IEC 61000-4-12:2017

Electromagnetic Compatibility (EMC) - Part 4-12: Testing and measurement techniques - Ring wave immunity test

IEC 61000-4-12:2017 relates to the immunity requirements and test methods for electrical and electronic equipment, under operational conditions, to ring waves occurring in low-voltage power, control and signal lines supplied by public and non-public networks.
The object of this document is to establish a common reference for evaluating the immunity of electrical and electronic equipment when subjected to ring waves. 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.
It has the status of a basic EMC publication in accordance with IEC Guide 107.
This edition includes the following significant technical changes with respect to the previous edition:
a) addition of a mathematical modelling of ring wave waveform;
b) new Annex B on selection of generators and test levels;
c) new Annex C on explanatory notes;
d) new Annex D on measurement uncertainty;
e) addition of high speed CDN;
f) addition of a calibration procedure for CDN.

Compatibilité électromagnétique (CEM) - Partie 4-12: Techniques d'essai et de mesure - Essai d'immunité à l'onde sinusoïdale amortie

L’IEC 61000-4-12:2017 traite des méthodes d'essai des matériels électriques et électroniques dans leurs conditions d'exploitation et des exigences d'immunité aux ondes sinusoïdales fortement amorties se manifestant sur les alimentations basse tension ainsi que sur les lignes de commande et de signal raccordées aux réseaux publics ou privés.
Le présent document a pour objet d'établir une référence commune dans le but d'évaluer l’immunité des matériels électriques et électroniques soumis à des ondes sinusoïdales fortement amorties. La méthode d’essai documentée dans la présente partie de l’IEC 61000 décrit une méthode cohérente en vue d'évaluer l'immunité d'un matériel ou d'un système vis‑à-vis d'un phénomène défini.
Elle a le statut de publication fondamentale en CEM en accord avec le Guide 107 de l’IEC.
Cette édition inclut les modifications techniques majeures suivantes par rapport à l'édition précédente:
a) ajout d’une modélisation mathématique de forme d’onde sinusoïdale fortement amortie;
b) ajout d’une nouvelle Annexe B relative à la sélection des générateurs et des niveaux d’essai;
c) ajout d’une nouvelle Annexe C relative aux notes explicatives;
d) ajout d’une nouvelle Annexe D relative à l’incertitude de mesure;
e) ajout d’un RCD à grande vitesse;
f) ajout d’une procédure d’étalonnage pour le RCD.

General Information

• Status: Published
• Publication Date: 17-Jul-2017
• 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: 18-Jul-2017
• Completion Date: 07-Aug-2017

Relations

• Revises: IEC 61000-4-12:2006 - Electromagnetic compatibility (EMC) - Part 4-12: Testing and measurement techniques - Ring wave immunity test
• Effective Date: 05-Sep-2023

Standards Content (Sample)

IEC 61000-4-12 ®
Edition 3.0 2017-07
REDLINE VERSION
INTERNATIONAL
STANDARD
colour
inside
BASIC EMC PUBLICATION
Electromagnetic compatibility (EMC) –
Part 4-12: Testing and measurement techniques – Ring wave immunity test

IEC 61000-4-12:2017-07 RLV(en)

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IEC 61000-4-12 ®
Edition 3.0 2017-07
REDLINE VERSION
INTERNATIONAL
STANDARD
colour
inside
BASIC EMC PUBLICATION
Electromagnetic compatibility (EMC) –

Part 4-12: Testing and measurement techniques – Ring wave immunity test

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 33.100.20 ISBN 978-2-8322-4625-2

– 2 – IEC 61000-4-12:2017 RLV © IEC 2017
CONTENTS
FOREWORD . 6
INTRODUCTION . 8
1 Scope and object . 9
2 Normative references . 9
3 Terms, definitions and abbreviated terms . 9
3.1 Terms and definitions . 9
3.2 Abbreviated terms . 11
4 General . 12
4.1 Description of the phenomenon . 12
4.2 Relevant parameters . 14
4.2.1 Repetition rate . 14
4.2.2 Phase angle . 14
5 Test levels . 14
6 Test equipment instrumentation . 15
6.1 Test Ring wave generator . 15
6.1.1 Ring wave generator circuit . 15
6.1.2 Impedance values . 15
6.1.3 Verification of the characteristics of the test generator .
6.1.3 Performance characteristics of the test ring wave generator . 16
6.1.4 Calibration of the ring wave generator . 17
6.2 Coupling/decoupling networks specifications . 18
6.2.1 Coupling/decoupling network for a.c./d.c. power supply ports .
6.2.2 Coupling/decoupling network for signals and control ports .
6.2.1 General . 19
6.2.2 Coupling/decoupling networks for AC/DC power port rated up to 63 A
per line . 20
6.2.3 Coupling/decoupling networks for interconnection lines . 23
6.3 Calibration of coupling/decoupling networks . 26
6.3.1 General . 26
6.3.2 Calibration of CDNs for AC/DC power port rated up to 63 A per line . 26
6.3.3 Calibration of CDNs for interconnection lines . 27
7 Test setup . 31
7.1 Test of power supply ports .
7.2 Test of input/output ports .
7.3 Test of communication ports .
7.4 Earthing connections .
7.5 Equipment under test .
7.6 Coupling/decoupling networks .
7.1 Test equipment . 31
7.2 Verification of the test instrumentation . 35
7.3 Test setup for ring waves applied to EUT power ports . 35
7.4 Test setup for ring waves applied to unshielded unsymmetrical
interconnection lines . 36
7.5 Test setup for ring waves applied to unshielded symmetrical interconnection
lines . 36
7.6 Test setup for ring waves applied to shielded lines . 36

7.7 Protective earth connection . 37
8 Test procedure . 38
8.1 General . 38
8.2 Laboratory reference conditions . 38
8.2.1 Climatic conditions . 38
8.2.2 Electromagnetic conditions . 38
8.3 Execution of the test . 38
9 Evaluation of test results . 41
10 Test report . 41
Annex A (informative) Information on test levels for the ring wave .
Annex A (informative) Information on electromagnetic environments, installation
classes and test levels . 50
Annex B (informative) Selection of generators and test levels . 52
B.1 General . 52
B.2 The classification of environments . 52
B.3 The definition of port types. 52
B.4 Selection of the test levels . 53
Annex C (informative) Explanatory notes . 55
C.1 Different source impedance . 55
C.2 Application of the tests . 55
C.2.1 Equipment level immunity . 55
C.2.2 System level immunity . 55
Annex D (informative) Measurement uncertainty (MU) considerations . 56
D.1 General . 56
D.2 Legend for ring wave parameters . 56
D.3 Uncertainty contributors to the ring wave measurement uncertainty . 57
D.4 Uncertainty of the generator output voltage and current measurement . 57
D.4.1 General . 57
D.4.2 Rise time of the ring wave . 57
D.4.3 Peak of the ring wave . 59
D.4.4 Further MU contributions to time measurements . 60
D.4.5 Rise time of the step response and bandwidth of the frequency
response of the measuring system . 60
D.4.6 Impulse peak and width distortion due to the limited bandwidth of the
measuring system . 61
D.5 Application of uncertainties in the ring waveform compliance criterion . 62
Bibliography . 63

Figure 1 – Waveform of the ring wave (open-circuit voltage and short-circuit current) . 13
Figure 2 – Example of schematic circuit of the ring wave generator . 15
Figure 3 – Example of test set-up for table-top equipment using the ground
reference plane .
Figure 4 – Example of test set-up for floor-standing equipment using the ground
reference plane .
Figure 5 – AC/DC power supply port, single phase, line-to-line test .
Figure 6 – AC/DC power supply port, single phase, line-to-ground test .
Figure 7 – Example of test setup for capacitive coupling on a.c. lines (3 phases) –
line L3 to line L1 coupling .

– 4 – IEC 61000-4-12:2017 RLV © IEC 2017
Figure 8 – Example of test setup for capacitive coupling on a.c. lines (3 phases) –
line L3 to ground coupling .
Figure 9 – Example of test setup for unshielded unsymmetrical interconnection lines –
line-to-line and line-to-ground coupling via capacitors .
Figure 10 – Example of test setup for unshielded unsymmetrical interconnection lines –
line-to-line and line-to-ground coupling via arrestors .
Figure 11 – Example of test setup for unshielded unsymmetrical interconnection lines –
line-to-line and line-to-ground coupling via a clamping circuit .
Figure 12 – Example of test setup for unshielded symmetrical interconnection lines
(communication lines) – lines-to-ground coupling via arrestors .
Figure 13 – Test of a system with communication ports with fast operating signals
(generator output earthed) .
Figure 3 – Selection of coupling/decoupling method . 20
Figure 4 – Example of coupling network and decoupling network for capacitive
coupling on AC/DC lines: line-to-line coupling . 21
Figure 5 – Example of coupling network and decoupling network for capacitive
coupling on AC/DC lines: line-to-ground coupling . 22
Figure 6 – Example of coupling network and decoupling network for capacitive
coupling on AC lines (three phases): line L3-to-line L2 coupling . 22
Figure 7 – Example of coupling network and decoupling network for capacitive
coupling on AC lines (three phases): line L3-to-ground coupling . 23
Figure 8 – Example of coupling network and decoupling network for unshielded
unsymmetrical interconnection lines: line-to-line and line-to-ground coupling . 24
Figure 9 – Example of coupling and decoupling network for unshielded symmetrical
interconnection lines: lines-to-ground coupling . 25
Figure 10 – Example of coupling and decoupling network for unshielded symmetrical
interconnection lines: lines-to-ground coupling via capacitors . 26
Figure 11 – Example of test setup for ring waves applied to shielded lines . 37

Table 1 – Test levels for ring wave. 14
Table 2 – Relationship between peak open-circuit voltage and peak short-circuit
current . 17
Table 3 – Ring wave specification at the EUT power port of the CDN . 21
Table 4 – Summary of calibration process for CDNs for unsymmetrical interconnection
lines . 28
Table 5 – Ring wave waveform specifications at the EUT port of the CDN for
unsymmetrical interconnection lines . 29
Table 6 – Summary of calibration process for CDNs for symmetrical interconnection
lines . 30
Table 7 – Ring wave waveform specifications at the EUT port of the CDN for
symmetrical interconnection lines . 30
Table B.1 – Power ports: Selection of the test levels (depending on the installation
class) . 53
Table B.2 – Circuits/lines: Selection of the test levels (depending on the installation
class) . 54
Table D.1 – Example of uncertainty budget for ring wave rise time (T ) . 58
Table D.2 – Example of uncertainty budget for the peak of the short-circuit current of
the ring wave (I ) . 59
Pk1
Table D.3 – α factor (Formula (D.3)) of different unidirectional impulse responses
corresponding to the same bandwidth of the system B . 61

– 6 – IEC 61000-4-12:2017 RLV © IEC 2017
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
ELECTROMAGNETIC COMPATIBILITY (EMC) –

Part 4-12: Testing and measurement techniques –
Ring wave immunity test
FOREWORD
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International Standard IEC 61000-4-12 has been prepared by subcommittee 77B: High
frequency phenomena, of IEC technical Committee 77: Electromagnetic compatibility.
It forms Part 4-12 of IEC 61000. It has the status of a basic EMC publication in accordance
with IEC Guide 107.
This third edition cancels and replaces the second edition published in 2006. 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 ring wave waveform;
b) new Annex B on selection of generators and test levels;
c) new Annex C on explanatory notes;
d) new Annex D on measurement uncertainty;
e) addition of high speed CDN;
f) addition of a calibration procedure for CDN.
The text of this International Standard is based on the following documents:
CDV Report on voting
77B/764/CDV 77B/774/RVC
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 publication 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 publication will remain unchanged until
the stability date indicated on the IEC web site under "http://webstore.iec.ch" in the data
related to the specific publication. At this date, the publication will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
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.
– 8 – IEC 61000-4-12:2017 RLV © IEC 2017
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 procedures
related to ring waves. It should be noted that edition 1 of IEC 61000-4-12, published in 1995,
covered immunity tests against two phenomena, ring waves and damped oscillatory waves.
This situation was changed in edition 2, published in 2006, where IEC 61000-4-12 covered
the ring wave phenomena only and the damped oscillatory wave phenomenon was moved into
a new standard IEC 61000-4-18.

ELECTROMAGNETIC COMPATIBILITY (EMC) –

Part 4-12: Testing and measurement techniques –
Ring wave immunity test
1 Scope and object
This part of IEC 61000 relates to the immunity requirements and test methods for electrical
and electronic equipment, under operational conditions, to non-repetitive damped oscillatory
transients ( ring waves) occurring in low-voltage power, control and signal lines supplied by
public and non-public networks.
The object of this document is to establish the immunity requirements and a common
reference for evaluating in a laboratory the performance of electrical and electronic equipment
intended for residential, commercial and industrial applications, as well as of equipment
intended for power stations and substations, as applicable the immunity of electrical and
electronic equipment when subjected to ring waves. 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 should be is 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 test and test levels for their products.
This document defines:
– test voltage and current waveforms;
– a range of test levels;
– test equipment;
– test setups;
– test procedures.
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) – Chapter 161: Electro-
magnetic compatibility
IEC 60050 (all parts), International Electrotechnical Vocabulary (IEV) (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 (all
parts) as well as the following apply.

– 10 – IEC 61000-4-12:2017 RLV © IEC 2017
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
burst
sequence of a limited number of distinct pulses or an oscillation of limited duration
[IEV 161-02-07]
3.1.1
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]
3.1.2
coupling
interaction between circuits, transferring energy from one circuit to another
3.1.3
coupling network
CN
electrical circuit for the purpose of transferring energy from one circuit to another
3.1.4
coupling/decoupling network
CDN
combination of a coupling network and a decoupling network
3.1.5
decoupling network
DN
electrical circuit for the purpose of preventing test voltages applied to the equipment under
test (EUT) from affecting other devices, equipment, or systems which are not under test
3.1.6
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]

3.1.7
port
particular interface of the EUT an equipment, which couples this equipment with the external
electromagnetic environment (IEC 60050-161:1990, 161-01-01) and through which the
equipment is influenced by the environment
[SOURCE: IEC 60050-161:1990, 161-01-27]
3.1.8
ring wave
damped oscillation, whose damping time constant is of the order of one period
[SOURCE: IEC 60050-161:1990, 161-02-30]
3.1.9
rise time
T
r
interval of time between the instants at which the instantaneous value of an impulse first
reaches 10 % value and then the 90 % value
[SOURCE: IEC 60050-161:1990, 161-02-05, modified – the content of the note has been
included in the definition and “pulse” has been changed to “impulse”]
3.1.10
transient (adj 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]
3.1.11
verification
set of operations which is used to check the test equipment system (e.g. the test generator
and the its 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 may be different from those used for calibration.
NOTE 2 The procedure of 6.1.2 and 6.2.2 is meant as a guide to insure the correct operation of the test generator
and other items making up the test set-up, so that the intended waveform is delivered to the EUT.
Note 2 to entry: For the purposes of this basic EMC standard this definition is different from the definition given in
IEC 60050-311:2001, 311-01-13.
3.2 Abbreviated terms
AE Auxiliary equipment
CD Coupling device
CDN Coupling/decoupling network
CLD Clamping device
CN Coupling network
DN Decoupling network
EMC Electromagnetic compatibility
EUT Equipment under test
GDT Gas discharge tube
MU Measurement uncertainty
– 12 – IEC 61000-4-12:2017 RLV © IEC 2017
PDF Probability density function
PE Protective earth
RGP Reference ground plane
RWG Ring wave generator
SPD Surge protective device
4 General
4.1 Description of the phenomenon
The ring wave (described in Figure 1) is a typical an oscillatory transient, induced in low-
voltage cables due to the switching of electrical networks and reactive loads, faults and
insulation breakdown of power supply circuits or lightning. It is, in fact, the most diffused
phenomenon occurring in power supply (high voltage, medium voltage, low voltage) networks,
as well as in control and signal lines.
The ring wave is representative of a wide range of electromagnetic environments of
residential, as well as industrial installations. It is suitable for checking the immunity of
equipment in respect of the above-mentioned phenomena, which give rise to impulses
characterized by sharp front-waves that, in the absence of filtering actions, are in the order of
10 ns to a fraction of µs. The duration of these impulses may range from 10 µs to 100 µs.
The rise time and duration of the parameters impulse are subject to modification, depending
dependent on the propagation characteristics of the media and the path.
The propagation of the wave in the lines (power and signal) is always subject to reflections,
due to the mismatching impedance (the lines are terminated on their own with loads or
connected to protection devices, input line filters, etc.). These reflections produce oscillations,
whose frequency is related to the propagation speed. The presence of parasitic parameters
(e.g. stray capacitance of components like motors, transformer windings, etc.) are other
conditioning additional influencing factors.
The rise time is reduced to slowing down due to the low-pass characteristic of the line
involved in the propagation. This modification is more relevant for the fast rise times (in the
order of 10 ns), and less relevant for values in the range of a fraction of µs.
The resultant phenomenon at the equipment ports is an oscillatory transient, or ring wave.
This ring wave with a defined 0,5 µs rise time and 100 kHz oscillation frequency has been
determined to be typical and is widely used by some industries for testing products.
The rise time can be increased by the low-pass characteristics of the line. This effect is more
relevant for fast rise times (in the order of 10 ns), and less relevant for slow rise times (in the
order of 1 µs).
Another cause of the ring wave is lightning, which itself is characterized by a unidirectional
waveform (standard 1,2/50 µs impulse). Circuits subjected to the indirect effects of lightning
(inductive coupling among lines) are influenced by the derivative of the primary impulse and
the coupling mechanisms involved, which gives rise to can cause oscillations. The
characteristics of the resulting ring wave depend on the reactive parameters of the ground
circuits, metal structures involved in the lightning current flow, and the propagation in the low-
voltage transmission lines.
The phenomenon, which is created by the above mentioned effects at the equipment ports, is
an oscillatory transient or a ring wave. Oscillatory transients are covered in IEC 61000-4-18. A
ring wave with a defined 0,5 µs rise time and 100 kHz oscillation frequency has been
determined to be typical and is widely used for testing products.

The formula of the ideal waveform of Figure 1, w(t), is as follows:
n
 
t
 
 
t
 
t
 1 
 
w(t) = A ⋅ K ⋅ ⋅ exp − ⋅cos(βt)
 
n
t
 
 t 
 
1+
 
t
 1 
with
2π
T 1
and β = and T = 10 µs
t = ⋅ = 7,21μs
2 ln R T
where the parameters for oscillation period T = 10 µs are:
A = 1; K = 1,81; n = 1,83; t = 0,507 µs
NOTE R is the ratio between Pk and Pk , Pk and Pk . The value of R ensures that the ratios Pk /Pk , Pk /Pk are
2 3 3 4 2 3 3 4
in the range specified by this document. The value of R cannot be too small otherwise the ratio Pk /Pk exceeds the
1 2
specified tolerance. R = 2 has been selected. The parameters n and t are adjusted to obtain T = 0,5 μs.
1 1
Pk (U or I )
1 Pk Pk
1 1
100 %
90 %
T
Pk
10 %
t
T Pk
1 4
110 % to 40%
Pk
IEC
Key
T Rise time
T Oscillation period
NOTE Only Pk is specified for the current waveform.
Figure 1 – Waveform of the ring wave
(open-circuit voltage and short-circuit current)
Other IEC standards, such as IEC 61000-4-5, refer to the 1,2/50 µs standard lightning
impulse, which may be considered to be complementary to the ring wave described in this
document.
It is the responsibility of the product committees to define the most appropriate test, according
to the phenomenon considered as relevant.

U/I
– 14 – IEC 61000-4-12:2017 RLV © IEC 2017
4.2 Relevant parameters
4.2.1 Repetition rate
The repetition rate of the transient is directly related to the frequency of occurrence of the
primary phenomenon (lightning and switching). It is higher whenever the primary cause is the
load switching in control lines, and less frequent in the case of faults and lightning. The
occurrence may typically range from 1/s to 1/month or 1/year once per second down to once
per year.
The repetition rate may be increased in order to reduce the duration of the test. However, It
should be selected according to the characteristics of the transient protectors involved the
protection device used for mitigation/suppression of transients.
4.2.2 Phase angle
Equipment failures related to the ring wave on power supply sources can depend on the
phase angle of the AC mains at which the transient is applied. When a protection element
operates during a ring wave test, power-follow might follow current may occur depending on
the phase angle at which the transient occurs. Power-follow Follow current is the current from
the connected power source that flows through a protective element, or from any arc in the
EUT both during and following the transient.
For semiconductors, the phenomenon may be related to the conduction state of the device at
the time the ring wave occurs. Semiconductor parameters that might may be involved, include
forward and reverse recovery characteristics and secondary breakdown performance.
Devices most likely to fail in a phase-related way are semiconductors involved in the power
input circuitry. Other devices in different areas of the EUT might can also exhibit such failure
modes.
5 Test levels
The preferred test levels for the ring wave applicable to power, signal and control ports of the
equipment, are given in Table 1. The test level is defined as the voltage of the first peak
(maximum or minimum) in the test waveform (Pk in Figure 1).
Different test levels may apply to power, signal and control ports. The level(s) used for signal
and control ports shall not differ by more than one level from that used for power supply ports.
Table 1 – Test levels for ring wave
Open-circuit test voltage
Level kV
b
Line-to-line Line-to-ground
1 0,25 0,5
2 0,5 1
3 1 2
4 2 4
a
X x Special x Special
a
"X" can be any level, above, below or in between the others. This level can be given in the product standard
shall be specified by product committees and/or equipment specification.
b
For symmetrical interconnection lines the test can be applied to multiple lines simultaneously with respect to

ground, i.e. “lines to ground”.

The applicability of the ring wave test, shall refer to the product specification.
The test levels from Table 1 should be selected in accordance with the most realistic
installation and environmental conditions.
The immunity tests are correlated with these levels in order to establish a performance level
for the environment in which the equipment is expected to operate, taking into account the
primary phenomena and the installation practices which determine the classes of the
electromagnetic environment.
The selection of the test levels should be done on the basis of the applicability to a given
location or installation.
The test levels shall be selected according to the installation conditions; classes of installation
are given in Annex C. Annex A gives information on test levels.
The test shall be applied at all test levels in Table 1 up to and including the specified test
level (see 8.3).
For selection of the test levels for the different interfaces, refer to Annex B.
6 Test equipment instrumentation
6.1 Test Ring wave generator
6.1.1 Ring wave generator circuit
The generator output shall have the capability to operate under short-circuit conditions.
A block diagram of a representative ring wave generator is shown in Figure 2.
R
S
S
R R
1 2
R
U C L C
1 1 2
IEC
Key
U: high-voltage source R : 30 Ω resistor
C : energy storage capacitor R : 12 Ω resistor
1 4
C : filter capacitor L : oscillating circuit coil
2 1
R : charging resistor S : high-voltage switch
1 1
R : filter resistor S : output impedance selector
2 2
Figure 2 – Example of schematic circuit of the ring wave generator
6.1.2 Impedance values
Two values of impedance (see R and R in Figure 2) have been selected as follows:
3 4
• 12 Ω when testing AC/DC power ports and shielded interconnection lines
• 30 Ω when testing unshielded interconnection lines

– 16 – IEC 61000-4-12:2017 RLV © IEC 2017
These values are applicable, respectively, to short and long branch circuits, corresponding to
the relative distance of the power supply source from the main distribution network. They
represent a technical compromise, because they include the need to test EUT ports normally
interfaced with low impedance circuits, according to the values given in IEC 60816. In
addition, they cover the requirements to test the transients protection devices, such as the
metal oxide varistors, Zener diodes, etc., installed in the EUT.
6.1.3 Performance characteristics of the test ring wave generator
A generator with a floating output shall be used.
The test generator is a single-shot ring wave generator with the following characteristics,
measured as it is to be applied to the EUT port at the output of the generator. If applied via a
coupling/decoupling network, the characteristics are to be as specified at the output of that
network.
The generator output shall be floating. This condition is necessary to test EUT control and
signal ports in line-to-line mode. It is not necessary for power ports and line-to-ground mode
tests of control and signal ports.
The generator shall have provisions to prevent the emission of heavy disturbances that may
be injected in the power supply network, or may influence the test results.
Specifications:
– voltage rise time (T in Figure 1): 0,5 µs
...

IEC 61000-4-12 ®
Edition 3.0 2017-07
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
BASIC EMC PUBLICATION
PUBLICATION FONDAMENTALE EN CEM
Electromagnetic compatibility (EMC) –
Part 4-12: Testing and measurement techniques – Ring wave immunity test

Compatibilité électromagnétique (CEM) –
Partie 4-12: Techniques d'essai et de mesure – Essai d'immunité à l’onde
sinusoïdale fortement amortie
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IEC 61000-4-12 ®
Edition 3.0 2017-07
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
BASIC EMC PUBLICATION
PUBLICATION FONDAMENTALE EN CEM

Electromagnetic compatibility (EMC) –

Part 4-12: Testing and measurement techniques – Ring wave immunity test

Compatibilité électromagnétique (CEM) –

Partie 4-12: Techniques d'essai et de mesure – Essai d'immunité à l’onde

sinusoïdale fortement amortie
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 33.100.20 ISBN 978-2-8322-4556-9

– 2 – IEC 61000-4-12:2017 © IEC 2017
CONTENTS
FOREWORD . 5
INTRODUCTION . 7
1 Scope . 8
2 Normative references . 8
3 Terms, definitions and abbreviated terms . 8
3.1 Terms and definitions . 8
3.2 Abbreviated terms . 10
4 General . 10
4.1 Description of the phenomenon . 10
4.2 Relevant parameters . 12
4.2.1 Repetition rate . 12
4.2.2 Phase angle . 12
5 Test levels . 13
6 Test instrumentation . 13
6.1 Ring wave generator . 13
6.1.1 Ring wave generator circuit . 13
6.1.2 Impedance values . 14
6.1.3 Performance characteristics of the ring wave generator . 14
6.1.4 Calibration of the ring wave generator . 15
6.2 Coupling/decoupling networks . 15
6.2.1 General . 15
6.2.2 Coupling/decoupling networks for AC/DC power port rated up to 63 A
per line . 16
6.2.3 Coupling/decoupling networks for interconnection lines . 19
6.3 Calibration of coupling/decoupling networks . 22
6.3.1 General . 22
6.3.2 Calibration of CDNs for AC/DC power port rated up to 63 A per line . 22
6.3.3 Calibration of CDNs for interconnection lines . 23
7 Test setup . 26
7.1 Test equipment . 26
7.2 Verification of the test instrumentation . 27
7.3 Test setup for ring waves applied to EUT power ports . 27
7.4 Test setup for ring waves applied to unshielded unsymmetrical
interconnection lines . 28
7.5 Test setup for ring waves applied to unshielded symmetrical interconnection
lines . 28
7.6 Test setup for ring waves applied to shielded lines . 28
7.7 Protective earth connection . 29
8 Test procedure . 30
8.1 General . 30
8.2 Laboratory reference conditions . 30
8.2.1 Climatic conditions . 30
8.2.2 Electromagnetic conditions . 30
8.3 Execution of the test . 30
9 Evaluation of test results . 31

10 Test report . 32
Annex A (informative) Information on electromagnetic environments, installation
classes and test levels . 33
Annex B (informative) Selection of generators and test levels . 35
B.1 General . 35
B.2 The classification of environments . 35
B.3 The definition of port types. 35
B.4 Selection of the test levels . 36
Annex C (informative) Explanatory notes . 38
C.1 Different source impedance . 38
C.2 Application of the tests . 38
C.2.1 Equipment level immunity . 38
C.2.2 System level immunity . 38
Annex D (informative) Measurement uncertainty (MU) considerations . 39
D.1 General . 39
D.2 Legend for ring wave parameters . 39
D.3 Uncertainty contributors to the ring wave measurement uncertainty . 40
D.4 Uncertainty of the generator output voltage and current measurement . 40
D.4.1 General . 40
D.4.2 Rise time of the ring wave . 40
D.4.3 Peak of the ring wave . 42
D.4.4 Further MU contributions to time measurements . 43
D.4.5 Rise time of the step response and bandwidth of the frequency
response of the measuring system . 43
D.4.6 Impulse peak and width distortion due to the limited bandwidth of the
measuring system . 44
D.5 Application of uncertainties in the ring waveform compliance criterion . 45
Bibliography . 46

Figure 1 – Waveform of the ring wave (open-circuit voltage and short-circuit current) . 12
Figure 2 – Example of schematic circuit of the ring wave generator . 14
Figure 3 – Selection of coupling/decoupling method . 16
Figure 4 – Example of coupling network and decoupling network for capacitive
coupling on AC/DC lines: line-to-line coupling . 17
Figure 5 – Example of coupling network and decoupling network for capacitive
coupling on AC/DC lines: line-to-ground coupling . 18
Figure 6 – Example of coupling network and decoupling network for capacitive
coupling on AC lines (three phases): line L3-to-line L2 coupling . 18
Figure 7 – Example of coupling network and decoupling network for capacitive
coupling on AC lines (three phases): line L3-to-ground coupling . 19
Figure 8 – Example of coupling network and decoupling network for unshielded
unsymmetrical interconnection lines: line-to-line and line-to-ground coupling . 20
Figure 9 – Example of coupling and decoupling network for unshielded symmetrical
interconnection lines: lines-to-ground coupling . 21
Figure 10 – Example of coupling and decoupling network for unshielded symmetrical
interconnection lines: lines-to-ground coupling via capacitors . 22
Figure 11 – Example of test setup for ring waves applied to shielded lines . 29

– 4 – IEC 61000-4-12:2017 © IEC 2017
Table 1 – Test levels . 13
Table 2 – Relationship between peak open-circuit voltage and peak short-circuit
current . 15
Table 3 – Ring wave specification at the EUT power port of the CDN . 17
Table 4 – Summary of calibration process for CDNs for unsymmetrical interconnection
lines . 24
Table 5 – Ring wave waveform specifications at the EUT port of the CDN for
unsymmetrical interconnection lines . 25
Table 6 – Summary of calibration process for CDNs for symmetrical interconnection
lines . 26
Table 7 – Ring wave waveform specifications at the EUT port of the CDN for
symmetrical interconnection lines . 26
Table B.1 – Power ports: Selection of the test levels (depending on the installation
class) . 36
Table B.2 – Circuits/lines: Selection of the test levels (depending on the installation
class) . 37
Table D.1 – Example of uncertainty budget for ring wave rise time (T ) . 41
Table D.2 – Example of uncertainty budget for the peak of the short-circuit current of
the ring wave (I ) . 42
Pk1
Table D.3 – α factor (Formula (D.3)) of different unidirectional impulse responses
corresponding to the same bandwidth of the system B . 44

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
ELECTROMAGNETIC COMPATIBILITY (EMC) –

Part 4-12: Testing and measurement techniques –
Ring 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
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with the International Organization for Standardization (ISO) in accordance with conditions determined by
agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
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3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
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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
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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 61000-4-12 has been prepared by subcommittee 77B: High
frequency phenomena, of IEC technical Committee 77: Electromagnetic compatibility.
It forms Part 4-12 of IEC 61000. It has the status of a basic EMC publication in accordance
with IEC Guide 107.
This third edition cancels and replaces the second edition published in 2006. 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 ring wave waveform;
b) new Annex B on selection of generators and test levels;
c) new Annex C on explanatory notes;
d) new Annex D on measurement uncertainty;

– 6 – IEC 61000-4-12:2017 © IEC 2017
e) addition of high speed CDN;
f) addition of a calibration procedure for CDN.
The text of this International Standard is based on the following documents:
CDV Report on voting
77B/764/CDV 77B/774/RVC
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 publication 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 publication will remain unchanged until
the stability date indicated on the IEC web site under "http://webstore.iec.ch" in the data
related to the specific publication. At this date, the publication will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
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
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 ring waves. It should be noted that edition 1 of IEC 61000-4-12, published in 1995,
covered immunity tests against two phenomena, ring waves and damped oscillatory waves.
This situation was changed in edition 2, published in 2006, where IEC 61000-4-12 covered
the ring wave phenomena only and the damped oscillatory wave phenomenon was moved into
a new standard IEC 61000-4-18.

– 8 – IEC 61000-4-12:2017 © IEC 2017
ELECTROMAGNETIC COMPATIBILITY (EMC) –

Part 4-12: Testing and measurement techniques –
Ring wave immunity test
1 Scope
This part of IEC 61000 relates to the immunity requirements and test methods for electrical
and electronic equipment, under operational conditions, to ring waves occurring in low-voltage
power, control and signal lines supplied by public and non-public networks.
The object of this document is to establish a common reference for evaluating the immunity of
electrical and electronic equipment when subjected to ring waves. 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. TC 77 and its sub-committees are prepared to co-operate with product committees in the
evaluation of the value of particular immunity test and test levels for their products.
This document defines:
– test voltage and current waveforms;
– a range of test levels;
– test equipment;
– test setups;
– test procedures.
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 (all parts), International Electrotechnical Vocabulary (IEV) (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 (all parts) as
well as 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
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]
3.1.2
coupling
interaction between circuits, transferring energy from one circuit to another
3.1.3
coupling network
CN
electrical circuit for the purpose of transferring energy from one circuit to another
3.1.4
coupling/decoupling network
CDN
combination of a coupling network and a decoupling network
3.1.5
decoupling network
DN
electrical circuit for the purpose of preventing test voltages applied to the equipment under
test (EUT) from affecting other devices, equipment, or systems which are not under test
3.1.6
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]
3.1.7
port
particular interface of an equipment, which couples this equipment with the external
electromagnetic environment (IEC 60050-161:1990, 161-01-01) and through which the
equipment is influenced by the environment
[SOURCE: IEC 60050-161:1990, 161-01-27]
3.1.8
ring wave
damped oscillation, whose damping time constant is of the order of one period
[SOURCE: IEC 60050-161:1990, 161-02-30]
3.1.9
rise time
T
r
interval of time between the instants at which the instantaneous value of an impulse first
reaches 10 % value and then the 90 % value

– 10 – IEC 61000-4-12:2017 © IEC 2017
[SOURCE: IEC 60050-161:1990, 161-02-05, modified – the content of the note has been
included in the definition and “pulse” has been changed to “impulse”]
3.1.10
transient (adj 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]
3.1.11
verification
set of operations which is used to check the test equipment system (e.g. the test generator
and its interconnecting cables) to demonstrate that the test system is functioning
Note 1 to entry: The methods used for verification may be different from those used for calibration.
Note 2 to entry: For the purposes of this basic EMC standard this definition is different from the definition given in
IEC 60050-311:2001, 311-01-13.
3.2 Abbreviated terms
AE Auxiliary equipment
CD Coupling device
CDN Coupling/decoupling network
CLD Clamping device
CN Coupling network
DN Decoupling network
EMC Electromagnetic compatibility
EUT Equipment under test
GDT Gas discharge tube
MU Measurement uncertainty
PDF Probability density function
PE Protective earth
RGP Reference ground plane
RWG Ring wave generator
SPD Surge protective device
4 General
4.1 Description of the phenomenon
The ring wave (described in Figure 1) is an oscillatory transient, induced in low-voltage cables
due to the switching of electrical networks and reactive loads, faults and insulation breakdown
of power supply circuits or lightning. It is, in fact, the most diffused phenomenon occurring in
power supply (high voltage, medium voltage, low voltage) networks, as well as in control and
signal lines.
The ring wave is representative of a wide range of electromagnetic environments of
residential, as well as industrial installations. It is suitable for checking the immunity of
equipment in respect of the above-mentioned phenomena, which give rise to impulses
characterized by sharp front-waves that, in the absence of filtering actions, are in the order of
10 ns to a fraction of µs. The duration of these impulses may range from 10 µs to 100 µs.

The rise time and duration of the impulse are dependent on the propagation characteristics of
the media and the path.
The propagation of the wave in the lines (power and signal) is always subject to reflections,
due to the mismatching impedance (the lines are terminated with loads or connected to
protection devices, input line filters, etc.). These reflections produce oscillations, whose
frequency is related to the propagation speed. The presence of parasitic parameters
(e.g. stray capacitance of components like motors, transformer windings, etc.) are additional
influencing factors.
The rise time can be increased by the low-pass characteristics of the line. This effect is more
relevant for fast rise times (in the order of 10 ns), and less relevant for slow rise times (in the
order of 1 µs).
Another cause of the ring wave is lightning, which itself is characterized by a unidirectional
waveform (standard 1,2/50 µs impulse). Circuits subjected to the indirect effects of lightning
(inductive coupling among lines) are influenced by the derivative of the primary impulse and
the coupling mechanisms involved, which can cause oscillations. The characteristics of the
resulting ring wave depend on the reactive parameters of the ground circuits, metal structures
involved in the lightning current flow, and the propagation in the low-voltage transmission
lines.
The phenomenon, which is created by the above mentioned effects at the equipment ports, is
an oscillatory transient or a ring wave. Oscillatory transients are covered in IEC 61000-4-18. A
ring wave with a defined 0,5 µs rise time and 100 kHz oscillation frequency has been
determined to be typical and is widely used for testing products.
The formula of the ideal waveform of Figure 1, w(t), is as follows:
n
 
t
 
 
t  
t
 
w(t) = A ⋅ K ⋅ ⋅ exp−  ⋅cos(βt)
 
n
t
 2 
 
t
1+  
 
t
 1 
with
2π
T 1
and β = and T = 10 µs
t = ⋅ = 7,21μs
2 ln R T
where the parameters for oscillation period T = 10 µs are:
A = 1; K = 1,81; n = 1,83; t = 0,507 µs
NOTE R is the ratio between Pk and Pk , Pk and Pk . The value of R ensures that the ratios Pk /Pk , Pk /Pk are
2 3 3 4 2 3 3 4
in the range specified by this document. The value of R cannot be too small otherwise the ratio Pk /Pk exceeds the
1 2
specified tolerance. R = 2 has been selected. The parameters n and t are adjusted to obtain T = 0,5 μs.
1 1
– 12 – IEC 61000-4-12:2017 © IEC 2017
Pk (U or I )
1 Pk Pk
1 1
100 %
90 %
T
Pk
10 %
t
T Pk
1 4
110 % to 40%
Pk
IEC
Key
T Rise time
T Oscillation period
NOTE Only Pk is specified for the current waveform.
Figure 1 – Waveform of the ring wave
(open-circuit voltage and short-circuit current)
Other IEC standards, such as IEC 61000-4-5, refer to the 1,2/50 µs standard lightning
impulse, which may be considered to be complementary to the ring wave described in this
document.
It is the responsibility of the product committees to define the most appropriate test, according
to the phenomenon considered as relevant.
4.2 Relevant parameters
4.2.1 Repetition rate
The repetition rate of the transient is directly related to the frequency of occurrence of the
primary phenomenon (lightning and switching). It is higher whenever the primary cause is the
load switching in control lines, and less frequent in the case of faults and lightning. The
occurrence may typically range from once per second down to once per year.
The repetition rate may be increased in order to reduce the duration of the test. It should be
selected according to the characteristics of the protection device used for
mitigation/suppression of transients.
4.2.2 Phase angle
Equipment failures related to the ring wave on power supply sources can depend on the
phase angle of the AC mains at which the transient is applied. When a protection element
operates during a ring wave test, follow current may occur depending on the phase angle at
which the transient occurs. Follow current is the current from the connected power source that
flows through a protective element, or from any arc in the EUT both during and following the
transient.
U/I
For semiconductors, the phenomenon may be related to the conduction state of the device at
the time the ring wave occurs. Semiconductor parameters that may be involved, include
forward and reverse recovery characteristics and secondary breakdown performance.
Devices most likely to fail in a phase-related way are semiconductors involved in the power
input circuitry. Other devices in different areas of the EUT can also exhibit such failure
modes.
5 Test levels
The preferred test levels for the ring wave applicable to power, signal and control ports of the
equipment, are given in Table 1. The test level is defined as the voltage of the first peak
(maximum or minimum) in the test waveform (Pk in Figure 1).
Different test levels may apply to power, signal and control ports.
Table 1 – Test levels
Open-circuit test voltage
Level kV
b
Line-to-line Line-to-ground
1 0,25 0,5
2 0,5 1
3 1 2
4 2 4
a
X Special Special
a
"X" can be any level, above, below or in between the others. This level shall be specified by product
committees and/or equipment specification.
b
For symmetrical interconnection lines the test can be applied to multiple lines simultaneously with respect to

ground, i.e. “lines to ground”.

The test levels shall be selected according to the installation conditions; classes of installation
are given in Annex C. Annex A gives information on test levels.
The test shall be applied at all test levels in Table 1 up to and including the specified test
level (see 8.3).
For selection of the test levels for the different interfaces, refer to Annex B.
6 Test instrumentation
6.1 Ring wave generator
6.1.1 Ring wave generator circuit
The generator output shall have the capability to operate under short-circuit conditions.
A block diagram of a representative ring wave generator is shown in Figure 2.

– 14 – IEC 61000-4-12:2017 © IEC 2017
R
S
S
R R
1 2
R
U C L C
1 1 2
IEC
Key
U: high-voltage source R : 30 Ω resistor
C : energy storage capacitor R : 12 Ω resistor
1 4
C : filter capacitor L : oscillating circuit coil
2 1
R : charging resistor S : high-voltage switch
1 1
R : filter resistor S : output impedance selector
2 2
Figure 2 – Example of schematic circuit of the ring wave generator
6.1.2 Impedance values
Two values of impedance (see R and R in Figure 2) have been selected as follows:
3 4
• 12 Ω when testing AC/DC power ports and shielded interconnection lines
• 30 Ω when testing unshielded interconnection lines
6.1.3 Performance characteristics of the ring wave generator
A generator with a floating output shall be used.
The generator is a single-shot ring wave generator with the following characteristics,
measured at the output of the generator:
– voltage rise time (T in Figure 1) 0,5 µs ± 30 % (open-circuit condition)
– current rise time (T in Figure 1) 0,2 µs to 1,0 µs (short-circuit condition)
– voltage oscillation frequency (1/T in Figure 1) 100 kHz ± 10 %
NOTE 1 Oscillation frequency is defined as the reciprocal of the period between the first and third zero crossings
after the initial peak.
– decay (voltage only; see Figure 1) 0,4 ≤ ratio of Pk to Pk ≤ 1,1
2 1
0,4 ≤ ratio of Pk to Pk ≤ 0,8
3 2
0,4 ≤ ratio of Pk to Pk ≤ 0,8
4 3
no requirements for Pk onwards
– repetition rate 1/min or faster
– output impedance see Table 2
NOTE 2 The output impedance is calculated from the open-circuit voltage U divided by the short-circuit current
Pk1
I
Pk1
– open-circuit voltage U (see Figure 1) adjustable from 0,25 kV to the required
Pk1
test level
– short-circuit current I (see Figure 1) see Table 2
Pk1
– phase shifting in a range between 0° to 360° relative to the
phase angle of the AC line voltage to the EUT
with a tolerance of ±10°
– polarity of Pk (see Figure 1) positive and negative
Table 2 – Relationship between peak open-circuit voltage
and peak short-circuit current
Open-circuit peak voltage ± 10 % Short-circuit peak current ± 10 % Short-circuit peak current ± 10 %
at generator output at 12 Ω generator output at 30 Ω generator output
0,25 kV 20,8 A 8,3 A
0,5 kV 41,7 A 16,7 A
1,0 kV 83,3 A 33,3 A
2,0 kV 166,7 A 66,7 A
4,0 kV 333,3 A 133,3 A
6.1.4 Calibration of the ring wave generator
The test generator characteristics shall be calibrated in order to establish that they meet the
requirements of this document. For this purpose the following procedure shall be undertaken.
The generator output shall be connected to a measurement system with a sufficient bandwidth
(minimum 20 MHz), voltage and current capability to monitor the characteristics of the
waveform.
The characteristics of the generator shall be measured both under open-circuit (load greater
than or equal to 10 kΩ) and short-circuit conditions at the same set voltage.
All performance characteristics stated in 6.1.3, with the exception of phase shifting and
repetition rate, shall be met at the output of the generator. Phase shifting performance shall
be met at the output of the CDN at 0°, 90°, 180° and 270° at one polarity.
6.2 Coupling/decoupling networks
6.2.1 General
Each coupling/decoupling network (CDN) consists of a coupling network and a decoupling
network as shown in the examples of Figure 4 through Figure 10.
NOTE The coupling capacitors can be part of the CDN or part of the generator or discrete external components.
The coupling network shall be provided with a coupling capacitor suitable for the selected
impedance of the test generator, i.e. ≥3 µF.
On the AC or DC power lines, the decoupling network provides relatively high impedance to
the ring wave transient but at the same time allows current to flow to the EUT. This
impedance allows the voltage waveform to be developed at the output of the
coupling/decoupling network and prevents the ring wave current from flowing back into the AC
or DC power supply. High voltage capacitors are used as the coupling element, sized to allow
the full waveform durations to be coupled to the EUT. The coupling/decoupling network for the
AC or DC power supply shall be designed so that the open-circuit voltage waveform and
short-circuit current waveform meet the requirements of Table 3.
For I/O and communication lines, the series impedance of the decoupling network limits the
available bandwidth for data transmission. Coupling elements can be capacitors, in cases
where the line tolerates the capacitive loading effects, clamping devices or arrestors. When
coupling to interconnection lines, the waveforms may be distorted by the coupling
mechanisms which are described in 6.2.3.

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The coupling/decoupling network for the unshielded interconnection lines shall be designed so
that the open-circuit voltage waveform and short-circuit current waveform meet the
...