IEC 61007:2020

Transformers and inductors for use in electronic and telecommunication equipment - Measuring methods and test procedures

IEC 61007:2020 describes a number of tests for use in determining the significant parameters and performance characteristics of transformers and inductors for use in electronics and telecommunication equipment. These test methods are designed primarily for transformers and inductors used in all types of electronics applications that can be involved in any specification for such components. Even though these tests can be useful to the other types of transformers used in power distribution applications in utilities, industry, and others, the tests discussed in this document can supplement or complement the tests but are not intended to replace the tests in standards for transformers. Some of the tests described are intended for qualifying a product for a specific application, while others are test practices used for manufacturing and customer acceptance testing. The test methods described here include those parameters most commonly used in the electronics transformer and inductor industry: electric strength, resistance, power loss, inductance, impedance, balance, transformation ratio and many others used less frequently.
This edition includes the following significant technical changes with respect to the previous edition:
a) scope: the application of the scope of IEC 61007 was extended;
b) Clause 2: added new references and updated the references;
c) Clause 3: new definitions were added in 3.3, and in 3.7 the voltage-time product was redefined;
d) test procedures were updated;
e) environmental test procedures: new references were added;
f) Annexes A to G were added.
The contents of the corrigendum of June 2021 have been included in this copy.

Transformateurs et inductances utilisés dans les équipements électroniques et de télécommunications - Méthodes de mesure et procédures d'essais

L'IEC 61007:2020 décrit plusieurs essais utilisés pour la détermination des paramètres importants et des caractéristiques de fonctionnement des transformateurs et inductances utilisés dans les équipements électroniques et de télécommunications. Ces méthodes d'essai sont principalement conçues pour les transformateurs et inductances utilisés dans tous les types d'applications électroniques qui peuvent être employés dans toute spécification de ces composants. Bien que ces essais puissent être utiles pour d'autres types de transformateurs utilisés dans les applications de distribution de puissance dans les services publics, dans l'industrie et d'autres secteurs, les essais traités dans le présent document peuvent s'ajouter aux essais décrits dans les normes relatives aux transformateurs ou les compléter, mais ne sont pas destinés à les remplacer. Certains des essais décrits visent à qualifier un produit pour une application spécifique, tandis que d'autres sont des pratiques d'essai utilisées lors de la fabrication et pour les essais d'acceptation client. Les méthodes d'essai décrites ici comprennent les paramètres les plus couramment utilisés dans l'industrie des transformateurs et inductances électroniques: rigidité diélectrique, résistance, perte de puissance, inductance, impédance, équilibre, rapport de transformation, et de nombreux autres paramètres utilisés moins fréquemment.
Cette édition inclut les modifications techniques majeures suivantes par rapport à l'édition précédente:
a) domaine d'application: extension du domaine d'application de l'IEC 61007;
b) Article 2: ajout de nouvelles références et mise à jour des références;
c) Article 3: ajout de nouvelles définitions en 3.3, et redéfinition du produit tension-temps en 3.7;
d) mise à jour des procédures d'essai;
e) procédures d'essais d'environnement: ajout de nouvelles références;
f) ajout des Annexes A à G.
Le contenu du corrigendum de juin 2021 a été pris en considération dans cet exemplaire.

General Information

• Status: Published
• Publication Date: 19-Jul-2020
• ICS: 29.100.10 - Magnetic components
• ICS: 29.180 - Transformers. Reactors
• Technical Committee: TC 51 - Magnetic components, ferrite and magnetic powder materials
• Drafting Committee: WG 9 - TC 51/WG 9
• Current Stage: PPUB - Publication issued
• Start Date: 20-Jul-2020
• Completion Date: 11-Aug-2020

Relations

• Corrected By: IEC 61007:2020/COR1:2021 - Corrigendum 1 - Transformers and inductors for use in electronic and telecommunication equipment - Measuring methods and test procedures
• Effective Date: 05-Sep-2023

Overview

IEC 61007:2020 is an international standard published by the International Electrotechnical Commission (IEC) that specifies measuring methods and test procedures for transformers and inductors used in electronic and telecommunication equipment. The standard focuses on evaluating significant parameters and performance characteristics of these components to ensure quality, reliability, and consistency in electronics applications. Although primarily designed for electronic and telecommunication transformers and inductors, the test methods can supplement testing for power distribution transformers, but they do not replace the dedicated standards for power transformers.

Key enhancements in the 2020 edition include an extended scope, updated definitions, revised test procedures, added environmental testing references, and the introduction of Annexes A to G covering specialized topics such as DC resistance, dielectric withstand, no-load loss, quality factor, electrostatic shielding, and corona testing.

Key Topics

The standard comprehensively covers the following essential test and measurement aspects:

• Electrical Test Procedures

  • Winding resistance measurement
  • Insulation and dielectric strength tests
  • Power loss determination
  • Inductance and impedance measurement
  • Balance and transformation ratio verification
  • Capacitance, resonant frequency, and signal transfer characteristics
  • Cross-talk and frequency response analysis
  • Pulse characteristics and voltage-time product rating
  • Total harmonic distortion and voltage regulation
  • Temperature rise and surface temperature monitoring
  • Polarity, screen construction, and noise tests
  • Corona discharge and magnetic field testing
  • Inrush current evaluation

• Visual and Physical Inspections

  • Dimensional checks and gauging
  • Construction quality including joint integrity and safety screen positioning

• Environmental and Endurance Tests

  • Soldering and termination robustness
  • Mechanical shock, vibration, and acceleration
  • Thermal cycling and rapid temperature changes
  • Climatic stress including damp heat, dry heat, salt mist, and mould growth
  • Fire hazard assessment and solvent immersion
  • Long-term and short-term endurance testing

• Measurement Uncertainty and Alternative Methods
  Procedures for accounting for uncertainties in measurement and guidelines for alternative test methods to adapt to different production or quality assurance requirements.

Applications

IEC 61007:2020 serves as a critical resource for manufacturers, designers, and quality engineers working with transformers and inductors in a wide range of electronic and telecommunication devices. Practical applications include:

• Manufacturing Quality Control
  Ensuring product conformity to technical specifications through standardized testing during production and before shipping.

• Product Development and Qualification
  Applying testing to validate designs for specific electronic or telecommunication applications.

• Customer Acceptance Testing
  Providing a uniform basis for testing agreement between suppliers and end-users.

• Performance Verification in Telecommunications
  Testing transformers and inductors for signal integrity, noise reduction, and impedance characteristics vital in telecommunication networks.

• Environmental Reliability Assessment
  Verifying the resilience of components under various environmental stresses to reduce failure rates in real-world usage.

Related Standards

IEC 61007:2020 is part of a framework of international standards that collectively address electrical and electronic component testing, including but not limited to:

• IEC standards on power transformers and inductors for utilities and industrial applications (complementary to IEC 61007 but distinct in scope).
• IEC 60076 series for power transformer testing procedures.
• IEC 61800 series related to electrical components in variable speed electrical drives.
• IEC 60738 series for switches and other electronic components testing standards.

These related standards complement IEC 61007 by covering broader or more specialized testing requirements beyond electronic and telecommunication transformers and inductors.

---

Adhering to IEC 61007:2020 ensures comprehensive and standardized evaluation of transformer and inductor components, promoting reliability, safety, and efficiency in electronics and telecommunication equipment globally. This supports manufacturers and end-users in meeting stringent quality requirements and maintaining high performance in complex electronic systems.

Standards Content (Sample)

IEC 61007 ®
Edition 3.0 2020-07
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Transformers and inductors for use in electronic and telecommunication
equipment – Measuring methods and test procedures

Transformateurs et inductances utilisés dans les équipements électroniques et
de télécommunications – Méthodes de mesure et procédures d'essais

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IEC 61007 ®
Edition 3.0 2020-07
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Transformers and inductors for use in electronic and telecommunication

equipment – Measuring methods and test procedures

Transformateurs et inductances utilisés dans les équipements électroniques et

de télécommunications – Méthodes de mesure et procédures d'essais

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 29.100.10; 29.180 ISBN 978-2-8322-8620-3

– 2 – IEC 61007:2020 © IEC 2020
CONTENTS
FOREWORD . 6
1 Scope . 8
2 Normative references . 8
3 Terms and definitions . 9
4 Test procedures . 13
4.1 Test and measurement conditions . 13
4.1.1 General . 13
4.1.2 Measurement uncertainty. 16
4.1.3 Alternative test methods . 16
4.2 Visual inspection . 16
4.2.1 General . 16
4.2.2 Safety screen position . 16
4.2.3 Quality of joints . 16
4.3 Dimensioning and gauging procedure . 19
4.4 Electrical test procedures . 19
4.4.1 Winding resistance . 19
4.4.2 Insulation tests . 20
4.4.3 Losses . 23
4.4.4 Inductance . 27
4.4.5 Unbalance . 27
4.4.6 Capacitance . 32
4.4.7 Transformation ratios. 35
4.4.8 Resonant frequency . 41
4.4.9 Signal transfer characteristics . 42
4.4.10 Cross-talk . 46
4.4.11 Frequency response . 47
4.4.12 Pulse characteristics . 48
4.4.13 Voltage-time product rating . 49
4.4.14 Total harmonic distortion . 50
4.4.15 Voltage regulation . 51
4.4.16 Temperature rise . 52
4.4.17 Surface temperature . 53
4.4.18 Polarity . 54
4.4.19 Screens . 56
4.4.20 Noise . 57
4.4.21 Corona tests . 58
4.4.22 Magnetic fields . 58
4.4.23 Inrush current . 61
4.5 Environmental test procedures . 61
4.5.1 General . 61
4.5.2 Soldering . 61
4.5.3 Robustness of terminations and integral mounting devices . 61
4.5.4 Shock . 61
4.5.5 Bump . 62
4.5.6 Vibration (sinusoidal) . 62
4.5.7 Acceleration, steady state . 62
4.5.8 Rapid change of temperature (thermal shock in air) . 62

4.5.9 Sealing . 62
4.5.10 Climatic sequence . 62
4.5.11 Damp heat, steady state . 62
4.5.12 Dry heat . 63
4.5.13 Mould growth . 63
4.5.14 Salt mist, cyclic (sodium chloride solution) . 63
4.5.15 Sulphur dioxide test for contacts and connections. 63
4.5.16 Fire hazard . 63
4.5.17 Immersion in cleaning solvents . 63
4.6 Endurance test procedures . 63
4.6.1 Short-term endurance (load run) . 63
4.6.2 Long-term endurance (life test) . 64
Annex A (normative) DC resistance test . 65
A.1 General . 65
A.2 Resistance values under 1 Ω – Kelvin double-bridge method . 65
A.3 Resistance values from 1 Ω to many kilo-ohms . 66
A.3.1 General . 66
A.3.2 Ammeter and voltmeter method . 66
A.3.3 Substitution method . 67
A.3.4 Wheatstone bridge . 68
A.3.5 Ohmmeter . 69
A.4 Digital ohmmeter – Resistance values from under 1 Ω to many kilo-ohms . 70
Annex B (normative) Dielectric voltage withstand test . 71
Annex C (normative) Induced voltage test . 73
C.1 Induced voltage test . 73
C.2 General test conditions . 73
C.3 General test methods . 73
C.4 Induced excitation voltage and frequency . 75
C.5 Repeated induced voltage testing . 75
C.6 Excitation current . 75
Annex D (normative) No-load loss . 76
D.1 General . 76
D.2 Excitation waveform . 76
D.2.1 General . 76
D.2.2 Sine-voltage (sine-flux) excitation . 76
D.2.3 Sine-current excitation . 77
D.2.4 Square-wave voltage excitation . 77
D.3 Test method and instrumentation . 78
D.3.1 General . 78
D.3.2 Wattmeter . 78
D.3.3 Ammeters . 79
D.3.4 Voltmeters . 79
D.4 Test specifications and results . 79
Annex E (normative) Quality factor, Q . 80
E.1 General . 80
E.2 Accuracy . 80
E.3 Generators . 80
E.3.1 Signal generator . 80

– 4 – IEC 61007:2020 © IEC 2020
E.3.2 Pulse generator . 80
E.3.3 Antenna . 80
E.4 Capacitor . 81
E.5 Measuring circuit. 81
E.5.1 Oscilloscope . 81
E.5.2 Probe . 81
E.6 Measuring procedure . 81
E.7 Calculation . 82
Annex F (normative) Electrostatic shielding . 84
F.1 Symbols . 84
F.2 Theoretical discussion . 86
F.3 Measurement methods . 87
F.3.1 Indirect method . 87
F.3.2 Direct method . 88
Annex G (normative) Corona test . 89
G.1 Detection of corona . 89
G.2 Analysis of corona . 89
G.3 Test conditions and specifications . 90
Bibliography . 91

Figure 1 – Pulse waveform parameters . 11
Figure 2 – Examples of good solder joints . 17
Figure 3 – Examples of defective joints . 18
Figure 4 – No-load current test schematic . 24
Figure 5 – No-load loss test schematic . 24
Figure 6 – Simplified diagram for short-circuit power test . 26
Figure 7 – Circuit for measuring capacitance unbalance . 28
Figure 8 – Circuit for determining common mode rejection ratio . 28
Figure 9 – Circuit for measuring impedance unbalance . 29
Figure 10 – Circuit for determining cross-talk attenuation . 30
Figure 11 – Schematic diagram of phase unbalance and amplitude unbalance . 32
Figure 12 – Typical graph for determining self-capacitance . 34
Figure 13 – Circuit for determining inter-winding capacitance . 35
Figure 14 – Circuit for measurement of voltage transformation ratio . 38
Figure 15 – Circuit for measuring current transformation ratio and phase displacement . 39
Figure 16 – Measuring circuit of current transformation ratio and phase displacement . 40
Figure 17 – Circuit for determining parallel self-resonant frequency . 41
Figure 18 – Circuit for determining resonant frequency of resonant assemblies . 42
Figure 19 – Circuit for determination of insertion loss . 43
Figure 20 – Use of two identical transformers when the transformation ratio is not unity
and/or a DC bias is required . 44
Figure 21 – Illustration of return loss . 45
Figure 22 – Basic return loss test circuit . 46
Figure 23 – Circuit diagram for measuring the crossover interference between two
transformer coils . 47
Figure 24 – Impulse waveform measuring circuit . 49

Figure 25 – Non-linearity of magnetizing current . 50
Figure 26 – Voltage regulation test schematic . 51
Figure 27 – Phase (polarity) test using voltage measurement . 54
Figure 28 – Series connection method . 55
Figure 29 – Helmholtz structure . 59
Figure A.1 – Measurement of low resistance . 65
Figure A.2 – Kelvin double-bridge method of measuring low resistance . 66
Figure A.3 – Ammeter and voltmeter method of resistance measurement . 67
Figure A.4 – Measurement of resistance by substitution. 68
Figure A.5 – Connections of Wheatstone bridge . 68
Figure A.6 – Principle of series ohmmeter . 69
Figure A.7 – Digital ohmmeter method of resistance measurement . 70
Figure B.1– Typical high-potential test, showing section 1 under test . 71
Figure B.2– Typical high-potential test of inductor . 71
Figure C.1 – Block diagram of induced voltage surge test . 73
Figure D.1 – Triangular flux-density variation in transformer core . 78
Figure D.2 – Test circuit for transformer no-load losses . 78
Figure E.1 – Damped oscillation method . 80
Figure E.2 – Oscilloscope sweep for damped oscillation method . 82
Figure F.1 – Shielded single winding, core floating . 84
Figure F.2 – Basic electrostatic symbol . 84
Figure F.3 – Multiple-shielded single winding, core terminal (lead) provided . 84
Figure F.4 – Shielded two-winding secondary, core grounded . 85
Figure F.5 – Shielded group of windings, core floating . 85
Figure F.6 – Multiple-shielded group of windings, core terminal (lead) provided . 85
Figure F.7 – Combination of shielding conditions . 86
Figure F.8 – Typical two-winding shielded transformer . 86
Figure F.9 – Simplified representation of Figure F.8 . 86
Figure F.10 – Indirect measuring method for electrostatic shielding . 87
Figure G.1 – Typical circuit for corona measurement (circuit 1) . 89
Figure G.2 – Typical circuit for corona measurement (circuit 2) . 90

Table 1 – Recommended tests and specifications for specific transformer and inductor
groups . 14
Table 2 – Voltage of dielectric withstanding voltage test . 20
Table 3 – Sound-level corrections for audible noise tests . 57
Table 4 – Cube dimensions, together with corresponding search coil data . 60

– 6 – IEC 61007:2020 © IEC 2020
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
TRANSFORMERS AND INDUCTORS FOR USE IN ELECTRONIC AND
TELECOMMUNICATION EQUIPMENT –
MEASURING METHODS AND TEST PROCEDURES

FOREWORD
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International Standard IEC 61007 has been prepared by IEC technical committee 51:
Magnetic components, ferrite and magnetic powder materials.
This third edition cancels and replaces the second edition published in 1994. This edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) scope: the application of the scope of IEC 61007 was extended;
b) Clause 2: added new references and updated the references;
c) Clause 3: new definitions were added in 3.3, and in 3.7 the voltage-time product was
redefined;
d) test procedures were updated:
1) addition of test method:
AC resistance (in 4.4.1.2); short-circuit power test (in 4.4.3.4); efficiency (in 4.4.3.5);
phase unbalance (in 4.4.5.7); amplitude unbalance (radio frequency) (in 4.4.5.8);
transformation ratio by impedance (in 4.4.7.1); coefficient of coupling (in 4.4.7.2);
cross-talk (in 4.4.10);
2) modification of test method:
Insulation resistance (an error range of the testing voltage, in 4.4.2.3);
3) deletion of test method:
Effective resistance;
e) environmental test procedures: new references were added;
f) Annexes A to G were added.
The text of this International Standard is based on the following documents:
CDV Report on voting
51/1319/CDV 51/1339/RVC
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.
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.
– 8 – IEC 61007:2020 © IEC 2020
TRANSFORMERS AND INDUCTORS FOR USE IN ELECTRONIC AND
TELECOMMUNICATION EQUIPMENT –
MEASURING METHODS AND TEST PROCEDURES

1 Scope
This document describes a number of tests for use in determining the significant parameters
and performance characteristics of transformers and inductors for use in electronics and
telecommunication equipment. These test methods are designed primarily for transformers
and inductors used in all types of electronics applications that can be involved in any
specification for such components. Even though these tests can be useful to the other types
of transformers used in power distribution applications in utilities, industry, and others, the
tests discussed in this document can supplement or complement the tests but are not
intended to replace the tests in standards for transformers. Some of the tests described are
intended for qualifying a product for a specific application, while others are test practices used
for manufacturing and customer acceptance testing. The test methods described here include
those parameters most commonly used in the electronics transformer and inductor industry:
electric strength, resistance, power loss, inductance, impedance, balance, transformation
ratio and many others used less frequently.
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 60050 (all parts), International Electrotechnical Vocabulary (IEV) (available at
www.electropedia.org)
IEC 60068-1: 2013, Environmental testing – Part 1: General and guidance
IEC 60068-2-1, Environmental testing – Part 2-1: Tests – Tests A: Cold
IEC 60068-2-2, Environmental testing – Part 2-2: Tests – Tests 8: Dry heat
IEC 60068-2-6, Environmental testing – Part 2-6: Tests – Test Fc: Vibration (sinusoidal)
IEC 60068-2-7, Basic environmental testing procedures – Part 2-7: Tests – Test Ga and
guidance: Acceleration, steady state
IEC 60068-2-10, Environmental testing – Part 2-10: Tests – Test J and guidance: Mould
growth
IEC 60068-2-13, Basic environmental testing procedures – Part 2-13: Tests – Test M: Low air
pressure
IEC 60068-2-14, Environmental testing – Part 2-14: Tests – Test N: Change of temperature
IEC 60068-2-17, Basic environmental testing procedure – Part 2-17: Tests – Test Q: Sealing
IEC 60068-2-20, Environmental testing – Part 2-20: Tests – Test T: Test methods for
solderability and resistance to soldering heat of devices with leads

IEC 60068-2-21, Environmental testing – Part 2-21: Tests – Test U: Robustness of
terminations and integral mounting devices
IEC 60068-2-27, Environmental testing – Part 2-27: Tests – Test Ea and guidance: Shock
IEC 60068-2-30, Environmental testing – Part 2-30: Tests – Test Db: Damp heat, cyclic (12 h
+ 12 h cycle)
IEC 60068-2-42, Environmental testing – Part 2-42: Tests – Test Kc: Sulphur dioxide test for
contacts and connections
IEC 60068-2-45, Basic environmental testing procedures – Part 2-45: Tests – Test XA and
guidance: Immersion in cleaning solvents
IEC 60068-2-52, Environmental testing – Part 2-52: Tests – Test Kb: Salt mist, cyclic (sodium
chloride solution)
IEC 60068-2-78, Environmental testing – Part 2-78: Tests – Test Cab: Damp heat, steady
state
IEC 60270, High-voltage test techniques – Partial discharge measurements
IEC 60695-11-2, Fire hazard testing – Part 11–2: Test flames – 1 kW pre-mixed flame –
Apparatus, confirmatory test arrangement and guidance
IEC 60695-11-5, Fire hazard testing – Part 11–5: Test flames – Needle-flame test method –
Apparatus, confirmatory test arrangement and guidance
IEC 61672-1, Electroacoustics – Sound level meters – Part 1: Specifications
3 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 60050 (all parts)
and the following apply.
ISO and IEC maintain terminological databases for use in standardization at the following
addresses:
• IEC Electromedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
3.1
component
transformer or inductor
3.2
peak working voltage
maximum instantaneous voltage for which the winding insulation is rated under working circuit
conditions
– 10 – IEC 61007:2020 © IEC 2020
3.3
pulse wave form parameters (see Figure 1)
3.3.1
peak pulse amplitude
U
m
maximum value of an extrapolated smooth curve through the top of the pulse, excluding any
initial "spike" or "overshoot", the duration of which is less than 10 % of the pulse duration
3.3.2
pulse duration
t
d
time interval between the first and last instant at which the pulse amplitude equals 50 % of the
peak pulse amplitude
3.3.3
pulse rise time
t
r
interval between the first instant at which the pulse amplitude reaches 10 % of the peak pulse
amplitude and the first instant at which the pulse amplitude reaches 90 % of the peak pulse
amplitude, excluding an unwanted or irrelevant portion of the waveform
3.3.4
pulse fall time
t
f
interval between the last instant at which the pulse amplitude reaches 90 % of the peak pulse
amplitude and the next instant at which the pulse amplitude reaches 10 % of the peak pulse
amplitude excluding any unwanted or irrelevant portion of the waveform
Note 1 to entry: Where the value of the droop approaches 10 % of the peak pulse amplitude, the upper point
defining fall time can be replaced by the last instant at which the pulse amplitude reaches 80 % of the peak pulse
amplitude.
3.3.5
droop
difference between the peak pulse amplitude and the amplitude of the extrapolated smooth
curve through the top of the pulse, excluding any initial "spike" of "overshoot", at its
intersection with the straight line through the points defining the pulse fall time, expressed as
a percentage of the peak pulse amplitude
3.3.6
pulse crest
maximum amplitude of the pulse
3.3.7
overshoot
amount by which the pulse crest exceeds the peak pulse amplitude, expressed as a
percentage of the peak pulse amplitude
3.3.8
backswing
maximum amplitude of the reverse pulse, i.e. the portion of the pulse after the zero-crossing,
expressed as a percentage of the peak pulse amplitude
3.3.9
return backswing
maximum amplitude of the swing that follows the backswing, expressed as a percentage of
the peak pulse amplitude
3.3.10
recovery time
time interval between the end of the pulse fall time and the time at which the pulse amplitude
last reaches 10 % of the peak pulse amplitude
Note 1 to entry: Exceptionally, a value of less than 10 % may be used, in which case the interval is termed "the
X % recovery time".
3.3.11
pulse repetition frequency
average number of pulses in unit time independent of the period over which it is measured

Leading edge: the interval between the first instant at which the pulse amplitude begins and the first instant at
which the pulse amplitude reaches the peak pulse amplitude.
Pulse top: the interval between the first instants at which the pulse amplitude equals the peak pulse amplitude and
the last instants at which the pulse amplitude equals 90 % of the peak pulse amplitude.
Trailing edge: the interval between the last instants at which the pulse amplitude equals 90 % of the peak pulse
amplitude and the first instants at which the pulse amplitude of the second cycle begins.
For clarity in illustrating droop, the 80 % and 10 % points have been used in constructing the line which determines the
border between the pulse top and the trailing edge.
Figure 1 – Pulse waveform parameters
3.4
quality factor
Q factor
ratio of the energy stored to the energy dissipated during one cycle at a particular frequency
in a specified winding
Note 1 to entry: The Q factor is expressed in terms of either the series or the parallel components of reactance
and loss resistance.
3.5
harmonic distortion
square root of the sum of the square of all harmonic voltages up to and including the seventh
harmonic (excluding the fundamental) expressed as a percentage or as a ratio in decibels of
the fundamental
– 12 – IEC 61007:2020 © IEC 2020
3.6
maximum winding temperature
mean temperature rise of any winding of the component under full load at maximum ambient
temperature, when thermal stability has been achieved, added to the specified maximum
ambient temperature
3.7
voltage-time product rating
voltage pulse amplitude multiplied by the time interval between the first and last instants at
which the pulse amplitude equals 50 % of the peak pulse amplitude
Note 1 to entry: The start of the pulse within which the non–linearity of the magnetizing current does not exceed a
specified value.
3.8
background noise
acoustic noise
noise measured at a measuring point with the component under test not electrically excited
3.9
compass safe distance
distance from the pivot of the test magnetometer of a compass to the nearest on the surface
of the component under test, at which the magnetic deviation is limited to a stated value
3.10
duty ratio
ratio of pulse duration t to the cycle time
d
3.11
current transformer parameters
3.11.1
burden
property of the circuit connected to the secondary winding of a current transformer which
determines the real and reactive power at the secondary terminals
Note 1 to entry: Burden is expressed as total impedance with effective resistive and reactive components or as
the total volt amperes and power factor at the specified values of current and frequency.
3.11.2
current transformation ratio
k
ratio of the RMS value of the primary current to the RMS value of the secondary current under
specified conditions
3.11.3
phase angle
angular displacement of the fundamental frequency between the vector representing the
primary and secondary currents of the transformer
Note 1 to entry: The phase angle is positive when the secondary current leads the primary current.
3.11.4
ratio error
difference between the measured current transformation ratio k and its nominal value k ,
n
divided by the measured value k, and expressed as a percentage
kk−
n
⋅100 %
k
3.12
electrostatic screen
conducting screen inserted between windings that, when it is connected to earth or the points
where the voltage potentials are constant, considerably reduces the transference of unwanted
signals from one winding to the other via inter-winding capacitance
3.13
safety screen
conducting screen inserted between windings that, when it is connected to earth, effectively
prevents fault currents flowing between those windings, in the event of an insulation failure
3.14
polarity
property of a single–phase winding such that a terminal on one
winding has the same polarity as a terminal on another winding if, when the other ends of the
windings are connected to form a common terminal and the transformer/inductor is energized
with a sinusoidal voltage, the induced voltage appearing between each of the two terminals
and the common terminal rise positively through zero at the same instant of time
3.15
uniformly-insulated winding
winding in which the insulation to earth is, at all points, designed to withstand an electric
strength test of a value appro
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