SIST EN IEC 63497:2026

• Abstract:

  IEC 63497:2026, which is a product standard, is intended to specify the EMC, performance and safety requirements of shunt-connected active correction devices (ACD) with rated system voltages not exceeding 1 000 V AC or 1 500 V DC.; These devices can be either cord or permanently connected. They can be movable, stationary, or fixed devices.; An ACD includes both a static VAR generator (SVG) and an active harmonic filter (AHF).; The primary function of a shunt connected ACD is to do one or more of the following:; - active harmonic filtering;; - reactive power compensation;; - unbalanced load compensation.; Additional functions of a shunt-connected ACD, not addressed by this document, can be the following:; - flicker compensation;; - interharmonic component filtering.; In case of hybrid devices, combining a passive harmonic filter and an ACD, this document covers only the active part.; This document does not cover; - active mitigation functions part of another device (variable speed drive, uninterruptible power supply, dynamic voltage restorer, etc.),; - switched power capacitors,; - switched inductors,; - passive harmonic filters,; - energy storage converters, and; - series-connected active correction devices.

• Status: Published
• Public Enquiry End Date: 30-Jul-2025
• Publication Date: 12-Oct-2026
• ICS: 29.200 - Rectifiers. Convertors. Stabilized power supply
• ICS: 29.240.01 - Power transmission and distribution networks in general
• Technical Committee: MOV - Measuring equipment for electromagnetic quantities
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 30-Apr-2026
• Due Date: 05-Jul-2026
• Completion Date: 13-Oct-2026
• Directive: 2014/35/EU - Directive 2014/35/EU of the European Parliament and of the Council of 26 February 2014 on the harmonisation of the laws of the Member States relating to the making available on the market of electrical equipment designed for use within certain voltage limits
• Mandate: M/511 - Mandate to CEN, CENELEC and ETSI relating to harmonised standards in the field of the Low Voltage Directive
• Ref Project: EN IEC 63497:2026 - Shunt-connected active correction devices (ACD)

• Refers: kSIST FprHD 60364-1:2025 - Low-voltage electrical installations - Part 1: Fundamental principles, assessment of general characteristics, and definitions
• Effective Date: 07-Apr-2026
• Refers: SIST EN IEC 61000-6-4:2019 - Electromagnetic compatibility (EMC) - Part 6-4: Generic standards - Emission standard for industrial environments
• Effective Date: 07-Apr-2026
• Refers: SIST EN IEC 60664-1:2020 - Insulation coordination for equipment within low-voltage supply systems - Part 1: Principles, requirements and tests (IEC 60664-1:2020)
• Effective Date: 07-Apr-2026
• Refers: SIST EN IEC 62477-1:2024 - Safety requirements for power electronic converter systems and equipment - Part 1: General (IEC 62477-1:2022)
• Effective Date: 07-Apr-2026
• Refers: SIST EN IEC 61000-6-2:2019 - Electromagnetic compatibility (EMC) - Part 6-2: Generic standards - Immunity standard for industrial environments
• Effective Date: 07-Apr-2026

Overview

SIST EN IEC 63497:2026 is a product standard developed by CLC, specifying the electromagnetic compatibility (EMC), performance, and safety requirements for shunt-connected active correction devices (ACD). These devices operate with rated system voltages not exceeding 1,000 V AC or 1,500 V DC and can be either cord- or permanently-connected, movable, stationary, or fixed. An ACD encompasses both a static VAR generator (SVG) and an active harmonic filter (AHF), designed to address core power quality issues in electrical systems.

As the prevalence of non-linear loads-such as industrial equipment, variable speed drives, and electric vehicle charging systems-increases, the need for effective harmonic filtering and power quality improvement becomes critical. SIST EN IEC 63497:2026 establishes the minimum requirements to ensure that ACDs operate safely, achieve reliable electromagnetic performance, and provide verifiable benefits in real-world electrical environments.

Key Topics

• Scope and Device Types

  • Devices covered can be movable, stationary, or fixed.
  • Rated for system voltages ≤ 1,000 V AC or 1,500 V DC.
  • Includes both static VAR generators (SVG) and active harmonic filters (AHF).
  • Excludes active mitigation within other equipment (e.g., UPS, VSD), passive harmonic filters, and series-connected correction devices.

• Primary Functions

  • Active Harmonic Filtering: Reduces harmonic current injections, improving the quality of supply voltage and reducing RMS current.
  • Reactive Power Compensation: Corrects lagging/leading power factor, helping maximize usable capacity and reduce losses.
  • Unbalanced Load Compensation: Balances source currents, mitigating negative and zero-sequence effects in three-phase systems.

• Performance Requirements

  • Devices must meet type and routine testing for EMC immunity and emission.
  • Performance tested for harmonic attenuation, reactive power compensation accuracy, and response times.
  • Devices classified based on functions, with AHFs supporting broader harmonic compensation than SVGs.

• Safety and Construction

  • Must conform to IEC 62477-1 for operational and mechanical safety.
  • Requirements address electric shock, fire, mechanical hazards, and environmental conditions.
  • Robust technical documentation and markings required.

Applications

Shunt-connected active correction devices specified by SIST EN IEC 63497:2026 deliver practical value across several sectors:

• Industrial Facilities: ACDs mitigate harmonics generated by heavy machinery, welding devices, or battery chargers, reducing energy losses and overheating.
• Commercial Buildings: Improve power factor and balance loads to avoid costly utility penalties and ensure smooth operation of sensitive electronics.
• Data Centers: Minimize harmonic distortion to maintain equipment reliability and stable voltage supply.
• Electric Vehicle Infrastructure: Ensure power quality standards are maintained during high-speed charging operations.

ACDs are ideal for scenarios where retrofitting is needed, as devices can be installed parallel to the load, offering flexibility without major network overhauls.

Related Standards

Compliance with SIST EN IEC 63497:2026 often involves referencing and integrating associated standards for harmonized safety and performance:

• IEC 62477-1: Safety requirements for power electronic converter systems and equipment.
• IEC 61000 Series: EMC immunity and emission requirements.
• IEC 60529: Degrees of protection by enclosures (IP code).
• IEC 60364-1: Fundamental principles for low-voltage electrical installations.
• IEC 60664-1: Insulation coordination for equipment within low-voltage systems.

Incorporating SIST EN IEC 63497:2026 into the design and procurement of ACDs ensures compliance with current best practices for power quality improvement, electromagnetic compatibility, and electrical safety in modern power systems. This standard is vital for manufacturers, specifiers, and operators aiming to maintain robust, efficient, and reliable electrical networks.

SLOVENSKI STANDARD
01-november-2026
Vzporedno priključeni aktivni korektorji (ADC) (IEC 63497:2026)
Shunt-connected active correction devices (ACD) (IEC 63497:2026)
Parallele aktive Korrekturgeräte (ACD) (IEC 63497:2026)
Dispositifs de correction active (ACD) à connexion shunt (IEC 63497:2026)
Ta slovenski standard je istoveten z: EN IEC 63497:2026
ICS:
29.200 Usmerniki. Pretvorniki. Rectifiers. Convertors.
Stabilizirano električno Stabilized power supply
napajanje
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD EN IEC 63497

NORME EUROPÉENNE
EUROPÄISCHE NORM April 2026
ICS 29.200; 29.240.01
English Version
Shunt-connected active correction devices (ACD)
(IEC 63497:2026)
Dispositifs de correction active (ACD) à connexion shunt Parallele aktive Korrekturgeräte (ACD)
(IEC 63497:2026) (IEC 63497:2026)
This European Standard was approved by CENELEC on 2026-04-20. CENELEC members are bound to comply with the CEN/CENELEC
Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration.
Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN-CENELEC
Management Centre or to any CENELEC member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by translation
under the responsibility of a CENELEC member into its own language and notified to the CEN-CENELEC Management Centre has the
same status as the official versions.
CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus, the Czech Republic,
Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, the
Netherlands, Norway, Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Türkiye and the United Kingdom.

European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2026 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.
Ref. No. EN IEC 63497:2026 E
European foreword
The text of document 22E/301/FDIS, future edition 1 of IEC 63497, prepared by SC 22E "Stabilized
power supplies" of IEC/TC 22 "Power electronic systems and equipment" was submitted to the IEC-
CENELEC parallel vote and approved by CENELEC as EN IEC 63497:2026.
The following dates are fixed:
• latest date by which the document has to be implemented at national (dop) 2027-04-30
level by publication of an identical national standard or by endorsement
• latest date by which the national standards conflicting with the (dow) 2029-04-30
document have to be withdrawn
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CENELEC shall not be held responsible for identifying any or all such patent rights.
This document has been prepared under a standardization request addressed to CENELEC by the
European Commission. The Standing Committee of the EFTA States subsequently approves these
requests for its Member States.
Any feedback and questions on this document should be directed to the users’ national committee. A
complete listing of these bodies can be found on the CENELEC website.
Endorsement notice
The text of the International Standard IEC 63497:2026 was approved by CENELEC as a European
Standard without any modification.
In the official version, for Bibliography, the following notes have to be added for the standard indicated:
IEC 61000-2-4:2024 NOTE Approved as EN IEC 61000-2-4:2024 (not modified)
IEC 61000-4-7 NOTE Approved as EN 61000-4-7
IEC 61000-4-13:2002 NOTE Approved as EN 61000-4-13:2002 (not modified)
IEC 61000-4-30:2025 NOTE Approved as EN IEC 61000-4-30:2025 (not modified)
IEC 61557-12 NOTE Approved as EN IEC 61557-12
IEC 61800-3 NOTE Approved as EN IEC 61800-3
IEC 62586-1 NOTE Approved as EN 62586-1
Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications
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.
NOTE 1  Where an International Publication has been modified by common modifications, indicated by (mod),
the relevant EN/HD applies.
NOTE 2  Up-to-date information on the latest versions of the European Standards listed in this annex is available
here: www.cencenelec.eu.
Publication Year Title EN/HD Year
IEC 60364-1 - Low-voltage electrical installations - Part 1: - -
Fundamental principles, assessment of
general characteristics, and definitions
IEC 60529 - Degrees of protection provided by - -
enclosures (IP Code)
IEC 60664-1 2020 Insulation coordination for equipment EN IEC 60664-1 2020
within low-voltage supply systems - Part 1:
Principles, requirements and tests
IEC 61000-6-2 2016 Electromagnetic compatibility (EMC) - Part EN IEC 61000-6-2 2019
6-2: Generic standards - Immunity
standard for industrial environments
IEC 61000-6-4 2018 Electromagnetic compatibility (EMC) - Part EN IEC 61000-6-4 2019
6-4: Generic standards - Emission
standard for industrial environments
IEC 62477-1 2022 Safety requirements for power electronic EN IEC 62477-1 2023
converter systems and equipment - Part 1:
General
IEC 63497 ®
Edition 1.0 2026-03
INTERNATIONAL
STANDARD
Shunt-connected active correction devices (ACD)

ICS 29.200; 29.240.01 ISBN 978-2-8327-1126-2

IEC 63497:2026-03(en)
IEC 63497:2026 © IEC 2026
CONTENTS
FOREWORD . 4
INTRODUCTION . 6
1 Scope . 8
2 Normative references . 8
3 Terms, definitions and abbreviated terms . 9
3.1 Terms related to devices . 9
3.2 Terms related to device electrical parameters . 9
3.3 Terms related to electrical phenomena . 10
3.4 Miscellaneous . 14
3.5 Abbreviated terms . 14
4 Ratings . 14
4.1 Rated frequency . 14
4.2 Rated voltage . 14
4.3 Connection wiring types . 14
5 Requirements for design and construction . 15
5.1 General requirements . 15
5.1.1 Architecture . 15
5.1.2 Functional classification . 16
5.2 Safety requirements . 17
5.2.1 General . 17
5.2.2 Protection against electric shocks . 17
5.2.3 Protection against mechanical hazards . 17
5.2.4 Protection against fire . 17
5.2.5 Temperature . 17
5.2.6 Protection against hazards from fluids . 17
5.2.7 Protection against radiation, including laser sources, and against sonic
and ultrasonic pressure . 17
5.2.8 Components and subassemblies . 17
5.2.9 Reasonably foreseeable misuses (hazards resulting from application) . 17
5.2.10 Protection against other hazards . 18
5.3 EMC requirements . 18
5.3.1 Immunity requirements . 18
5.3.2 Emission requirements . 18
5.4 Climatic requirements . 18
5.4.1 Temperature and humidity . 18
5.4.2 Altitude . 18
5.5 Mechanical requirements . 19
5.5.1 Vibrations . 19
5.5.2 Shocks . 19
5.5.3 Enclosure robustness (IK code) . 19
5.5.4 Degree of protection by enclosures (IP code) . 19
5.6 Earthing scheme . 19
5.7 Markings and technical documentation . 19
5.7.1 General . 19
5.7.2 Product specific markings . 19
5.7.3 Product specific items in technical documentation . 20
IEC 63497:2026 © IEC 2026
6 Type tests . 21
6.1 Reference conditions for testing . 21
6.2 Safety tests . 22
6.3 EMC tests . 22
6.3.1 EMC immunity and emission . 22
6.3.2 Voltage harmonic immunity . 22
6.4 Climatic tests . 23
6.5 Mechanical tests . 23
6.5.1 Vibrations . 23
6.5.2 Shocks . 23
6.6 Functional tests . 24
6.6.1 Reference conditions for testing . 24
6.6.2 Harmonic global compensation . 24
6.6.3 Harmonic attenuation capability . 25
6.6.4 Reactive power compensation output current . 25
6.6.5 Reactive power compensation accuracy . 25
6.6.6 Source current balancing . 26
6.6.7 Minimum fault level test . 28
6.6.8 Harmonic response time . 29
6.6.9 Reactive power compensation response time . 30
6.6.10 Losses . 30
6.7 Performance criteria . 31
7 Routine tests . 31
7.1 Safety tests . 31
7.2 Functional tests . 32
7.3 Limited thermal tests . 32
7.3.1 Target . 32
7.3.2 Procedure . 32
7.3.3 Acceptance criteria . 32
Annex A (normative) Response time test specification . 33
A.1 Assumption . 33
A.2 Specification . 33
Annex B (normative) Non-linear reference load for harmonic test . 35
B.1 General . 35
B.2 Mathematical representation . 35
B.3 General principle . 35
B.4 Load specification for 3W system . 36
B.5 Load specification for 4W system . 38
Annex C (informative) Self-resonance tests . 41
C.1 General . 41
C.2 Proposed method . 41
C.2.1 Test setup . 41
C.2.2 Test method . 41
C.3 Evaluation . 42
Bibliography . 43

IEC 63497:2026 © IEC 2026
Figure 1 – Typical current waveforms for single-phase non-linear loads . 6
Figure 2 – Typical current waveforms for three-phase non-linear loads . 7
Figure 3 – Internal architecture of an ACD . 15
Figure 4 – Principle of operation of an ACD (for AHF function) . 16
Figure 5 – Negative sequence current creation . 27
Figure 6 – Zero sequence current creation . 28
Figure 7 – Response time illustration . 29
Figure A.1 – Current waveforms. 34
Figure A.2 – Calculated RMS current of ACD versus time . 34
Figure B.1 – Load waveform for 3W system . 36
Figure B.2 – ACD waveform for 3W system. 37
Figure B.3 – Load waveform for 4W system . 39
Figure B.4 – ACD waveform for 4W system. 40

Table 1 –Temperature classes . 18
Table 2 – Items to document in technical documentation . 20
Table 3 – Additional reference conditions for testing . 21
Table 4 – Individual voltage harmonic limits for odd non-multiple 3 harmonics . 23
Table 5 – Negative sequence component specification . 27
Table 6 – Zero-sequence component specification . 27
Table 7 – Test specification . 28
Table 8 – Definition of response time parameters . 29
Table 9 – Performance criteria for ACD. 31
Table B.1 – Phase sequence for load harmonics . 35
Table B.2 – Load spectrum for 3W system . 36
Table B.3 – ACD spectrum for 3W system . 37
Table B.4 – Load spectrum for 4W system . 38
Table B.5 – ACD spectrum for 4W systems . 39

IEC 63497:2026 © IEC 2026
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
Shunt-connected active correction devices (ACD)

FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote international
co-operation on all questions concerning standardization in the electrical and electronic fields. To this end and
in addition to other activities, IEC publishes International Standards, Technical Specifications, Technical Reports,
Publicly Available Specifications (PAS) and Guides (hereafter referred to as "IEC Publication(s)"). Their
preparation is entrusted to technical committees; any IEC National Committee interested in the subject dealt with
may participate in this preparatory work. International, governmental and non-governmental organizations liaising
with the IEC also participate in this preparation. IEC collaborates closely with the International Organization for
Standardization (ISO) in accordance with conditions determined by agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
consensus of opinion on the relevant subjects since each technical committee has representation from all
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3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
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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) IEC draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). IEC takes no position concerning the evidence, validity or applicability of any claimed patent rights in
respect thereof. As of the date of publication of this document, IEC had not received notice of (a) patent(s), which
may be required to implement this document. However, implementers are cautioned that this may not represent
the latest information, which may be obtained from the patent database available at https://patents.iec.ch. IEC
shall not be held responsible for identifying any or all such patent rights.
IEC 63497 has been prepared by subcommittee 22E: Stabilized power supplies of IEC technical
committee 22: Power electronic systems and equipment. It is an International Standard.
The text of this International Standard is based on the following documents:
Draft Report on voting
22E/301/FDIS 22E/306/RVD
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 International Standard is English.
IEC 63497:2026 © IEC 2026
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.
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, or
– revised.
IEC 63497:2026 © IEC 2026
INTRODUCTION
Loads with non-linear behaviour, causing power quality issues, are increasingly frequent in all
industrial, commercial and residential installations, and their percentage in overall electrical
consumption is growing steadily.
This type of loads can be found in
– industrial equipment (welding machines, arc and induction furnaces, battery chargers,
rectifiers like electrolysers, etc.),
– variable speed drives (VSD) for AC or DC motors,
– uninterruptible power supplies, and
– electric vehicle charging system.
In power systems, when non-linear loads are connected, they generate harmonics, whose
effects are described in IEC TS 63191. The major consequences of harmonics are the increase
of the RMS current in the different circuits and the deterioration of the supply voltage quality.
The negative impact can remain un-noticed, but economical results can be compromised:
– increased overloading on the electrical system, thereby limiting usable capacity;
– increased energy losses;
– increased risks of outage;
– overheating of equipment and cables in installation leading to reduction of equipment
lifetime;
– perturbation of some electronic systems.
Figure 1 and Figure 2 present typical current waveforms for single-phase and three-phase non-
linear loads respectively, measured by devices such as power metering and monitoring devices
(PMD) compliant to IEC 61557-12 or power quality instruments (PQI) compliant to IEC 62586-1.

Figure 1 – Typical current waveforms for single-phase non-linear loads
IEC 63497:2026 © IEC 2026
Figure 2 – Typical current waveforms for three-phase non-linear loads
A shunt-connected active correction device is used in parallel with the load to minimize these
distortions, in order to obtain an approximately sinusoidal waveform.

IEC 63497:2026 © IEC 2026
1 Scope
This document, which is a product standard, is intended to specify the EMC, performance and
safety requirements of shunt-connected active correction devices (ACD) with rated system
voltages not exceeding 1 000 V AC or 1 500 V DC.
These devices can be either cord or permanently connected. They can be movable, stationary,
or fixed devices.
An ACD includes both a static VAR generator (SVG) and an active harmonic filter (AHF).
The primary function of a shunt connected ACD is to do one or more of the following:
– active harmonic filtering;
– reactive power compensation;
– unbalanced load compensation.
Additional functions of a shunt-connected ACD, not addressed by this document, can be the
following:
– flicker compensation;
– interharmonic component filtering.
In case of hybrid devices, combining a passive harmonic filter and an ACD, this document
covers only the active part.
This document does not cover
– active mitigation functions part of another device (variable speed drive, uninterruptible
power supply, dynamic voltage restorer, etc.),
– switched power capacitors,
– switched inductors,
– passive harmonic filters,
– energy storage converters, and
– series-connected active correction devices.
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 60364-1, Low-voltage electrical installations - Part 1: Fundamental principles, assessment
of general characteristics, and definitions
IEC 60529, Degrees of protection provided by enclosures (IP Code)
IEC 60664-1:2020, Insulation coordination for equipment within low-voltage supply systems -
Part 1: Principles, requirements and tests
IEC 61000-6-2:2016, Electromagnetic compatibility (EMC) - Part 6-2: Generic standards -
Immunity standard for industrial environments
IEC 63497:2026 © IEC 2026
IEC 61000-6-4:2018, Electromagnetic compatibility (EMC) - Part 6-4: Generic standards -
Emission standard for industrial environments
IEC 62477-1:2022, Safety requirements for power electronic converter systems and
equipment - Part 1: General
3 Terms, definitions and abbreviated terms
3.1 Terms related to devices
For the purposes of this document, the terms and definitions given in IEC 62477-1 and the
following 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
3.1.1
static var generator
SVG
active device mainly used either for stepless reactive power compensation or load balancing,
or both
Note 1 to entry: An SVG can be called an EVC (electronic VAR compensator) or a STATCOM (static synchronous
compensator).
3.1.2
active harmonics filter
AHF
active device used for harmonic filtering and possibly either stepless reactive power
compensation or load balancing, or both
Note 1 to entry: An AHF can be called an APF (active power filter).
3.1.3
dynamic voltage restorer
DVR
system to mitigate the sags and swells in supply voltage
3.2 Terms related to device electrical parameters
3.2.1
rated voltage
rated value of the voltage assigned by the manufacturer to a component, device or equipment
and to which operation and performance characteristics are referred
Note 1 to entry: Equipment can have more than one rated voltage value or can have a rated voltage range.
Note 2 to entry: For three-phase power supply, the line-to-line voltage applies.
[SOURCE: IEC 60050-442:2014, 442-09-10]
IEC 63497:2026 © IEC 2026
3.2.2
rated current
RMS current assigned by the manufacturer for a specified operating condition of a device
[SOURCE: IEC 60050-442:1998, 442-01-02, modified – "RMS" added and "accessory" replaced
with "device".]
3.2.3
rated frequency
frequency at which the device is designed to operate
[SOURCE: IEC 60050-421:1990, 421-04-03, modified – "transformer or reactor" replaced with
"device".]
3.2.4
operating range
environmental conditions and use conditions for which a device is able to perform its intended
function(s)
Note 1 to entry: Environmental conditions can be temperature, range, EMC environment, etc. Use conditions can
be voltage range, current range, etc.
3.3 Terms related to electrical phenomena
3.3.1
total harmonic ratio
total harmonic distortion
THD
ratio of the RMS value of the harmonic content to the RMS value of the fundamental component
or the reference fundamental component of an alternating quantity
Note 1 to entry: The total harmonic ratio depends on the choice of the fundamental component. If it is not clear
from the context which one is used, an indication should be given.
Note 2 to entry: The total harmonic ratio may be restricted to a certain harmonic order. This is to be stated.
[SOURCE: IEC 60050-551:2001, 551-20-13]
3.3.2
commutation notch
periodic voltage transient that may appear in the AC side voltage of a line or machine
commutated converter due to the commutation
[SOURCE: IEC 60050-551:1998, 551-16-06]
3.3.3
fundamental frequency
frequency of the fundamental component
[SOURCE: IEC 60050-551:2001, 551-20-03]
IEC 63497:2026 © IEC 2026
3.3.4
fundamental component
fundamental
sinusoidal component of the Fourier series of a periodic quantity having the
frequency of the quantity itself
Note 1 to entry: For practical analysis, an approximation of the periodicity may be necessary.
[SOURCE: IEC 60050-551:2001, 551-20-01]
3.3.5
harmonic frequency
frequency which is an integer multiple of the fundamental frequency
Note 1 to entry: The ratio of the harmonic frequency to the fundamental frequency is named harmonic order
(recommended notation "h").
[SOURCE: IEC 61000-2-4:2024, 3.2.3, modified – Note to entry added.]
3.3.6
harmonic component
component having a harmonic frequency
Note 1 to entry: A harmonic component's value is normally expressed as an RMS value.
Note 2 to entry: For brevity, such a component can be referred to simply as a harmonic.
3.3.7
interharmonic frequency
frequency which is not an integer multiple of the fundamental frequency
Note 1 to entry: By extension from harmonic order, the interharmonic order is the ratio of interharmonic frequency
to the fundamental frequency. This ratio is not an integer. The recommended notation for an interharmonic frequency
is "m").
Note 2 to entry: In the case where m < 1, the term sub-harmonic frequency can also be used.
3.3.8
interharmonic component
component having an interharmonic frequency
Note 1 to entry: An interharmonic component's value is normally expressed as an RMS value.
Note 2 to entry: For the purpose of this document, and as stated in IEC 61000-4-7, the time window has a width of
10 fundamental periods (for 50 Hz systems) or 12 fundamental periods (for 60 Hz systems), i.e. approximately
200 ms. The difference in frequency between two consecutive interharmonic components is, therefore, approximately
5 Hz.
Note 3 to entry: For brevity, such a component can be referred to simply as an interharmonic.
[SOURCE: IEC 61000-2-4:2024, 3.2.8, modified – Word "spectral" removed from definition and
Notes 1 and 2 to entry added.]
IEC 63497:2026 © IEC 2026
3.3.9
power factor
under periodic conditions, ratio of the absolute value of the active power P to the apparent
power S:
λ = |P| / S
Note 1 to entry: Under sinusoidal conditions, the power factor is the fundamental power factor.
[SOURCE: IEC 60050-131:2002, 131-11-46, modified – Words "absolute value of the active
factor" replaced with "fundamental power factor" in Note 1 to entry.]
3.3.10
fundamental power factor
ratio of the absolute value of the fundamental active power P to the fundamental apparent
power S :
λ = |P | / S
1 1 1
Note 1 to entry: The fundamental power factor is also given by: λ1 = |cos φ |.
Note 2 to entry: The fundamental power factor only refers to fundamental quantities.
Note 3 to entry: The fundamental power factor is sometimes called displacement factor or displacement power
factor.
[SOURCE: IEC 60050-845:2020, 845-27-127]
3.3.11
load balancing
improvement of the unbalance factor
Note 1 to entry: The load balancing refers to the balancing of the source current.
3.3.12
negative sequence component
negative component
one of the three symmetrical sequence components which exists only in
an unsymmetrical three-phase system of sinusoidal quantities and which is defined by the
following complex mathematical expression:
X = 1/3(X + a X + a X )
2 L1 L2 L3
where
a is the 120-degree operator;
X , X and X are the complex expressions of the phase quantities concerned;
L1 L2 L3
X denotes the system current or voltage phasors
[SOURCE IEC 60050-448:1995, 448-11-28]
IEC 63497:2026 © IEC 2026
3.3.13
zero sequence component
zero component
one of the three symmetrical sequence components which exists only in
an unsymmetrical three-phase system of sinusoidal quantities and which is defined by the
following complex mathematical expression:
X = 1/3 (X + X + X )
0 L1 L2 L3
where
X , X and X are the complex expressions of the phase quantities concerned;
L1 L2 L3
X denotes the system current or voltage phasors
[SOURCE IEC 60050-448:1995, 448-11-29]
3.3.14
positive sequence component
positive component
one of the three symmetrical sequence components which exists in
symmetrical and unsymmetrical three-phase system(s) of sinusoidal quantities and which is
defined by the following complex mathematical expression:
X = 1/3(X + a X + a X )
1 L1 L2 L3
where
a is the 120-degree operator;
X , X and X are the complex expressions of the phase quantities concerned;
L1 L2 L3
X denotes the system current or voltage phasors
[SOURCE IEC 60050-448:1995, 448-11-27]
3.3.15
unbalance factor
in a three-phase system, degree of unbalance expressed by the ratio (in per cent) of the RMS
values of the negative sequence component (or the zero sequence component) to the positive
sequence component of the fundamental component of the voltage or the electric current
[SOURCE IEC 60050-614:2016, 614-01-33]
3.3.16
attenuation factor
α
h
ratio of the load-side current to the (filtered) grid-side current, measured at the same time, for
a specific harmonic order h
3.3.17
global attenuation factor
α
global
ratio of the RMS harmonic current on the load-side to the (filtered) RMS harmonic current on
the grid-side, measured at the same time
I
∑
h,load
h≠1
α =
global
I
∑ h,grid
h≠1
IEC 63497:2026 © IEC 2026
3.3.18
filtering efficiency
η
h
ratio of the ACD current to the load-side current for a specific harmonic order h, usually
expressed in percent
α −1
h
η=1−=
h
αα
hh
3.3.19
crest factor
ratio between the maximum instantaneous value and the RMS value
3.3.20
rate of change of frequency
ROCOF
amount of frequency change per unit of time
[SOURCE: IEC TS 62786-1:2023, 3.1.25]
3.4 Miscellaneous
3.4.1
reasonably foreseeable misuse
use of a product, process or service in a way not intended by the supplier, but which may result
from readily predictable human behaviour
[SOURCE IEC 60050-903:2013, 903-01-14]
3.5 Abbreviated terms
EUT equipment under test
4 Ratings
4.1 Rated frequency
For AC applications covered by this document, the standard values of the rated frequency are
50 Hz and 60 Hz.
4.2 Rated voltage
The rated line to line voltage, or rated line to line voltage range, shall be specified by the
manufacturer, taking into account IEC 60664-1:2020, Annex B, and in particular the "nominal
voltages presently used in the world" as specified in IEC 60664-1:2020, Table B.2.
4.3 Connection wiring types
For three-phase networks, the type of wiring shall be specified by the manufacturer:
– 3-wire (3W) connection, when the ACD is connected to the mains with three phases without
neutral;
– 4-wire (4W) connection, when the ACD is connected to the mains with three phases and
neutral.
IEC 63497:2026 © IEC 2026
5 Requirements for design and construction
5.1 General requirements
5.1.1 Architecture
The high-level block diagram representing the internal architecture of an ACD is shown in
Figure 3. It consists of
– a power converter,
– a set of sensors, and
– a controller.
Figure 3 – Internal architecture of an ACD
The operation principle of an ACD is described in Figure 4 and is based on controlling the
converter such that power quality metrics like fundamental power factor or THD are improved.
As an example for active harmonics filter (AHF), a typical way is to operate it as a current
source, opposite in phase to the current that is produced by non-linear loads, so that the grid
current presents a pure sinusoidal waveform. The concept is shown in Figure 4.
Figure 4 is a pictorial representation of the ACD filtering function on display. ACD can be
configured for power factor correction or unbalance correction as well.
IEC 63497:2026 © IEC 2026
Figure 4 – Principle of operation of an ACD (for AHF function)
5.1.2 Functional classification
The segmentation described in 5.1.2 intends to help users in selecting the relevant device to
mitigate their grid.
ACD can be called SVG (static var generator) if it covers the following compensation
functionalities:
– either fundamental reactive power compensation or load balancing, or both;
– optional limited harmonic filtering (either limited harmonic orders or lower current ratings,
or both).
ACD can be called AHF (active harmonic filter) if it covers the following two compensation
functionalities:
– fundamental reactive power compensation or load balancing, or both;
th
– active and parameterizable harmonic filtering for all harmonics up to 49 order or higher.
th
NOTE Devices that are capable of filtering below the 49 order can be called SVG.
IEC 63497:2026 © IEC 2026
5.2 Safety requirements
5.2.1 General
ACD shall comply with all the requirements of IEC 62477-1:2022.
ACD are intended to be installed, commissioned, operated and maintained by skilled persons.
5.2.2 Protection against electric shocks
ACD shall comply with IEC 62477-1:2022, 4.1, 4.2, 4.3, 4.5, 4.8, 4.11 and 4.13.
5.2.3 Protection against mechanical hazards
ACD shall comply with IEC 62477-1:2022, 4.1, 4.4, 4.7, 4.9 and 4.12.
5.2.4 Protection against fire
ACD shall comply with IEC 62477-1:2022, 4.1, 4.2, 4.3, 4.5.1.2 and 4.6.
5.2.5 Temperature
ACD shall comply with IEC 62477-1:2022, 4.1, 4.2, 4.6.4 and 4.9.
5.2.6 Protection against hazards from fluids
ACD shall comply with IEC 62477-1:2022, 4.1, 4.7.2.
5.2.7 Protection against radiation, including laser sources, and against sonic and
ultrasonic pressure
ACD shall comply with IEC 62477-1:2022, 4.1, 4.10.
5.2.8 Components and subassemblies
ACD shall comply with IEC 62477-1:2022, 4.1, 4.11.2.
5.2.9 Reasonably foreseeable misuses (hazards resulting from application)
5.2.9.1 Device requirements
The following common foreseeable misuses of the device shall not lead to hazardous situations
for the user:
– incorrect phase order of power cables resulting in negative phase sequence system;
– insufficient cooling, for example due to blocked air flow, where IEC 62477-1:2022, 5.2.4.9
applies.
5.2.9.2 Technical documentation requirements
The following foreseeable misuses of the device shall be addressed with relevant information
provided in the technical documentation:
– incorrect current transformer connection: incorrect phase order, missing signals, inverted
signals, signals from differen
...