Cores made of soft magnetic materials - Measuring methods - Part 3: Magnetic properties at high excitation level

Provides 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.

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

Donne les méthodes de mesure de la perte de puissance et de la perméabilité d'amplitude des noyaux magnétiques formant les circuits magnétiques fermés destinés à être utilisés à des niveaux élevés d'excitation dans les bobines d'inductance, les bobines d'arrêt, les transformateurs et les dispositifs similaires pour les applications d'électronique de puissance.

Cores made of soft magnetic materials - Measuring methods - Part 3: Magnetic properties at high excitation level (IEC 62044-3:2000)

V tem standardu so predstavljene merilne metode za izgubo moči in amplitudno prepustnost magnetnih jeder, ki tvorijo zaprta magnetna vezja, namenjena za uporabo pri močnem vzbujanju v induktorjih, dušilkah, transformatorjih in podobnih napravah za aplikacije močnostne elektronike Metode, podane v tem standardu, lahko zajemajo merjenje magnetnih lastnosti za frekvence v območju od enosmernega toka do 10 MHz in morda še celo več, za kalorimetrične in odbojne metode. Uporabnost posameznih metod za določena frekvenčna območja je odvisna od stopnje natančnosti, ki jo je treba doseči.
Metode v tem standardu so v osnovi najprimernejše za sinusno vzbujanje. Uporabiti je mogoče tudi druge periodične valovne oblike, vendar zadostno natančnost je mogoče doseči le, če so uporabljena merilna vezja in instrumenti zmožni obravnavati ter obdelati amplitude in faze signalov, vključene v frekvenčnem spektru, ki ustreza danim valovnim oblikam indukcije in jakosti polja z le nekoliko manjšo natančnostjo.
OPOMBA: Za nekatere magnetno mehke kovinske materiale bo morda treba upoštevati posebna splošna načela v zvezi s pripravo primerkov in predpisanimi izračuni, ki so za takšne materiale običajna. Ta načela so navedena v standardu IEC 60404-8-6.

General Information

Status
Withdrawn
Publication Date
31-May-2001
Withdrawal Date
29-Feb-2004
Current Stage
6060 - Document made available - Publishing
Start Date
21-May-2001
Completion Date
21-May-2001

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SLOVENSKI STANDARD
SIST EN 62044-3:2002
01-september-2002
Cores made of soft magnetic materials - Measuring methods - Part 3: Magnetic
properties at high excitation level (IEC 62044-3:2000)
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 62044-3:2001
ICS:
17.220.20 0HUMHQMHHOHNWULþQLKLQ Measurement of electrical
PDJQHWQLKYHOLþLQ and magnetic quantities
29.100.10 Magnetne komponente Magnetic components
SIST EN 62044-3:2002 en

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

---------------------- Page: 1 ----------------------
SIST EN 62044-3:2002
---------------------- Page: 2 ----------------------
SIST EN 62044-3:2002
EUROPEAN STANDARD EN 62044-3
NORME EUROPÉENNE
EUROPÄISCHE NORM May 2001
ICS 29.030; 29.100.10
English version
Cores made of soft magnetic materials - Measuring methods
Part 3: Magnetic properties at high excitation level
(IEC 62044-3:2000)
Noyaux en matériaux magnétiques doux - Kerne aus weichmagnetischen
Méthodes de mesure Materialien - Messverfahren
Partie 3: Propriétés magnétiques à niveau Teil 3: Messungen der magnetischen
élevé d'excitation Eigenschaften im
(CEI 62044-3:2000) Leistungsapplikationsbereich
(IEC 62044-3:2000)

This European Standard was approved by CENELEC on 2001-03-01. 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 Central Secretariat 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 Central Secretariat has the same status as the official versions.

CENELEC members are the national electrotechnical committees of Austria, Belgium, Czech Republic,

Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway,

Portugal, Spain, Sweden, Switzerland and United Kingdom.
CENELEC
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
Central Secretariat: rue de Stassart 35, B - 1050 Brussels

© 2001 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.

Ref. No. EN 62044-3:2001 E
---------------------- Page: 3 ----------------------
SIST EN 62044-3:2002
EN 62044-3:2001 - 2 -
Foreword

The text of document 51/573/FDIS, future edition 1 of IEC 62044-3, prepared by IEC TC 51, Magnetic

components and ferrite materials, was submitted to the IEC-CENELEC parallel vote and was

approved by CENELEC as EN 62044-3 on 2001-03-01.
The following dates were fixed:
– latest date by which the EN has to be implemented
at national level by publication of an identical
national standard or by endorsement (dop) 2001-12-01
– latest date by which the national standards conflicting
with the EN have to be withdrawn (dow) 2004-03-01
Annexes designated "normative" are part of the body of the standard.
Annexes designated "informative" are given for information only.
In this standard, annex ZA is normative and annexes A to E are informative.
Annex ZA has been added by CENELEC.
__________
Endorsement notice

The text of the International Standard IEC 62044-3:2000 was approved by CENELEC as a European

Standard without any modification.
__________
---------------------- Page: 4 ----------------------
SIST EN 62044-3:2002
- 3 - EN 62044-3:2001
Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications

This European Standard incorporates by dated or undated reference, provisions from other

publications. These normative references are cited at the appropriate places in the text and the

publications are listed hereafter. For dated references, subsequent amendments to or revisions of any

of these publications apply to this European Standard only when incorporated in it by amendment or

revision. For undated references the latest edition of the publication referred to applies (including

amendments).

NOTE When an international publication has been modified by common modifications, indicated by (mod), the relevant

EN/HD applies.
Publication Year Title EN/HD Year
IEC 60050-221 1990 International electrotechnical vocabulary--
Chapter 221: Magnetic materials and
components
A1 1993 - -
A2 1999 - -
IEC 60205 1966 Calculation of the effective parameters--
of magnetic piece parts
IEC 60367-1 1982 Cores for inductors and transformers for--
telecommunications
Part 1: Measuring methods
IEC 60401 1993 Ferrite materials - Guide on the format--
of data appearing in manufacturers'
catalogues of transformer and inductor
cores
IEC 60404-8-6 1999 Magnetic materials --
Part 8-6: Specifications for individual
materials - Soft magnetic metallic
materials
IEC 61332 1995 Soft ferrite material classification EN 61332 1997
---------------------- Page: 5 ----------------------
SIST EN 62044-3:2002
---------------------- Page: 6 ----------------------
SIST EN 62044-3:2002
NORME
CEI
INTERNATIONALE IEC
62044-3
INTERNATIONAL
Première édition
STANDARD
First edition
2000-12
Noyaux en matériaux magnétiques doux –
Méthodes de mesure –
Partie 3:
Propriétés magnétiques à niveau élevé d'excitation
Cores made of soft magnetic materials –
Measuring methods –
Part 3:
Magnetic properties at high excitation level
© IEC 2000 Droits de reproduction réservés ⎯ Copyright - all rights reserved

Aucune partie de cette publication ne peut être reproduite ni No part of this publication may be reproduced or utilized in

utilisée sous quelque forme que ce soit et par aucun procédé, any form or by any means, electronic or mechanical,

électronique ou mécanique, y compris la photocopie et les including photocopying and microfilm, without permission in

microfilms, sans l'accord écrit de l'éditeur. writing from the publisher.
International Electrotechnical Commission 3, rue de Varembé Geneva, Switzerland
Telefax: +41 22 919 0300 e-mail: inmail@iec.ch IEC web site http://www.iec.ch
CODE PRIX
Commission Electrotechnique Internationale
PRICE CODE
International Electrotechnical Commission
Pour prix, voir catalogue en vigueur
For price, see current catalogue
---------------------- Page: 7 ----------------------
SIST EN 62044-3:2002
62044-3 © IEC:2000 – 3 –
CONTENTS
Page

FOREWORD .......................................................................................................................... 5

Clause

1 Scope .............................................................................................................................. 9

2 Normative references....................................................................................................... 9

3 Terms, definitions and symbols ...................................................................................... 11

3.1 Definitions ............................................................................................................ 11

3.2 Symbols................................................................................................................ 13

4 General precautions for measurements at high excitation level ...................................... 15

4.1 General statements............................................................................................... 15

4.2 Measuring coil ...................................................................................................... 15

4.3 Mounting of cores consisting of more than one part .............................................. 17

4.4 Measuring equipment............................................................................................ 19

5 Specimens ..................................................................................................................... 23

6 Measuring procedures ................................................................................................... 23

6.1 General procedure................................................................................................ 23

6.2 Measuring method for the (effective) amplitude permeability................................. 25

6.3 Measuring methods for the power loss.................................................................. 29

7 Information to be stated ................................................................................................. 33

8 Test report ..................................................................................................................... 35

Annex A (informative) Basic circuits and related equipment for the measurement

of amplitude permeability ..................................................................................................... 37

Annex B (informative) Root-mean-square method for the measurement of power loss –

Example of a circuit and related procedure........................................................................... 41

Annex C (informative) Multiplying methods for the measurement of power loss –

Basic circuits and related measurement procedures ............................................................. 47

Annex D (informative) Reflection method for the measurement of power loss –

Basic circuit and related measurement procedures............................................................... 55

Annex E (informative) Calorimetric measurement methods for the measurement

of power loss........................................................................................................................ 59

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SIST EN 62044-3:2002
62044-3 © IEC:2000 – 5 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
CORES MADE OF SOFT MAGNETIC MATERIALS –
MEASURING METHODS –
Part 3: Magnetic properties at high excitation level
FOREWORD

1) The IEC (International Electrotechnical Commission) is a worldwide organization for standardization comprising

all national electrotechnical committees (IEC National Committees). The object of the IEC is to promote

international co-operation on all questions concerning standardization in the electrical and electronic fields. To

this end and in addition to other activities, the IEC publishes International Standards. Their preparation is

entrusted to technical committees; any IEC National Committee interested in the subject dealt with may

participate in this preparatory work. International, governmental and non-governmental organizations liaising

with the IEC also participate in this preparation. The IEC collaborates closely with the International

Organization for Standardization (ISO) in accordance with conditions determined by agreement between the

two organizations.

2) The formal decisions or agreements of the 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 National Committees.

3) The documents produced have the form of recommendations for international use and are published in the form

of standards, technical specifications, technical reports or guides and they are accepted by the National

Committees in that sense.

4) In order to promote international unification, IEC National Committees undertake to apply IEC International

Standards transparently to the maximum extent possible in their national and regional standards. Any

divergence between the IEC Standard and the corresponding national or regional standard shall be clearly

indicated in the latter.

5) The IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for any

equipment declared to be in conformity with one of its standards.

6) Attention is drawn to the possibility that some of the elements of this International Standard may be the subject

of patent rights. The IEC shall not be held responsible for identifying any or all such patent rights.

International Standard IEC 62044-3 has been prepared by IEC technical committee 51:

Magnetic components and ferrite materials.
The text of this standard is based on the following documents:
FDIS Report on voting
51/573/FDIS 51/583/RVD

Full information on the voting for the approval of this standard can be found in the report on

voting indicated in the above table.

This publication has been drafted in accordance with the ISO/IEC Directives, Part 3.

Annexes A, B, C, D, and E are for information only.

IEC 62044, presented under the general title Cores made of soft magnetic materials –

Measuring methods, will include the following parts:
Part 1: Generic specification (under consideration)
Part 2: Magnetic properties at low excitation level (under consideration)
Part 3: Magnetic properties at high excitation level
Part 4: Non-magnetic properties (under consideration)
---------------------- Page: 9 ----------------------
SIST EN 62044-3:2002
62044-3 © IEC:2000 – 7 –

Part 3 is the first to be published. IEC 60367-1 and IEC 60367-2 will be cancelled after parts

1, 2 and 3 of IEC 62044 are published.

This standard cancels and replaces 11.2 and annex J of IEC 60367-1. The remaining clauses

of IEC 60367-1 will be replaced by IEC 62044-1 and IEC 62044-2.

The committee has decided that the contents of this publication will remain unchanged

until 2006. At this date, the publication will be
 reconfirmed;
 withdrawn;
 replaced by a revised edition, or
 amended.
---------------------- Page: 10 ----------------------
SIST EN 62044-3:2002
62044-3 © IEC:2000 – 9 –
CORES MADE OF SOFT MAGNETIC MATERIALS –
MEASURING METHODS –
Part 3: Magnetic properties at high excitation level
1 Scope

This standard provides 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 standard can cover the measurement of magnetic properties for

frequencies ranging practically from d.c. 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 standard 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

induction and field strength waveforms with only slightly degraded accuracy.

NOTE It may be necessary for some magnetically soft metallic materials to follow specific general principles,

customary for these materials, related to the preparation of specimens and prescribed calculations. These

principles are formulated in IEC 60404-8-6.
2 Normative references

The following normative documents contain provisions which, through reference in this text,

constitute provisions of this part of IEC 62044. For dated references, subsequent

amendments to, or revisions of, any of these publications do not apply. However, parties to

agreements based on this part of IEC 62044 are encouraged to investigate the possibility of

applying the most recent editions of the normative documents indicated below. For undated

references, the latest edition of the normative document referred to applies. Members of IEC

and ISO maintain registers of currently valid International Standards.

IEC 60050(221):1990, International Electrotechnical Vocabulary (IEV) – Chapter 221:

Magnetic materials and components
Amendment 1 (1993)
Amendment 2 (1999)
IEC 60205:1966, Calculation of the effective parameters of magnetic piece parts

IEC 60367-1:1982, Cores for inductors and transformers for telecommunications – Part 1:

Measuring methods

IEC 60401:1993, Ferrite materials – Guide on the format of data appearing in manufacturers’

catalogues of transformer and inductor cores

IEC 60404-8-6:1999, Magnetic materials – Part 8-6: Specifications for individual materials –

Soft magnetic metallic materials
IEC 61332:1995, Soft ferrite material classification
---------------------- Page: 11 ----------------------
SIST EN 62044-3:2002
62044-3 © IEC:2000 – 11 –
3 Terms, definitions and symbols
3.1 Definitions

For the purposes of this International Standard, the following definitions apply in addition to

those of IEC 60050(221).
3.1.1
µ ,
(effective) amplitude permeability (symbols: amplitude permeability:
effective amplitude permeability: µ )

magnetic permeability obtained from the peak value of the effective magnetic induction, B ,

and the peak value of the magnetic field strength, , at the stated value of either, when the

magnetic induction and magnetic field vary periodically with time and with an average of zero,

and the material is initially in a specified neutralized state
NOTE 1 This definition differs from that of IEC 60050 [221-03-07].
NOTE 2 Two amplitude permeabilities are in common use, namely:

– that in which the peak values apply to the actual waveforms of the induction and field strength,

– that in which the peak values apply to the fundamental components of waveforms of the induction

and the field strength.

NOTE 3 The induction and the field strength and, consequently, the amplitude permeability may even be quasi-

static quantities, provided the core is cyclically magnetized and no excursion of the B-H curve appears.

3.1.2
maximum (effective) amplitude permeability (symbol µ )
ea max

maximum value of the (effective) amplitude permeability when the amplitude of excitation

( B or H ) is varied
e e
NOTE This definition differs from that of IEC 60050 [221-03-10].
3.1.3
excitation

either induction or field strength for which the waveform and amplitude both remain within the

specified tolerance

NOTE When the induction (field strength) mode of excitation is chosen, the resultant waveform of field strength

(induction) may 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) and/or at which the power loss results in a noticeable temperature rise

(particularly at high frequencies)
3.1.5
sinusoidal excitation
excitation of harmonic content of less than 1 %
3.1.6
exciting winding

winding of measuring coil to which the exciting voltage is applied or through which the

exciting current is flowing
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SIST EN 62044-3:2002
62044-3 © IEC:2000 – 13 –
3.1.7
voltage sensing winding

unloaded winding of a measuring coil across which the electromotive force induced by the

excitation may be determined
3.1.8
measuring winding

winding, usually secondary, loaded or unloaded, which can be used for measurement apart

from the exciting and/or voltage sensing winding
3.1.9
power loss
power absorbed by the core
3.2 Symbols

All the formulae in this standard 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
B peak value of the effective induction in the core
f frequency
H peak value of the effective magnetic field strength in the core
l effective magnetic path length of the core
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
δ relative error, deviation, etc.
∆ absolute error, deviation, etc.
µ (effective) amplitude permeability
µ magnetic constant = 4π ×10 H/m
π the number 3,14159...
ϕ phase shift
ω angular frequency = 2πf

NOTE 1 Additional subscript, upper script, etc. gives a more specific meaning to the given symbol.

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.

NOTE 4 In the further text of this standard, the terms induction and field strength stand for the shortened terms

magnetic induction and magnetic field strength.
---------------------- Page: 13 ----------------------
SIST EN 62044-3:2002
62044-3 © IEC:2000 – 15 –
4 General precautions 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

appropriate to the effective induction B and the effective field strength H in the core.

e e

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 outer to 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

m c c

magnetic 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 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.

NOTE When winding a sharp-edge core, care should be taken to ensure that the wire insulation is not ruptured

and, in the case of stranded wire, strands are not broken.
---------------------- Page: 14 ----------------------
SIST EN 62044-3:2002
62044-3 © IEC:2000 – 17 –

4.2.2 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 induction 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 input(s) of measuring instruments.

NOTE When 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 should be galvanically separated from the voltage

and the current measuring instruments, for example, to avoid a floating or d.c. connection to

their inputs.

NOTE 1 When the exciting and voltage sensing windings are used, it is critical to make their magnetic coupling

coefficient as close to 100 % as possible.

NOTE 2 When the voltage needed for calculation of the induction in the core is measured across the voltage

sensing winding then only the power loss in the core is determined with the exclusion of the ohmic power loss in

the current-carrying (exciting) winding.
NOTE 3 The use of two windings is recommended at more than 200 kHz.
4.3 Mounting of cores consisting of more than one part

The core, which consists 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 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 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.

---------------------- Page: 15 ----------------------
SIST EN 62044-3:2002
62044-3 © IEC:2000 – 19 –

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 clause 3 of IEC 60367-1) for a time sufficient to allow any variation

of stress effects, due to clamping, gluing or taping, to become negligible.
4.4 Measuring equipment

Any suitable measuring equipment may be used. Examples of appropriate circuits are given in

annexes A to E.

In addition to any requirement specified for the particular method and/or measuring circuit

used, the following general requirements shall be met.

4.4.1 To ensure the induction (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.

4.4.2 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 clause 16 of IEC 60367-1 shall be met.

4.4.3 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.

4.4.4 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.

4.4.5 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

capacitance can reduce the load effects.

4.4.6 The accuracy of the voltmeters and/or voltage sensing instruments, determined for

the calibrating sinusoidal waveform, shall be within ±0,5 % for r.m.s. and average values and

±1 % for peak values, provided that the peak factor of waveforms to be measured is within

limits imposed by the instrument.

If inaccuracies exceed the above limits, only a sine-wave excitation of total harmonic

...

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