EN IEC 62044-3:2023

SLOVENSKI STANDARD
01-november-2023
Jedra iz mehkomagnetnih materialov - Merilne metode - 3. del: Magnetne lastnosti
pri močnem vzbujanju
Cores made of soft magnetic materials - Measuring methods - Part 3: Magnetic
properties at high excitation level
Kerne aus weichmagnetischen Materialien - Messverfahren - Teil 3: Messungen der
magnetischen Eigenschaften im Leistungsapplikationsbereich
Noyaux en matériaux magnétiques doux - Méthodes de mesure - Partie 3: Propriétés
magnétiques à niveau élevé d'excitation
Ta slovenski standard je istoveten z: EN IEC 62044-3:2023
ICS:
17.220.20 Merjenje električnih in Measurement of electrical
magnetnih veličin and magnetic quantities
29.100.10 Magnetne komponente Magnetic components
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD EN IEC 62044-3

NORME EUROPÉENNE
EUROPÄISCHE NORM September 2023
ICS 29.030; 29.100.10 Supersedes EN 62044-3:2001;
EN 62044-3:2001/AC:2021-11
English Version
Cores made of soft magnetic materials - Measuring methods -
Part 3: Magnetic properties at high excitation level
(IEC 62044-3:2023)
Noyaux en matériaux magnétiques doux - Méthodes de Kerne aus weichmagnetischen Materialien - Messverfahren
mesure - Partie 3: Propriétés magnétiques à niveau élevé - Teil 3: Messungen der magnetischen Eigenschaften im
d'excitation Leistungsapplikationsbereich
(IEC 62044-3:2023) (IEC 62044-3:2023)
This European Standard was approved by CENELEC on 2023-08-11. CENELEC members are bound to comply with the CEN/CENELEC
Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration.
Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN-CENELEC
Management Centre or to any CENELEC member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by translation
under the responsibility of a CENELEC member into its own language and notified to the CEN-CENELEC Management Centre has the
same status as the official versions.
CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus, the Czech Republic,
Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, the
Netherlands, Norway, Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Türkiye and the United Kingdom.

European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2023 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.
Ref. No. EN IEC 62044-3:2023 E

European foreword
The text of document 51/1426/CDV, future edition 2 of IEC 62044-3, prepared by IEC/TC 51
"Magnetic components, ferrite and magnetic powder materials" was submitted to the IEC-CENELEC
parallel vote and approved by CENELEC as EN IEC 62044-3:2023.
The following dates are fixed:
• latest date by which the document has to be implemented at national (dop) 2024-05-11
level by publication of an identical national standard or by endorsement
• latest date by which the national standards conflicting with the (dow) 2026-08-11
document have to be withdrawn
This document supersedes EN 62044-3:2001 and all of its amendments and corrigenda (if any).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CENELEC shall not be held responsible for identifying any or all such patent rights.
Any feedback and questions on this document should be directed to the users’ national committee. A
complete listing of these bodies can be found on the CENELEC website.
Endorsement notice
The text of the International Standard IEC 62044-3:2023 was approved by CENELEC as a European
Standard without any modification.
In the official version, for Bibliography, the following notes have to be added for the standard indicated:
IEC 60051-1 NOTE Approved as EN 60051-1
IEC 60205 NOTE Approved as EN 60205
IEC 60401-3:2015 NOTE Approved as EN 60401-3:2016 (not modified)
IEC 60404-8-6 NOTE Approved as EN 60404-8-6
IEC 61332:2016 NOTE Approved as EN 61332:2017 (not modified)
Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments)
applies.
NOTE 1 Where an International Publication has been modified by common modifications, indicated by (mod), the
relevant EN/HD applies.
NOTE 2 Up-to-date information on the latest versions of the European Standards listed in this annex is available
here: www.cencenelec.eu.
Publication Year Title EN/HD Year
IEC 62044-1 2002 Cores made of soft magnetic materials - EN 62044-1 2002
Measuring methods - Part 1: Generic
specification
IEC 62044-3 ®
Edition 2.0 2023-07
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Cores made of soft magnetic materials – Measuring methods –

Part 3: Magnetic properties at high excitation level

Noyaux en matériaux magnétiques doux – Méthodes de mesure –

Partie 3: Propriétés magnétiques à niveau élevé d'excitation

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 29.030, 29.100.10 ISBN 978-2-8322-7172-8

– 2 – IEC 62044-3:2023 © IEC 2023
CONTENTS
FOREWORD . 5
INTRODUCTION . 7
1 Scope . 8
2 Normative references . 8
3 Terms, definitions and symbols. 8
3.1 Terms and definitions . 8
3.2 Symbols . 12
4 General requirements for measurements at high excitation level . 13
4.1 General statements . 13
4.1.1 Relation to practice . 13
4.1.2 Core effective parameters and material properties . 13
4.1.3 Reproducibility of the magnetic state . 13
4.2 Measuring coil . 13
4.2.1 General . 13
4.2.2 Number of turns . 14
4.2.3 Single winding and double winding . 14
4.3 Mounting of cores consisting of more than one part . 15
4.4 Measuring equipment . 15
5 Specimens . 18
6 Measuring procedures . 18
6.1 General procedure . 18
6.2 Measuring method for the effective amplitude permeability . 19
6.2.1 Purpose . 19
6.2.2 Principle of the measurement . 19
6.2.3 Circuit and equipment . 19
6.2.4 Measuring procedure . 19
6.2.5 Calculation . 20
6.3 Measuring methods for the power loss . 20
6.3.1 Purpose . 20
6.3.2 Methods and principles of the measurements . 20
7 Information to be stated . 23
8 Test report . 24
Annex A (informative) Basic circuits and related equipment for the measurement of
amplitude permeability . 25
Annex B (informative) Root-mean-square method for the measurement of power loss –
Example of a circuit and related procedure . 27
B.1 Method of measurement . 27
B.2 Measuring coil . 27
B.3 Measuring equipment . 28
B.4 Measuring procedure . 28
B.5 Pulse measurement and accuracy . 29
Annex C (informative) Multiplying methods for the measurement of power loss – Basic
circuits and related measurement procedures . 30
C.1 Basic circuits . 30
C.2 Requirements . 31
C.3 Measuring coil . 31

IEC 62044-3:2023 © IEC 2023 – 3 –
C.4 Accuracy . 31
C.5 V-A-W (volt-ampere-watt) meter method . 32
C.6 Impedance analyzer method . 32
C.7 Digitizing method . 32
C.8 Vector spectrum method . 33
C.9 Cross-power method . 33
Annex D (informative) Reflection method for the measurement of power loss – Basic
circuit and related measurement procedures . 34
D.1 Basic circuit . 34
D.2 Requirements . 34
D.3 Measuring coil . 34
D.4 Measuring procedure and accuracy . 35
Annex E (informative) Calorimetric measurement methods for the measurement of
power loss . 36
E.1 Basic circuit . 36
E.2 Requirements . 37
E.3 Measuring coil . 37
E.4 Accuracy . 37
E.5 Measurements at thermal equilibrium . 37
E.5.1 General . 37
E.5.2 Measurement across calibrated thermal resistance . 37
E.5.3 Measurement by matching the temperature rise in the core and resistor . 38
E.6 Measurements at non-thermal equilibrium . 38
Annex F (normative) Magnetic properties under pulse condition . 39
F.1 Object . 39
F.2 Measurement methods . 39
F.3 Principle of the methods . 39
F.4 Specimens . 39
F.5 Measuring coil . 39
F.6 Measuring equipment . 40
F.7 Measuring procedure . 41
F.7.1 General . 41
F.7.2 Measurement of pulse inductance factor and magnetizing current . 42
F.7.3 Measurement of the non-linearity of the magnetizing current . 43
F.8 Calculation . 44
Annex G (informative) Examples of circuits for pulse measurements . 46
Bibliography . 47

Figure 1 – Pulse excitation without biasing field . 10
Figure 2 – Pulse excitation with biasing field . 10
Figure A.1 – Basic circuits for the measurement of amplitude permeability . 26
Figure B.1 – Example of a measuring circuit for the RMS method . 27
Figure C.1 – Basic circuits for multiplying methods . 31
Figure D.1 – Basic circuit . 34
Figure E.1 – Basic circuit and related measurement procedures – Measurement set-up . 36
Figure F.1 – Voltage pulse parameters . 42
Figure F.2 – Typical measuring waveforms . 43

– 4 – IEC 62044-3:2023 © IEC 2023
Figure F.3 – Non-linearity of magnetizing current . 44
Figure G.1 – Measurement without bias and with single pulses . 46
Figure G.2 – Measurement with bias and with repeated pulses . 46

Table 1 – Some multiplying methods and related domains of excitation waveforms,
acquisition, processing . 21

IEC 62044-3:2023 © IEC 2023 – 5 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
CORES MADE OF SOFT MAGNETIC MATERIALS –
MEASURING METHODS –
Part 3: Magnetic properties at high excitation level

FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote international
co-operation on all questions concerning standardization in the electrical and electronic fields. To this end and
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Standardization (ISO) in accordance with conditions determined by agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
consensus of opinion on the relevant subjects since each technical committee has representation from all
interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
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4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
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6) All users should ensure that they have the latest edition of this publication.
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Publications.
8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) IEC draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). IEC takes no position concerning the evidence, validity or applicability of any claimed patent rights in
respect thereof. As of the date of publication of this document, IEC had not received notice of (a) patent(s), which
may be required to implement this document. However, implementers are cautioned that this may not represent
the latest information, which may be obtained from the patent database available at https://patents.iec.ch. IEC
shall not be held responsible for identifying any or all such patent rights.
IEC 62044-3 has been prepared by IEC technical committee 51: Magnetic components, ferrite
and magnetic powder materials. It is an International Standard.
This second edition cancels and replaces the first edition published in 2000. This edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) addition of Annex F and Annex G.

– 6 – IEC 62044-3:2023 © IEC 2023
The text of this International Standard is based on the following documents:
Draft Report on voting
51/1426/CDV 51/1439/RVC
Full information on the voting for its approval can be found in the report on voting indicated in
the above table.
The language used for the development of this International Standard is English.
This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in
accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement, available
at www.iec.ch/members_experts/refdocs. The main document types developed by IEC are
described in greater detail at www.iec.ch/publications.
A list of all parts in the IEC 62044 series, published under the general title Cores made of soft
magnetic materials – Measuring methods, can be found on the IEC website.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under webstore.iec.ch in the data related to the
specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
IEC 62044-3:2023 © IEC 2023 – 7 –
INTRODUCTION
IEC 62044, under the general title Cores made of soft magnetic materials – Measuring methods,
includes the following parts:
IEC 62044-1: Generic specification
IEC 62044-2: Magnetic properties at low excitation level
IEC 62044-3: Magnetic properties at high excitation level

– 8 – IEC 62044-3:2023 © IEC 2023
CORES MADE OF SOFT MAGNETIC MATERIALS –
MEASURING METHODS –
Part 3: Magnetic properties at high excitation level

1 Scope
This part of IEC 62044 specifies measuring methods for power loss and amplitude permeability
of magnetic cores forming the closed magnetic circuits intended for use at high excitation levels
in inductors, chokes, transformers and similar devices for power electronics applications.
The methods given in this document can cover the measurement of magnetic properties for
frequencies ranging practically from direct current to 10 MHz, and even possibly higher, for the
calorimetric and reflection methods. The applicability of the individual methods to specific
frequency ranges is dependent on the level of accuracy that is to be obtained.
The methods in this document are basically the most suitable for sine-wave excitations. Other
periodic waveforms can also be used; however, adequate accuracy can only be obtained if the
measuring circuitry and instruments used are able to handle and process the amplitudes and
phases of the signals involved within the frequency spectrum corresponding to the given
magnetic flux density and field strength waveforms with only slightly degraded accuracy.
NOTE It can be necessary for some magnetically soft metallic materials to follow specific general principles,
customary for these materials, related to the preparation of specimens and specified calculations. These principles
are formulated in IEC 60404-8-6.
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 62044-1:2002, Cores made of soft magnetic materials – Measuring methods – Part 1:
Generic specification
3 Terms, definitions and symbols
3.1 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following
addresses:
• IEC Electropedia: available at https://www.electropedia.org/
• ISO Online browsing platform: available at https://www.iso.org/obp

IEC 62044-3:2023 © IEC 2023 – 9 –
3.1.1
effective amplitude permeability
μ
ea
ˆ
magnetic permeability obtained from the peak value of the effective magnetic flux density, B ,
e
ˆ
H
and the peak value of the effective magnetic field strength, , at the stated value of either,
e
when the magnetic flux density and magnetic field vary periodically with time and with an
average of zero, and the material is initially in a specified demagnetized state
3.1.2
maximum effective amplitude permeability
μ
ea max
ˆ
maximum value of the effective amplitude permeability when the amplitude of excitation ( B or
e
ˆ
H ) is varied
e
3.1.3
excitation
either magnetic flux density or field strength for which the waveform and amplitude both remain
within the specified tolerance
Note 1 to entry: When the magnetic flux density (field strength) mode of excitation is chosen, the resultant waveform
of field strength (magnetic flux density) can be distorted with respect to the excitation waveform due to the non-linear
behaviour of the magnetic material.
3.1.4
high excitation level
excitation at which the permeability depends on excitation amplitude (particularly at low
frequencies) or at which the power loss results in a noticeable temperature rise (particularly at
high frequencies), or both
3.1.5
exciting winding
winding of measuring coil to which the exciting voltage is applied or through which the exciting
current is flowing
3.1.6
voltage sensing winding
unloaded winding of a measuring coil across which the electromotive force induced by the
excitation can be determined
3.1.7
measuring winding
winding, usually secondary, loaded or unloaded, which can be used for measurement apart
from the exciting or voltage sensing winding, or both
3.1.8
power loss
power absorbed by the core
3.1.9
pulse excitation without biasing field
excitation in which a core is energized by a voltage pulse, from a remanent flux density to a
higher value of flux density in the same direction, and in which the core recovers to the same
remanent flux density
Note 1 to entry: The excursion in the B-H plane associated with such a pulse is shown in Figure 1.

– 10 – IEC 62044-3:2023 © IEC 2023

Figure 1 – Pulse excitation without biasing field
Note 2 to entry: If the back-e.m.f. during recovery is limited only by the time constant of the test circuit, then the
magnetizing current decays exponentially.
Alternatively the back-e.m.f. can be limited to a constant value, for example by returning the energy via a secondary
winding to a voltage source; then the magnetizing current decay is approximately linear. The latter method can
prevent excessively high back-e.m.f. and high rates of change of flux. The distinction is mainly relevant to loss
measurements.
3.1.10
pulse excitation with biasing field
excitation in which a core is energized by a voltage pulse, from a value of the flux density
determined by a biasing field to a flux density in the opposite direction, and in which the core
recovers to the same value determined by the biasing field
Note 1 to entry: The excursion in the B-H plane associated with such a pulse is shown in Figure 2.

Figure 2 – Pulse excitation with biasing field
Note 2 to entry: See Note to entry 2 of 3.1.9.

IEC 62044-3:2023 © IEC 2023 – 11 –
3.1.11
pulse permeability
μ
p
relative permeability obtained from the change of flux density and the corresponding change of
the field strength when either quantity is varying in an arbitrary form between stated limits:
1 ΔB
μ ⋅
p
μ ΔH
SEE: Figure 1 and Figure 2.
Note 1 to entry: The value of the pulse permeability depends strongly on the limits of the flux density or field strength
excursions; it is not necessary for these limits to be symmetrical with respect to zero.
Note 2 to entry: Often pulse permeability refers to the special case of square voltage pulses being applied to an
exciting winding; the flux density waveform is then approximately triangular.
3.1.12
pulse amplitude
U
m
maximum instantaneous value which an ideal voltage pulse would have with respect to the
steady value of the voltage between pulses
Note 1 to entry: An ideal pulse is derived from an actual voltage pulse by ignoring unwanted or non-pertinent
phenomena such as overshoot (see Figure 1).
3.1.13
pulse duration
t
d
time interval during which the instantaneous value of the pulse exceeds 50 % of the pulse
amplitude
U
m
L =
p
Δi t
md
where
L
p is the pulse inductance
Δi is the total change in i during the pulse
m m
SEE: Figure F.1.
Note 1 to entry: For unidirectional drive pulses Δi = î .
m m
3.1.14
pulse inductance factor
A
LP
pulse inductance divided by the square of the number of turns of the test coil
L
p
A =
LP
N
=
– 12 – IEC 62044-3:2023 © IEC 2023
3.1.15
voltage-time product limit
(U·t)
lim
specified limit of the product of the amplitude of a voltage pulse and the time elapsed from the
start of the pulse
Note 1 to entry: Within this limit the non-linearity of the magnetizing current through the measuring coil placed on
the core should not exceed a specified value.
3.1.16
non-linearity (with time)
ratio of the actual instantaneous value of a characteristic at a time t to the value reached by the
extrapolated linear portion of its graph versus time, at the same instant
SEE: Figure F.3.
3.1.17
pulse repetition rate
frequency of recurrence of the pulses in a periodic sequence of pulses
3.2 Symbols
All the formulae in this document use basic SI units. When multiples or sub-multiples are used,
the appropriate power of 10 shall be introduced.
A effective cross-sectional area of the core
e
ˆ
peak value of the effective magnetic flux density in the core
B
e
f frequency
ˆ
H
peak value of the effective magnetic field strength in the core
e
l effective magnetic path length of the core
e
L inductance
i instantaneous value of the current
I current
N number of turns of winding of the measuring coil
P power loss in the core
Q quality factor of the core for a given frequency
R resistance
t time
T temperature
u instantaneous value of the voltage
U voltage
V effective volume of the core
e
δ relative error, deviation, etc.
∆ absolute error, deviation, etc.
µ effective amplitude permeability
ea
−7
µ permeability of vacuum: approximately 4π ×10 H/m
ϕ phase shift
ω angular frequency = 2πf
NOTE 1 The additional subscript, upper script, etc., gives a more specific meaning to the given symbol.

IEC 62044-3:2023 © IEC 2023 – 13 –
NOTE 2 Symbols which are used sporadically are defined in the place where they appear in the text.
NOTE 3 Effective parameters, such as effective magnetic path length, l , effective cross-sectional area, A , and
e e
effective volume of the core, V , are calculated in accordance with IEC 60205.
e
NOTE 4 In the text of this document, the term flux density stands for the shortened term of magnetic flux density.
4 General requirements for measurements at high excitation level
4.1 General statements
4.1.1 Relation to practice
The measuring conditions, methods and procedures shall be chosen in such a way that the
measured results are suitable for predicting the performance of the core under practical
circumstances. This does not imply that all these stipulations, especially those related to the
excitation waveforms, have to correspond to terms encountered in practice.
4.1.2 Core effective parameters and material properties
Since the core is in general of non-uniform cross-section and generally has non-uniformly
distributed windings along the core path, the measurement does not yield the amplitude
permeability and the power loss of the material, but the effective values of these parameters
ˆ ˆ
appropriate to the effective magnetic flux density B and the effective field strength H in the
e e
core.
For the measurement of the amplitude permeability and the power loss of the material, the core
shall have a ring or toroidal shape in which the ratio of the outer to the inner diameter should
not be greater than 1,4 and should have windings distributed uniformly, close to the core, of
inductive coupling coefficient practically equal to unity.
4.1.3 Reproducibility of the magnetic state
To obliterate various remanence and time effects in the core material, the measurement shall
be made at a well-defined and reproducible magnetic state.
Any measurement under specified excitation, unless otherwise stated, is to be made at the time
t = t + ∆t after the magnetic conditioning start; t is the time period within which the magnetic
m c c
conditioning is completed and, whereupon, the specified excitation is set; ∆t is the time period
during which the core is kept stable under the excitation being set.
4.2 Measuring coil
4.2.1 General
Normally, a measuring coil will be used, but in principle any coaxial line, cavity or other suitable
device providing the necessary interaction between the magnetic material and the
electromagnetic signal, may also be used.
For measurement on toroid using coils, the turns of the measuring coil shall be distributed in
such a way as to keep both the stray capacitance and the stray field as low as necessary for
sufficiently accurate measurement.
For measurements made on cores assembled around a coil, the shape of the measuring coil
shall correspond to that of the coils used for normal application of the core and its influence on
the variation of the inductance to be measured shall be negligible.

– 14 – IEC 62044-3:2023 © IEC 2023
Unless otherwise specified, the test coil complete with coil former or encapsulation, or both,
shall be positioned in a coaxial way to the limb which it embraces, and the side of the coil at
which the start of the winding is located shall be lightly pressed into contact with the core at
one end of this limb as follows:
• for a symmetrical core, the coil assembly shall contact the core at either one end or the
other;
• for a core with an air-gap that is asymmetrical because the gap has been made by grinding
away material on the leg of one core half and not the other, the coil assembly shall make
end contact to the half of the core that has not been ground away to create the gap.
One of the coil faces shall be marked so as to define its orientation. The coil shall be kept in
the defined position during the whole measurement in order to obtain the maximum
reproducibility of the measurement.
4.2.2 Number of turns
The number of turns shall be specified for each winding in relation to the measuring conditions,
the equipment used and the accuracy to be obtained. The windings shall be wound as close to
the core as possible, to make the coupling (magnetic flux linkage) coefficients between the
measuring coil windings and the core and between the windings of measuring coil, as close to
100 % as possible.
The resistance, self-capacitance and inter-winding capacitance of windings should be as low
as possible to make the related errors negligible.
In the case of ring or toroidal cores, the turns shall be distributed evenly around the core
circumference.
The connectors, primarily of exciting winding, should consist of insulated strands, if this is
necessary for measurements at high frequencies.
When winding a sharp-edge core, the wire insulation should not rupture and, in the case of
stranded wire, the strands should not break.
4.2.3 Single winding and double winding
The use of a single winding both for excitation and voltage sensing is recommended if
– the coupling between the exciting winding and the voltage sensing winding is so reduced
that it results in a non-negligible error in the determination of the measuring magnetic flux
density B in the core;
– the inter-winding capacitance is too high;
– there is no measuring circuitry contra-indication against the direct connection of the exciting
winding to the input(s) of measuring instruments.
When a single winding is used, it is recommended that its resistance be made as low as possible
to make the winding ohmic power loss negligible compared to the power loss in the core.
The use of separate exciting and voltage sensing windings (double winding) is recommended
if, for whatever reason, the exciting winding is galvanically separated from the voltage and the
current measuring instruments, for example, to avoid a floating or DC connection to their inputs.
When the exciting and voltage sensing windings are used, their magnetic coupling coefficient
shall be as close to 100 % as possible.

IEC 62044-3:2023 © IEC 2023 – 15 –
The voltage necessary for calculation of the magnetic flux density in the core is typically
measured across a voltage sensing winding that is separate from the current-carrying (exciting)
winding. When measuring core losses, ohmic losses in the voltage sensing winding do not affect
the calculation, but ohmic losses in the current-carrying (exciting) winding shall be excluded
from the core loss calculation.
The use of two windings is recommended at more than 200 kHz.
4.3 Mounting of cores consisting of more than one part
A ferrite core set consisting of more than one part and which is to be assembled around the
measuring coil, shall be held together with glue, tape or a clamping device throughout the
measurement.
Whichever method is used to join the core parts together, it shall have the following
characteristics:
• distribution of the joining force uniformly over the mating surfaces, without the introduction
of bending stresses in the core;
• holding of all the core parts rigidly and without changing the position with regard to each
other;
• when a specified clamping method is used, an initial over-force of about 10 % shall be
applied when the core is closed, in order to break down fine irregularities between the
cleaned mating surfaces. Next, the specified clamping force ±5 % shall be applied;
• keeping the joining force constant within ±1 % during all measuring operations within all
measuring conditions, including the full specified temperature range.
The mounting of such cores shall be carried out in accordance with the following instructions.
The mating surface shall be inspected for damage and cleanness. Damaged cores shall not be
used. The mating surface shall be cleaned by non-abrasive means, for example, by rubbing
gently on a dry washing-leather. Next, the mating surfaces shall be degreased if they have to
be glued. Dust particles shall be blown off with clean dry compressed air. The mating surfaces
shall never be touched with bare fingers. The core parts shall then be assembled around the
measuring coil, the latter being locked in position with respect to the core by suitable means,
for example, a foam-washer. The core parts are centered and glued or placed in a clamping
device. The glue, if used, shall be spread evenly on the mating surface to form a film as thin as
possible and then properly hardened.
In the case where the clamping device is used, the clamping force specified in the relevant
specification shall be applied. The glued, taped or clamped cores shall relax under the specified
conditions (see IEC 62044-1:2002, Clause 3) for a long enough time to allow any variation of
stress effects, due to clamping, gluing or taping, to become negligible.
4.4 Measuring equipment
4.4.1 Any suitable measuring equipment may be used. Examples of appropriate circuits are
given in Annex A to Annex E.
In addition to any requirement specified for the particular method or measuring circuit, or both,
used, the following general requirements shall be met.
4.4.2 To ensure the magnetic flux density (field strength) mode of excitation, the output
impedance of the exciting source shall be low (high) compared with the series impedance of
the exciting winding of the measuring coil assembled with the core under test and the current
sensing resistor.
– 16 – IEC 62044-3:2023 © IEC 2023
4.4.3 When the sinusoidal waveform of excitation is specified, the total harmonic content of
the excitation source shall be less than 1 %. When square pulses are specified, the relevant
requirements of Annex F shall be met.
4.4.4 During the period of measurement, the excitation amplitude variations shall not exceed
±0,05 % and the frequency stability shall be adequate for the measuring method and the
equipment used.
4.4.5 The frequency range of voltmeters and other voltage sensing instruments shall include
all harmonics of the measured voltage having amplitudes of 1 % or more of their fundamentals.
This frequency range shall be specified in the relevant instrument specification.
4.4.6 The voltmeters and other voltage sensing instruments used shall be high-impedance
instruments, the connection of which will have only a negligible effect on the measuring circuit,
especially at high frequencies. The probes of a high-input resistance and a low-input capa-
citance c
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