IEC TR 61000-1-4:2005

TECHNICAL IEC
REPORT TR 61000-1-4
First edition
2005-05
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
Reference number
IEC/TR 61000-1-4:2005(E)
Publication numbering
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TECHNICAL IEC
REPORT TR 61000-1-4
First edition
2005-05
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 2005  Copyright - all rights reserved
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– 2 – TR 61000-1-4  IEC:2005(E)
CONTENTS
FOREWORD.4
INTRODUCTION.6

1 Scope.7
2 Normative references .7
3 Definitions .8
4 General appraisal .8
5 Acceptable provisions in standards related to regulatory legislation.9
6 History of IEC 61000-3-2 and its predecessors .10
6.1 Before 1960 .10
6.2 1960 to 1975 .10
6.3 1975 to 1982 .11
6.4 1982 to 1995 .11
6.5 1995 to 2000 .13
6.6 The 'Millennium Amendment' .14
6.7 Future development of IEC 61000-3-2 .14
7 History of IEC 61000-3-12 and its predecessor.14
7.1 1989 to 1998 .14
7.2 After 1998 .15
8 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 .15

Annex A (informative) Compatibility level and compensation factor .16
Annex B (informative) Comparison of Class A limits and the harmonic spectra of
phase-controlled dimmers of incandescent lamps at 90° firing angle.20
Annex C (informative) Comparison of Class C ( Table 2 of IEC 61000-3-2) limits and
the harmonic spectrum of a discharge lamp with inductive ballast.21
Annex D (informative) Comparison of Class D limits and the harmonic spectra of
capacitor-filtered single-phase rectifiers with 35° and 65° conduction angles .22
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 .23
Annex F (Informative) Concept plan for the full revision of IEC 61000-3-2.25
Annex G (informative) Derivation of the limits in IEC 61000-3-12 .27
Annex H (informative) Explanation of the reasons for using the concepts of total
harmonic distortion (THD) and partial weighted harmonic distortion (PWHD) .39

Bibliography.41

Figure 1 – Diagram showing compatibility level in relation to disturbance and
immunity levels .9
Figure A.1 – Allocation of harmonic voltage drops over the transformer impedances in
a typical system .17
Figure B.1 – Comparison of Class A limits and spectra of dimmers.20
Figure C.1 – Comparison of Class C limits and the harmonic spectrum
of a discharge lamp .21

TR 61000-1-4  IEC:2005(E) – 3 –
Figure D.1 – Comparison of Class D limits and harmonic spectra of single-phase
230 W rectifiers with capacitor filters .22
Figure E.1 – Illustration of the concept of total aggregate cost trade-offs for meeting
compatibility levels.24
Figure H.1a – Diagram of a LV system consisting of a transformer, a busbar and n
equal feeders.40
Figure H.1b – Equivalent circuit for the LV system with "fictitious" feeders.40
Figure H.2 – Relative total distortion weight “tdw” as a function of the short-circuit
ratio R .40
sce
Table A.1 – Compensation factors k .18
p,h
Table A.2 – Sub-factors of k .19
p,h
Table G.1 – Relative total distortion weight depending on the point x where the
distorting load is connected .31
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).32
Table G.3 – Compatibility levels.35
Table G.4 – Maximum harmonic currents and voltages for one piece of single phase
equipment (from Table 2 of IEC 61000-3-12) .35
Table G.5 – Maximum harmonic currents and voltages for one piece of balanced three
phase equipment (from Table 3 of IEC 61000-3-12) .36
Table G.6 – Maximum harmonic currents and voltages for one piece of balanced three
phase equipment (from Table 4 of IEC 61000-3-12): .36
Table G.7 – Maximum harmonic currents and voltages for n pieces of single phase
equipment (from Table 2 of IEC 61000-3-12) .36
Table G.8- Maximum harmonic currents and voltages for n pieces of balanced three
phase equipment (from Table 3 of IEC 61000-3-12): .37
Table G.9 – Maximum harmonic currents and voltages for n pieces of balanced three
phase equipment (from Table 4 of IEC 61000-3-12): .37
Table G.10 – Maximum harmonic currents and voltages for n pieces of single phase
equipment (from Table 2 of IEC 61000-3-12): .37
Table G.11- Maximum harmonic currents and voltages for n pieces of balanced three
phase equipment (from Table 3 of IEC 61000-3-12): .38
Table G.12 – Maximum harmonic currents and voltages for n pieces of balanced three
phase equipment (from Table 4 of IEC 61000-3-12): .38

– 4 – TR 61000-1-4  IEC:2005(E)
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-
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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
consensus of opinion on the relevant subjects since each technical committee has representation from all
interested IEC National Committees.
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between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
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8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
The main task of IEC technical committees is to prepare International Standards. However, a
technical committee may propose the publication of a technical report when it has collected
data of a different kind from that which is normally published as an International Standard, for
example "state of the art".
IEC 61000-1-4, which is a technical report, has been prepared by subcommittee 77A: Low
frequency phenomena, of IEC technical committee 77: Electromagnetic compatibility.
The text of this technical report is based on the following documents:
DTR Report on voting
77A/477/DTR 77A/481/RVC
Full information on the voting for the approval of this technical report can be found in the
report on voting indicated in the above table.

TR 61000-1-4  IEC:2005(E) – 5 –
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
The committee has decided that the contents of this publication will remain unchanged until
the maintenance result 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.
– 6 – TR 61000-1-4  IEC:2005(E)
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).

TR 61000-1-4  IEC:2005(E) – 7 –
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 an IEC 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 second edition (2000) and its first amendment (2001), and in the first edition of
IEC 61000-3-12 (2004).
The concepts in this technical report 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 referenced documents are indispensable for the application 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.
1)
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
)
IEC 61000-3-2:2000 , Electromagnetic compatibility (EMC) – Part 3-2: Limits – Limits for
3)
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
4)
current ≤ 16 A
Amendment 1 (2001)
———————
1)
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.
)
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.
3)
A consolidated edition 2.2 exists, which includes IEC 61000-3-2:2000 and its Amendments 1 (2001) and 2
(2004).
4)
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
– 8 – TR 61000-1-4  IEC:2005(E)
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 Definitions
Definitions of terms used in this technical report can be found in other publications in the
IEC 61000 series.
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 may 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 '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. The correspondences between
these levels and other values are shown schematically in Figure 1. See Annex A of
IEC 61000-2-2 from which that figure is taken. 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.
NOTE For the purposes of this technical report, the compatibility levels in the first edition of IEC 61000-2-2 apply.
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 1 Emissions into the medium-voltage (MV) and high voltage (HV) systems can be controlled by other
methods and procedures. See IEC 61000-3-6.
NOTE 2 In some countries, the electricity supply industry places reliance on IEC 61000-3-2 to control emissions
from portable equipment, whether the point of common coupling is at LV, MV or HV.

TR 61000-1-4  IEC:2005(E) – 9 –
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 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
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 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 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.
5)
Both 7.1 of EN 50006 and 5.3.1 of IEC (60)555-2 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 clause C.1 of IEC 61000-3-2:1995 and
was not removed until the publication of Amendment 1 to IEC 61000-3-2:2000.
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.
———————
5) IEC (60)555-2 was withdrawn in 1995 and replaced by IEC 61000-3-2.
Probability density
– 10 – TR 61000-1-4  IEC:2005(E)
6 History of IEC 61000-3-2 and its predecessors
6.1 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 d.c. 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 d.c. component to cause corrosion problems in underground cables.
6.2 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, and this value was included in IEC 60725. 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.
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 of 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 and IEC 61000-3-11.
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) ohms. However, the test
procedure actually required measurement of the harmonic currents, from which the voltage
distortions were calculated. The standard 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. 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, however, 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.)
TR 61000-1-4  IEC:2005(E) – 11 –
6.3 1975 to 1982
During this period, a more comprehensive standard, IEC (60)555-2:1982, was developed. Still
effectively restricted to 220(380) V-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 this standard 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.
6.4 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 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 d.c. 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 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 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.)
The standard 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.
– 12 – TR 61000-1-4  IEC:2005(E)
NOTE It is still not known whether the characteristics of 220V – 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.
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 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. The limits are quite
stringent and some of these originally appeared, with similar values, in the product standard
IEC 60082, 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 d.c. 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 if single-phase supplies. This class was intended to
apply to d.c. 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 milliamps per watt, 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 [12] and [13] .
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 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 must be contemporaneous; National Committees cannot determine which way they should 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.
———————
6)
Figures in square brackets refer to the Bibliography.

TR 61000-1-4  IEC:2005(E) – 13 –
Consequently, this requirement was, and still is, by far the most controversial. It 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 fifth
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 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 d.c. 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 may 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 'Equal rights' also suggests that the allowable harmonic emissions should 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 may 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, and it was not editorially suited to such a role.
6.5 1995 to 2000
Amendment 1 to the 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 require-
ment, 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 may 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 d.c.
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 SC77A/WG1 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.
– 14 – TR 61000-1-4  IEC:2005(E)
6.6 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 1998-99, and the IEC
procedures resulted in a divergence of the editions of the IEC standard from those of
CENELEC, which implemented the Millennium Amendment, but not the 3rd IEC amendment,
in a consolidated edition, creating confusion that might have been avoided.
The Millennium Amendment eliminated many of the ambiguities and uncertainties that made
the 1995 edition difficult to use in a regulatory situation. It also abandoned the mask for
determining Class D membership, on the technical grounds that for some products it was
impossible to be sure whether they should be in Class D or not. Instead, it substituted what
was finally a rather short list, of high-volume products with high simultaneity of use, which
contribute (in the absence of built-in mitigation measures) to odd harmonic currents of little
phase diversity (rather than the overall harmonic content of the system voltage): personal
computers, personal computer monitors and television receivers.
The amendment also included a clarification of the requirements for lighting equipment.
6.7 Future development of IEC 61000-3-2
A detailed consideration of this subject is a matter for IEC 61000-1-X (to be published). Initial
considerations are described in
...