SIST EN IEC 62475:2026
(Main)High-current test techniques - Definitions and requirements for test currents and measuring systems
- Abstract
IEC 62475:2026 is applicable to high-current testing and measurements on both high-voltage and low-voltage equipment. It deals with steady-state and short-time direct current (as e.g. encountered in high-power DC testing), steady-state and short-time alternating current (as e.g. encountered in high-power AC testing), and impulse-current. In general, currents above 100 A are considered in this International Standard, although currents less than this can occur in tests.
This standard:
• defines the terms used;
• defines parameters and their tolerances;
• describes methods to estimate uncertainties of high-current measurements;
• states the requirements applicable to a complete measuring system;
• describes the methods for approving a measuring system and checking its components;
• describes the procedure by which the user shows that a measuring system meets the requirements of this document, including limits set for uncertainty of measurement.
This standard also covers fault detection during, for example, lightning impulse testing.
This second edition cancels and replaces the first edition published in 2010. This edition constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous edition:
• minor errors in edition 1 have corrected;
• terms and definitions have been modified to achieve best possible adherence to IEC 60060‑2:2025 and have been ascribed appropriate [SOURCE];
• terms and definitions which in edition 1 were presented in clauses other than Clause 3 have been moved into Clause 3.
• Annex B, Clause B.4 has been amended to provide an example of uncertainty calculation for the use of an approved measuring system;
• Clause C.2 has been deleted since the definitions given there are not referred to, with the exception of the origin of the step, which is used in Annex D. The applicable information has been added to Annex D as Note 1.
• Annex G, Clause G.8 has been amended to replace “peak factor” by “a factor”. Texts have been clarified. Equations for relation between factor κ and cos ϕ have been developed to a simplified form.
• Annex G, Clause G.9 has been added.
- Status
- Published
- Public Enquiry End Date
- 30-Jun-2025
- Publication Date
- 12-Oct-2026
- Technical Committee
- IVNT - High-voltage testing techniques
- Current Stage
- 6060 - National Implementation/Publication (Adopted Project)
- Start Date
- 17-Sep-2026
- Due Date
- 22-Nov-2026
- Completion Date
- 13-Oct-2026
SIST EN IEC 62475:2026 is the European standard on high-current test techniques for definitions and requirements for test currents and measuring systems. It applies to high-current testing and measurement on high-voltage and low-voltage equipment, covering direct current, alternating current, and impulse current, and it is intended for people who need to qualify, check, or use measuring systems for those tests.
What does SIST EN IEC 62475:2026 specify?
SIST EN IEC 62475:2026 specifies the terms, current parameters, tolerances, uncertainty methods, and measuring-system requirements needed for high-current testing. It also gives the structure for approving a measuring system, checking its components, and demonstrating that the system meets the document’s uncertainty limits in practice.
The document applies to high-current testing and measurements on both high-voltage and low-voltage equipment. It treats steady-state and short-time direct current, steady-state and short-time alternating current, and impulse current, with currents above 100 A generally in view, although lower currents can also occur in tests.
A note in the scope also says the standard covers fault detection during lightning impulse testing.
The document is organized into Clauses 1 to 12 and informative Annexes A to H.
| Annex | What it covers |
|---|---|
| Annex A | Uncertainty of measurement |
| Annex B | Examples of uncertainty calculation in high-current measurements |
| Annex C | Step-response measurements |
| Annex D | Convolution method for estimating dynamic behaviour from step-response measurements |
| Annex E | Constraints for certain wave shapes |
| Annex F | Temperature rise of measuring resistors |
| Annex G | Determination of RMS values of short-time AC current |
| Annex H | Examples of IEC standards with high-current tests |
What are the key requirements of SIST EN IEC 62475:2026?
SIST EN IEC 62475:2026 focuses on how to prove that a measuring system is suitable for a given current waveform and test duty. The core idea is that the user must control scale factor, dynamic behaviour, stability, and uncertainty, then keep a record that shows the system remains valid.
Measuring systems, approval, and records
Clause 3 defines a measuring system as the complete set of devices used to measure a quantity, including software where it is used to obtain or calculate results. Clause 4 requires a record of performance that describes the system and holds the evidence that the standard’s requirements have been met.
In practice, this means the user cannot rely only on a device nameplate or a single calibration certificate. The system has to be documented as a whole, including the parts used together and the tests used to support its approval.
Scale factor and calibration
Clause 5.2 gives the preferred method for determining the scale factor by comparison with a reference measuring system. If the assigned measurement range is wider than the reference system can cover, the comparison is limited to the available range and is supplemented by a linearity test.
Clause 5.2.2 allows an alternative component method, where the assigned scale factor is built up from the converting device, transmission system, any secondary attenuator, and the measuring instrument. In practice, this is useful when the system is assembled from separate parts and the user needs to trace the calibration through those parts.
Linearity, dynamic behaviour, and interference
Clause 5.3 requires a linearity test when comparison calibration does not cover the full assigned measurement range. Clause 5.4 then addresses dynamic behaviour, using amplitude-frequency response for AC systems and step-response based methods for impulse systems.
This matters because a system can read correctly at one current level or frequency and still behave differently elsewhere in its range. The document therefore links the approval of the measuring system to the waveform family it will actually measure.
Clause 5.8 covers the effect of nearby current paths, and Clause 5.12 covers interference tests. This is important for multi-phase test circuits and similar installations, where nearby conductors and electromagnetic coupling can change the reading even when the measuring system itself is unchanged.
Stability, temperature, and periodic checking
Clause 5.5 covers short-term stability, Clause 5.6 long-term stability, and Clause 5.7 ambient temperature effect. Together, these clauses require the user to check whether heating, drift, and ambient conditions change the scale factor enough to matter for use.
In practice, this means the user has to decide not only whether the system was correct at calibration, but whether it stays correct long enough for the intended work. The record of performance must show the conditions under which the system remains valid.
Steady-state direct current and ripple current
Clause 6 sets the requirements for steady-state direct current. It includes the test current requirements and tolerances, the measurement of the test current, measurement of ripple amplitude, and the needed test procedures.
For ripple amplitude, the measuring system must achieve the uncertainty limit stated in the clause, and the scale factor has to be determined at the ripple frequency. That matters when the DC source is not perfectly smooth, because ripple can affect both the test result and the way the current is measured.
Steady-state alternating current, short-time currents, and impulse currents
Clause 7 covers steady-state alternating current, including a near-sinusoidal wave shape and the permitted tolerance on the test current. Clause 8 covers short-time direct current, Clause 9 short-time alternating current, and Clause 10 impulse currents, each with its own current tolerances, measuring-system requirements, and test procedures.
This structure matters because the measurement needs are not the same for power-frequency current, brief fault-like current, and impulse waveforms. The user has to match the measuring system to the actual test type and its waveform limits.
Clause 10 also requires impulse-current systems to measure peak value, time parameters, and enough waveform detail to calculate charge and Joule integral when needed. For users, that means the system must capture both magnitude and shape, not just a single peak reading.
High-voltage dielectric testing and reference systems
Clause 11 addresses current measurement in high-voltage dielectric testing, where the aim is detection of insulation breakdown during lightning-impulse voltage tests. In that case, the emphasis is on detecting breakdown and verifying linearity with applied voltage, rather than on determining actual current values.
Clause 12 sets requirements for reference measuring systems. A reference system must be traceable to national and/or international standards and have sufficient accuracy and stability for use in approving other systems, which is what makes comparative calibration credible.
What terms does SIST EN IEC 62475:2026 define?
SIST EN IEC 62475:2026 defines the terms needed to describe current-measuring setups, calibration, and uncertainty in a consistent way.
- Measuring system - the complete set of devices used to make the measurement, including software when it calculates the result.
- Record of performance - the user-maintained file that describes the system and shows that the standard’s requirements have been met.
- Approved measuring system - a measuring system shown to comply with one or more of the requirement sets in SIST EN IEC 62475:2026.
- Reference measuring system - a traceable system with enough accuracy and stability to be used for approving other systems by comparison.
- Current-converting shunt - a resistor across which the voltage is proportional to the current being measured.
- Rogowski coil - an inductive current-converting device without iron, used with an integrating circuit.
- Scale factor - the factor used to convert the instrument reading into the value of the input quantity.
- Assigned measurement range - the current range in which the system can be used within the uncertainty limits of the standard.
Who uses SIST EN IEC 62475:2026?
SIST EN IEC 62475:2026 is used by high-voltage and high-current test laboratories, manufacturers of current measuring systems, calibration and accreditation laboratories, and users who run qualification or withstand tests. It is also relevant to engineers and quality managers who need to decide whether a measuring system is suitable for DC, AC, ripple, short-time, or impulse current work.
The standard is especially relevant in test facilities for power equipment, arrester tests, EMC tests, lightning-impulse testing, and high-voltage dielectric testing on items such as transformers and reactors. It also matters to people who maintain records of performance, schedule performance checks, and assess uncertainty for routine and comparative measurements.
What changed in SIST EN IEC 62475:2026 from the previous edition?
SIST EN IEC 62475:2026 cancels and replaces the first edition published in 2010, and the edition is described as a technical revision.
The changes stated in the document are:
- minor errors from edition 1 were corrected
- terms and definitions were adjusted to align as closely as possible with IEC 60060-2:2025 and were given the appropriate source references
- terms and definitions that had appeared outside Clause 3 in edition 1 were moved into Clause 3
- Annex B, Clause B.4 was amended with an example of uncertainty calculation for use of an approved measuring system
- Clause C.2 was deleted, and the relevant information was moved to Annex D as Note 1
- Annex G was revised so that Clause G.8 uses “a factor” instead of “peak factor”, with clarified text and simplified equations relating factor κ and cos ϕ
- Annex G, Clause G.9 was added
Which standards are used with SIST EN IEC 62475:2026?
SIST EN IEC 62475:2026 refers to the following normative standards and guides:
- IEC 60051-2:1984 - gives special requirements for direct acting analogue ammeters and voltmeters, which supports instrument selection and calibration.
- IEC 60060-1:2025 - provides general definitions and test requirements for high-voltage test techniques, which frames the test environment and terminology.
- IEC 61083-3:2020 - sets requirements for hardware used in measurements in high-voltage and high-current tests with alternating and direct voltages and currents.
- IEC 61083-4:20XX - sets requirements for software used in those measurement systems.
- IEC 61180:2016 - covers high-voltage test techniques for low-voltage equipment, including definitions, test and procedure requirements, and test equipment.
- ISO/IEC Guide 98-3:2008 - gives the Guide to the Expression of Uncertainty in Measurement, which underpins the uncertainty method used in the standard.
The document also aligns many definitions with IEC 60060-2:2025, which is the terminology source used throughout the terms and definitions.
What does the SIST EN IEC 62475:2026 document contain?
SIST EN IEC 62475:2026 contains the scope, normative references, terms and definitions, procedures for qualification and use of a measuring system, and detailed requirements for different current types. It also includes informative annexes with uncertainty methods, worked examples, step-response and convolution methods, temperature-rise considerations, and RMS evaluation for short-time AC current.
The annexes and figures are used to support design, calibration, testing, and performance checking of measuring systems. In particular, Annex B gives worked uncertainty examples, Annex C and Annex D support dynamic-behaviour work on impulse systems, and Annex G provides methods for evaluating RMS values and related short-circuit quantities.
Relations
- Effective Date
- 15-Sep-2026
- Effective Date
- 15-Sep-2026
- Effective Date
- 09-Feb-2021
- Effective Date
- 01-Nov-2026
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Frequently Asked Questions
SIST EN IEC 62475:2026 is a standard published by the Slovenian Institute for Standardization (SIST). Its full title is "High-current test techniques - Definitions and requirements for test currents and measuring systems". This standard covers: IEC 62475:2026 is applicable to high-current testing and measurements on both high-voltage and low-voltage equipment. It deals with steady-state and short-time direct current (as e.g. encountered in high-power DC testing), steady-state and short-time alternating current (as e.g. encountered in high-power AC testing), and impulse-current. In general, currents above 100 A are considered in this International Standard, although currents less than this can occur in tests. This standard: • defines the terms used; • defines parameters and their tolerances; • describes methods to estimate uncertainties of high-current measurements; • states the requirements applicable to a complete measuring system; • describes the methods for approving a measuring system and checking its components; • describes the procedure by which the user shows that a measuring system meets the requirements of this document, including limits set for uncertainty of measurement. This standard also covers fault detection during, for example, lightning impulse testing. This second edition cancels and replaces the first edition published in 2010. This edition constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition: • minor errors in edition 1 have corrected; • terms and definitions have been modified to achieve best possible adherence to IEC 60060‑2:2025 and have been ascribed appropriate [SOURCE]; • terms and definitions which in edition 1 were presented in clauses other than Clause 3 have been moved into Clause 3. • Annex B, Clause B.4 has been amended to provide an example of uncertainty calculation for the use of an approved measuring system; • Clause C.2 has been deleted since the definitions given there are not referred to, with the exception of the origin of the step, which is used in Annex D. The applicable information has been added to Annex D as Note 1. • Annex G, Clause G.8 has been amended to replace “peak factor” by “a factor”. Texts have been clarified. Equations for relation between factor κ and cos ϕ have been developed to a simplified form. • Annex G, Clause G.9 has been added.
IEC 62475:2026 is applicable to high-current testing and measurements on both high-voltage and low-voltage equipment. It deals with steady-state and short-time direct current (as e.g. encountered in high-power DC testing), steady-state and short-time alternating current (as e.g. encountered in high-power AC testing), and impulse-current. In general, currents above 100 A are considered in this International Standard, although currents less than this can occur in tests. This standard: • defines the terms used; • defines parameters and their tolerances; • describes methods to estimate uncertainties of high-current measurements; • states the requirements applicable to a complete measuring system; • describes the methods for approving a measuring system and checking its components; • describes the procedure by which the user shows that a measuring system meets the requirements of this document, including limits set for uncertainty of measurement. This standard also covers fault detection during, for example, lightning impulse testing. This second edition cancels and replaces the first edition published in 2010. This edition constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition: • minor errors in edition 1 have corrected; • terms and definitions have been modified to achieve best possible adherence to IEC 60060‑2:2025 and have been ascribed appropriate [SOURCE]; • terms and definitions which in edition 1 were presented in clauses other than Clause 3 have been moved into Clause 3. • Annex B, Clause B.4 has been amended to provide an example of uncertainty calculation for the use of an approved measuring system; • Clause C.2 has been deleted since the definitions given there are not referred to, with the exception of the origin of the step, which is used in Annex D. The applicable information has been added to Annex D as Note 1. • Annex G, Clause G.8 has been amended to replace “peak factor” by “a factor”. Texts have been clarified. Equations for relation between factor κ and cos ϕ have been developed to a simplified form. • Annex G, Clause G.9 has been added.
SIST EN IEC 62475:2026 is classified under the following ICS (International Classification for Standards) categories: 19.080 - Electrical and electronic testing. The ICS classification helps identify the subject area and facilitates finding related standards.
SIST EN IEC 62475:2026 has the following relationships with other standards: It is inter standard links to SIST EN IEC 60060-1:2025, SIST EN IEC 61083-3:2021, SIST EN 62475:2011, SIST EN 62475:2011. Understanding these relationships helps ensure you are using the most current and applicable version of the standard.
SIST EN IEC 62475:2026 is available in PDF format for immediate download after purchase. The document can be added to your cart and obtained through the secure checkout process. Digital delivery ensures instant access to the complete standard document.
Standards Content (Sample)
SLOVENSKI STANDARD
01-november-2026
Visokotokovne preskusne tehnike - Definicije in zahteve za preskusne toke in
merilne sisteme
High-current test techniques - Definitions and requirements for test currents and
measuring systems
Hochstrom-Prüftechnik - Begriffe und Anforderungen für Hochstrom-Messungen
Techniques des essais à haute intensité - Définitions et exigences relatives aux courants
d'essai et systèmes de mesure
Ta slovenski standard je istoveten z: EN IEC 62475:2026
ICS:
19.080 Električno in elektronsko Electrical and electronic
preskušanje testing
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
EUROPEAN STANDARD EN IEC 62475
NORME EUROPÉENNE
EUROPÄISCHE NORM September 2026
ICS 19.080 Supersedes EN 62475:2010
English Version
High-current test techniques - Definitions and requirements for
test currents and measuring systems
(IEC 62475:2026)
Techniques des essais à haute intensité - Définitions et Hochstrom-Prüftechnik - Begriffe und Anforderungen für
exigences relatives aux courants d'essai et systèmes de Hochstrom-Messungen
mesure (IEC 62475:2026)
(IEC 62475:2026)
This European Standard was approved by CENELEC on 2026-09-03. 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 62475:2026 E
European foreword
The text of document 42/472/FDIS, future edition 2 of IEC 62475, prepared by TC 42 "High-voltage
and high-current test techniques" was submitted to the IEC-CENELEC parallel vote and approved by
CENELEC as EN IEC 62475:2026.
The following dates are fixed:
• latest date by which the document has to be implemented at national (dop) 2027-09-30
level by publication of an identical national standard or by endorsement
• latest date by which the national standards conflicting with the (dow) 2029-09-30
document have to be withdrawn
This document supersedes EN 62475:2010 and all of its amendments and corrigenda (if any).
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.
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 62475:2026 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 60051-2:2018 NOTE Approved as EN IEC 60051-2:2021 (not modified)
IEC 60060-1:2025 NOTE Approved as EN IEC 60060-1:2025 (not modified)
IEC 60060-2:2025 NOTE Approved as EN IEC 60060-2:2025 (not modified)
IEC 60076-5:2006 NOTE Approved as EN 60076-5:2006 (not modified)
IEC 60099-4:2014 NOTE Approved as EN 60099-4:2014 (not modified)
IEC 60099-4:2014 NOTE Approved as EN 60099-4:2014 (not modified)
IEC 60282-1:2020 NOTE Approved as EN IEC 60282-1:2020 (not modified)
IEC 60947-1:2020 NOTE Approved as EN IEC 60947-1:2021 (not modified)
IEC 60947-2:2024 NOTE Approved as EN IEC 60947-2:2025 (not modified)
IEC 60947-3:2020 NOTE Approved as EN IEC 60947-3:2021 (not modified)
IEC 61000-4-5:2014 NOTE Approved as EN 61000-4-5:2014 (not modified)
IEC 61083-3:2020 NOTE Approved as EN IEC 61083-3:2021 (not modified)
IEC 61180:2016 NOTE Approved as EN 61180:2016 (not modified)
IEC 61230:2008 NOTE Approved as EN 61230:2008 (not modified)
IEC 61439-1:2020 NOTE Approved as EN IEC 61439-1:2021 (not modified)
IEC 61439-6:2012 NOTE Approved as EN 61439-6:2012 (not modified)
IEC 61643-11:2025 NOTE Approved as EN IEC 61643-11:2025 (not modified) +A11:2025
IEC 61643-21:2000 NOTE Approved as EN 61643-21:2001 (not modified)
IEC 62271-1 NOTE Approved as EN 62271-1
IEC 62271-100:2021 NOTE Approved as EN IEC 62271-100:2021 (not modified)
IEC 62271-101 NOTE Approved as EN IEC 62271-101
IEC 62271-102:2018 NOTE Approved as EN IEC 62271-102:2018 (not modified)
IEC 62271-103:2021 NOTE Approved as EN IEC 62271-103:2023 (not modified)
IEC 62271-104 NOTE Approved as EN IEC 62271-104
IEC 62271-105:2021 NOTE Approved as EN IEC 62271-105:2023 (not modified)
IEC 62271-110:2023 NOTE Approved as EN IEC 62271-110:2023 (not modified)
IEC 62305-1:2024 NOTE Approved as EN IEC 62305-1:2024 (not modified)
ISO/IEC 17025:2017 NOTE Approved as EN ISO/IEC 17025:2017 (not modified)
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
ISO/IEC Guide 98-3 2008 Uncertainty of measurement - Part 3: - -
Guide to the expression of uncertainty in
measurement (GUM:1995)
IEC 62475 ®
Edition 2.0 2026-07
INTERNATIONAL
STANDARD
High-current test techniques - Definitions and requirements for test currents and
measuring systems
ICS 19.080 ISBN 978-2-8327-1400-3
IEC 62475:2026-07(en)
IEC 62475:2026 © IEC 2026
CONTENTS
FOREWORD . 7
1 Scope . 9
2 Normative references . 9
3 Terms and definitions . 9
3.1 Measuring systems . 10
3.2 Components of a measuring system . 11
3.3 Scale factors . 12
3.4 Rated values . 12
3.5 Terms and definitions related to the dynamic behaviour . 13
3.6 Terms related to uncertainty . 14
3.7 Terms and definitions related to tests on measuring systems . 17
3.8 Terms and definitions related to steady state direct current . 18
3.9 Terms related to steady state alternating current . 18
3.10 Terms and definitions related to short-time direct current . 18
3.11 Terms and definitions related to short-time alternating current . 19
3.12 Terms and definitions related to impulse currents . 21
4 Procedures for qualification and use of a measuring system . 25
4.1 General principles . 25
4.2 Schedule of performance tests . 26
4.3 Schedule of performance checks . 26
4.4 Requirements for the record of performance . 26
4.4.1 Contents of the record of performance . 26
4.4.2 Exceptions . 27
4.5 Operating conditions . 27
4.6 Uncertainty . 27
5 Tests and test requirements for an approved measuring system . 28
5.1 General requirements . 28
5.2 Calibration – Determination of the scale factor . 29
5.2.1 Calibration of a measuring system by comparison with a reference
measuring system (preferred method) . 29
5.2.2 Determination of the scale factor of a measuring system from those of
its components (alternative method) . 33
5.3 Linearity test in addition to comparison over the limited current range . 34
5.3.1 Application. 34
5.3.2 Alternative methods in order of suitability . 34
5.4 Dynamic behaviour . 35
5.4.1 General . 35
5.4.2 Determination of the amplitude-frequency response of AC
measuring systems . 35
5.4.3 Reference method for impulse current measuring systems . 35
5.5 Short-term stability . 36
5.5.1 Method . 36
5.5.2 Steady-state current . 36
5.5.3 Impulse current and short-time current . 37
5.5.4 Periodic impulse current and periodic short-time current . 38
5.6 Long-term stability . 39
5.7 Ambient temperature effect . 40
IEC 62475:2026 © IEC 2026
5.8 Effect of nearby current paths . 40
5.9 Software effect . 43
5.10 Uncertainty calculation . 44
5.10.1 General . 44
5.10.2 Uncertainty of calibration . 44
5.10.3 Uncertainty of measurement using an approved measuring system . 45
5.11 Uncertainty calculation of time-parameter measurements (impulse currents
only) . 46
5.11.1 General . 46
5.11.2 Uncertainty of the time-parameter calibration . 46
5.11.3 Uncertainty of a time-parameter measurement using an approved
measuring system. 48
5.12 Interference test. 49
5.12.1 Application. 49
5.12.2 Current-converting shunts and current transformers with iron . 49
5.12.3 Inductive measuring systems without iron (Rogowski coils) . 51
5.13 Withstand tests . 52
5.13.1 Voltage withstand tests . 52
5.13.2 Current withstand tests . 52
6 Steady-state direct current . 52
6.1 Application . 52
6.2 Test current . 52
6.2.1 Requirements . 52
6.2.2 Tolerances . 52
6.3 Measurement of the test current . 53
6.3.1 Requirements for an approved measuring system . 53
6.3.2 Uncertainty contributions . 53
6.3.3 Dynamic behaviour . 53
6.3.4 Calibrations and tests on an approved measuring system . 53
6.3.5 Performance check . 54
6.4 Measurement of ripple amplitude . 54
6.4.1 Requirements for an approved measuring system . 54
6.4.2 Uncertainty contributions . 54
6.4.3 Dynamic behaviour for ripple . 54
6.4.4 Calibrations and tests on an approved ripple-current measuring system . 55
6.4.5 Measurement of the scale factor at the ripple frequency . 55
6.4.6 Performance check for ripple current measuring system . 55
6.5 Test procedures . 56
7 Steady-state alternating current . 56
7.1 Application . 56
7.2 Test current . 56
7.2.1 Requirements . 56
7.2.2 Tolerances . 56
7.3 Measurement of the test current . 57
7.3.1 Requirements for an approved measuring system . 57
7.3.2 Uncertainty contributions . 57
7.3.3 Dynamic behaviour . 57
7.3.4 Calibrations and tests on an approved measuring system . 59
7.3.5 Performance check . 60
IEC 62475:2026 © IEC 2026
7.4 Test procedures . 60
8 Short-time direct current . 60
8.1 Application . 60
8.2 Test currents . 61
8.2.1 Requirements for the test current. 61
8.2.2 Tolerances . 61
8.3 Measurement of the test current . 61
8.3.1 Requirements for an approved measuring system . 61
8.3.2 Uncertainty contributions . 61
8.3.3 Dynamic behaviour . 61
8.3.4 Calibrations and tests on an approved measuring system . 62
8.3.5 Performance check . 63
8.3.6 Linearity test . 63
8.4 Test procedures . 63
9 Short-time alternating current . 64
9.1 Application . 64
9.2 Test current . 64
9.2.1 Requirements for the test current. 64
9.2.2 Tolerances . 64
9.3 Measurement of the test current . 65
9.3.1 Requirements for an approved measuring system . 65
9.3.2 Uncertainty contributions . 65
9.3.3 Dynamic behaviour . 65
9.3.4 Calibrations and tests on an approved measuring system . 67
9.3.5 Performance check . 67
9.3.6 Linearity test . 68
9.3.7 Interference test . 68
9.4 Test procedures . 68
10 Impulse currents . 68
10.1 Application . 68
10.2 Test current . 69
10.2.1 General . 69
10.2.2 Tolerances . 69
10.3 Measurement of the test current . 70
10.3.1 Requirements for an approved measuring system . 70
10.3.2 Uncertainty contributions . 70
10.3.3 Dynamic behaviour . 70
10.3.4 Calibrations and tests on an approved measuring system . 72
10.3.5 Performance check . 73
10.4 Test procedures . 73
11 Current measurement in high-voltage dielectric testing . 73
11.1 Application . 73
11.2 Test current . 74
11.3 Measurement of the test current . 74
11.3.1 Requirements for an approved measuring system . 74
11.3.2 Uncertainty contributions . 74
11.3.3 Dynamic behaviour . 74
11.3.4 Calibrations and tests on an approved measuring system . 74
IEC 62475:2026 © IEC 2026
11.3.5 Performance check . 75
11.3.6 Linearity test . 75
11.3.7 Interference test . 75
11.4 Test procedures . 75
12 Reference measuring systems . 75
12.1 General . 75
12.2 Interval between subsequent calibrations of reference measuring systems . 76
Annex A (informative) Uncertainty of measurement . 77
A.1 General . 77
A.2 Model function . 77
A.3 Type A evaluation of standard uncertainty . 78
A.4 Type B evaluation of standard uncertainty . 79
A.5 Combined standard uncertainty . 80
A.6 Expanded uncertainty . 81
A.7 Effective degrees of freedom . 82
A.8 Uncertainty budget . 82
A.9 Statement of the measurement result . 83
Annex B (informative) Examples of the uncertainty calculation in high-current
measurements . 85
B.1 General . 85
B.2 Example 1: Calibration of the scale factor of an AC current measuring
system (comparison or reference method) . 85
B.3 Example 2: Expanded uncertainty of measurement using an approved
measuring system . 89
B.4 Example 3: Scale factor when using an approved high current measuring
system (component method) . 91
Annex C (informative) Generation of current step . 94
Annex D (informative) Convolution method for estimation of dynamic behaviour from
step-response measurements . 96
D.1 General . 96
D.2 Convolution method . 96
D.3 Procedure for performing the convolution calculation . 97
D.4 Uncertainty contributions . 98
D.5 Discussion of the calculated errors of impulse parameters . 99
D.5.1 Error in the peak amplitude . 99
D.5.2 Error in the front time . 99
D.5.3 Error in the time to half-value . 99
Annex E (informative) Constraints for certain wave shapes . 100
Annex F (informative) Temperature rise of measuring resistors . 102
Annex G (informative) Determination of RMS values of short-time AC current . 103
G.1 General characterization of a short-time alternating current . 103
G.2 True RMS value . 104
G.3 Symmetrical AC component (RMS value) . 105
G.4 Numerical method of obtaining the true RMS value using the trapezium rule . 105
G.5 Conventional RMS value of the AC component . 106
G.6 Conventional RMS value of an arc current . 108
G.7 Equivalent RMS value of a short-time current during a short-circuit of a given
duration . 109
G.8 Determination of the impedance angle from the factor κ . 110
IEC 62475:2026 © IEC 2026
G.9 Determination of the impedance angle by means of the phase shift between
current and voltage . 111
Annex H (informative) Examples of IEC standards with high-current tests . 113
Bibliography . 115
Figure 1 – Amplitude frequency response with examples for limit frequencies (f ; f ) . 14
1 2
Figure 2 – Example of short-time direct current . 19
Figure 3 – Exponential impulse current . 21
Figure 4 – Exponential impulse current – Oscillating tail . 22
Figure 5 – Impulse current – Rectangular, smooth . 23
Figure 6 – Impulse current – Rectangular with oscillations . 23
Figure 7 – Calibration by comparison over full assigned measurement range, h = 5 . 31
Figure 8 – Uncertainty contributions for calibrations over five current levels. 31
Figure 9 – Combining calibration and linearity test . 33
Figure 10 – Linearity test in the extended current range . 34
Figure 11 – Short-term stability test for steady-state current . 37
Figure 12 – Short-term stability test for impulse current and short-time current . 38
Figure 13 – Short-term stability test for periodic impulse-current and periodic short-
time current . 39
Figure 14 – Test circuit for effect of nearby current path for current-converting shunts
and current transformers with iron. 42
Figure 15 – Test circuit for effect of nearby current path for inductive measuring
systems without iron (Rogowski coils) . 43
Figure 16 – Principle of interference test circuit . 50
Figure 17 – Interference test on the measuring system i (t) based on
current-converting shunt or current transformer with iron in a typical 3-phase
short-circuit set-up . 50
Figure 18 – Test circuit for interference test for inductive systems without iron
(Rogowski coils) . 51
Figure 19 – Acceptable normalized amplitude-frequency response of an AC measuring
system intended for a single fundamental frequency f . 58
nom
Figure 20 – Acceptable normalized amplitude-frequency response of an AC measuring
system intended for a range of fundamental frequencies f to f . 59
nom1 nom2
Figure 21 – Example of short-time alternating current . 64
Figure A.1 – Normal probability distribution p(x) of a continuous random variable x . 83
Figure A.2 – Rectangular probability distribution p(x) . 84
Figure B.1 – Comparison between the system under calibration X and the reference
system N . 85
Figure C.1 – Circuit to generate current step using a coaxial cable . 94
Figure C.2 – Circuit to generate current step using a capacitor . 95
Figure E.1 – Attainable time parameters (shaded area) for 8/20 µs current impulse . 101
Figure G.1 – Equivalent circuit of short-circuit test . 103
Figure G.2 – Symmetrical AC component of an alternating short-circuit current . 105
Figure G.3 – Numerical evaluation of RMS value showing both instantaneous current
and instantaneous squared value of the current . 106
Figure G.4 – Three-crest method . 107
IEC 62475:2026 © IEC 2026
Figure G.5 – Evaluation of conventional RMS value of an arc current using the three-
crest method . 108
Figure G.6 – Evaluation of equivalent RMS value of a short-time current during a short-
circuit test . 109
Figure G.7 – Relation between factor κ and power factor cos(φ). 111
Figure G.8 – Phase displacement based on an ohmic-inductive circuit . 111
Table 1 – Required tests for steady-state direct current . 53
Table 2 – Required tests for ripple current . 55
Table 3 – Required tests for steady-state alternating current . 59
Table 4 – Tolerance requirement on test-current parameters for short-time direct
current . 61
Table 5 – Required tests for short-time direct current . 62
Table 6 – Tolerance requirements on the short-time alternating current test parameters . 65
Table 7 – List of typical tests in a high-power laboratory and required minimum
frequency range of the measuring system . 66
Table 8 – Tolerance requirements on scale factor . 66
Table 9 – Required tests for short-time alternating current . 67
Table 10 – Examples of exponential impulse-current types . 69
Table 11 – Tolerance requirements on exponential impulse current . 69
Table 12 – Tolerance requirements on rectangular impulse current. 70
Table 13 – Required tests for impulse current . 72
Table 14 – Required tests for impulse current in high-voltage dielectric testing . 74
Table A.1 – Coverage factor k for effective degrees of freedom ν (p = 95 %) . 82
eff
Table A.2 – Schematic of an uncertainty budget . 83
Table B.1 – Result of the comparison measurement . 87
Table B.2 – Result of the comparison measurement . 88
Table B.3 – Uncertainty budget for calibration of scale factor F . 88
x
Table B.4 – Result of linearity test . 90
Table B.5 – Uncertainty budget of scale factor F . 90
X,mes
Table B.6 – Uncertainty budget of the assigned scale factor F . 93
Table H.1 – List of typical tests with short-time alternating current . 113
Table H.2 – List of typical tests with exponential impulse current . 113
Table H.3 – List of typical tests with rectangular impulse current . 114
IEC 62475:2026 © IEC 2026
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
High-current test techniques -
Definitions and requirements for test currents and measuring systems
FOREWORD
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8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
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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
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shall not be held responsible for identifying any or all such patent rights.
IEC 62475 has been prepared by IEC technical committee 42: High-voltage and high-current
test techniques. It is an International Standard.
This second edition cancels and replaces the first edition published in 2010. This edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) minor errors in edition 1 have corrected;
b) terms and definitions have been modified to achieve best possible adherence to
IEC 60060-2:2025 and have been ascribed appropriate [SOURCE];
c) terms and definitions which in edition 1 were presented in clauses other than Clause 3 have
been moved into Clause 3.
IEC 62475:2026 © IEC 2026
d) Annex B, Clause B.4 has been amended to provide an example of uncertainty calculation
for the use of an approved measuring system;
e) Clause C.2 has been deleted since the definitions given there are not referred to, with the
exception of the origin of the step, which is used in Annex D. The applicable information has
been added to Annex D as Note 1.
f) Annex G, Clause G.8 has been amended to replace “peak factor” by “a factor”. Texts have
been clarified. Equations for relation between factor κ and cos ϕ have been developed to a
simplified form.
g) Annex G, Clause G.9 has been added.
The text of this International Standard is based on the following documents:
Draft Report on voting
42/472/FDIS 42/475/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.
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 uncha
...