IEC 61000-4-18:2019

Electromagnetic compatibility (EMC) - Part 4-18: Testing and measurement techniques - Damped oscillatory wave immunity test

IEC 61000-4-18: 2019 focuses on the immunity requirements and test methods for electrical and electronic equipment, under operational conditions, with regard to:
a) repetitive slow damped oscillatory waves occurring mainly in power, control and signal cables installed in high voltage and medium voltage (HV/MV) substations;
b) repetitive fast damped oscillatory waves occurring mainly in power, control and signal cables installed in gas insulated substations (GIS) and in some cases also air insulated substations (AIS) or in any installation due to high-altitude electromagnetic pulse (HEMP) phenomena.
The object of this document is to establish a common and reproducible reference for evaluating the immunity of electrical and electronic equipment when subjected to damped oscillatory waves on supply, signal, control and earth ports. The test method documented in this part of IEC 61000 describes a consistent method to assess the immunity of an equipment or system against a defined phenomenon. NOTE As described in IEC Guide 107, this 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 applied or not, and if applied, they are responsible for determining the appropriate test levels and performance criteria. The document defines:
test voltage and current waveforms;
ranges of test levels;
test equipment;
calibration and verification procedures of test equipment;
test setups;
test procedure.
This second edition cancels and replaces the first edition published in 2006 and its Amendment 1:2010. This edition constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition:
a) addition of a mathematical modelling of damped oscillatory wave waveform;
b) new Annex B on measurement uncertainty;
c) addition high speed CDN;
d) addition of calibration procedures for CDNs;
e) addition of the use of the capacitive coupling clamp on interconnection lines for fast damped oscillatory waves;
f) addition of a test procedure for DC/DC converters in case the CDN does not work;
g) new Annex C on issues relating to powering EUTs having DC/DC converters at the input.
Keywords: immunity requirements and test methods for electrical and electronic equipment
The contents of the corrigendum of August 2019 have been included in this copy.

Compatibilité électromagnétique (CEM) - Partie 4-18: Techniques d'essai et de mesure - Essai d'immunité à l'onde oscillatoire amortie

IEC 61000-4-18: 2019 traite des exigences d'immunité et des méthodes d'essai des matériels électriques et électroniques dans des conditions d'exploitation, vis-à-vis:
a) des ondes oscillatoires amorties lentes répétitives se manifestant principalement sur les câbles d’alimentation, de commande et de signal installés dans les postes à haute et à moyenne tension (HT/MT);
b) des ondes oscillatoires amorties rapides répétitives se produisant principalement sur les câbles d'alimentation, de commande et de signal installés dans les postes métalliques sous enveloppes à isolation gazeuse (GIS) et dans certains cas également dans les postes à isolation par air (AIS) ou toute installation du fait des phénomènes d’impulsion électromagnétique à haute altitude (IEMN-HA).
Le présent document a pour objet d'établir une référence commune reproductible dans le but d'évaluer l’immunité des matériels électriques et électroniques, quand ils sont soumis aux ondes oscillatoires amorties sur des accès d’alimentation, de signal, de commande et par les bornes de terre. La méthode d'essai documentée dans cette partie de l’IEC 61000 décrit une méthode logique en vue d'évaluer l'immunité d'un équipement ou d'un système vis-à-vis d'un phénomène donné.NOTE Comme décrit dans le Guide 107 de l’IEC, il s’agit d’une publication fondamentale en CEM pour une utilisation par les comités de produits de l’IEC. Comme indiqué également dans le Guide 107, les comités de produits de l’IEC sont chargés de déterminer si cette norme d’essai d’immunité est appliquée ou non. Si tel est le cas, il leur incombe de déterminer les niveaux d’essai et les critères d’aptitude à la fonction appropriés. Le document définit:
la tension d'essai et les formes d'ondes de courant;
les plages de niveaux d'essais;
le matériel d'essai;
les procédures d’étalonnage et de vérification du matériel d'essai;
les montages d'essai;
une procédure d’essai.
Cette deuxième édition annule et remplace la première édition parue en 2006 et l'Amendement 1:2010. Cette édition constitue une révision technique. Cette édition inclut les modifications techniques majeures suivantes par rapport à l'édition précédente:
a) ajout d’une modélisation mathématique de la forme d’onde oscillatoire amortie;
b) nouvelle Annexe B sur l’incertitude de mesure;
c) ajout d’un CDN à grande vitesse;
d) ajout des procédures d’étalonnage pour les CDN;
e) ajout de l’utilisation de la pince de couplage capacitive sur les lignes d’interconnexion pour les ondes oscillatoires amorties rapides;
f) ajout d’une procédure d'essai pour les convertisseurs continu/continu en cas de non-fonctionnement du CDN;
g) nouvelle Annexe C sur les problèmes liés à l’alimentation des EUT équipés de convertisseurs continu/continu en entrée.
Mots clés : exigences d'immunité et des méthodes d'essai des matériels électriques et électroniques
Le contenu du corrigendum d'août 2019 a été pris en considération dans cet exemplaire.

General Information

• Status: Published
• Publication Date: 15-May-2019
• ICS: 33.100.20 - Immunity
• Technical Committee: SC 77B - High frequency phenomena
• Drafting Committee: MT 12 - TC 77/SC 77B/MT 12
• Current Stage: PPUB - Publication issued
• Start Date: 16-May-2019
• Completion Date: 26-Apr-2019

Relations

• Corrected By: IEC 61000-4-18:2019/COR1:2019 - Corrigendum 1 - Electromagnetic compatibility (EMC) - Part 4-18: Testing and measurement techniques - Damped oscillatory wave immunity test
• Effective Date: 05-Sep-2023
• Revises: IEC 61000-4-18:2006 - Electromagnetic compatibility (EMC) - Part 4-18: Testing and measurement techniques - Damped oscillatory wave immunity test
• Effective Date: 05-Sep-2023
• Revises: IEC 61000-4-18:2006/AMD1:2010 - Amendment 1 - Electromagnetic compatibility (EMC) - Part 4-18: Testing and measurement techniques - Damped oscillatory wave immunity test
• Effective Date: 05-Sep-2023

Standards Content (Sample)

IEC 61000-4-18 ®
Edition 2.0 2019-05
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Electromagnetic compatibility (EMC) –
Part 4-18: Testing and measurement techniques – Damped oscillatory wave
immunity test
Compatibilité électromagnétique (CEM) –
Partie 4-18: Techniques d'essai et de mesure – Essai d'immunité à l'onde
oscillatoire amortie
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IEC 61000-4-18 ®
Edition 2.0 2019-05
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Electromagnetic compatibility (EMC) –

Part 4-18: Testing and measurement techniques – Damped oscillatory wave

immunity test
Compatibilité électromagnétique (CEM) –

Partie 4-18: Techniques d'essai et de mesure – Essai d'immunité à l'onde

oscillatoire amortie
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 33.100.20 ISBN 978-2-8322-6707-3

– 2 – IEC 61000-4-18:2019 © IEC 2019
CONTENTS
FOREWORD . 5
INTRODUCTION . 7
1 Scope . 8
2 Normative references . 8
3 Terms, definitions and abbreviated terms . 9
3.1 Terms and definitions . 9
3.2 Abbreviated terms . 11
4 General . 12
4.1 Types of damped oscillatory waves . 12
4.2 Slow damped oscillatory wave phenomenon . 13
4.3 Fast damped oscillatory wave phenomenon . 14
4.3.1 General . 14
4.3.2 Disturbances produced by switchgear and controlgear . 14
4.3.3 Disturbances produced by high-altitude electromagnetic pulse (HEMP) . 15
5 Test levels . 15
6 Test instrumentation . 16
6.1 General . 16
6.2 Damped oscillatory wave generators . 17
6.2.1 Slow damped oscillatory wave generator . 17
6.2.2 Fast damped oscillatory wave generator . 19
6.3 Coupling/decoupling networks . 21
6.3.1 General . 21
6.3.2 Coupling/decoupling networks for slow damped oscillatory waves . 22
6.3.3 Coupling/decoupling networks for fast damped oscillatory waves . 28
6.4 Calibration of coupling/decoupling networks . 30
6.4.1 General . 30
6.4.2 Calibration of CDNs for slow damped oscillatory waves . 31
6.4.3 Calibration of CDNs for fast damped oscillatory waves . 32
6.5 Capacitive coupling clamp for fast damped oscillatory waves . 34
6.5.1 Characteristics of the capacitive coupling clamp . 34
6.5.2 Calibration of the capacitive coupling clamp . 35
7 Test setup . 36
7.1 Test equipment . 36
7.2 Verification of the test instrumentation . 36
7.3 Test setup . 37
7.3.1 General . 37
7.3.2 Particular requirements for tests on shielded lines for slow damped
oscillatory waves . 39
7.3.3 Particular requirements for the test setup for fast damped oscillatory
waves testing . 40
7.4 Equipment under test . 42
7.5 Coupling/decoupling networks . 42
8 Test procedure . 42
8.1 General . 42
8.2 Laboratory reference conditions . 42
8.2.1 Climatic conditions . 42

8.2.2 Electromagnetic conditions . 42
8.3 Execution of the test . 43
9 Evaluation of test results . 44
10 Test report . 44
Annex A (informative) Information on test levels for the damped oscillatory wave . 46
Annex B (informative) Measurement uncertainty (MU) considerations . 47
B.1 General . 47
B.2 Legend for damped oscillatory wave parameters . 47
B.3 Uncertainty contributors to the damped oscillatory wave MU . 48
B.4 Uncertainty of the output voltage and current measurement . 48
B.4.1 General . 48
B.4.2 Rise time of the 3 MHz damped oscillatory wave . 48
B.4.3 Peak of the 3 MHz damped oscillatory wave . 50
B.4.4 Further MU contributions to time measurements . 51
B.4.5 Rise time of the step response and bandwidth of the frequency
response of the measuring system . 51
B.4.6 Impulse peak and width distortion due to the limited bandwidth of the
measuring system . 52
B.5 Application of uncertainties in the damped oscillatory waveform compliance
criterion . 53
Annex C (informative) Issues relating to powering EUTs having DC/DC converters at
the input . 54
C.1 General . 54
C.2 Considerations for remediation . 55
Bibliography . 57

Figure 1 – Example of waveform of the damped oscillatory wave . 13
Figure 2 – Example of schematic circuit of the generator for the slow damped
oscillatory wave . 17
Figure 3 – Representation of a slow damped oscillatory wave . 18
Figure 4 – Example of schematic circuit of the test generator for the fast damped
oscillatory wave . 19
Figure 5 – Representation of a fast damped oscillatory wave . 20
Figure 6 – Selection of coupling/decoupling method for slow damped oscillatory waves . 22
Figure 7 – Example of a CDN for capacitive coupling on AC/DC lines: line-to-ground
coupling . 23
Figure 8 – Example of a CDN for capacitive coupling on AC lines (three phases): line-
to-ground coupling . 23
Figure 9 – Example of a CDN for capacitive coupling on AC/DC lines: line-to-line
coupling . 24
Figure 10 – Example of a CDN for capacitive coupling on AC lines (three phases): line
L2-to-line N coupling . 24
Figure 11 – Example of a CDN for interconnection lines: line-to-ground coupling . 25
Figure 12 – Example of a CDN for unshielded unsymmetrical interconnection lines:
line-to-line and line-to-ground coupling . 26
Figure 13 – Example of a CDN for unshielded symmetrical interconnection lines: line-
to-ground coupling . 27
Figure 14 – Example of a CDN for unshielded symmetrical interconnection lines: line-
to-ground coupling via capacitors . 28

– 4 – IEC 61000-4-18:2019 © IEC 2019
Figure 15 – Example of CDN for AC/DC single-phase power supply: line-to-ground
coupling . 29
Figure 16 – Example of CDN for AC three-phase power supply: line-to-ground coupling . 29
Figure 17 – Example of CDN for interconnection lines for fast damped oscillatory
waves: line-to-ground coupling. 30
Figure 18 – Example of a calibration setup of CDNs for AC/DC power ports for fast
damped oscillatory waves . 33
Figure 19 – Example of a calibration setup of CDNs for interconnection lines for fast
damped oscillatory waves . 33
Figure 20 – Example of a capacitive coupling clamp . 35
Figure 21 – Transducer plate for coupling clamp calibration . 35
Figure 22 – Calibration of a capacitive coupling clamp using the transducer plate . 36
Figure 23 – Example of a verification setup of the capacitive coupling clamp . 37
Figure 24 – Example of a test setup . 39
Figure 25 – Example of test setup applied to shielded lines . 40
Figure 26 – Example of test setup using a floor standing system of two EUTs . 41
Figure C.1 – Example of the addition of a damping circuit to the CDN for DC/DC
converter EUTs . 55
Figure C.2 – Example of direct injection of damped oscillatory waves . 56

Table 1 – Values of the parameters of w(t) for each standard oscillation frequency . 12
Table 2 – Test levels for the slow damped oscillatory wave (100 kHz or 1 MHz) . 16
Table 3 – Test levels for the fast damped oscillatory wave (3 MHz, 10 MHz or 30 MHz) . 16
Table 4 – Damped oscillatory waveform specifications at the EUT port of CDNs for
slow damped oscillatory waves . 32
Table 5 – Damped oscillatory waveform specifications at the EUT port of CDNs for
fast damped oscillatory waves . 34
Table B.1 – Example of uncertainty budget for the rise time of the open circuit voltage
of the 3 MHz damped oscillatory wave (T ) . 49
Table B.2 – Example of uncertainty budget for the peak of the open circuit voltage of
the 3 MHz damped oscillatory wave (Pk ) . 50
Table B.3 – α factor of different unidirectional impulse responses corresponding to the
same bandwidth of system B. 52

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
ELECTROMAGNETIC COMPATIBILITY (EMC) –

Part 4-18: Testing and measurement techniques –
Damped oscillatory wave 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
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between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
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8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 61000-4-18 has been prepared by subcommittee 77B: High
frequency phenomena, of IEC Technical Committee 77: Electromagnetic compatibility.
It forms Part 4-18 of the IEC 61000 series. 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 2006 and its
Amendment 1:2010. This edition constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) addition of a mathematical modelling of damped oscillatory wave waveform;
b) new Annex B on measurement uncertainty;
c) addition high speed CDN;
– 6 – IEC 61000-4-18:2019 © IEC 2019
d) addition of calibration procedures for CDNs;
e) addition of the use of the capacitive coupling clamp on interconnection lines for fast
damped oscillatory waves;
f) addition of a test procedure for DC/DC converters in case the CDN does not work;
g) new Annex C on issues relating to powering EUTs having DC/DC converters at the input.
The text of this International Standard is based on the following documents:
FDIS Report on voting
77B/797/FDIS 77B/799/RVD
Full information on the voting for the approval of this International Standard can be found in
the report on voting indicated in the above table.
This document has been drafted in accordance with the ISO/IEC Directives, Part 2.
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 "http://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.
The contents of the corrigendum of August 2019 have been included in this copy.
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.
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
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 procedures
related to damped oscillatory waves.

– 8 – IEC 61000-4-18:2019 © IEC 2019
ELECTROMAGNETIC COMPATIBILITY (EMC) –

Part 4-18: Testing and measurement techniques –
Damped oscillatory wave immunity test

1 Scope
This part of IEC 61000 focuses on the immunity requirements and test methods for electrical
and electronic equipment, under operational conditions, with regard to:
a) repetitive slow damped oscillatory waves occurring mainly in power, control and signal
cables installed in high voltage and medium voltage (HV/MV) substations;
b) repetitive fast damped oscillatory waves occurring mainly in power, control and signal
cables installed in gas insulated substations (GIS) and in some cases also air insulated
substations (AIS) or in any installation due to high-altitude electromagnetic pulse (HEMP)
phenomena.
The object of this document is to establish a common and reproducible reference for
evaluating the immunity of electrical and electronic equipment when subjected to damped
oscillatory waves on supply, signal, control and earth ports. The test method documented in
this part of IEC 61000 describes a consistent method to assess the immunity of an equipment
or system against a defined phenomenon.
NOTE As described in IEC Guide 107, this 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 applied or not, and if applied, they are responsible for determining the appropriate test levels and
performance criteria.
The document defines:
– test voltage and current waveforms;
– ranges of test levels;
– test equipment;
– calibration and verification procedures of test equipment;
– test setups;
– test procedure.
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, International Electrotechnical Vocabulary (IEV) – Part 161: Electromagnetic
compatibility (available at www.electropedia.org)
___________
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.

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
NOTE Several of the most relevant terms and definitions from IEC 60050-161 are presented among the definitions
below.
3.1.1
air insulated substation
AIS
substation which is made up with only air insulated switchgear
Note 1 to entry: This note applies to the French language only.
3.1.2
auxiliary equipment
AE
equipment necessary to provide the equipment under test (EUT) with the signals required for
normal operation and to verify the performance of the EUT
Note 1 to entry: This note applies to the French language only.
3.1.3
burst
sequence of a limited number of distinct pulses or an oscillation of limited duration
[SOURCE: IEC 60050-161:1990, 161-02-07]
3.1.4
calibration
set of operations which establishes, by reference to standards, the relationship which exists
under specified conditions, between an indication and a result of a measurement
Note 1 to entry This term is based on the "uncertainty" approach.
Note 2 to entry The relationship between the indications and the results of measurement can be expressed, in
principle, by a calibration diagram.
[SOURCE: IEC 60050-311:2001, 311-01-09]
3.1.5
capacitive coupling clamp
device of defined dimensions and characteristics for common mode coupling of the
disturbance signal to the circuit under test without any galvanic connection to it
3.1.6
coupling
interaction between circuits, transferring energy from one circuit to another

– 10 – IEC 61000-4-18:2019 © IEC 2019
3.1.7
coupling network
electrical circuit for the purpose of transferring energy from one circuit to another
3.1.8
decoupling network
electrical circuit for the purpose of preventing test voltages applied to the EUT from affecting
other devices, equipment, or systems which are not under test
3.1.9
degradation (in performance)
undesired departure 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 60050-161:1990, 161-01-19]
3.1.10
gas insulated substation
GIS
substation which is made up with only gas insulated metal enclosed switchgear
Note 1 to entry: This note applies to the French language only.
[SOURCE: IEC 60050-605:1983,605-02-14, modified – "metal-enclosed" has been removed
from the term.]
3.1.11
high-altitude electromagnetic pulse
HEMP
electromagnetic pulse produced by a nuclear explosion outside the earth’s atmosphere
Note 1 to entry: Typically above an altitude of 30 km.
3.1.12
electromagnetic compatibility
EMC
ability of an 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]
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
port
particular interface of the EUT with the external electromagnetic environment

3.1.15
reference ground plane
RGP
flat conductive surface that is at the same electric potential as reference ground, which is
used as a common reference, and which contributes to a reproducible parasitic capacitance
with the surroundings of the equipment under test (EUT)
Note 1 to entry A reference ground plane is needed for the measurements of conducted disturbances, and serves
as reference for the measurement of unsymmetrical and asymmetrical disturbance voltages.
Note 2 to entry In some regions, the term ‘earth’ is used in place of ‘ground’.
Note 3 to entry: This note applies to the French language only.
[SOURCE: IEC 60050-161:1990,161-04-36]
3.1.16
rise time
interval of time between the instants at which the instantaneous value of a pulse first reaches
the 10 % value and then the 90 % value
[SOURCE: IEC 60050-161:1990, 161-02-05, modified – The note has been included in the
definition]
3.1.17
transient, adjective and noun
pertaining to or designating a phenomenon or a quantity which varies between two
consecutive steady states during a time interval short compared with the time-scale of interest
[SOURCE: IEC 60050-161:1990,161-02-01]
3.1.18
verification
set of operations which is used to check the test equipment system (e.g. the test generator
and the interconnecting cables) and to demonstrate that the test system is functioning within
the specifications given in Clause 6
Note 1 to entry: The methods used for verification can be different from those used for calibration.
Note 2 to entry: The procedure of 6.2.1.3 and 6.2.2.3 is meant as a guide to ensure the correct operation of the
test generator and other items making up the test setup so that the intended waveform is delivered to the EUT.
3.2 Abbreviated terms
AE auxiliary equipment
AIS air insulated substation
CDN coupling/decoupling network
EFT/B electrical fast transient/burst
EMC electromagnetic compatibility
EUT equipment under test
FDOW fast damped oscillatory wave
FDOWG fast damped oscillatory wave generator
GDT gas discharge tube
GIS gas insulated substation
HEMP high-altitude electromagnetic pulse
HV high voltage
MU measurement uncertainty
– 12 – IEC 61000-4-18:2019 © IEC 2019
MV medium voltage
PE protective earth
PWM pulse width modulation
RGP reference ground plane
SDOW slow damped oscillatory wave
SDOWG slow damped oscillatory wave generator
4 General
4.1 Types of damped oscillatory waves
The damped oscillatory wave phenomena are divided into two parts. The first part is referred
to as the slow damped oscillatory wave and includes oscillation frequencies between 100 kHz
and 1 MHz. The second part is referred to as the fast damped oscillatory wave, and it includes
oscillation frequencies above 1 MHz.
The formula of the ideal waveform of Figure 1, w(t) (open circuit voltage or short circuit
current), is as follows:
n

t

t 
t
1
wt()= A⋅ K⋅ ⋅ exp− ⋅cos 2π f⋅+t ϕ
 ( )
n
t
 
t
1+

t
1
The values of the parameters of w(t) for the open circuit voltage are given in Table 1 for each
standard oscillation period T = 1/f.
Table 1 – Values of the parameters of w(t) for each standard
oscillation frequency
Waveform A K n t f t
φ
1 2
Fast 30 MHz Pk 1,19 1,67 2,26 ns 30 MHz 126 ns -π/2
Fast 10 MHz Pk 1,04 2,65 1,69 ns 10 MHz 377 ns
-π/4
Fast 3 MHz Pk 1,07 2,30 2,89 ns 3 MHz 1,26 μs 0
Slow 1 MHz Pk 1,12 2,45 49,8 ns 1 MHz 3,77 μs
-π/4
Slow 100 kHz Pk 1,04 1,96 32,7 ns 100 kHz 37,7 μs 0
The causes of these two types of damped oscillatory waves are described below.

Figure 1 – Example of waveform of the damped oscillatory wave
4.2 Slow damped oscillatory wave phenomenon
This phenomenon is representative of the switching of disconnectors in HV/MV open-air
substations, and is particularly related to the switching of HV busbars.
In substations, the opening and closing operations of HV disconnectors give rise to sharp
front-wave transients, with rise times of the order of some tens of nanoseconds.
The voltage front-wave includes reflections due to the mismatch of the characteristic
impedance of HV circuits involved. In this respect, the resulting transient voltage and current
in HV busbars are characterized by a fundamental oscillation frequency that depends on the
length of the circuit and on the propagation time.
The oscillation frequency ranges from about 100 kHz to a few megahertz for open-air sub-
stations, depending on the influence of the parameters mentioned above and the length of the
busbars, which can vary from some tens of metres to hundreds of metres (400 m can occur).
In this respect, the oscillation frequency of 1 MHz can be considered representative of most
situations, but 100 kHz has been considered appropriate for large HV substations.
The repetition frequency is variable between a few hertz and a few kilohertz depending on the
distance between the switching contacts. For contacts in close proximity, the repetition
frequency is at its maximum, while for contact distances close to allowing re-ignitions between
the contacts, the repetition rate is at its minimum and is equivalent to twice the power
frequency with respect to each phase (100/s per phase for 50 Hz grids and 120/s per phase
for 60 Hz grids).
The repetition rates of 40/s and 400/s represent a compromise, taking into account the
different durations of the phenomena, different frequencies considered and the energy to
which the circuits under test are subjected.
Repetitive oscillatory transients can be generated by switching transients and the injection of
impulsive currents in power systems (networks and electrical equipment).

– 14 – IEC 61000-4-18:2019 © IEC 2019
4.3 Fast damped oscillatory wave phenomenon
4.3.1 General
The fast damped oscillatory wave immunity test should cover phenomena present in two
specific environments:
– substations of the power network (produced by switchgear and controlgear);
– all installations exposed to high-altitude electromagnetic pulse (HEMP).
4.3.2 Disturbances produced by switchgear and controlgear
During opening or closing disconnector operations, between both contacts of the operated
device, a large number of restrikes take place due to the slow speed of the contacts.
Therefore, disconnector switch operations generate very fast transients, which propagate as
travelling waves in the busbars of the substation. The electrical length of conductors and
busbars will determine the oscillation frequencies of the transient overvoltages.
For air insulated substations (AIS) these transients will radiate an electromagnetic field in the
substation environment. Measurements have been performed in air insulated substations
using instruments with a large frequency bandwidth [1] . These measurements have shown
that transient phenomena with frequencies higher than 1 MHz can also take place in these
substations.
For gas insulated substations (GIS), these transients propagate inside the metallic enclosure,
which contains the SF gas. Due to the skin effect, high frequency transients are confined
inside the enclosure and cause no problems. Transient current is transferred to the external
surface of the enclosure tube at any enclosure discontinuity. As a consequence, the enclosure
potential rises and the current flowing on the enclosure surface radiates an electromagnetic
field in the substation environment. The transient ground potential rise is a direct source of
transient common mode currents in the secondary circuits. The radiated electromagnetic field
also induces common mode currents in the secondary circuits.
Measurements have shown that the maximum frequency of significant components in the
spectral density of these currents can be as high as 30 MHz to 50 MHz [2].
As summarized in [1], the oscillation frequency of transients occurring in HV substations has
increased due to the reduction of the overall sizes of substations, the use of GIS and the
installation of electronic equipment nearer to switching devices.
Therefore, the oscillation frequencies of 3 MHz, 10 MHz and 30 MHz for the fast damped
oscillatory waves are suitable to represent the environment both in some AIS and in all GIS.
The repetition frequency varies between a few hertz and many kilohertz depending on the
distance between the switching contacts. With close contacts, there will be a high repetition
frequency, while as the distances increase as the contacts open further, the minimum
repetition frequency, with respect to each phase, is twice the power frequency (100/s per
phase for 50 Hz and 120/s per phase for 60 Hz HV systems).
The repetition rate of 5 000/s represents the higher repetition rates measured in GIS. This
rate still represents a compromise, taking into account the different durations of the
phenomena, the suitability of the different frequencies considered and the problem related to
the energy to which the circuits under test are subjected.
___________
2 Numbers in square brackets refer to the Bibliography.

4.3.3 Disturbances produced by high-altitude electromagnetic pulse (HEMP)
HEMP as presented in IEC 61000-2-9 [4] describes an intense, plane wave electromagnetic
pulsed field which has a rise time of 2,5 ns and a pulse width of approximately 25 ns. This
field interacts with exposed transmission lines to produce an oscillating voltage and current
which depends on the length of the line (see IEC 61000-2-10 [5]). Outdoor power and
communication lines have sufficient length (longer than 1 km), so that the coupled currents
and voltages are normally impulsive in nature.
For indoor power and communication lines the incident HEMP is partially attenuated. Even so,
the field couples to short indoor cables, causing a threat to connected electronic equipment.
The HEMP fields couple to these short lines and produce high-frequency damped oscillatory
waveforms with frequencies up to 100 MHz. Frequencies below 30 MHz are the most
commonly observed (see IEC 61000-2-10 [5]). The damping rate of the oscillatory wave is fast
due to the presence of absorbing walls, and a resonance quality factor Q between 10 and 20
is typical.
Short outdoor wiring (for example control circuits in substations or power plants) will couple to
HEMP fields. Damped oscillatory transients will be induced, which will have frequencies of
1 MHz to 100 MHz.
The HEMP event typically generates one or two pulses. A high repetition rate is not necessary
to replicate the HEMP event. Due to reliability concerns with digital electronics, it is
recommended that a repetition rate of 5 000/s similar to switchgear and controlgear generated
disturbances be used.
...