrum of a broadband test signal
measured with a 120 kHz resolution bandwidth
6 Test equipment and level setting procedures
6.1 Test generator
The test generator (see Figure 3) includes all the necessary equipment and to provide a
broadband input to the CDND that causes the required test signal to be applied to the EUT
with the required level, frequency range, modulation, etc.
A typical arrangement comprises the following items which may be separate or integrated into
one or more test instruments:
• a white noise source, G1, capable of generating a broadband signal over the frequency
band of interest. The parameters can be set by manual control or programmable control
(e.g. frequency band, amplitude). For more details, see Annex B.
• a pulse modulation capability of 1 Hz and 2 Hz (50 % duty cycle);
• a variable attenuator, A1, (typically from 0 dB to 40 dB) to control the output level of the
generated disturbing source, and which is optional;
• an RF switch, S1, by which the disturbing broadband signal can be switched on and off
when evaluating the immunity of the EUT. S1 may be included in G1 and is optional;
• a broadband power amplifier, PA, which may be necessary to amplify the signal if the
output power of the G1 is insufficient;
• a low-pass filter (LPF), and/or a high-pass filter (HPF), which may be necessary to avoid
interference caused by (higher order or sub-) harmonics with some types of EUT, for
example RF receivers. When required, they shall be inserted between the output of the
broadband power amplifier, PA, and the coupling device (CDND).
The characteristics of the test generator are given in Table 2.
Level, dB (µV)
– 14 – IEC 61000-4-31:2016 © IEC 2016
Table 2 – Characteristics of the test generator
50 Ω typical, VSWR < 2
Output impedance
Within 150 kHz and 80 MHz or capable of covering the
Broadband signal flatness
frequency band of interest. The flatness of the output
signal shall be within ± 3 dB.
The output of the test generator shall be at least 20 dB
Out-of-band contribution above 80 MHz
below the specified test level for all frequencies above
100 MHz.
Between 80 MHz and 100 MHz the output of the test
generator shall not be greater than 3 dB above the
target signal level.
This contribution is not significant.
Out-of-band contribution below 150 kHz
If a product committee selects a dedicated frequency range different from 150 kHz to 80 MHz, then the
frequency limits for out-of-band contribution should be adjusted accordingly. For example, the out-of-band
contribution to the test signal at the output of the test generator should be reduced by at least 20 dB at
37,5 MHz if 30 MHz is chosen as the maximum frequency of the intended test signal.

G1 T1 S1 PA LPF/HPF
(optional)
White noise Broadband
source power amplifier
IEC
Key
G1 White noise source T1 Variable attenuator
PA Broadband power amplifier
LPF/HPF Low-pass filter and/or high-pass filter (optional) S1 RF switch
Figure 3 – Principle of the test generator
6.2 Coupling and decoupling devices
6.2.1 General
Coupling devices shall be used to apply the broadband test signal over the frequency range of
interest, with a defined common mode and differential mode impedance at the EUT port under
test.
Decoupling devices shall be used to prevent the other devices, equipment and systems that
are not under test from being disturbed by the test signal.
The coupling and decoupling devices can be combined into one box (a coupling/decoupling
network) or can consist of several parts. The preferred coupling and decoupling devices are
CDNDs for AC ports and CDNs for all other ports, this is to ensure reproducibility of the test
and protection of the AE.
Coupling and decoupling devices shall be used for the following two purposes:
• CDNDs shall be used for the purpose of applying the broadband test signal into the AC
mains port under test of the EUT and, where applicable, for decoupling or terminating the
AC cables not under test.
• CDNs shall be used for the purpose of decoupling or terminating all other cables (other
than AC cables) not under test.

IEC 61000-4-31:2016 © IEC 2016 – 15 –
6.2.2 CDND for the port under test
A CDND combines the coupling and decoupling functions in one box and is used to inject the
broadband test signal into the AC mains port of the EUT. The CDND shall have a longitudinal
conversion loss (LCL) of 16 dB in order to inject the common mode signal as well as the
differential mode signal simultaneously. Table 3 and Figure 4 show the basic requirements for
CDND and an example of a simplified diagram, respectively.
Table 3 – Specification of the main parameters of the CDND for current ≤ 16 A
Common mode Differential mode
Parameter
(L to N)
(L + N to PE)
Frequency range 150 kHz to 80 MHz 150 kHz to 80 MHz
Impedance (EUT port)
25 Ω ± 3 Ω 100 Ω ± 25 Ω
0° ± 25° 0° ± 25°
Insertion loss (RF input port – EUT) –
3 dB ± 1 dB
Isolation (AC mains port – EUT port)
> 15 dB > 15 dB
Longitudinal conversion loss (EUT port) 16 dB ± 3 dB

RF input port
L L
N EUT port
AC mains N
PE PE
IEC
L, N and PE are mains terminal connections
Figure 4 – Example of simplified diagram for the circuit of CDND
6.2.3 Coupling/decoupling networks (CDNs) for cables that are not under test
6.2.3.1 General
These networks comprise the coupling and decoupling circuits in one box. An example of a
coupling and decoupling network for the use on power ports (other than AC mains) is given in
Figure 5. Table 4 summarizes the usage of the different types of CDNs as outlined in
IEC 61000-4-6:2013, Annex D. The CDNs selected shall not unduly affect the functional
signals. Constraints on such effects may be specified in the product standards.

– 16 – IEC 61000-4-31:2016 © IEC 2016
The CDNs used in 6.2.3 for decoupling circuits or for defining the common mode impedance
of the EUT shall be as specified in IEC 61000-4-6.
Table 4 – Usage of CDNs
Line type Examples CDN-type
Power ports (other than AC mains) 24 V DC in industrial installations, CDN-Mx (see IEC 61000-4-6:2013,
and earth connection earth connection Figure D.2)
Screened cables Coaxial cables, cables used for CDN-Sx (see IEC 61000-4-6:2013,
LAN- and USB connections. Cables Figure D.1)
for audio systems
Unscreened balanced lines ISDN-lines, telephone lines CDN-Tx (see IEC 61000-4-6:2013,
Figures D.4, D.5, D.7 and Annex H)
Unscreened unbalanced lines Any line not belonging to other CDN-AFx or CDN-Mx (see
groups IEC 61000-4-6:2013, Figures D.3
and D.6)
RF Input port
PE
AE port N
EUT port
L
IEC
L, N and PE are mains terminal connections
Figure 5 – Example of coupling and decoupling network
for power ports other than AC mains
6.2.3.2 CDNs for power supply lines other than AC mains
Coupling/decoupling networks such as CDN-M1, CDN-M2 and CDN-M3 as prescribed in
IEC 61000-4-6 shall be used for all power supply connections except the AC mains ports.
6.2.3.3 Unscreened balanced lines
For coupling and decoupling signals to an unscreened cable with balanced lines, CDN-T2,
CDN-T4 or CDN-T8 shall be used as specified in IEC 61000-4-6:
• CDN-T2 for a cable with 1 symmetrical pair (2 wires);
• CDN-T4 for a cable with 2 symmetrical pairs (4 wires);
• CDN-T8 for a cable with 4 symmetrical pairs (8 wires).

IEC 61000-4-31:2016 © IEC 2016 – 17 –
6.2.3.4 Coupling and decoupling for unscreened unbalanced lines
For coupling and decoupling signals to an unscreened cable with unbalanced lines, a suitable
CDN-X as defined in IEC 61000-4-6 can be used, for example CDN-AF2 for two wires or
CDN-AF8 for 8 wires.
6.2.3.5 Coupling and decoupling for screened cables
For coupling and decoupling signals to a screened cable, for example, CDN-S1 can be used
as prescribed in IEC 61000-4-6.
6.2.3.6 Decoupling networks
The decoupling network generally comprises several inductors to create and maintain a high
impedance value over the testing frequency range. This inductance determined by the ferrite
material used shall be at least 280 µH at 150 kHz.
The reactance shall remain high, ≥ 260 Ω up to 24 MHz and ≥ 150 Ω above 24 MHz. The
inductance can be achieved either by having a number of windings on ferrite toroids or by
using a number of ferrite toroids over the cable (usually as a clamp-on tube).
NOTE The specification for clamps is given in IEC 61000-4-6.
The CDNs can be used as decoupling networks with the RF input port left unloaded. When
CDNs are used in this way, they shall meet the requirements of IEC 61000-4-6.
6.3 Verification of the test systems
6.3.1 General
The test system (including the test generator and the CDND) shall have the capability to apply
a constant and flat broadband test signal to the AC mains port of the EUT over the test
frequency range.
The characteristics of the test generator and the CDND are described in 6.1 and 6.2.2 and
parameters are given in Tables 2 and 3 respectively.
The verification of the flatness and level setting of the broadband test signal applicable to the
EUT are described in 6.3.2 to 6.4.
6.3.2 Verification procedure of test generator flatness
The broadband signal provided by the test generator to the CDND shall satisfy the flatness
requirement of ± 3dB over the test frequency range.
The verification of the signal flatness over the test frequency range shall be performed using
a spectrum analyser and measured in a resolution bandwidth of (100 ± 30) kHz.
The measurement set-up is illustrated in Figure 6a), and the typical output test generator
signal is illustrated in Figure 6b).
NOTE Information on test signal generation is given in Annex B.
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