IEC TR 61000-1-4:2022
(Main)Electromagnetic compatibility (EMC) - Part 1-4: General - Historical rationale for the limitation of power-frequency conducted harmonic current emissions from equipment, in the frequency range up to 2 kHz
Electromagnetic compatibility (EMC) - Part 1-4: General - Historical rationale for the limitation of power-frequency conducted harmonic current emissions from equipment, in the frequency range up to 2 kHz
IEC TR 61000-1-4:2022 which is a technical report, reviews the sources and effects of power frequency conducted harmonic current emissions in the frequency range up to 2 kHz on the public electricity supply, and gives an account of the reasoning and calculations leading to the existing emission limits for equipment in the editions of IEC 61000-3-2, up to and including the fifth edition (2018) with Amendment 1 (2020), and in the second edition of IEC 61000-3-12. The history is traced from the first supra-national standard on low-frequency conducted emissions into the public electricity supply, EN 50006:1975 and its evolution through IEC (60)555-2 to IEC 61000-3-2, IEC TR 61000-3-4 and IEC 61000-3-12. To give a full picture of the history, that of the standard for the measuring instrument IEC 61000-4-7 is mentioned as well. NOTE All IEC standards were renumbered starting from 60000 from 1998-01-01. To indicate the references of standards withdrawn before, or not reprinted after, that date, the “60x” prefix is here enclosed in parentheses. Hence “IEC (60)555-2”. Some concepts in this document apply to all low voltage AC systems, but the numerical values apply specifically to the European 230 V;400 V 50 Hz system. This second edition cancels and replaces the first edition published in 2005. This edition constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition:
- relation between compatibility levels, emission limits and immunity requirements clarified;
- sharing of emission levels between LV, MV and HV clarified;
- new historical information added.
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IEC TR 61000-1-4 ®
Edition 2.0 2022-06
TECHNICAL
REPORT
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Electromagnetic compatibility (EMC) –
Part 1-4: General – Historical rationale for the limitation of power-frequency
conducted harmonic current emissions from equipment, in the frequency range
up to 2 kHz
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IEC TR 61000-1-4 ®
Edition 2.0 2022-06
TECHNICAL
REPORT
colour
inside
Electromagnetic compatibility (EMC) –
Part 1-4: General – Historical rationale for the limitation of power-frequency
conducted harmonic current emissions from equipment, in the frequency range
up to 2 kHz
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 33.100.10 ISBN 978-2-8322-2263-8
– 2 – IEC TR 61000-1-4:2022 © IEC 2022
CONTENTS
FOREWORD . 4
INTRODUCTION . 6
1 Scope . 7
2 Normative references . 7
3 Terms and definitions . 7
4 General appraisal . 8
5 Acceptable provisions in standards related to regulatory legislation . 8
6 History of IEC 61000-3-2 and its predecessors . 9
6.1 History table . 9
6.2 Before 1960 . 9
6.3 1960 to 1975 . 9
6.4 1975 to 1982 . 10
6.5 1982 to 1995 . 10
6.6 1995 to 2000 . 12
6.7 The “Millennium Amendment”. 13
6.8 2000 to 2019 . 13
6.9 2020 to 2022 . 14
6.9.1 Impact factor approach . 14
6.9.2 Effect of the coronavirus pandemic from 2020 to 2022 . 15
7 History of IEC 61000-3-12 and its predecessor . 15
7.1 Origin . 15
7.2 1989 to 1998 . 15
7.3 After 1998 . 16
8 History of IEC 61000-4-7 up to 2008 . 16
8.1 First edition in 1991 . 16
8.2 Second edition in 2002 . 16
8.3 Amendment 1 to the second edition . 16
8.4 Developments since 2008 . 17
9 Economic considerations taken into account in setting limits in IEC 61000-3-2
before publication in 1995, and before the finalization of the text of the Millennium
Amendment . 17
Annex A (informative) Compatibility level and compensation factor . 19
A.1 Explanation of the allocation of only part of the total compatibility level to the
low-voltage network . 19
A.2 Compensation factor . 20
A.2.1 Maximum permissible current emission – original approach . 20
A.2.2 Detailed consideration . 21
A.2.3 New work prompted by the preparation of this document . 23
Annex B (informative) Comparison of Class A limits and the harmonic spectra of
phase-controlled dimmers of incandescent lamps at 90° firing angle . 27
Annex C (informative) Comparison of Class C (IEC 61000-3-2:2018 and IEC 61000-3-
2:2018/AMD1:2020, Table 2) limits and the harmonic spectrum of a discharge lamp
with inductive ballast . 28
Annex D (informative) Comparison of Class D limits and the harmonic spectra of
capacitor-filtered single-phase rectifiers with 35° and 65° conduction angles . 29
Annex E (informative) Economic considerations taken into account in setting limits,
before finalization of the text of the Millennium Amendment to IEC 61000-3-2 . 30
Annex F (Informative) Concept plan for a full revision of IEC 61000-3-2 . 32
F.1 Rationale . 32
F.2 Density . 32
F.3 Usage factor . 32
F.4 Contribution . 32
F.5 Phase angle factor . 32
F.6 System and site mitigation . 33
F.7 Network factors . 33
Annex G (informative) Histories of IEC 61000-3-2 and IEC 61000-3-12 and related
standards . 34
Bibliography . 36
Figure A.1 – Harmonic voltage drops and harmonic current injections in a typical
system . 20
Figure A.2 – Permissible number of Class A loads versus harmonic order, with an
additional 10 Ω load on the feeder . 26
Figure B.1 – Comparison of Class A limits and spectra of dimmers . 27
Figure C.1 – Comparison of Class C limits and the harmonic spectrum of a discharge
lamp . 28
Figure D.1 – Comparison of Class D limits and harmonic spectra of single-phase
230 W rectifiers with capacitor filters. 29
Figure E.1 – Illustration of the concept of total aggregate cost trade-offs for meeting
compatibility levels . 31
Table A.1 – Compensation factors k considered valid in 1995 (IEC 61000-3-2:1995
p,h
[1] (first edition)) . 21
Table A.2 – Sub-factors of k . 22
p,h
Table A.3 – Compensated sharing factors . 24
Table G.1 – Publication history of IEC 61000-3-2 . 34
Table G.2 – Publication history of IEC 61000-3-12 . 35
Table G.3 – Publication history of IEC 61000-4-7 . 35
– 4 – IEC TR 61000-1-4:2022 © IEC 2022
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
ELECTROMAGNETIC COMPATIBILITY (EMC) –
Part 1-4: General – Historical rationale for the limitation
of power-frequency conducted harmonic current emissions
from equipment, in the frequency range up to 2 kHz
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
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IEC TR 61000-1-4 has been prepared by subcommittee 77A: EMC – Low frequency
phenomena, of IEC technical committee 77: Electromagnetic compatibility. It is a Technical
Report.
This second edition cancels and replaces the first edition published in 2005. This edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) relation between compatibility levels, emission limits and immunity requirements clarified;
b) sharing of emission levels between LV, MV and HV clarified;
c) new historical information added.
The text of this Technical Report is based on the following documents:
Draft Report on voting
77A/1136/DTR 77A/1141/RVDTR
Full information on the voting for its approval can be found in the report on voting indicated in
the above table.
The language used for the development of this Technical Report is English.
This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in
accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement, available
at www.iec.ch/members_experts/refdocs. The main document types developed by IEC are
described in greater detail at www.iec.ch/publications.
A list of all parts in the IEC 61000 series, published under the general title Electromagnetic
compatibility (EMC), can be found on the IEC website.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under webstore.iec.ch in the data related to the
specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
IMPORTANT – The "colour inside" logo on the cover page of this document indicates that it
contains colours which are considered to be useful for the correct understanding of its
contents. Users should therefore print this document using a colour printer.
– 6 – IEC TR 61000-1-4:2022 © IEC 2022
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 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).
IEC TR 61000-1-4:2005 (first edition) gave a historical rationale for the emission limits for
equipment up to 2005. Since there is new historical material available about the developments
in the past several years, SC77A is adding this new historical material as a revision of
IEC TR 61000-1-4. The revision also clarifies and amends some existing statements that are
now known not to report the history until 2005 correctly.
ELECTROMAGNETIC COMPATIBILITY (EMC) –
Part 1-4: General – Historical rationale for the limitation
of power-frequency conducted harmonic current emissions
from equipment, in the frequency range up to 2 kHz
1 Scope
This part of IEC 61000, which is a technical report, reviews the sources and effects of power
frequency conducted harmonic current emissions in the frequency range up to 2 kHz on the
public electricity supply, and gives an account of the reasoning and calculations leading to the
existing emission limits for equipment in the editions of IEC 61000-3-2 [1] , up to and including
the fifth edition (2018) with Amendment 1 (2020), and in the second edition of IEC 61000-3-12
(2011) [2].
The history is traced from the first supra-national standard on low-frequency conducted
emissions into the public electricity supply, EN 50006:1975 [3] and its evolution through IEC
(60)555-2 [4] to IEC 61000-3-2 [1], IEC TR 61000-3-4 [5] and IEC 61000-3-12 [2]. To give a full
picture of the history, that of the standard for the measuring instrument IEC 61000-4-7 [6] is
mentioned as well.
NOTE All IEC standards were renumbered starting from 60000 from 1998-01-01. To indicate the references of
standards withdrawn before, or not reprinted after, that date, the “60x” prefix is here enclosed in parentheses. Hence
“IEC (60)555-2”.
Some concepts in this document apply to all low voltage AC systems, but the numerical values
apply specifically to the European 230 V/400 V 50 Hz system.
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 61000 (all parts), Electromagnetic compatibility (EMC)
3 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 61000 (all parts)
apply.
ISO and IEC maintain terminology databases for use in standardization at the following
addresses:
• IEC Electropedia: available at https://www.electropedia.org/
• ISO Online browsing platform: available at https://www.iso.org/obp
___________
1 Numbers in square brackets refer to the Bibliography.
– 8 – IEC TR 61000-1-4:2022 © IEC 2022
4 General appraisal
The electricity supply industry intends to supply electric power with a sinusoidal voltage
waveform, and customers' equipment is designed to operate correctly on such a supply.
However, because the internal impedance of the supply system is not zero, a non-linear load
connected by one customer produces distortion of the voltage waveform that can adversely
affect another customer's equipment, as well as equipment in the supply system itself. There is
no type of load or supply system equipment that is totally immune to distortion of the voltage
waveform, and “natural” immunity levels (those achieved by customary designs without special
attention to improving immunity) vary greatly. Based largely on experience of the amounts of
voltage distortion that give rise to evidence of malfunction of, or damage to, equipment,
compatibility levels of voltage distortion for the low-voltage (LV) public supply system have been
determined and are given in IEC 61000-2-2 [7]. The correspondences between these levels and
other values are shown schematically in IEC 61000-2-2:2002, Figure A.1. Compatibility levels
are set as an acceptable compromise between immunity to harmonics and reduction of
emissions. Methods to check that the immunity of equipment to voltage distortion is adequate
are given in IEC 61000-4-13 [8].
NOTE 1 Logically, compatibility levels would be set somewhat below the lowest acceptable immunity levels, but
those data were hard to come by in the past. Recommended immunity levels were first established in IEC 61000-4-13.
The intention of applying limits on the harmonic current emissions of equipment connected to
the public low-voltage (LV) system is to keep the actual levels of voltage distortion on the
system below the compatibility levels for a very large proportion of the time, and below lower
levels, known as planning levels, for a lesser but still large proportion of the time.
NOTE 2 Emissions into the medium-voltage (MV) and high voltage (HV) systems can be controlled by other methods
and procedures. See IEC TR 61000-3-6. [9]
NOTE 3 In some countries, the electricity supply industry places reliance on IEC 61000-3-2 [1] to control emissions
from portable equipment, whether the point of common coupling is at LV, MV or HV.
Emissions from equipment are expressed as currents, because these are largely, but not
completely, independent of the source impedance of the supply system, whereas the voltage
distortion produced by the equipment is almost proportional to the supply-system impedance
and therefore has no definite value. A product that draws a non-linear current from the supply
system can alternatively be regarded as drawing a sinusoidal current, while emitting into the
supply system harmonic currents of the opposite polarity to those that it actually draws.
Compatibility levels are set, using system disturbance data and standardized immunity levels,
so that the probability of the system disturbance level exceeding the lowest immunity test level
is acceptably low, and at present is set at 5 %.
NOTE 4 Because the system disturbance level is an aggregate of the emissions of very many loads, the emission
limits for equipment are set at quite low disturbance levels.
NOTE 5 For system design, planning values of disturbance levels are adopted unilaterally by distribution system
operators; these are not expected to be exceeded but are not subject to standardization.
5 Acceptable provisions in standards related to regulatory legislation
The equipment manufacturing industry can accept requirements in a voluntary standard, whose
application can be determined by custom or moderated during individual contract negotiations,
that would be unacceptable in a standard backed by regulatory enforcement. For example, a
standard can contain provisions that, if fully applied, would result in very long test times. Parties
to a contract might waive these provisions, wholly or partly (calculation or simulation might be
employed, for example) whereas in an enforcement situation, no deviation from the provisions
might be allowed.
Both EN 50006:1975, 7.1 and IEC (60)555-2:1988, IEC (60)555-2:1988/AMD1:1988 and
IEC (60)555-2:1988/AMD2:1988 ,5.3.1 [4], required the test operator to search for worst-case
conditions using the controls of the equipment under test, and in IEC (60)555-2, this was
required for each harmonic in turn. Such a test might well take many days, with no assurance
that another test operator might not find a different worst-case condition for just one harmonic.
Such a provision was also contained in IEC 61000-3-2:1995 (first edition), Clause C.1 and was
not removed until the publication of IEC 61000-3-2:2000/AMD1:2001 (second edition) [1].
A standard must not include regulatory requirements: it is concerned only with the procedures
necessary to determine whether a product within its scope meets its requirements.
6 History of IEC 61000-3-2 and its predecessors
6.1 History table
The revision histories of IEC 61000-3-2 and IEC 61000-3-12 are given in Annex G (informative).
An up-to-date table of the entire publication history of each IEC publication can be obtained via
the IEC webstore at https://webstore.iec.ch.
6.2 Before 1960
The most numerous non-linear loads were television receivers with half-wave rectifiers.
Because most of these had mains connectors of reversible polarity, the DC components
approximately cancelled. The number of receivers installed was insufficient to create any
significant system problems due to harmonic current emissions, but there is evidence that there
was enough random unbalance of polarity of connection in some countries for the resultant DC
component to cause corrosion problems in underground cables.
6.3 1960 to 1975
Phase-controlled dimmers for household lighting began to be marketed. These created high-
frequency conducted emissions, thus initially drawing the attention of radio-spectrum protection
authorities. Measures to limit these emissions could be made mandatory, but it was also noted
that the dimmers produced harmonic currents and there was no practicable way of reducing the
ratios of harmonic to fundamental current.
A system survey in Europe determined the 90th percentile value for supply impedance for
residential customers (who were mostly fed by overhead LV distribution) as (0,4 + j0,25) Ω, and
this value was included in IEC TR 60725:1981 [10]. In addition it was determined that without
some control of emissions from dimmers, the voltage distortion might grow to exceed acceptable
levels (later to be called “compatibility levels”).
NOTE In IEC (60)555-2:1982, Annex A [4], the supply impedance was regarded as purely resistive and inductive
((0,4 + jh0,25) Ω, where h is the harmonic order number). However, evidence was later presented that showed that
the impedance rises above 500 Hz more nearly proportional to the square root of frequency, rather than proportional
to frequency. The impedance presented to a particular load at the interface with the network (which is what
determines the voltage distortion produced by the current emissions from that load) includes the effect of the
impedances of other loads on the feeder. Even a light 10 kW load due to other equipment considerably lowers the
impedance at high-order harmonic frequencies. See 6.9.
The first standard on this subject (according to its own text it is not based on any previous
standard) was the European standard EN 50006:1975, implemented as various national
standards, including BS 5406:1976. This standard took burst-firing techniques into account and
also covered voltage fluctuations, now the subject of IEC 61000-3-3 [11] and IEC 61000-3-11
[12]. Limitation of harmonic current emissions was achieved by:
___________
2 IEC (60)555-2 was withdrawn in 1995 and replaced by IEC 61000-3-2.
– 10 – IEC TR 61000-1-4:2022 © IEC 2022
• prohibiting the use of phase control for heating loads over 200 W;
• applying limits for odd-harmonic emissions;
• applying limits for even-harmonic emissions to both symmetrical and asymmetrical control
techniques.
The limits were expressed as voltage-harmonic percentages, produced with a supply system
whose impedance (for single-phase loads) was (0,4 + jh0,25) Ω. However, the test procedure
actually required measurement of the harmonic currents, from which the voltage distortions
were calculated.
EN 50006 [3] does not include any explanation of the derivation of the limits, which are
preserved as the Class A limits in IEC 61000-3-2, up to the 2000 edition (second edition). In
fact, the numerical values were undoubtedly established piecemeal by negotiation between
supply industry and equipment manufacturer experts. The retention of a strict mathematical rule
for determining the values would not have been a priority for either group.
There was a study that led to an approximate algorithm for determining the cumulative
contribution of many dimmers set at different firing angles to a net voltage distortion level at the
terminals of the LV transformer feeding the final distribution. (See also Annex A.)
6.4 1975 to 1982
During this period, a more comprehensive standard, IEC (60)555-2 (published in 1982), was
developed. Still effectively restricted to 220 (380) V to 240 (415) V 50 Hz European systems, it
was adopted by CENELEC as EN (60)555-2 in 1987. It introduced three sets of limits; the
original current limits unchanged from EN 50006, limits 1,5 times greater for products used only
for short periods, such as portable tools, and special limits for television receivers, although an
exemption for receivers whose input power was less than 165 W caused the limits to apply only
to a small proportion of the receivers manufactured. The limits were expressed directly as
currents, even for television receivers.
Although IEC (60)555-2 included an annex that claimed to explain the derivation of the original
current limits, in fact, it did not do so, merely citing the voltage distortion limits that were
included in EN 50006 without explanation.
6.5 1982 to 1995
This period saw three profound changes; the great expansion of the use of switch-mode power
supplies, both in business and in the home, the intimation that mandatory regulation of the
electromagnetic compatibility (EMC) characteristics of electronic products would be introduced
in Europe, and the further intimation that the European public electricity supply would be subject
to “product quality” requirements.
The early standards, EN 50006 [3]and IEC (60)555-2, did not apply to professional equipment,
but there is no relevant definition in either standard, although EN 50006 cites “office machinery”
as an example. Thus it was unclear whether the standards applied to desktop computers. This
was clarified in Europe by a decision that such computers were “household appliances”, so that
the original current limits applied. However the great expansion of single phase consumer
electronics using direct on line switch mode DC power units, such as television receivers and
desktop computers, led to significant peak flattening of the supply voltage waveforms due to
near coincidence of the large current pulses drawn by these products. Although direct-on-line
switch mode DC power units provided technology advantages (higher efficiency, lighter weight,
smaller size), the near coincidence of the large current pulses being drawn can result in
significant distortion of the supply voltage waveform. (Products with transformer-fed non-
switching supplies have proportionally lower emissions because the series impedance of the
transformer results in a larger conduction angle of the rectifiers.)
As a result, the development of the successor to IEC (60)555-2 was extremely controversial. It
has been suggested that while the electricity supply industry continued to work in depth on the
development of IEC 61000-3-2, the involvement of the equipment manufacturing industry was
less structured. This could be true, but should be seen in the context that “equipment
manufacture” is a very diverse industry sector, whose sub-sectors have very different priorities
in considering harmonic current emissions, while the supply industry has very little diversity in
priorities, mainly deriving from differing infra-structure configurations in different countries.
IEC 61000-3-2:1995 (first edition) introduced many new features. Most notably, it applies to
“[all] electrical and electronic equipment having an input current up to and including 16 A per
phase and intended to be connected to public low-voltage distribution systems.” (However,
“professional equipment”, as defined in the standard, enjoys exemption from some
requirements.)
IEC 61000-3-2:1995 thus includes requirements and limits that apply to several different types
of product, grouped into four classes. It effectively applies only to European systems, as for
previous standards.
NOTE 1 It is still not known whether the characteristics of 220 V to 240 V, 50 Hz supply systems in other countries
are sufficiently similar to the European for the standard to be applied, while it has been shown that “scaling”
operations, intended to make the provisions applicable to systems of other voltages and frequencies, are rather
unreliable. Different distribution system configurations affect the effective supply impedance and the propagation of
harmonic currents through the system. The characteristics of electricity supplies world-wide are under study in
SC77A.
Class A is a general class, applying to products within the scope that are not specifically
included in another class. The limits are derived from the original voltage limits, dating
effectively from before 1975, and the assumed supply impedances at the fundamental and
harmonic frequencies. The limits are related to the current emissions of dimmers for
incandescent lamps. See Annex B.
Class B is a specific class, applying to portable tools, which are assumed to be used for short
periods only (a few minutes). The limits are 1,5 times the Class A limits. As far as can be
determined, this factor of 1,5 is purely heuristic, although for the third harmonic, one piece of
equipment that just meets the third-harmonic limit of 3,45 A thereby takes up almost all the
allowable fraction (0,25) of the compatibility level of 5 % that can be allocated to the low-voltage
network.
NOTE 2 For an explanation of the “allowable fraction of the compatibility level”, see Annex A.
Class C is for lighting equipment, which has to be carefully defined. There is not a single set of
limits for this class, and the limits are quite stringent. Some of these originally appeared, with
similar values, in the product standard IEC (600)82 [24], now withdrawn. See Annex C.
Class D applied originally to products drawing a current pulse from the supply that lay within a
specified mask centred on the peak of the current waveform. The rectifier conduction angle of
a typical high-efficiency direct-on-line DC power unit is 35°. The individual low-order odd
harmonic currents emitted by a group of such products add nearly arithmetically, producing
peak-flattening of the voltage waveform of single-phase supplies. This class was intended to
apply to DC power units, separate or built into products, and was based, after considerable
study (including the effect of supplying the rectifier with already peak-flattened sine waves), on
a rectifier conduction angle of approximately 65°, with some heuristic adjustments to
accommodate other products. See Annex D.
The Class D limits, which are proportional to the active power drawn and are thus expressed in
mA/W, were nominally aligned with the (fixed current) Class A limits at a power of 600 W, but
because of rounding errors, the limits of the two classes for each harmonic become equal at
significantly different powers, which caused some confusion initially. It was possible to
determine that the expected effect on the supply system was that the compatibility limits would
not be exceeded with these limits applied. The details of this prediction are given in [31] and
[22].
– 12 – IEC TR 61000-1-4:2022 © IEC 2022
It was also agreed that there should be a lower bound to Class D below which no limits would
apply, because the impact on the network of a large variety of such products would be
acceptable. The lower bound was set at 75 W, with a provision to reduce to 50 W “after four
years”. It was not realised that this is not a provision that could actually be implemented as
stated. Consequently, those who relied on this provision have been disappointed that it has not
been implemented.
NOTE 3 There is no definite date from which to count the period of four years, because IEC standards are voluntary
and can be applied, or not, at any time. Furthermore, IEC standards can only be amended by a voting process, which
is contemporaneous; National committees cannot determine which way they will vote on a provision that would
become effective many years in the future.
Unfortunately, the conduction angle of 65° required to meet the limits of Class D results in a
rather unacceptably low efficiency of the power unit, manifesting as heat emission or the need
for the inclusion of an inductor or an active power-factor correction circuit, at extra cost. This
requirement was introduced on the grounds that statistical evidence showed a rising level of
voltage distortion on European networks, together with daily variations in the 5th harmonic
levels that tracked with television viewing habits. The rate of rise determined in several
European countries was about 1 % over ten years, although not all the data were measurements
at the same sites or at the same times over the ten-year period. But the “background” level due
to miscellaneous sources was about 3 % in some places and the compatibility level was 5 %
for the 5th harmonic at that time, so an unchecked rise could have had serious consequences
in about ten years. Considering the service lifetimes of the products concerned (3 years to 10
years), it was clearly necessary to forestall any close approach to the compatibility level some
years before it was forecast to occur.
A principle known as “equal rights” was applied in the setting of limits at that time. This can be
simply stated as, “any product consuming x watts has an equal right to produce y % of harmonic
currents”. Consequently, the classification and limits derived for television receivers were
applied to all products with a DC power unit. However, this principle does not allow for the fact
that there are, for example, far more television receivers in use than, say, some rare piece of
scientific equipment, of which there might be only ten in any one country. So applying the limits
to the ten rare units, at a cost, achieves nothing of any significance to the well-being of the
supply network or its load equipment.
NOTE 4 “Equal rights” also suggests that the allowable harmonic emissions would be proportional to the power
drawn by the product. From the equipment design point of view, this is entirely logical. Fixed current limits are very
lax for low-power equipment and can be very stringent indeed for higher-power equipment.
The introduction in Europe of mandatory control of EMC characteristics effectively turned
IEC 61000-3-2 into a quasi-legal document, although it was not editorially suited to such a role.
6.6 1995 to 2000
Amendment 1 to IEC 61000-3-2:1995 (first edition) was issued in 1997. It introduced the
following changes:
• “The designation shall be specified by the manufacturer” was added to the definition of
“professional equipment". (Unfortunately, a definition is not allowed to contain a
requirement, so other committees have not been allowed to adopt this definition verbatim.)
• Test conditions for vacuum cleaners and air-conditioners were added to Annex C.
Amendment 2 was issued in February 1998. This introduced requirements for lighting equipment
with active input power not greater than 25 W. The limits applying to Class D, without the lower
bound of 75 W, can be applied, or, in addition to limits for low-order harmonic currents, the
current waveform can meet shape requirements. In setting these requirements, note was taken
of the fact that there can be partial cancellation of the 5th harmonic current produced by
discharge lamps by the 5th harmonic current produced by DC power units with capacitive filter,
such as in television receivers.
Amendment 3 resulted from a proposal to amend the CENELEC version of the standard
unilaterally, which was changed to a request for IEC to prepare it. Additional amendments were
consolidated with it, resulting in a combined text dealing with:
– limits for motor driven equipment with phase angle control;
– test conditions for kitchen machines;
– asymmetrical control methods;
– symmetrical control methods;
– test condition for arc welding equipment intended for non-professional use.
None of these involved fundamental changes to the standard.
In accordance with IEC publication procedures, this third amendment resulted in a second
edition, dated August 2000.
6.7 The “Millennium Amendment”
An initiative in CENELEC led to a reappraisal of the standard, with much discussion in a working
group. The output document was referred to IEC SC 77A, and this resulted in further very
extensive discussions. During this time, economic considerations were introduced as a specific
subject (see Annex E). By the end of 1999, a somewhat reluctant consensus had been achieved,
mainly on the grounds that further discussion would not produce significant improvement, and
it had been agreed to begin work, immediately after finalizing the amendment, on a full revision
of the standard, with documented rationales for all provisions. The resulting amendment
became known as the 'Millennium Amendment', because it was substantially finalized at the
beginning of 2000.
Unfortunately, Amendment 3 was also in process in IEC during 1998 and 1999, and the IEC
procedures resulted in a divergence of the editions of t
...
IEC TR 61000-1-4 ®
Edition 2.0 2022-06
REDLINE VERSION
TECHNICAL
REPORT
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Electromagnetic compatibility (EMC) –
Part 1-4: General – Historical rationale for the limitation of power-frequency
conducted harmonic current emissions from equipment, in the frequency range
up to 2 kHz
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IEC TR 61000-1-4 ®
Edition 2.0 2022-06
REDLINE VERSION
TECHNICAL
REPORT
colour
inside
Electromagnetic compatibility (EMC) –
Part 1-4: General – Historical rationale for the limitation of power-frequency
conducted harmonic current emissions from equipment, in the frequency range
up to 2 kHz
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 33.100.10 ISBN 978-2-8322-3848-6
– 2 – IEC TR 61000-1-4:2022 RLV © IEC 2022
CONTENTS
FOREWORD . 5
INTRODUCTION . 7
1 Scope . 8
2 Normative references . 8
3 Terms and definitions . 9
4 General appraisal . 9
5 Acceptable provisions in standards related to regulatory legislation . 11
6 History of IEC 61000-3-2 and its predecessors . 11
6.1 History table . 11
6.2 Before 1960 . 12
6.3 1960 to 1975 . 12
6.4 1975 to 1982 . 13
6.5 1982 to 1995 . 13
6.6 1995 to 2000 . 15
6.7 The “Millennium Amendment”. 16
6.7 Future development of IEC 61000-3-2 .
6.8 2000 to 2019 . 16
6.9 2020 to 2022 . 17
6.9.1 Impact factor approach . 17
6.9.2 Effect of the coronavirus pandemic from 2020 to 2022 . 17
7 History of IEC 61000-3-12 and its predecessor . 17
7.1 Origin . 17
7.2 1989 to 1998 . 18
7.3 After 1998 . 19
8 History of IEC 61000-4-7 up to 2008 . 19
8.1 First edition in 1991 . 19
8.2 Second edition in 2002 . 19
8.3 Amendment 1 to the second edition . 19
8.4 Developments since 2008 . 20
9 Economic considerations taken into account in setting limits in IEC 61000-3-2
before publication in 1995, and before the finalization of the text of the Millennium
Amendment . 20
Annex A (informative) Compatibility level and compensation factor . 22
A.1 Explanation of the allocation of only part of the total compatibility level to the
low-voltage network . 22
A.2 Compensation factor . 24
A.2.1 Derivation from the model in Figure A.1 Maximum permissible current
emission – original approach . 24
A.2.2 Detailed consideration . 25
A.2.3 New work prompted by the preparation of this document . 27
Annex B (informative) Comparison of Class A limits and the harmonic spectra of
phase-controlled dimmers of incandescent lamps at 90° firing angle . 31
Annex C (informative) Comparison of Class C (IEC 61000-3-2:2018 and IEC 61000-3-
2:2018/AMD1:2020, Table 2) limits and the harmonic spectrum of a discharge lamp
with inductive ballast . 32
Annex D (informative) Comparison of Class D limits and the harmonic spectra of
capacitor-filtered single-phase rectifiers with 35° and 65° conduction angles . 33
Annex E (informative) Economic considerations taken into account in setting limits,
before finalization of the text of the Millennium Amendment to IEC 61000-3-2 . 34
Annex F (Informative) Concept plan for a full revision of IEC 61000-3-2 . 36
F.1 Introduction Rationale . 36
F.2 Density . 36
F.3 Usage factor . 36
F.4 Contribution . 36
F.5 Phase angle factor . 36
F.6 System and site mitigation . 37
F.7 Network factors . 37
Annex G (informative) Derivation of the limits in IEC 61000-3-12 .
Annex H (informative) Explanation of the reasons for using the concepts of total
harmonic distortion (THD) and partial weighted harmonic distortion (PWHD) .
Annex G (informative) Histories of IEC 61000-3-2 and IEC 61000-3-12 and related
standards . 52
Bibliography . 54
Figure 1 – Diagram showing compatibility level in relation to disturbance and
immunity levels .
Figure A.1 – Allocation of harmonic voltage drops over the transformer impedances in
a typical system .
Figure A.1 – Harmonic voltage drops and harmonic current injections in a typical
system . 24
Figure A.2 – Permissible number of Class A loads versus harmonic order, with an
additional 10 Ω load on the feeder . 30
Figure B.1 – Comparison of Class A limits and spectra of dimmers . 31
Figure C.1 – Comparison of Class C limits and the harmonic spectrum of a discharge
lamp . 32
Figure D.1 – Comparison of Class D limits and harmonic spectra of single-phase
230 W rectifiers with capacitor filters. 33
Figure E.1 – Illustration of the concept of total aggregate cost trade-offs for meeting
compatibility levels . 35
Figure H.1a – Diagram of a LV system consisting of a transformer, a busbar and n
equal feeders .
Figure H.1b – Equivalent circuit for the LV system with "fictitious" feeders .
Figure H.2 – Relative total distortion weight “tdw” as a function of the short-circuit ratio
R .
sce
Table A.1 – Compensation factors k considered valid in 1995 (IEC 61000-3-2:1995
p,h
[1] (first edition)) . 25
Table A.2 – Sub-factors of k . 26
p,h
Table A.3 – Compensated sharing factors . 28
Table G.1 – Relative total distortion weight depending on the point x where the
distorting load is connected .
Table G.2 – Comparison of limit values of IEC 61000-3-12 (columns 2 and 4) with the
approximation by equation (8) (columns 3 and 5) .
– 4 – IEC TR 61000-1-4:2022 RLV © IEC 2022
Table G.3 – Compatibility levels .
Table G.4 – Maximum harmonic currents and voltages for one piece of single phase
equipment (from Table 2 of IEC 61000-3-12) .
Table G.5 – Maximum harmonic currents and voltages for one piece of balanced three
phase equipment (from Table 3 of IEC 61000-3-12) .
Table G.6 – Maximum harmonic currents and voltages for one piece of balanced three
phase equipment (from Table 4 of IEC 61000-3-12): .
Table G.7 – Maximum harmonic currents and voltages for n pieces of single phase
equipment (from Table 2 of IEC 61000-3-12) .
Table G.8- Maximum harmonic currents and voltages for n pieces of balanced three
phase equipment (from Table 3 of IEC 61000-3-12): .
Table G.9 – Maximum harmonic currents and voltages for n pieces of balanced three
phase equipment (from Table 4 of IEC 61000-3-12): .
Table G.10 – Maximum harmonic currents and voltages for n pieces of single phase
equipment (from Table 2 of IEC 61000-3-12): .
Table G.11- Maximum harmonic currents and voltages for n pieces of balanced three
phase equipment (from Table 3 of IEC 61000-3-12): .
Table G.12 – Maximum harmonic currents and voltages for n pieces of balanced three
phase equipment (from Table 4 of IEC 61000-3-12): .
Table G.1 – Publication history of IEC 61000-3-2 . 52
Table G.2 – Publication history of IEC 61000-3-12 . 53
Table G.3 – Publication history of IEC 61000-4-7 . 53
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
ELECTROMAGNETIC COMPATIBILITY (EMC) –
Part 1-4: General – Historical rationale for the limitation
of power-frequency conducted harmonic current emissions
from equipment, in the frequency range up to 2 kHz
FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote international
co-operation on all questions concerning standardization in the electrical and electronic fields. To this end and
in addition to other activities, IEC publishes International Standards, Technical Specifications, Technical Reports,
Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC Publication(s)”). Their
preparation is entrusted to technical committees; any IEC National Committee interested in the subject dealt with
may participate in this preparatory work. International, governmental and non-governmental organizations liaising
with the IEC also participate in this preparation. IEC collaborates closely with the International Organization for
Standardization (ISO) in accordance with conditions determined by agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
consensus of opinion on the relevant subjects since each technical committee has representation from all
interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
misinterpretation by any end user.
4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
transparently to the maximum extent possible in their national and regional publications. Any divergence between
any IEC Publication and the corresponding national or regional publication shall be clearly indicated in the latter.
5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any
services carried out by independent certification bodies.
6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
members of its technical committees and IEC National Committees for any personal injury, property damage or
other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
Publications.
8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of patent
rights. IEC shall not be held responsible for identifying any or all such patent rights.
This redline version of the official IEC Standard allows the user to identify the changes made to
the previous edition IEC TR 61000-1-4:2005. A vertical bar appears in the margin wherever a
change has been made. Additions are in green text, deletions are in strikethrough red text.
– 6 – IEC TR 61000-1-4:2022 RLV © IEC 2022
IEC TR 61000-1-4 has been prepared by subcommittee 77A: EMC – Low frequency
phenomena, of IEC technical committee 77: Electromagnetic compatibility. It is a Technical
Report.
This second edition cancels and replaces the first edition published in 2005. This edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) relation between compatibility levels, emission limits and immunity requirements clarified;
b) sharing of emission levels between LV, MV and HV clarified;
c) new historical information added.
The text of this Technical Report is based on the following documents:
Draft Report on voting
77A/1136/DTR 77A/1141/RVDTR
Full information on the voting for its approval can be found in the report on voting indicated in
the above table.
The language used for the development of this Technical Report is English.
This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in
accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement, available
at www.iec.ch/members_experts/refdocs. The main document types developed by IEC are
described in greater detail at www.iec.ch/publications.
A list of all parts in the IEC 61000 series, published under the general title Electromagnetic
compatibility (EMC), can be found on the IEC website.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under webstore.iec.ch in the data related to the
specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
IMPORTANT – The "colour inside" logo on the cover page of this document indicates that it
contains colours which are considered to be useful for the correct understanding of its
contents. Users should therefore print this document using a colour printer.
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 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).
IEC TR 61000-1-4:2005 (first edition) gave a historical rationale for the emission limits for
equipment up to 2005. Since there is new historical material available about the developments
in the past several years, SC77A is adding this new historical material as a revision of
IEC TR 61000-1-4. The revision also clarifies and amends some existing statements that are
now known not to report the history until 2005 correctly.
– 8 – IEC TR 61000-1-4:2022 RLV © IEC 2022
ELECTROMAGNETIC COMPATIBILITY (EMC) –
Part 1-4: General – Historical rationale for the limitation
of power-frequency conducted harmonic current emissions
from equipment, in the frequency range up to 2 kHz
1 Scope
This part of IEC 61000, which is a technical report, reviews the sources and effects of power
frequency conducted harmonic current emissions in the frequency range up to 2 kHz on the
public electricity supply, and gives an account of the reasoning and calculations leading to the
existing emission limits for equipment in the editions of IEC 61000-3-2 [1] , up to and including
the second edition (2000) and its first amendment (2001), and in the first edition of IEC 61000-
3-12 (2004) the fifth edition (2018) with Amendment 1 (2020), and in the second edition of
IEC 61000-3-12 (2011) [2].
The history is traced from the first supra-national standard on low-frequency conducted
emissions into the public electricity supply, EN 50006:1975 [3] and its evolution through IEC
(60)555-2 [4] to IEC 61000-3-2 [1], IEC TR 61000-3-4 [5] and IEC 61000-3-12 [2]. To give a full
picture of the history, that of the standard for the measuring instrument IEC 61000-4-7 [6] is
mentioned as well.
NOTE All IEC standards were renumbered starting from 60000 from 1998-01-01. To indicate the references of
standards withdrawn before, or not reprinted after, that date, the “60x” prefix is here enclosed in parentheses. Hence
“IEC (60)555-2”.
Some concepts in this document apply to all low voltage AC systems, but the numerical values
apply specifically to the European 230 V/400 V 50 Hz system.
NOTE A rationale for the limits in future complete revisions of IEC 61000-3-2 or IEC 61000-3-12 or both will be
included in a new technical report.
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 61000 (all parts), Electromagnetic compatibility (EMC)
2)
IEC 61000-2-2:2002 , Electromagnetic compatibility (EMC) – Part 2-2: Environment –
Compatibility levels for low-frequency conducted disturbances and signalling in public low-
voltage power supply systems
___________
1 Numbers in square brackets refer to the Bibliography.
2)
This technical report also refers to the first edition of IEC 61000-2-2 (1990), Electromagnetic compatability (EMC)
– Part 2: Environment – Section 2: Compatibility levels for low-frequency conducted disturbances and signalling
in public low-voltage power supply systems, since superseded by the second edition of that publication.
3)
IEC 61000-3-2:2000 , Electromagnetic compatibility (EMC) – Part 3-2: Limits – Limits for
4)
harmonic current emissions (equipment input current ≤ 16 A per phase)
Amendment 1 (2001)
IEC 61000-3-3:1994, Electromagnetic compatibility (EMC) – Part 3-3: Limits – Limitation of
voltage fluctuations and flicker in public low-voltage supply systems for equipment with rated
5)
current ≤ 16 A
Amendment 1 (2001)
IEC 61000-3-4, Electromagnetic compatibility (EMC – Part 3-4: Limits – Limitation of emission
of harmonic currents in low-voltage power supply systems for equipment with rated current
greater than 16 A
IEC 61000-3-6, Electromagnetic compatibility (EMC) – Part 3: Limits – Section 6: Assessment
of emission limits for distorting loads in MV and HV power systems
IEC 61000-3-11, Electromagnetic compatibility (EMC) – Part 3-11: Limits – Limitation of voltage
changes, voltage fluctuations and flicker in public low-voltage supply systems – Equipment with
rated current ≤ 75 A and subjet to conditional connection
IEC 61000-3-12, Electromagnetic compatibility (EMC) – Part 3-12: Limits for harmonic currents
produced by equipment connected to public low-voltage systems with input current > 16 A and
≤ 75 A per phase
IEC 61000-4-13, Electromagnetic compatibility (EMC) – Part 4-13: Testing and measurement
techniques – Harmonics and interharmonics including mains signalling at a.c. power port, low
frequency immunity tests
3 Terms and definitions
Definitions of terms used in this technical report can be found in other publications in the
IEC 61000 series.
For the purposes of this document, the terms and definitions given in IEC 61000 (all parts)
apply.
ISO and IEC maintain terminology databases for use in standardization at the following
addresses:
• IEC Electropedia: available at https://www.electropedia.org/
• ISO Online browsing platform: available at https://www.iso.org/obp
4 General appraisal
The electricity supply industry intends to supply electric power with a sinusoidal voltage
waveform, and customers' equipment is designed to operate correctly on such a supply.
___________
3)
This technical report also refers to the first edition of IEC 61000-3-2 (1995), Electromagnetic compatability (EMC)
– Part 3: Limits – Section 2: Limits for harmonic current emissions (equipment input current ≤ 16 A per phase),
and its Amendment 1 (1995), since superseded by the second edition and its amendments of that publication.
4)
A consolidated edition 2.2 exists, which includes IEC 61000-3-2:2000 and its Amendments 1 (2001) and 2 (2004).
5)
A consolidated edition 1.1 exists, which includes IEC 61000-3-3:1994 and its Amendment 1 (2001),
Electromagnetic compatibility (EMC) – Part 3-3: Limits – Limitation of voltage changes, voltage fluctuations and
flicker in public low-voltage supply systems, for equipment with rated current ≤ 16 A per phase and not subject
to conditional connection
– 10 – IEC TR 61000-1-4:2022 RLV © IEC 2022
However, because the internal impedance of the supply system is not zero, a non-linear load
connected by one customer produces distortion of the voltage waveform that may can adversely
affect another customer's equipment, as well as equipment in the supply system itself. There is
no type of load or supply system equipment that is totally immune to distortion of the voltage
waveform, although and “natural” immunity levels (those achieved by customary designs
without special attention to improving immunity) vary greatly. Based largely on experience of
the amounts of voltage distortion that give rise to evidence of malfunction of, or damage to,
equipment, compatibility levels of voltage distortion for the low-voltage (LV) public supply
system have been determined and are given in IEC 61000-2-2 [7]. The correspondences
between these levels and other values are shown schematically in IEC 61000-2-2:2002, Figure
A.1. Compatibility levels are set as an acceptable compromise between immunity to harmonics
and reduction of emissions. Methods to check that the immunity of equipment to voltage
distortion is adequate are given in IEC 61000-4-13 [8].
NOTE 1 For the purposes of this technical report, the compatibility levels in the first edition of IEC 61000-2-2 apply.
Logically, compatibility levels would be set somewhat below the lowest acceptable immunity levels, but those data
were hard to come by in the past. Recommended immunity levels were first established in IEC 61000-4-13.
The intention of applying limits on the harmonic current emissions of equipment connected to
the public low-voltage (LV) system is to keep the actual levels of voltage distortion on the
system below the compatibility levels for a very large proportion of the time, and below lower
levels, known as planning levels, for a lesser but still large proportion of the time. (See
Figure 1.)
NOTE 12 Emissions into the medium-voltage (MV) and high voltage (HV) systems can be controlled by other
methods and procedures. See IEC TR 61000-3-6. [9]
NOTE 23 In some countries, the electricity supply industry places reliance on IEC 61000-3-2 [1] to control emissions
from portable equipment, whether the point of common coupling is at LV, MV or HV.
Emissions from equipment are expressed as currents, because these are largely, but not
completely, independent of the source impedance of the supply system, whereas the voltage
distortion produced by the equipment is almost proportional to the supply-system impedance
and therefore has no definite value. A product that draws a non-linear current from the supply
system may can alternatively be regarded as drawing a sinusoidal current, while emitting into
the supply system harmonic currents of the opposite polarity to those that it actually draws.
Compatibility levels are set, using system disturbance data and standardized immunity levels,
so that the probability of the system disturbance level exceeding the lowest immunity test level
is acceptably low, and at present is set at 5 %.
NOTE 4 Because the system disturbance level is an aggregate of the emissions of very many loads, the emission
limits for equipment are set at quite low disturbance levels.
NOTE 5 For system design, planning values of disturbance levels are adopted unilaterally by distribution system
operators; these are not expected to be exceeded but are not subject to standardization.
Compatibility
level
System Equipment
disturbance immunity
level level
Emission limits Planning Immunity
individual sources levels test levels
IEC 748/05
Disturbance level
Figure 1 – Diagram showing compatibility level in relation to
disturbance and immunity levels
5 Acceptable provisions in standards related to regulatory legislation
The equipment manufacturing industry can accept requirements in a voluntary standard, whose
application may can be determined by custom or moderated during individual contract
negotiations, that would be unacceptable in a standard backed by regulatory enforcement. For
example, a standard may can contain provisions that, if fully applied, would result in very long
test times. Parties to a contract might waive these provisions, wholly or partly (calculation or
simulation might be employed, for example) whereas in an enforcement situation, no deviation
from the provisions might be allowed.
Both EN 50006:1975, 7.1 and IEC (60)555-2:1988, IEC (60)555-2:1988/AMD1:1988 and
IEC (60)555-2:1988/AMD2:1988 , 5.3.1 [4], required the test operator to search for worst-case
conditions using the controls of the equipment under test, and in IEC (60)555-2, this was
required for each harmonic in turn. Such a test might well take many days, with no assurance
that another test operator might not find a different worst-case condition for just one harmonic.
Such a provision was also contained in IEC 61000-3-2:1995 (first edition), Clause C.1 and was
not removed until the publication of IEC 61000-3-2:2000/AMD1:2001 (second edition) [1].
A standard must not include regulatory requirements: it is concerned only with the procedures
necessary to determine whether a product within its scope meets its requirements.
6 History of IEC 61000-3-2 and its predecessors
6.1 History table
The revision histories of IEC 61000-3-2 and IEC 61000-3-12 are given in Annex G (informative).
An up-to-date table of the entire publication history of each IEC publication can be obtained via
the IEC webstore at https://webstore.iec.ch.
___________
6 IEC (60)555-2 was withdrawn in 1995 and replaced by IEC 61000-3-2.
Probability density
– 12 – IEC TR 61000-1-4:2022 RLV © IEC 2022
6.2 Before 1960
The most numerous non-linear loads were television receivers with half-wave rectifiers.
Because most of these had mains connectors of reversible polarity, the DC components
approximately cancelled. The number of receivers installed was insufficient to create any
significant system problems due to harmonic current emissions, but there is evidence that there
was enough random unbalance of polarity of connection in some countries for the resultant DC
component to cause corrosion problems in underground cables.
6.3 1960 to 1975
Phase-controlled dimmers for household lighting began to be marketed. These created high-
frequency conducted emissions, thus initially drawing the attention of radio-spectrum protection
authorities. Measures to limit these emissions could be made mandatory, but it was also noted
that the dimmers produced harmonic currents and there was no practicable way of reducing the
ratios of harmonic to fundamental current.
A system survey in Europe determined the 90th percentile value for supply impedance for
residential customers (who were mostly fed by overhead LV distribution) as (0,4 + jh0,25) ohms,
where h is the harmonic order (0,4 + j0,25) Ω, and this value was included in IEC TR
60725:1981 [10]. In addition it was determined that without some control of emissions from
dimmers, the voltage distortion might grow to exceed acceptable levels (later to be called
“compatibility levels”).
NOTE There is no direct relationship between compatibility levels and emission limits generally. Further information
on this subject can be found in Annex A.
NOTE In IEC (60)555-2:1982, Annex A [4], the supply impedance was regarded as purely resistive and inductive
((0,4 + jh0,25) Ω, where h is the harmonic order number). However, evidence was later presented that showed that
the impedance rises above 500 Hz more nearly proportional to the square root of frequency, rather than proportional
to frequency. The impedance presented to a particular load at the interface with the network (which is what
determines the voltage distortion produced by the current emissions from that load) includes the effect of the
impedances of other loads on the feeder. Even a light 10 kW load due to other equipment considerably lowers the
impedance at high-order harmonic frequencies. See 6.9.
The first standard on this subject (according to its own text it is not based on any previous
standard) was the European standard EN 50006:1975, implemented as various national
standards, including BS 5406:1976. This standard took burst-firing techniques into account and
also covered voltage fluctuations, now the subject of IEC 61000-3-3 [11] and IEC 61000-3-11
[12]. Limitation of harmonic current emissions was achieved by:
• prohibiting the use of phase control for heating loads over 200 W;
• applying limits for odd-harmonic emissions;
• applying limits for even-harmonic emissions to both symmetrical and asymmetrical control
techniques.
The limits were expressed as voltage-harmonic percentages, produced with a supply system
whose impedance (for single-phase loads) was (0,4 + jh0,25) Ω. However, the test procedure
actually required measurement of the harmonic currents, from which the voltage distortions
were calculated.
EN 50006 [3] does not include any explanation of the derivation of the limits, which are
preserved as the Class A limits in IEC 61000-3-2, up to the 2000 edition (second edition). In
fact, the numerical values were undoubtedly established piecemeal by negotiation between
supply industry and equipment manufacturer experts. The retention of a strict mathematical rule
for determining the values would not have been a priority for either group.
There was a study that led to an approximate algorithm for determining the cumulative
contribution of many dimmers set at different firing angles to a net voltage distortion level at the
terminals of the LV transformer feeding the final distribution. (See also Annex A.)
6.4 1975 to 1982
During this period, a more comprehensive standard, IEC (60)555-2 (published in 1982), was
developed. Still effectively restricted to 220 (380) V to 240 (415) V 50 Hz European systems, it
was adopted by CENELEC as EN (60)555-2 in 1987. It introduced three sets of limits; the
original current limits unchanged from EN 50006, limits 1,5 times greater for products used only
for short periods, such as portable tools, and special limits for television receivers, although an
exemption for receivers whose input power was less than 165 W caused the limits to apply only
to a small proportion of the receivers manufactured. The limits were expressed directly as
currents, even for television receivers.
NOTE All IEC standards were renumbered in the 60000 series from 1998-01-01. To indicate the references of
standards withdrawn before, or not reprinted after, that date, the '6xxx' prefix is here enclosed in parentheses. Hence
'IEC (60)555-2'.
Although IEC (60)555-2 included an annex that claimed to explain the derivation of the original
current limits, in fact, it did not do so, merely citing the voltage distortion limits that were
included in EN 50006 without explanation.
6.5 1982 to 1995
This period saw three profound changes; the great expansion of the use of switch-mode power
supplies, both in business and in the home, the intimation that mandatory regulation of the
electromagnetic compatibility (EMC) characteristics of electronic products would be introduced
in Europe, and the further intimation that the European public electricity supply would be subject
to “product quality” requirements.
The early standards, EN 50006 [3]and IEC (60)555-2, did not apply to professional equipment,
but there is no relevant definition in either standard, although EN 50006 cites “office machinery”
as an example. Thus it was unclear whether the standards applied to desktop computers. This
was clarified in Europe by a decision that such computers were “household appliances”, so that
the original current limits applied. (But CISPR 14/EN 55014 was not applied for high-frequency
emissions.) However the great expansion of single phase consumer electronics using direct on
line switch mode DC power units, such as television receivers and desktop computers, led to
significant peak flattening of the supply voltage waveforms due to near coincidence of the large
current pulses drawn by these products. Although direct-on-line switch mode DC power units
provided technology advantages (higher efficiency, lighter weight, smaller size), the near
coincidence of the large current pulses being drawn can result in significant distortion of the
supply voltage waveform. (Products with transformer-fed non-switching supplies have
proportionally lower emissions because the series impedance of the transformer results in a
larger conduction angle of the rectifiers.)
As a result, the development of the successor to IEC (60)555-2 was extremely controversial. It
has been suggested that while the electricity supply industry continued to work in depth on the
development of IEC 61000-3-2, the involvement of the equipment manufacturing industry was
less structured. This may could be true, but should be seen in the context that “equipment
manufacture” is a very diverse industry sector, whose sub-sectors have very different priorities
in considering harmonic current emissions, while the supply industry has very little diversity in
priorities, mainly deriving from differing infra-structure configurations in different countries.
IEC 61000-3-2:1995 (first edition) introduced many new features. Most notably, it applies to
“[all] electrical and electronic equipment having an input current up to and including 16 A per
phase and intended to be connected to public low-voltage distribution systems.” (However,
“professional equipment”, as defined in the standard, enjoys exemption from some
requirements.)
IEC 61000-3-2:1995 thus includes requirements and limits that apply to several different types
of product, grouped into four classes. It effectively applies only to European systems, as for
previous standards.
– 14 – IEC TR 61000-1-4:2022 RLV © IEC 2022
NOTE 1 It is still not known whether the characteristics of 220 V to 240 V, 50 Hz supply systems in other countries
are sufficiently similar to the European for the standard to be applied, while it has been shown that “scaling”
operations, intended to make the provisions applicable to systems of other voltages and frequencies, are rather
unreliable. Different distribution system configurations affect the effective supply impedance and the propagation of
harmonic currents through the system. The characteristics of electricity supplies world-wide are under study in
SC77A.
Class A is a general class, applying to products within the scope that are not specifically
included in another class. The limits are derived from the original voltage limits, dating
effectively fro
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