IEC 62475:2010

High-current test techniques - Definitions and requirements for test currents and measuring systems

IEC 62475:2010 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 d.c. testing), steady-state and short-time alternating current (as e.g. encountered in high-power a.c. 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 also covers fault detection during, for example, lightning impulse testing.

Techniques des essais à haute intensité - Définitions et exigences relatives aux courants d'essai et systèmes de mesure

La CEI 62475:2010 s'applique aux essais et mesures à haute intensité sur des matériels haute et basse tensions. Elle couvre les essais à haute intensité en courant continu et courant alternatif en régime établi et de courte durée ainsi que des essais de courant de choc. De manière générale, la présente Norme internationale prend en compte des courants de plus de 100 A, même si des intensités moindres peuvent apparaître dans les essais. La présente norme couvre également la détection de défauts, comme par exemple dans le cadre d'essais aux chocs de foudre.

General Information

• Status: Published
• Publication Date: 28-Sep-2010
• ICS: 19.080 - Electrical and electronic testing
• Technical Committee: TC 42 - High-voltage and high-current test techniques
• Drafting Committee: MT 12 - TC 42/MT 12
• Current Stage: PPUB - Publication issued
• Start Date: 29-Sep-2010
• Completion Date: 31-Oct-2010

Overview

The IEC 62475:2010 standard, titled "High-current test techniques - Definitions and requirements for test currents and measuring systems", provides comprehensive guidelines for performing high-current testing and measurement in electrical equipment. This International Electrotechnical Commission (IEC) standard applies to both high-voltage and low-voltage equipment, covering steady-state and short-time direct current (DC), steady-state and short-time alternating current (AC), as well as impulse current tests.

Designed for currents generally above 100 A, IEC 62475:2010 also accommodates currents below this threshold in specific test scenarios. Additionally, the standard addresses fault detection, such as during lightning impulse testing, ensuring reliable and accurate measurement and testing practices across various electrical industries.

Key Topics

IEC 62475:2010 encompasses a range of critical subjects within the domain of high-current testing:

• Definitions and Terminology: Clear terms related to measuring systems, scale factors, rated values, dynamic behavior, uncertainty, and specific test scenarios are rigorously defined to ensure common understanding.

• Measuring Systems:

  • Components, calibration methods, linearity assessments, and dynamic behavior are outlined to qualify and use measuring systems effectively.
  • Special focus is given to stability (short-term and long-term), temperature effects, and interference impacts on measurement accuracy.

• Test Current Specifications:

  • Requirements and tolerances for different types of currents including steady-state DC/AC, short-time DC/AC, and impulse currents are detailed.
  • The standard prescribes procedures for measuring these currents with approved measurement systems, accounting for uncertainty and dynamic effects.

• Fault Detection and Withstand Tests:

  • Guidelines for identifying faults during high-current testing, including those due to lightning impulse phenomena.
  • Voltage and current withstand testing requirements ensure equipment safety and durability.

• Uncertainty and Performance Evaluation:

  • Procedures for uncertainty calculations in various measurement contexts, including time-parameter measurements for impulse currents.
  • Schedules for performance tests, routine checks, and record-keeping of measuring system data.

Applications

IEC 62475:2010 is essential for professionals involved in high-current testing across multiple sectors:

• Electrical Equipment Manufacturers: Ensure compliance with standardized testing conditions, enhancing product reliability and certification readiness.

• High-Voltage and Low-Voltage Testing Laboratories: Implement calibrated and validated measurement systems based on globally accepted protocols, improving test accuracy.

• Power Generation and Distribution Utilities: Perform safe and accurate testing on transformers, switchgear, and circuit breakers subjected to high current conditions.

• Quality Assurance and Compliance Teams: Maintain records of performance and calibrations, demonstrate consistent uncertainty management, and comply with regulatory requirements.

• Research and Development: Apply standardized high-current test techniques for validating new electrical components and technologies involving high-power current loads.

Related Standards

Professionals working with IEC 62475:2010 should consider these related standards for a broader technical framework:

• IEC 60060 series – High-voltage test techniques covering voltage testing methods complementing current tests.

• IEC 61242 – For design and performance requirements of measuring current transformers.

• IEC 61000 series – Electromagnetic compatibility (EMC) testing, encompassing interference considerations relevant to measurement systems.

• IEC 60529 – Degrees of protection provided by enclosures important during high-current testing conditions.

Conclusion

IEC 62475:2010 sets a rigorous foundation for high-current test techniques, defining essential requirements for test currents and measuring systems. By following this standard, industries can achieve consistent, accurate, and reliable testing and measurement outcomes, ensuring electric equipment safety, performance, and compliance with international benchmarks. The standard’s detailed approach to uncertainty, dynamic behavior, and fault detection makes it a critical resource for high-current testing in modern electrical engineering applications.

Standards Content (Sample)

IEC 62475 ®
Edition 1.0 2010-09
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
High-current test techniques – Definitions and requirements for test currents
and measuring systems
Techniques des essais à haute intensité – Définitions et exigences relatives
aux courants d'essai et systèmes de mesure

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IEC 62475 ®
Edition 1.0 2010-09
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
High-current test techniques – Definitions and requirements for test currents
and measuring systems
Techniques des essais à haute intensité – Définitions et exigences relatives
aux courants d'essai et systèmes de mesure

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
XE
CODE PRIX
ICS 19.080 ISBN 978-2-88912-184-7
– 2 – 62475 © IEC:2010
CONTENTS
FOREWORD.8
1 Scope.10
2 Normative references .10
3 Terms and definitions .10
3.1 Measuring systems.11
3.2 Components of a measuring system .11
3.3 Scale factors .12
3.4 Rated values .13
3.5 Definitions related to the dynamic behaviour .13
3.6 Definitions related to uncertainty .14
3.7 Definitions related to tests on measuring systems .16
4 Procedures for qualification and use of a measuring system.17
4.1 General principles .17
4.2 Schedule of performance tests .17
4.3 Schedule of performance checks.17
4.4 Requirements for the record of performance.18
4.4.1 Contents of the record of performance.18
4.4.2 Exceptions.18
4.5 Operating conditions .18
4.6 Uncertainty.19
5 Tests and test requirements for an approved measuring system.20
5.1 General requirements.20
5.2 Calibration – Determination of the scale factor .20
5.2.1 Calibration of a measuring system by comparison with a reference
measuring system (preferred method) .20
5.2.2 Determination of the scale factor of a measuring system from those
of its components .24
5.3 Linearity test .25
5.3.1 Application .25
5.3.2 Alternative methods in order of suitability .26
5.4 Dynamic behaviour.26
5.5 Short-term stability .27
5.5.1 Method .27
5.5.2 Steady-state current .27
5.5.3 Impulse current and short-time current .28
5.5.4 Periodic impulse current and periodic short-time current.28
5.6 Long-term stability.29
5.7 Ambient temperature effect .29
5.8 Effect of nearby current paths .30
5.9 Software effect .32
5.10 Uncertainty calculation .32
5.10.1 General .32
5.10.2 Uncertainty of calibration .32
5.10.3 Uncertainty of measurement using an approved measuring system .33
5.11 Uncertainty calculation of time-parameter measurements (impulse currents
only).34
5.11.1 General .34

62475 © IEC:2010 – 3 –
5.11.2 Uncertainty of the time-parameter calibration.34
5.11.3 Uncertainty of a time-parameter measurement using an approved
measuring system .35
5.12 Interference test .36
5.12.1 Application .36
5.12.2 Current-converting shunts and current transformers with iron .37
5.12.3 Inductive measuring systems without iron (Rogowski coils) .38
5.13 Withstand tests .38
5.13.1 Voltage withstand tests.38
5.13.2 Current withstand tests.39
6 Steady-state direct current .39
6.1 Application .39
6.2 Terms and definitions .39
6.3 Test current.39
6.3.1 Requirements .39
6.3.2 Tolerances .39
6.4 Measurement of the test current .40
6.4.1 Requirements for an approved measuring system.40
6.4.2 Uncertainty contributions .40
6.4.3 Dynamic behaviour .40
6.4.4 Calibrations and tests on an approved measuring system.40
6.4.5 Performance check.41
6.5 Measurement of ripple amplitude.41
6.5.1 Requirements for an approved measuring system.41
6.5.2 Uncertainty contributions .41
6.5.3 Dynamic behaviour for ripple .41
6.5.4 Calibrations and tests on an approved ripple-current measuring
system.42
6.5.5 Measurement of the scale factor at the ripple frequency .42
6.5.6 Performance check for ripple current measuring system .42
6.6 Test procedures .43
7 Steady-state alternating current.43
7.1 Application .43
7.2 Terms and definitions .43
7.3 Test current.43
7.3.1 Requirements .43
7.3.2 Tolerances .44
7.4 Measurement of the test current .44
7.4.1 Requirements for an approved measuring system.44
7.4.2 Uncertainty contributions .44
7.4.3 Dynamic behaviour .44
7.4.4 Calibrations and tests on an approved measuring system.46
7.4.5 Performance check.47
7.5 Test procedures .47
8 Short-time direct current.47
8.1 Application .47
8.2 Terms and definitions .48
8.3 Test currents .49
8.3.1 Requirements for the test current .49

– 4 – 62475 © IEC:2010
8.3.2 Tolerances .49
8.4 Measurement of the test current .49
8.4.1 Requirements for an approved measuring system.49
8.4.2 Uncertainty contributions .49
8.4.3 Dynamic behaviour .49
8.4.4 Calibrations and tests on an approved measuring system.50
8.4.5 Performance check.51
8.4.6 Linearity test.51
8.5 Test procedures .51
9 Short-time alternating current .51
9.1 Application .51
9.2 Terms and definitions .52
9.3 Test current.53
9.3.1 Requirements for the test current .53
9.3.2 Tolerances .53
9.4 Measurement of the test current .54
9.4.1 Requirements for an approved measuring system.54
9.4.2 Uncertainty contributions .54
9.4.3 Dynamic behaviour .54
9.4.4 Calibrations and tests on an approved measuring system.55
9.4.5 Performance check.56
9.4.6 Linearity test.56
9.4.7 Interference test .57
9.5 Test procedures .57
10 Impulse currents.57
10.1 Application .57
10.2 Terms and definitions .57
10.3 Test current.61
10.3.1 General .61
10.3.2 Tolerances .61
10.4 Measurement of the test current .62
10.4.1 Requirements for an approved measuring system.62
10.4.2 Uncertainty contributions .62
10.4.3 Dynamic behaviour .62
10.4.4 Calibrations and tests on an approved measuring system.64
10.4.5 Performance check.64
10.5 Test procedures .65
11 Current measurement in high-voltage dielectric testing.65
11.1 Application .65
11.2 Terms and definitions .65
11.3 Measurement of the test current .66
11.3.1 Requirements for an approved measuring system.66
11.3.2 Uncertainty contributions .66
11.3.3 Dynamic behaviour .66
11.3.4 Calibrations and tests on an approved measuring system.66
11.3.5 Performance check.67
11.3.6 Linearity test.67
11.3.7 Interference test .67
11.4 Test procedures .67

62475 © IEC:2010 – 5 –
12 Reference measuring systems.67
12.1 General .67
12.2 Interval between subsequent calibrations of reference measuring systems.67
Annex A (informative) Uncertainty of measurement.68
Annex B (informative) Examples of the uncertainty calculation in high-current
measurements .76
Annex C (informative) Step-response measurements.82
Annex D (informative) Convolution method for estimation of dynamic behaviour from
step-response measurements .85
Annex E (informative) Constraints for certain wave shapes.88
Annex F (informative) Temperature rise of measuring resistors.90
Annex G (informative) Determination of r.m.s. values of short-time a.c. current .91
Annex H (informative) Examples of IEC standards with high current tests .98
Bibliography.100

Figure 1 – Examples of amplitude frequency responses for limit frequencies (f ; f ). .14
1 2
Figure 2 – Calibration by comparison over full assigned measurement range.22
Figure 3 – Uncertainty contributions of the calibration (example with the minimum of 5
current levels).23
Figure 4 – Calibration by comparison over a limited current range with a linearity test
(see 5.3) providing extension up to the largest value in the assigned measurement
range .24
Figure 5 – Linearity test of the measuring system with a linear device in the extended
voltage range.26
Figure 6 – Short-term stability test for steady-state current. .28
Figure 7 – Short-term stability test for impulse current and short-time current.28
Figure 8 – Short-term stability test for periodic impulse-current and periodic short-time
current .29
Figure 9 – Test circuit for effect of nearby current path for current-converting shunts
and current transformers with iron. .31
Figure 10 – Test circuit for effect of nearby current path for inductive measuring
systems without iron (Rogowski coils).31
Figure 11 – Principle of interference test circuit. .37
Figure 12 – 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 (example). .37
Figure 13 – Test circuit for interference test for inductive systems without iron. .38
Figure 14 – Acceptable normalized amplitude-frequency response of an a.c. measuring
system intended for a single fundamental frequency f .45
nom.
Figure 15 – Acceptable normalized amplitude-frequency response of an a.c. measuring
system intended for a range of fundamental frequencies f to f .46
nom1 nom2
Figure 16 – Example of short-time direct current.48
Figure 17 – Example of short-time alternating current. .52
Figure 18 – Exponential impulse current. .58
Figure 19 – Exponential impulse current – oscillating tail. .58
Figure 20 – Impulse current – Rectangular, smooth. .59

– 6 – 62475 © IEC:2010
Figure 21 – Impulse current – Rectangular with oscillations. .59
Figure A.1 – Normal probability distribution p(x) of a continuous random variable x.75
Figure A.2 – Rectangular symmetric probability distribution p(x) of the estimate x of an
input quantity X.75
Figure B.1 – Comparison between the system under calibration X and the reference
system N .81
Figure C.1 – Circuit to generate current step using a coaxial cable. .82
Figure C.2 – Circuit to generate current step using a capacitor. .82
Figure C.3 – Definition of response parameters with respect to step response.84
Figure E.1 – Attainable combinations of time parameters (shaded area) for the 8/20
impulse at maximum 20 % undershoot and for 20 % tolerance on the time parameters .88
Figure E.2 – Locus for limit of attainable time parameters as a function of permissible
undershoot for the 8/20 impulse.89
Figure E.3 – Locus for limit of attainable time parameters as a function of permissible
undershoot for the 30/80 impulse.89
Figure G.1 – Equivalent circuit of short-circuit test. .91
Figure G.2 – Symmetrical a.c. component of an alternating short-circuit current .92
Figure G.3 – Numerical evaluation of r.m.s value showing both instantaneous current
and instantaneous squared value of the current. .93
Figure G.4 – Three-crest method .94
Figure G.5 – Evaluation of conventional r.m.s. value of an arc current using the three-
crest method.95
Figure G.6 – Evaluation of equivalent r.m.s value of a short-time current during a
short-circuit test.96
Figure G.7 – Relation between peak factor κand power factor cos(ϕ). .97

Table 1 – Required tests for steady-state direct current .40
Table 2 – Required tests for ripple current .42
Table 3 – Required tests for steady-state alternating current .46
Table 4 – Tolerance requirement on test-current parameters for short-time direct
current .49
Table 5 – Required tests for short-time direct current.50
Table 6 – Tolerance requirements on the short-time alternating current test parameters.53
Table 7 – List of typical tests in a high-power laboratory and required minimum
frequency range of the measuring system.54
Table 8 – Tolerance requirements on scale factor.55
Table 9 – Required tests for short-time alternating current.55
Table 10 – Examples of exponential impulse-current types .61
Table 11 – Required tests for impulse current.64
Table 12 – Required tests for impulse current in high-voltage dielectric testing.66
Table A.1 – Coverage factor k for effective degrees of freedom ν (p = 95,45 %) .73
eff
Table A.2 – Schematic of an uncertainty budget .74
Table B.1 – Result of the comparison measurement .78
Table B.2 – Result of the comparison measurement .78
Table B.3 – Uncertainty budget for calibration of scale factor F .79
x
Table B.4 – Result of linearity test .80

62475 © IEC:2010 – 7 –
Table B.5 – Uncertainty budget of scale factor F .81
X,mes
Table H.1 – List of typical tests with short-time alternating current.98
Table H.2 – List of typical tests with exponential impulse current .99
Table H.3 – List of typical tests with rectangular impulse current .99

– 8 – 62475 © IEC:2010
INTERNATIONAL ELECTROTECHNICAL COMMISSION
______________
HIGH-CURRENT TEST TECHNIQUES –
DEFINITIONS AND REQUIREMENTS FOR TEST CURRENTS
AND MEASURING SYSTEMS
FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
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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.
International Standard IEC 62475 has been prepared by IEC technical committee 42: High-
voltage test techniques.
The text of this standard is based on the following documents:
FDIS Report on voting
42/278/FDIS 42/283/RVD
Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.

62475 © IEC:2010 – 9 –
The committee has decided that the contents of this publication will remain unchanged until
the stability date indicated on the IEC website under "http://webstore.iec.ch" in the data
related to this specific publication. At this date, the publication will be:
• reconfirmed;
• withdrawn;
• replaced by a revised edition; or
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IMPORTANT – The 'colour inside' logo on the cover page of this publication indicates
that it contains colours which are considered to be useful for the correct
understanding of its contents. Users should therefore print this document using a
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– 10 – 62475 © IEC:2010
HIGH-CURRENT TEST TECHNIQUES –
DEFINITIONS AND REQUIREMENTS FOR TEST CURRENTS
AND MEASURING SYSTEMS
1 Scope
This International Standard 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 d.c. testing), steady-state and short-time
alternating current (as e.g. encountered in high-power a.c. 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.
NOTE This standard also covers fault detection during, for example, lightning impulse testing.
This standard:
• defines the terms used;
• defines parameters and their tolerances;
• describes methods to estimate uncertainties of high-current measurements;
• states the requirements which a complete measuring system shall meet;
• describes the methods for approving a measuring system and checking its components;
• describes the procedure by which the user shall show that a measuring system meets the
requirements of this standard, including limits set for uncertainty of measurement.
2 Normative references
The following referenced documents are indispensable for the application of this International
Standard. For dated references, only the edition cited applies. For undated references, the
latest edition of the referenced document (including any amendments) applies.
IEC 60051-2:1984, Direct acting analogue electrical measuring instruments and their
accessories – Part 2: Special requirements for ammeters and voltmeters
IEC 60060-1:2010, High-voltage test techniques – Part 1: General definitions and test
requirements
IEC 61180-1, High-voltage test techniques for low-voltage equipment – Part 1: Definitions,
test and procedure requirements
ISO/IEC Guide 98-3:2008, Uncertainty of measurement – Part 3: Guide to the expression of
uncertainty in measurement (GUM: 1995)
NOTE Further related standards, guides, etc. on subjects included in this standard are given in the bibliography.
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.

62475 © IEC:2010 – 11 –
3.1 Measuring systems
3.1.1
measuring system
complete set of devices suitable for performing measurements of a quantity to be measured
(measurand). Software used to obtain or calculate measurement results also forms a part of
the measuring system
NOTE 1 A high-current measuring system usually comprises the following components:
• converting device with either terminals to connect this device in circuit or appropriate coupling to the circuit,
and connections to earth;
• transmission system(s) connecting the output terminals of the converting device to the measuring
instrument(s) with its attenuating, terminating, and adapting impedances or networks; and
• measuring instrument(s) together with any connections to the power supply.
Measuring systems which comprise only some of the above components or which are based on non-conventional
principles are acceptable if they meet the uncertainty requirements specified in this standard.
NOTE 2 The environment in which a measuring system functions, its clearances to live, current carrying, and
earthed structures, and the presence of electromagnetic fields may significantly affect the measurement result and
its uncertainty.
3.1.2
record of performance
detailed record, established and maintained by the user, describing the measuring system
and containing evidence that the requirements given in this standard have been met. This
evidence includes the results of the initial performance test and the schedule and results of
each subsequent performance test and performance check
3.1.3
approved measuring system
measuring system that is shown to comply with one or more of the sets of requirements set
out in this standard
3.1.4
reference measuring system
measuring system with its calibration traceable to relevant national and/or international
standards, and having sufficient accuracy and stability for use in the approval of other
systems by making simultaneous comparative measurements with specific types of waveform
and ranges of current
NOTE A reference measuring system (maintained according to the requirements of this standard) can be used as
an approved measuring system but the converse is not true.
3.2 Components of a measuring system
3.2.1
converting device
device for converting the quantity to be measured (measurand) into a quantity, compatible
with the measuring instrument
3.2.2
current-converting shunt
resistor across which the voltage is proportional to the current to be measured
3.2.3
current transformer
instrument transformer in which the secondary current, in normal conditions of use, is
substantially proportional to the primary current and differs in phase from it by an angle which
is approximately zero for an appropriate direction of the connections

– 12 – 62475 © IEC:2010
[IEC 60050-321:1986, 321-02-01]
NOTE Current transformers are usually defined for a single frequency, but special designs with a wide frequency
range are possible.
3.2.4
Rogowski coil
inductive current-converting device without iron; measuring systems based on a Rogowski coil
include an integrating circuit (passive, active, or numerical)
NOTE Measuring systems based on a Rogowski coil can be designed for current measurements in a wide range
of frequencies.
3.2.5
transmission system
set of devices that transfers the output signal of a converting device to a measuring
instrument(s)
NOTE 1 A transmission system usually consists of a coaxial cable with its terminating impedance, but it may
include attenuators, amplifiers, or other devices connected between the converting device and the measuring
instrument(s). For example, an optical link includes a transmitter, an optical cable, and a receiver as well as related
amplifiers.
NOTE 2 A transmission system may be partially or completely included in the converting device or in the
measuring instrument.
3.2.6
measuring instrument
device intended to make measurements, alone or in conjunction with supplementary devices
[IEC 60050-300:2001, 311-03-01]
3.3 Scale factors
3.3.1
scale factor of a measuring system
factor by which the value of the measuring-instrument reading is to be multiplied to obtain the
value of the input quantity of the complete measuring system
NOTE 1 A measuring system may have multiple scale factors for different current ranges, frequency ranges or
waveforms.
NOTE 2 Some measuring systems display the value of the input quantity directly (i.e., the scale factor of the
measuring system is unity).
3.3.2
scale factor of a converting device
factor by which the output of the converting device is to be multiplied to obtain its input
quantity
NOTE The scale factor of a converting device may be dimensionless (for example, the ratio of a current
transformer) or may have dimensions (for example, related to the impedance of a current-converting shunt).
3.3.3
scale factor of a transmission system
factor by which the output of a transmission system is to be multiplied to obtain its input
quantity
3.3.4
scale factor of a measuring instrument
factor by which the instrument reading is to be multiplied to obtain its input quantity

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