IEC 61083-1:2021

Instruments and software used for measurements in high-voltage and high-current tests - Part 1: Requirements for instruments for impulse tests

IEC 61083-1:2021 is applicable to digital recorders, including digital oscilloscopes, used for measurements during tests with high impulse voltages and high impulse currents. It specifies the measuring characteristics and calibrations required to meet the measuring uncertainties and procedures specified in IEC 60060-2 and IEC 62475.
This document
• defines the terms specifically related to digital recorders;
• specifies the necessary requirements for such instruments to ensure their compliance with the requirements for high-voltage and high-current impulse tests;
• establishes the tests and procedures necessary to demonstrate their compliance;
• covers digital recorders that permit access to raw data from permanent or temporary storage;
• covers peak meters used for measuring the extreme value of lightning impulses, the peak value of switching or current impulses.
It has the status of a horizontal standard in accordance with IEC Guide 108.
This horizontal standard is primarily intended for use by technical committees in the preparation of standards in accordance with the principles laid down in IEC Guide 108. One of the responsibilities of a technical committee is, wherever applicable, to make use of horizontal standards in the preparation of its publications. The contents of this horizontal standard will not apply unless specifically referred to or included in the relevant publications.
This third edition cancels and replaces the second edition published in 2001. This edition constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous edition:
a) Requirements for static integral non-linearity and static differential non-linearity have been removed.
b) Requirement for impulse scale factor non-linearity has been added.
c) Uncertainty requirements for impulse calibrators have been revised.
d) Requirements for peak voltmeter have been revised.

Appareils et logiciels utilisés pour les mesurages pendant les essais à tension et courant élevés - Partie 1: Exigences pour les appareils utilisés pour les essais de choc

IEC 61083-1:2021 s’applique aux enregistreurs numériques, y compris les oscilloscopes numériques, utilisés pour les mesures lors de tests avec des tensions d’impulsion élevées et des courants d’impulsion élevés. Il précise les caractéristiques de mesure et les étalonnages nécessaires pour répondre aux incertitudes et procédures de mesure spécifiées dans la CEI 60060-2 et l’IEC 62475.
Ce document
• définit les termes spécifiquement liés aux enregistreurs numériques;
• précise les exigences nécessaires à ces instruments pour s’assurer qu’ils sont conformes aux exigences relatives aux tests impulsifs à haute tension et à courant élevé;
• établit les tests et les procédures nécessaires pour démontrer leur conformité;
• couvre les enregistreurs numériques qui permettent l’accès aux données brutes provenant d’un stockage permanent ou temporaire;
• couvre les compteurs de pointe utilisés pour mesurer la valeur extrême des impulsions de foudre, la valeur maximale de la commutation ou des impulsions actuelles.
Il a le statut d’une norme horizontale conformément au Guide 108 de la CEI.
Cette norme horizontale est principalement destinée aux comités techniques dans l’préparation des normes conformément aux principes énoncés dans le Guide 108 de la CEI. L’une des responsabilités d’un comité technique est, le cas échéant, d’utiliser des normes horizontales dans la préparation de ses publications. Le contenu de cette norme horizontale ne s’appliquera pas à moins qu’il ne soit expressément mentionné ou inclus dans les publications pertinentes.
Cette troisième édition annule et remplace la deuxième édition publiée en 2001. Cette édition constitue une révision technique.
Cette édition comprend les changements techniques importants suivants par rapport à l’édition précédente :
a) Les exigences relatives à la non-linéarité intégrale statique et à la non-linéarité différentielle statique ont été supprimées.
b) L’exigence de non-linéarité du facteur d’échelle d’impulsion a été ajoutée.
c) Les exigences en matière d’incertitude pour les étalonneurs impulsifs ont été révisées.
d) Les exigences relatives aux voltmètres de pointe ont été révisées.

General Information

• Status: Published
• Publication Date: 27-Jan-2021
• ICS: 17.220.20 - Measurement of electrical and magnetic quantities
• ICS: 19.080 - Electrical and electronic testing
• ICS: 29.080.10 - Insulators
• ICS: 29.240.20 - Power transmission and distribution lines
• Technical Committee: TC 42 - High-voltage and high-current test techniques
• Drafting Committee: MT 16 - TC 42/MT 16
• Current Stage: PPUB - Publication issued
• Start Date: 28-Jan-2021
• Completion Date: 26-Oct-2025

Relations

• Revises: IEC 61083-1:2001 - Instruments and software used for measurement in high-voltage impulse tests - Part 1: Requirements for instruments
• Effective Date: 05-Sep-2023

Overview

IEC 61083-1:2021 is an international standard published by the International Electrotechnical Commission (IEC) that sets requirements for instruments used in impulse tests involving high-voltage and high-current measurements. This third edition focuses primarily on digital recorders, including digital oscilloscopes, and peak voltmeters that are used in high impulse voltage and current testing. The standard specifies measuring characteristics, calibration methods, and required tests to ensure instruments meet the accuracy and uncertainty criteria established in related standards IEC 60060-2 and IEC 62475.

As a horizontal standard, IEC 61083-1:2021 offers foundational specifications intended for use by technical committees developing test-related standards, ensuring consistency and interoperability in high-voltage and high-current impulse testing across the electrotechnical industry.

Key Topics

• Scope and Definitions: The standard clarifies terminology related to digital recorders, including their rated values, scale factors, dynamic performance, uncertainty, and specific test conditions relevant to impulse testing.

• Operating Conditions and Calibration: Comprehensive guidelines on operating environments, calibration of scale factor and time base, impulse and step calibration methods, and tests for constancy and linearity of scale factors ensure the reliability and repeatability of measurements.

• Measurement Requirements: It covers detailed performance criteria such as:

  • Sampling rate and resolution of digital instruments
  • Errors in time parameters and time base accuracy
  • Impulse scale factor linearity and rise time requirements
  • Interference voltage limits and internal noise levels
  • Input impedance and record length specifications for reliable data capture

• Tests and Procedures: Mandatory type, routine, and performance tests are defined to verify compliance with the standard, along with performance checks to maintain ongoing measurement accuracy.

• Peak Voltmeter Requirements: Specific provisions for peak voltmeters used to measure lightning and switching impulse extremes are included to ensure precise peak value capture.

• Uncertainty and Electromagnetic Interference: The standard revises uncertainty contributions for complete measuring systems and provides guidance on mitigating electromagnetic interference in high-voltage test environments through shielding and signal transmission precautions.

Applications

IEC 61083-1:2021 is essential for manufacturers, testers, and users of measurement instruments engaged in:

• High-voltage impulse testing of equipment such as transformers, insulators, circuit breakers, and cables
• High-current impulse testing for electrical apparatus and components under surge conditions
• Calibration laboratories setting up and validating impulse testing instrumentation
• Ensuring compliance with international testing procedures during product certification and quality assurance
• Development of precise measurement systems to meet the growing demands for accuracy and reliability in electrical testing laboratories worldwide

This standard enhances the quality, safety, and comparability of impulse test results, directly supporting industries involved in power generation, transmission, and electrical equipment manufacturing.

Related Standards

IEC 61083-1:2021 should be used in conjunction with these key IEC publications for a comprehensive approach to high-voltage and high-current impulse testing:

• IEC 60060-2: High-voltage test techniques – Part 2: Measuring systems – Specifies procedures and uncertainty requirements during high-voltage testing.

• IEC 62475: High-current test techniques – Focuses on measurement techniques and calibration methods applicable to current impulse testing.

• Additional parts of IEC 61083 series, which elaborate on software and instruments used in these measurement contexts.

By aligning with IEC 60060-2 and IEC 62475, IEC 61083-1:2021 ensures that digital measurement instruments meet standardized accuracy and performance thresholds, facilitating global harmonization of test methodologies.

---

Keywords: IEC 61083-1, impulse test instruments, high-voltage measurement, high-current tests, digital recorders, digital oscilloscopes, peak voltmeters, impulse calibration, measurement uncertainty, electrotechnical standards, IEC standards, high-voltage test techniques, IEC 60060-2, IEC 62475, electromagnetic interference, power equipment testing.

Standards Content (Sample)

IEC 61083-1 ®
Edition 3.0 2021-01
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Instruments and software used for measurements in high-voltage and
high-current tests –
Part 1: Requirements for instruments for impulse tests

Appareils et logiciels utilisés pour les mesurages pendant les essais à tension
et courant élevés –
Partie 1: Exigences pour les appareils utilisés pour les essais de choc

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IEC 61083-1 ®
Edition 3.0 2021-01
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Instruments and software used for measurements in high-voltage and

high-current tests –
Part 1: Requirements for instruments for impulse tests

Appareils et logiciels utilisés pour les mesurages pendant les essais à tension

et courant élevés –
Partie 1: Exigences pour les appareils utilisés pour les essais de choc

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 17.220.20; 19.080 ISBN 978-2-8322-9261-7

– 2 – IEC 61083-1:2021 © IEC 2021
CONTENTS
FOREWORD . 4
INTRODUCTION . 6
1 Scope . 7
2 Normative references . 7
3 Terms and definitions . 7
3.1 General definitions related to digital recorders . 8
3.2 Definitions related to rated values . 9
3.3 Definitions related to scale factor . 9
3.4 Definitions related to dynamic performance . 9
3.5 Definitions related to uncertainties . 10
3.6 Definitions related to tests . 11
4 Operating conditions . 11
5 Calibration and test methods . 12
5.1 Calibration of scale factor and time base . 12
5.2 Impulse calibration . 12
5.3 Step calibration . 13
5.4 Test of constancy of scale factor within time interval . 14
5.5 Calibration of time base . 15
5.6 Test of impulse scale factor non-linearity . 15
5.7 Internal noise level . 15
5.8 Interference test . 15
6 Requirements for impulse measurements . 16
6.1 Requirements for digital recorders used in approved measuring systems . 16
6.2 Individual requirements . 16
6.2.1 General . 16
6.2.2 Sampling rate . 16
6.2.3 Rated resolution . 16
6.2.4 Impulse scale factor . 16
6.2.5 Errors of time parameters . 17
6.2.6 Error of time base . 17
6.2.7 Rise time . 17
6.2.8 Interference voltage . 17
6.2.9 Record length . 17
6.2.10 Input impedance . 17
6.2.11 Internal noise level . 17
6.2.12 Assigned measurement range. 18
6.3 Requirements for digital recorders used in reference measuring systems . 18
6.3.1 General requirements . 18
6.3.2 Sampling rate . 18
6.3.3 Rated resolution . 18
6.3.4 Error of time base . 18
6.3.5 Rise time . 18
6.3.6 Interference voltage . 18
6.3.7 Record length . 18
6.3.8 Internal noise level . 19
6.3.9 Scale factor . 19

6.4 Tests . 19
6.4.1 General . 19
6.4.2 Type tests . 19
6.4.3 Routine tests . 19
6.4.4 Performance tests . 19
6.4.5 Performance checks . 20
7 Requirements for peak voltmeters . 20
8 Uncertainty contributions for complete measuring systems . 20
9 Record of performance . 20
Annex A (normative) Electromagnetic interference in high-voltage and high-current
laboratories and test fields . 22
A.1 General . 22
A.2 Precautions . 22
A.2.1 Electromagnetic shielding . 22
A.2.2 Reduction of conducted interference from the supply line . 22
A.2.3 Reduction of interference on the signal line . 22
A.2.4 Signal transmission by optical means . 22
A.3 Tests with transient induced electromagnetic fields . 23
Bibliography . 24

Figure 1 – Step calibration . 14
Figure A.1 – Application of electric and magnetic fields. 23

Table 1 – Operating conditions . 12
Table 2 – Requirements for reference impulse generators . 13
Table 3 – Tests required for approved digital recorders . 19

– 4 – IEC 61083-1:2021 © IEC 2021
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
INSTRUMENTS AND SOFTWARE USED FOR MEASUREMENTS
IN HIGH-VOLTAGE AND HIGH-CURRENT TESTS –

Part 1: Requirements for instruments for impulse tests

FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote international
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rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 61083-1 has been prepared by IEC technical committee 42: High-
voltage and high-current test techniques.
This third edition cancels and replaces the second edition published in 2001. This edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) Requirements for static integral non-linearity and static differential non-linearity have been
removed.
b) Requirement for impulse scale factor non-linearity has been added.
c) Uncertainty requirements for impulse calibrators have been revised.
d) Requirements for peak voltmeter have been revised.

The text of this International Standard is based on the following documents:
FDIS Report on voting
42/386/FDIS 42/388/RVD
Full information on the voting for the approval of this International Standard can be found in the
report on voting indicated in the above table.
This document has been drafted in accordance with the ISO/IEC Directives, Part 2.
A list of all the parts in the IEC 61083, under the general title Instruments and software used
for measurements in high-voltage and high-current tests, can be found on the IEC website.
Future standards in this series will carry the new general title as cited above.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under "http://webstore.iec.ch" in the data related to
the specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
– 6 – IEC 61083-1:2021 © IEC 2021
INTRODUCTION
The electric power industry requires standardized tools to provide confidence in high-voltage
and high-current testing results, and to prove equivalence between tests performed in different
test facilities.
Analogue capture of test data has today been largely replaced by digital capture with recording
instruments based on sampling technology. This part of IEC 61083 specifies requirements for
the performance of digital recorders used for high-voltage and high-current impulse tests.
Since the last revision of this standard, significant improvements have been made in many
aspects of digitising instruments used for high-voltage and high-current tests. In particular,
digitising resolutions have improved several folds since the last revision, with 12-bit to 14-bit
being typical resolutions for impulse measurement digitisers. Furthermore, the improvement of
A/D converters has led to a situation where other aspects of the instruments, such as linearity
of front-end amplifiers and performance of immunity to interference, have replaced performance
of A/D converters as the main concern of measurement accuracy and instrument reliability.
The requirements in this edition of the standard have been revised to reflect these technological
changes. For example, the number of type tests aimed for evaluating the performance of A/D
converters has been reduced, and new requirements for the linearity of complete system
(A/D converter and analogue components) have been added.
During preparation of the second edition of this standard in 2001, the need to keep analogue
oscilloscopes and peak voltmeters was thoroughly discussed. Requirements for analogue
oscilloscopes have now been removed, and only essential requirements for peak voltmeters
have been kept.
INSTRUMENTS AND SOFTWARE USED FOR MEASUREMENTS
IN HIGH-VOLTAGE AND HIGH-CURRENT TESTS –

Part 1: Requirements for instruments for impulse tests

1 Scope
This part of IEC 61083 is applicable to digital recorders, including digital oscilloscopes, used
for measurements during tests with high impulse voltages and high impulse currents. It specifies
the measuring characteristics and calibrations required to meet the measuring uncertainties
and procedures specified in IEC 60060-2 and IEC 62475.
This document
• defines the terms specifically related to digital recorders;
• specifies the necessary requirements for such instruments to ensure their compliance with
the requirements for high-voltage and high-current impulse tests;
• establishes the tests and procedures necessary to demonstrate their compliance;
• covers digital recorders that permit access to raw data from permanent or temporary storage;
• covers peak meters used for measuring the extreme value of lightning impulses, the peak
value of switching or current impulses.
It has the status of a horizontal standard in accordance with IEC Guide 108.
This horizontal standard is primarily intended for use by technical committees in the preparation
of standards in accordance with the principles laid down in IEC Guide 108. One of the
responsibilities of a technical committee is, wherever applicable, to make use of horizontal
standards in the preparation of its publications. The contents of this horizontal standard will not
apply unless specifically referred to or included in the relevant publications.
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 60060-1, High-voltage test techniques – Part 1: General definitions and test requirements
IE 60060-2:2010, High-voltage test techniques – Part 2: Measuring systems
IEC 62475, High-current test techniques – Definitions and requirements for test currents and
measuring systems
ISO/IEC Guide 98-3:2008, Uncertainty of measurement – Part 3: Guide to the expression of
uncertainty in measurements (GUM:1995)
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.

– 8 – IEC 61083-1:2021 © IEC 2021
ISO and IEC maintain terminological databases for use in standardization at the following
addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
3.1 General definitions related to digital recorders
3.1.1
digital recorder
digitiser
recording instrument in which the recording is made in digital form on a magnetic or optical
medium, or on a solid-state memory medium
Note 1 to entry: The waveform of the digital record is usually displayed on a screen, plotted or printed. This process
may change the appearance of the waveform due to the processing involved.
[SOURCE: IEC 60050-313:2001, 313-02-16, modified – "digitiser" and a note to entry have been
added]
3.1.2
approved digital recorder
digital recorder that is shown to comply with the requirements set out in this document
3.1.3
assigned measurement range
range of input voltage for which the instrument can be used within the uncertainty limits given
in this document
3.1.4
output of a digital recorder
numerical value recorded by a digital recorder at a specific instant
3.1.5
full-scale deflection
minimum input voltage, which produces the nominal maximum output of the instrument in the
specified range
3.1.6
offset
output of an instrument for zero input
3.1.7
raw data
original record of sampled and quantized information obtained when a digital recorder converts
an analogue signal into a digital form, with the correction of the output for offset and multiplying
the record by a constant factor being permitted
3.1.8
processed data
data obtained by any processing (other than correction for offset and/or multiplying by a
constant scale factor) of the raw data
Note 1 to entry: Digital recorders which do not allow access to the raw data are not covered by this document.

3.2 Definitions related to rated values
3.2.1
rated resolution
r
-N
reciprocal of two to the power of the rated number of bits N of the A/D converter, namely r =2
3.2.2
sampling rate
number of samples taken per unit of time
Note 1 to entry: The sampling time interval is the reciprocal of the sampling rate.
3.2.3
record length
duration of the record expressed either in a time unit or as the total number of samples
3.2.4
warm-up time
time interval from when the instrument is first switched on to when the instrument meets
operational requirements
3.3 Definitions related to scale factor
3.3.1
scale factor
factor by which the output corrected for offset is multiplied in order to determine the measured
value of the input quantity
Note 1 to entry: The scale factor includes the ratio of any built-in or external attenuator and is determined by
calibration.
3.3.2
static scale factor
scale factor for a direct voltage or a direct current input
3.3.3
impulse scale factor
scale factor for an input representing the shape of the relevant impulse
3.3.4
assigned impulse scale factor
impulse scale factor of a digitiser determined at the most recent calibration
3.3.5
base line
value of the output of the recorder during the initial flat part of the record of the impulse, with
the value determined from the mean of at least 20 samples in the initial flat part
3.4 Definitions related to dynamic performance
3.4.1
nominal epoch
τ
N
range of values between the minimum (t ) and the maximum (t ) of the relevant time
min max
parameter of impulse voltage or impulse current for which the digitiser is to be approved, with
the relevant time parameter being:

– 10 – IEC 61083-1:2021 © IEC 2021
– the front time T for full and tail-chopped lightning voltage impulse and
exponential current impulse
for front-chopped lightning voltage impulse
– the time to chopping T
c
– the time to-peak T for switching voltage impulses
p
– pulse rise time 0,5·(T – T ) for rectangular current impulse
t d
Note 1 to entry: Nominal epoch is applicable to the front part of an impulse only.
Note 2 to entry: A digitiser usually has one, two or more nominal epochs for different waveforms. For example, a
particular digitiser is approved for:
• full and tail-chopped lightning impulses with an assigned impulse scale factor F over a nominal epoch τ from
1 N1
T = 0,84 µs (t ) to T = 1,56 µs (t ),
1 min 1 max
• full lightning impulses with an assigned impulse scale factor F over a nominal epoch τ from T = 2,0 µs (t )
1 N1 1 min
to T = 5,0 µs (t ),
1 max
• front-chopped lightning impulses with an assigned impulse scale factor F over a nominal epoch τ from
2 N2
T = 0,5 µs (t ) to T = 0,9 µs (t ),
c min c max
• and/or standard switching impulses with an assigned impulse scale factor F over a nominal epoch τ from
3 N3
T = 150 µs (t ) to T = 500 µs (t ).
p min p max
3.4.2
step calibration epoch
time interval in which the impulse scale factor is determined with the step calibration method,
with its lower limit being 0,5 times of the lower limit of the nominal epoch ( 0,5t ) and its upper
min
limit being 2 times the upper limit of the nominal epoch (2t ), both of which are evaluated
max
from the start of the recorded voltage step
3.4.3
rise time
time interval within which the response to an applied step passes from 10 % to 90 % of its
steady-state amplitude
3.4.4
time base
unit of the digitiser horizontal scale against which a time interval is measured
3.5 Definitions related to uncertainties
3.5.1
error
measured quantity value minus a reference quantity value (VIM 2.16)
3.5.2
uncertainty (of measurement)
parameter, associated with the result of a measurement, that characterises the dispersion of
the values that could reasonably be attributed to the measurand
Note 1 to entry: Uncertainty is positive and given without sign.
Note 2 to entry: Uncertainty of measurement should not be confused with the tolerance of the test value.
[SOURCE: IEC 60050-311:2001, 311-01-02, modified – notes 1 and 2 to entry have been
changed and note 3 to entry deleted]
3.5.3
standard uncertainty
uncertainty of the result of a measurement expressed as a standard deviation

[SOURCE: ISO/IEC Guide 98-3:2008, 2.3.1]
3.5.4
type A evaluation
method of evaluation of uncertainty by statistical analysis of a series of observations
3.5.5
type B evaluation
method of evaluation of uncertainty by means other than statistical analysis of a series of
observations
3.6 Definitions related to tests
3.6.1
calibration
set of operations that establishes, by reference to standards, the relationship which exists,
under specified conditions, between an indication and a result of a measurement
[SOURCE: IEC 60050-311:2001, 311-01-09, modified – the notes to entry have been deleted]
3.6.2
type test
conformity test made on one or more items representative of the production
Note 1 to entry: For a measuring system, this is understood as a test performed on a component or on a complete
measuring system of the same design to characterize it under operating conditions.
[SOURCE: IEC 60050-151:2001, 151-16-16, modified – the note 1 to entry has been added]
3.6.3
routine test
conformity test made on each individual item during or after manufacture
Note 1 to entry: This is understood as a test performed on each component or on each complete measuring system
to characterize it under operating conditions
[SOURCE: IEC 60050-151:2001, 151-16-17, modified – the note 1 to entry has been added]
3.6.4
performance test
test performed on a complete measuring system to characterize it under operating conditions
3.6.5
performance check
a simple procedure to ensure that the most recent performance test is still valid
3.6.6
record of performance
detailed record, established and maintained by the user, describing the measuring system and
containing evidence that the requirements given in this document have been met, which
includes the results of the initial performance test and the schedule and results of each
subsequent performance test and performance check
4 Operating conditions
The limits of operating conditions given in Table 1 are those under which the digitiser shall
operate and meet the uncertainty requirements specified for this instrument.

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Table 1 – Operating conditions
Condition Range
Environment
Ambient temperature 5 °C to 40 °C
Ambient relative humidity (non-condensing) 10 % to 90 %
Mains power supply
Supply voltage Rated voltage ±10 % (RMS)
Rated voltage ±12 % (AC peak)
Supply frequency Rated frequency ±5 %

Any exceptions to the values given in Table 1 shall be explicitly and clearly stated in the record
of performance with an indication that they are exceptions.
NOTE The general requirements for testing electromagnetic compatibility of electrical equipment for measurement,
control and laboratory use are described in IEC 61326-1.
5 Calibration and test methods
5.1 Calibration of scale factor and time base
The scale factor and time base shall be determined by either
– impulse calibration (5.2) with two waveforms covering the nominal epoch, or
– step calibration (5.3) with test of scale factor constancy (5.4) and calibration of time base
(5.5), or
– an impulse calibration (5.2) with one impulse waveform within the nominal epoch with the
constancy of scale factor test (5.4).
5.2 Impulse calibration
Impulse calibration is the reference method to establish the impulse scale factor of approved
digital recorders. It is also the reference method to determine the errors of the impulse time
parameters caused by the digital recorders. Requirements on reference calibration impulses for
calibrating approved digital recorders are given in Table 2. The wave shapes shall be chosen
from Table 2 according to the type and polarity of the high-voltage or high-current impulses that
the digitiser is approved to measure. The uncertainties of the peak value and time parameters
of the applied calibration impulses shall be within the limits given in Table 2, and the actual
values shall be entered in the record of performance.
The number of calibration impulses to be applied shall be sufficient for obtaining sufficiently low
type A uncertainties for all relevant parameters.
The impulse scale factor is the ratio of the peak value of the input calibration impulse and the
peak value of its corresponding impulse recorded by the digitiser. The assigned impulse scale
factor is the mean of impulse scale factors determined from a set of individual calibration
impulses.
The error of a time parameter is the mean of the time parameter errors determined from
individual calibration impulses.
This impulse calibration shall be made in each range of each channel that the digitiser is
approved for use in impulse tests.

A digital recorder can be calibrated for exponential current impulses (IEC 62475) and the
standard chopped (tail chopped) impulses using the full lightning impulse of a reference impulse
generator.
Table 2 – Requirements for reference impulse generators
Impulse type Parameter being Value Expanded Short-term
measured uncertainty stability
% %
Full and standard Time-to-half value 55 µs to 65 µs ≤ 2 ≤ 0,2
chopped (tail
chopped) lightning
voltage impulse
Front time 0,8 µs to 1,0 µs ≤ 2 ≤ 0,5
or
0,8 µs to 1,0 µs and ≤ 2 ≤ 0,5
1,5 µs to 1,7 µs
Peak voltage Within assigned ≤ 0,7 ≤ 0,2
measurement range
Front chopped Time-to-chopping 0,45 µs to 0,55 µs ≤ 2 ≤ 1
lightning voltage
Peak voltage Within assigned ≤ 2 ≤ 0,2
impulse
measurement range
Standard switching Time-to-peak 200 µs to 300 µs ≤ 2 ≤ 0,2
impulse
Time-to-half value 1 000 µs to 4 000 µs ≤ 2 ≤ 0,2
Within assigned ≤ 0,7 ≤ 0,2
Peak voltage
measurement range
Rectangular impulse Duration 0,5 ms to 3,5 ms ≤ 2 ≤ 0,5
current
Peak value Within assigned
measurement range ≤ 2 ≤ 1
The short-term stability is the standard deviation of a sequence of at least 10 output impulses.

NOTE A digital recorder can be calibrated for exponential current impulses (IEC 62475) using either a lightning
impulse generator or a switching impulse generator that best matches the waveform of the current impulse.
5.3 Step calibration
The step calibration is the alternative method for establishing the impulse scale factor of an
approved digital recorder. To qualify an approved digitiser for measuring impulse time
parameters, the scale factor constancy test specified in 5.4 and the calibration of time base as
specified in 5.5 shall also be performed if the impulse calibration as specified in 5.2 is not
performed.
A direct voltage V , with an uncertainty less than 0,1 % and within the assigned measurement
CAL
range of the instrument, is applied to the input and then short-circuited to ground by an
appropriate switching device, preferably based on a mercury-wetted relay. The resultant
transition to zero level is recorded as the output O(t) (an example is shown in Figure 1) and
evaluated within the time interval of the step calibration epoch. A number of records (e.g. 10)
of the response shall be averaged to reduce the random noise. The deviation of the sample
values O(t) in the time interval of the step calibration epoch from their mean O shall be within
sm
the uncertainty limits specified for the assigned impulse scale factor. The value of O shall be
sm
evaluated as the mean of all O(t) values within the step calibration epoch (IEC 60060-2:2010).
The impulse scale factor is the quotient of the input voltage V and O . The rise time of the
CAL sm
step shall be less than 10 % of the lower limit of the step calibration epoch.

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This voltage calibration shall be made in each range of each channel that the digitiser approved
for use in impulse tests. This test shall be performed using both voltage polarities. If the scale
factors determined with the two polarities agree to within ± 0,5 %, then the impulse scale factor
determined by this method is valid. Otherwise, impulse calibration according to 5.2 of
appropriate polarity shall be used.

t and t are either the lower and upper limits of the step calibration epoch or the time interval
L U
of scale factor constancy test (see 5.4).
Figure 1 – Step calibration
5.4 Test of constancy of scale factor within time interval
A direct voltage within the measurement range of the digital recorder is applied to the input and
then short-circuited to ground by an appropriate switching device, preferably based on a
mercury-wetted relay. The resultant transition to zero level of the step response (see Figure 1)
is recorded and evaluated within the following time intervals:
0,5 t to T for full lightning impulses and exponential current impulses;
min 2max
0,5 t to t for front-chopped impulses;
min max
0,5 T to T for switching impulses, and 10/350 µs current impulses;
p 2max
0,5 (T – T ) to T for rectangular current impulses;
t d t
where T is the maximum time to half-value the digitiser is approved to measure for each of
2max
the corresponding impulse type.
Within these time intervals, the output magnitude O(t) of the recorded step response shall be
constant within the limits specified in this document.
It is permitted that several records of the response are averaged to reduce the random noise.
This scale factor constancy measurement shall be made in each range used for tests.

NOTE T , T and T are defined in IEC 60060-1. t and t are as defined in 3.4.1. T is the maximum value
1 2 c min max 2max
of T that is to be measured by the approved digitiser.
5.5 Calibration of time base
Calibration of time base shall be performed if the errors of impulse time parameters are not
determined by performing the impulse calibration as specified in 5.2.
Calibration of a time base shall be performed by comparison with a reference rectangular signal
of known frequency. The period of the signal shall be T of the impulse to be measured. The
calibration shall be performed over the time interval of one full period.
5.6 Test of impulse scale factor non-linearity
The test is to assess the non-linearity of the scale factor obtained in accordance with 5.2 or 5.3,
over the range settings within the assigned measurement range(s) of the digital recorder. Apart
from being one of the qualifying tests of an approved digitiser, the test is for estimating
contribution of non-linearity to the measurement uncertainty of the impulse peak voltage.
Ratios of the output of the digitiser and the input voltage of the digitiser shall be obtained with
both voltage polarities. The input voltage shall cover the complete assigned measurement range.
The non-linearity of the impulse scale factor is calculated as the maximum deviation of ratio
values R , obtained at b different range settings of one channel of the digitiser, from the mean
g
ratio, R . The maximum deviation shall be taken as a type B estimate of the standard
m
uncertainty related to non-linearity of the scale factor:
b
R
1 g
u = ⋅ max − 1
B1
R
g= 1
m
where
R …R are ratios, scale factors or errors determined in the assigned measurement range,
1 b
determined against a linear voltage source (or digitiser of a different model);
R is the mean of the values R …R ;
m 1 b
b is the number of range settings at which the ratios R …R are obtained, where one
1 b
voltage level is tested in each range setting;
u is the type B standard uncertainty due to non-linearity of the impulse scale factor.
B1
NOTE If sufficiently low non-linearity is not obtained by using a particular voltage source, using a different voltage
source can yield a lower value of impulse scale factor non-linearity.
5.7 Internal noise level
A direct voltage within the range of the digital recorder shall be applied. A sufficient number of
samples at one voltage shall be taken at a specified sampling rate to acquire at least 1 000
samples. The standard deviation of these samples is taken as the internal noise level.
5.8 Interference test
Interference tests shall be performed according to Annex A of this document.

– 16 – IEC 61083-1:2021 © IEC 2021
6 Requirements for impulse measurements
6.1 Requirements for digital recorders used in approved measuring systems
The expanded uncertainty of a digital recorder used in an approved measuring system
according to IEC 60060-2 shall be not more than (at a level of confidence of not less than 95 %)
• 2 % in the voltage (current) measurement of full and standard-chopped (tail chopped)
lightning voltage impulses, switching voltage impulses, exponential current impulses and
rectangular current impulses;
• 3 % in the voltage measurement of front-chopped lightning impulses;
• 4 % in the measurement of the time parameters (front time, time to chopping, etc.) of the
impulse.
Digitiser can be qualified for measurement of one, or more, or all types of impulses.
These uncertainties shall be estimated according to ISO/IEC Guide 98-3:2008.
NOTE The estimated uncertainty of the digitiser is used as a component of uncertainty of the complete measurement
system according to IEC 60060-2 or IEC 62475.
The digital recorder shall allow storage of the raw data.
6.2 Individual requirements
6.2.1 General
In order to stay within the limits given in 6.1, the limits for individual contributions given in 6.2
should usually be met. In some cases, it is permissible that one or more of these limits be
exceeded provided that it is demonstrated by estimation in accordance with
ISO/IEC Guide 98-3:2008 that overall uncertainty specified in 6.1 is not exceeded.
6.2.2 Sampling rate
The sampling rate shall be not less than 30/T where T is the time interval to be measured.
x x
NOTE T = 0,6 T is
...