SIST EN 60404-15:2013

Magnetic materials - Part 15: Methods for the determination of the relative magnetic permeability of feebly magnetic materials

This part of IEC 60404 specifies a solenoid method, a magnetic moment method, a magnetic balance method and a permeability meter method for the determination of the relative magnetic permeability of feebly magnetic materials (including austenitic stainless steel). The magnetic balance and permeability meter methods are both comparison methods calibrated using reference materials to determine the value of the relative magnetic permeability of the test specimen. The relative magnetic permeability range for each of these methods is shown in Table 1. The methods given are for applied magnetic field strengths of between 5 kA/m and 100 kA/m. The solenoid method is the reference method. The magnetic moment method described is used mainly for the measurement of the relative magnetic permeability of mass standards. Two comparator methods used by industry are described. These can be calibrated using reference materials for which the relative magnetic permeability has been determined using the reference method. When suitable, the magnetic moment method can also be used. The dimensions of the reference material need to be given careful consideration when determining the uncertainty in the calibration value due to self-demagnetization effects. See Annex A for more information on correcting for self-demagnetization.

Magnetische Werkstoffe – Teil 15: Verfahren zur Bestimmung der Permeabilitätszahl schwachmagnetischer Werkstoffe

Matériaux magnétiques - Partie 15: Méthode de détermination de la perméabilité magnétique relative des matériaux faiblement magnétiques

La CEI 60404-15:2012 spécifie une méthode utilisant un solénoïde, une méthode utilisant le moment magnétique, une méthode utilisant une balance magnétique et une méthode utilisant un appareil de mesure de la perméabilité pour déterminer la perméabilité magnétique relative des matériaux faiblement magnétiques (y compris l'acier inoxydable austénitique). La méthode utilisant une balance magnétique et la méthode utilisant un appareil de mesure de la perméabilité sont toutes les deux des méthodes de comparaison étalonnées utilisant des matériaux de référence en vue de déterminer la valeur de la perméabilité magnétique relative de l'éprouvette.

Magnetni materiali - 15. del: Metode za ugotavljanje relativne magnetne permeabilnosti mehkomagnetnih materialov

Ta del standarda IEC 60404 določa elektromagnetno metodo, metodo magnetnega momenta, metodo magnetnega ravnotežja in metodo z merilnikom permeabilnosti za ugotavljanje relativne magnetne permeabilnosti mehkomagnetnih materialov (vključno z avstenitnim nerjavnim jeklom). Metodi z magnetnim ravnotežjem in merilnikom permeabilnosti sta primerjalni metodi, umerjeni z referenčnimi materiali, da se določi vrednost relativne magnetne permeabilnosti preskusnega vzorca. Razpon relativne magnetne permeabilnosti za posamezno metodo je naveden v preglednici 1. Navedene metode se uporabljajo pri magnetni poljski jakosti od 5 kA/m do 100 kA/m. Elektromagnetna metoda je referenčna metoda. Opisana metoda magnetnega momenta se uporablja predvsem za merjenje relativne magnetne permeabilnosti masnih standardov. Opisani sta primerjalni metodi, ki se uporabljata v industriji. Ti metodi se lahko umerita z referenčnimi materiali, katerih relativna magnetna permeabilnost je bila ugotovljena z referenčno metodo. Kadar je primerno, se lahko uporabi tudi metoda magnetnega momenta. Mere referenčnega materiala je treba zaradi učinkov razmagnetenja natančno upoštevati pri določanju negotovosti vrednosti za umerjanje. Za več informacij o popravljanju zaradi razmagnetenja glej dodatek A.

General Information

• Status: Published
• Publication Date: 21-Jan-2013
• ICS: 17.220.20 - Measurement of electrical and magnetic quantities
• ICS: 29.030 - Magnetic materials
• Technical Committee: I11 - Imaginarni 11
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 11-Jan-2013
• Due Date: 18-Mar-2013
• Completion Date: 22-Jan-2013
• Ref Project: EN 60404-15:2012 - Magnetic materials - Part 15: Methods for the determination of the relative magnetic permeability of feebly magnetic materials

Relations

• Amended By: SIST EN 60404-15:2013/A1:2017 - Magnetic materials - Part 15: Methods for the determination of the relative magnetic permeability of feebly magnetic materials (IEC 60404-15:2012/A1:2016)
• Effective Date: 19-Jan-2016

Standards Content (Sample)

SLOVENSKI STANDARD
SIST EN 60404-15:2013
01-marec-2013
Magnetni materiali - 15. del: Metode za ugotavljanje relativne magnetne
permeabilnosti mehkomagnetnih materialov
Magnetic materials - Part 15: Methods for the determination of the relative magnetic
permeability of feebly magnetic materials
Matériaux magnétiques - Partie 15: Méthode de détermination de la perméabilité
magnétique relative des matériaux faiblement magnétiques
Ta slovenski standard je istoveten z: EN 60404-15:2012
ICS:
17.220.20 0HUMHQMHHOHNWULþQLKLQ Measurement of electrical
PDJQHWQLKYHOLþLQ and magnetic quantities
29.030 Magnetni materiali Magnetic materials
SIST EN 60404-15:2013 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN 60404-15:2013

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SIST EN 60404-15:2013

EUROPEAN STANDARD
EN 60404-15

NORME EUROPÉENNE
November 2012
EUROPÄISCHE NORM

ICS 17.220.01; 29.030


English version


Magnetic materials -
Part 15: Methods for the determination of the relative magnetic
permeability of feebly magnetic materials
(IEC 60404-15:2012)


Matériaux magnétiques -  Magnetische Werkstoffe -
Partie 15: Méthodes de détermination de Teil 15: Verfahren zur Bestimmung der
la perméabilité magnétique relative des Permeabilitätszahl schwachmagnetischer
matériaux faiblement magnétiques Werkstoffe
(CEI 60404-15:2012) (IEC 60404-15:2012)





This European Standard was approved by CENELEC on 2012-10-23. 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, Former Yugoslav Republic of Macedonia, France, Germany,
Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland,
Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom.

CENELEC
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung

Management Centre: Avenue Marnix 17, B - 1000 Brussels


© 2012 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.
Ref. No. EN 60404-15:2012 E

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SIST EN 60404-15:2013
EN 60404-15:2012 - 2 -

Foreword
The text of document 68/442/FDIS, future edition 1 of IEC 60404-15, prepared by IEC/TC 68 "Magnetic
alloys and steels" was submitted to the IEC-CENELEC parallel vote and approved by CENELEC as
EN 60404-15:2012.

The following dates are fixed:
(dop) 2013-07-23
• latest date by which the document has
to be implemented at national level by
publication of an identical national
standard or by endorsement
• latest date by which the national (dow) 2015-10-23

standards conflicting with the
document have to be withdrawn

Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CENELEC [and/or CEN] shall not be held responsible for identifying any or all such patent
rights.

Endorsement notice
The text of the International Standard IEC 60404-15:2012 was approved by CENELEC as a European
Standard without any modification.

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SIST EN 60404-15:2013
- 3 - EN 60404-15:2012
Annex ZA
(normative)

Normative references to international publications
with their corresponding European publications

The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including any amendments) applies.

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 Series International electrotechnical vocabulary - -


ISO/IEC Guide 98-3 2008 Uncertainty of measurement - - -
Part 3: Guide to the expression of uncertainty
in measurement (GUM:1995)

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SIST EN 60404-15:2013

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SIST EN 60404-15:2013



IEC 60404-15

®


Edition 1.0 2012-09




INTERNATIONAL



STANDARD




NORME



INTERNATIONALE











Magnetic materials –

Part 15: Methods for the determination of the relative magnetic permeability of

feebly magnetic materials




Matériaux magnétiques –

Partie 15: Méthodes de détermination de la perméabilité magnétique relative des


matériaux faiblement magnétiques













INTERNATIONAL

ELECTROTECHNICAL

COMMISSION


COMMISSION

ELECTROTECHNIQUE

PRICE CODE
INTERNATIONALE

CODE PRIX S


ICS 17.220.01; 29.030 ISBN 978-2-83220-343-9



Warning! Make sure that you obtained this publication from an authorized distributor.

Attention! Veuillez vous assurer que vous avez obtenu cette publication via un distributeur agréé.

® Registered trademark of the International Electrotechnical Commission
Marque déposée de la Commission Electrotechnique Internationale

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SIST EN 60404-15:2013
– 2 – 60404-15  IEC:2012
CONTENTS
FOREWORD . 3
INTRODUCTION . 5
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 7
4 Solenoid and magnetic moment method . 7
4.1 General . 7
4.2 Principle . 7
4.3 Apparatus . 8
4.4 Test specimen for the solenoid method . 10
4.5 Procedure . 11
4.6 Calculation . 12
4.7 Uncertainty . 13
5 Magnetic balance method . 13
5.1 Principle . 13
5.2 Disc inserts and reference materials . 14
5.3 Test specimen . 14
5.4 Procedure . 15
5.5 Evaluation of the relative magnetic permeability . 15
5.6 Uncertainty . 15
6 Permeability meter method . 15
6.1 Principle . 15
6.2 Reference specimens and materials . 16
6.3 Test specimen . 17
6.4 Procedure . 17
6.5 Uncertainty . 17
7 Test report . 17
Annex A (informative) Correction for self-demagnetization . 18
Bibliography . 20

Figure 1 – Circuit diagram for the solenoid method . 8
Figure 2 – Coil system for the determination of the magnetic dipole moment . 9
Figure 3 – Magnetic balance: side view . 14
Figure 4 – Schematic of the permeability meter arrangement and magnetic field
distribution without and with test specimen . 16

Table 1 – Relative magnetic permeability ranges for the methods described . 6
Table 2 – Cylindrical sample with a 1:1 aspect ratio . 10
Table 3 – Circular cross section rod with an aspect ratio of 10:1 . 10

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SIST EN 60404-15:2013
60404-15  IEC:2012 – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________

MAGNETIC MATERIALS –

Part 15: Methods for the determination of the relative
magnetic permeability of feebly magnetic materials


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 in addition to other activities, IEC publishes International Standards, Technical Specifications,
Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC
Publication(s)”). 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. 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 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
Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
misinterpretation by any end user.
4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
transparently to the maximum extent possible in their national and regional publications. Any divergence
between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
the latter.
5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any
services carried out by independent certification bodies.
6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
members of its technical committees and IEC National Committees for any personal injury, property damage or
other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
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) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 60404-15 has been prepared by IEC technical committee 68:
Magnetic alloys and steels.
The text of this standard is based on the following documents:
FDIS Report on voting
68/442/FDIS 68/443/RVD

Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.

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SIST EN 60404-15:2013
– 4 – 60404-15  IEC:2012
A list of all the parts in the IEC 60404 series, under the general title Magnetic materials, can
be found on the IEC website.
The committee has decided that the contents of this publication will remain unchanged until
the stability date indicated on the IEC web site under "http://webstore.iec.ch" in the data
related to the specific publication. At this date, the publication will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.

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SIST EN 60404-15:2013
60404-15  IEC:2012 – 5 –
INTRODUCTION
The determination of the relative magnetic permeability of feebly magnetic materials is often
required to assess their effect on the ambient magnetic field. Typical feebly magnetic
materials are austenitic stainless steels and "non-magnetic" brass.
The relative magnetic permeability of some of these materials can vary significantly with the
applied magnetic field strength. In the majority of cases, these materials find application in the
ambient earth's magnetic field. This field in Europe is 35 A/m to 40 A/m, in the far East, it is
25 A/m to 35 A/m and in North America, it is 25 A/m to 35 A/m. However, at present, methods
of measurement are not available to determine the relative magnetic permeability of feebly
magnetic materials at such a low value of magnetic field strength.
Studies of the properties of feebly magnetic materials have been carried out, primarily with a
1
view to the production of improved reference materials. These studies have shown [1] that it
is possible to produce reference materials which have a substantially constant relative
magnetic permeability over the range from the earth's magnetic field to at least a magnetic
field strength of 100 kA/m.
Since conventional metallic materials can also be used as reference materials their relative
magnetic permeability can be determined using the reference method. It is important that the
magnetic field strength used during the determination of the relative magnetic permeability is
stated for all materials but in particular for conventional materials since the changes with
applied magnetic field can be large. This behaviour also needs to be considered when using
reference materials made from conventional materials to calibrate comparator methods. This
is because these methods use magnetic fields that vary through the volume of the material
being tested and this makes it difficult to know the relative magnetic permeability to use for
the calibration.
Where the effect of a feebly magnetic material on the ambient earth's magnetic field is critical,
the direct measurement of this effect using a sensitive magnetometer should be considered.

___________
1
 Figures in square brackets refer to the bibliography.

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SIST EN 60404-15:2013
– 6 – 60404-15  IEC:2012
MAGNETIC MATERIALS –

Part 15: Methods for the determination of the relative
magnetic permeability of feebly magnetic materials



1 Scope
This part of IEC 60404 specifies a solenoid method, a magnetic moment method, a magnetic
balance method and a permeability meter method for the determination of the relative
magnetic permeability of feebly magnetic materials (including austenitic stainless steel). The
magnetic balance and permeability meter methods are both comparison methods calibrated
using reference materials to determine the value of the relative magnetic permeability of the
test specimen. The relative magnetic permeability range for each of these methods is shown
in Table 1. The methods given are for applied magnetic field strengths of between 5 kA/m and
100 kA/m.
Table 1 – Relative magnetic permeability ranges for the methods described
Measurement method Relative magnetic permeability range
Solenoid 1,003 to 2
Magnetic moment 1,003 to 1,2
Magnetic balance 1,003 to 5
Permeability meter 1,003 to 2

NOTE 1 The relative magnetic permeability range given for the magnetic balance method covers the inserts
provided with a typical instrument. These can only be assessed at values for which calibrated reference materials
exist.
NOTE 2 For a relative magnetic permeability larger than 2, a reference material cannot be calibrated using this
written standard. A note of this is given in the test report explaining that the values measured using the magnetic
balance are for indication only.
The solenoid method is the reference method. The magnetic moment method described is
used mainly for the measurement of the relative magnetic permeability of mass standards.
Two comparator methods used by industry are described. These can be calibrated using
reference materials for which the relative magnetic permeability has been determined using
the reference method. When suitable, the magnetic moment method can also be used. The
dimensions of the reference material need to be given careful consideration when determining
the uncertainty in the calibration value due to self-demagnetization effects. See Annex A for
more information on correcting for self-demagnetization.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and
are indispensable for its application. 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 (available at

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SIST EN 60404-15:2013
60404-15  IEC:2012 – 7 –
ISO/IEC Guide 98-3:2008, Uncertainty of measurement – Part 3: Guide to the expression of
uncertainty in measurement (GUM:1995)
3 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 60050-221,
IEC 60050-121 as well as the following apply.
3.1
self-demagnetization
generation of a magnetic field within a magnetized body that opposes the magnetization
3.2
demagnetize
to bring a magnetic material to a magnetically neutral state
3.3
feebly magnetic material
material that is essentially non-magnetic in character
4 Solenoid and magnetic moment method
4.1 General
The methods that are described in Clause 4 are reference methods for determining the
relative magnetic permeability of test specimens of feebly magnetic materials with a length to
diameter ratio of at least 10:1. When the relative magnetic permeability is less than 1,2, it is
possible to use a moment detection coil and a test specimen with a length to diameter ratio of
1:1. Both methods use similar equipment and involve similar calculations to determine the
relative magnetic permeability. The descriptions of both methods are therefore presented
together here with significant differences explained in the text.
4.2 Principle
The relative magnetic permeability of a feebly magnetic test specimen is determined from the
magnetic polarization J and the corresponding magnetic field strength H measured using the
circuit shown in Figure 1, using
J
= 1+
μ
r
H
μ
0
 (1)
where
μ  is the relative magnetic permeability of the test specimen (ratio);
r
-7
μ is the magnetic constant (4π × 10 ) (in H/m);
0
J  is the magnetic polarization (in T);
H is the magnetic field strength (as calculated from the magnetizing current and the
magnetic field strength to current ratio (known as the coil constant) for the solenoid)
(in A/m).

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SIST EN 60404-15:2013
– 8 – 60404-15  IEC:2012

N
1
N
2
Test specimen
R S
A
F
E
IEC  1691/12

Key
A current measuring device or ammeter
E d.c. supply
F flux integrator
N solenoid
1
N search coil or magnetic moment detection coil
2
R variable resistor (controlling magnetizing current)
S switch
Figure 1 – Circuit diagram for the solenoid method
NOTE In Figure 1, the search coil N is replaced by a moment detection coil for the magnetic moment method.
2
4.3 Apparatus
4.3.1 Solenoid. The solenoid shall have a length to diameter ratio of not less than 10:1 or, in
the case of lower length, it shall contain coaxial supplementary coils at the ends or it shall
consist of a split pair coil system (Garrett [2]). The last two coil systems shall yield at least the
same degree of field homogeneity in the centre as is obtained with the long solenoid. The
coils shall be wound on non-magnetic, non-conducting formers. The winding shall have a
sufficient number of turns of wire to be capable of carrying a current that will produce a
magnetic field strength of 100 kA/m. The magnetic field to current ratio of the solenoid (known
as the coil constant) shall be determined with an uncertainty of ± 0,5 % or better, either by an
independent calibration or alternatively by measuring the magnetic field strength by means of
a calibrated Hall effect probe and by measuring the corresponding magnetizing current (using
the method described in 4.3.5).
NOTE 1 More than one solenoid (or split pair coil system) may be required to cover the complete range of
magnetic field strength.
NOTE 2 The optimal diameter of the solenoid depends upon the diameter of test specimens to be measured and
the sensitivity of the measurement. For measurements on bars up to 30 mm in diameter having a relative magnetic
permeability of 1,005, the internal diameter of the solenoid would be approximately 80 mm to accommodate the
requisite search coil.

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SIST EN 60404-15:2013
60404-15  IEC:2012 – 9 –
4.3.2 Search coil. The search coil shall be wound on a non-magnetic, non-conducting former.
Typically, for test specimens up to 30 mm in diameter, the internal diameter of the aperture in
the search coil is 32 mm to allow test specimens to be freely inserted and withdrawn. The
length of the winding shall be 40 mm; end cheeks of between 75 mm and 80 mm diameter
shall be fitted to the former. The winding can be, for example, 10 000 turns of 0,2 mm
diameter insulated wire with interleaving as necessary.
NOTE The winding may be tapped at intervals to facilitate the adjustment of the sensitivity of the measuring
system when determining the relative magnetic permeability of test specimens in the higher part of the permeability
range.
4.3.3 For much shorter solid right cylinders with a length to diameter ratio of 1:1, a moment
detection coil with a homogeneous sensitivity over the volume of the test specimen shall be
used for measuring the magnetic dipole moment of the cylinder (see Figure 2). The magnetic
polarization is calculated from
j
 J= (2)
V
where
j is the magnetic dipole moment (in Wbm);
3
V is the volume of the test specimen (in m ).
The moment detection coil can be a solenoid with additional homogenizing windings close to
the ends of the coil.

Test specimen
Moment detection coil
Compensation coil
Magnetizing solenoid
IEC  1692/12

Figure 2 – Coil system for the determination
of the magnetic dipole moment
The measurement of the magnetic moment of short cylinders with a length to diameter ratio of
1:1 shall be restricted to materials having a relative permeability smaller than μ = 1,2. If this
r
condition is not met, the magnetic field strength inside the test specimen and the polarization
become inhomogeneous and this will produce significant errors in the measured relative
magnetic permeability.
In the region μ = 1,003 to 1,2, a linear correction for the effect of the self-demagnetizing field
r
is appropriate. See Annex A for more information.
NOTE Typically, weight pieces of the classes E , E and F according to OIML R111-1 (2004) [3] fall into this
1 2 1
range.
For this correction, equation (A.2) of Annex A is to be used together with the value of the
magnetometric self-demagnetization factor N as obtained from reference [6].
m
For example, for a cylindrical sample with a 1:1 aspect ratio, values of the relative correction
to the applied magnetic field for different relative magnetic permeabilities due to self-
demagnetization are given in Table 2.

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SIST EN 60404-15:2013
– 10 – 60404-15  IEC:2012
Table 2 – Cylindrical sample with a 1:1 aspect ratio
µ N ∆H/H
r m
1,000 1 0,311 6 0,003 %
1,007 0,311 4 0,22 %
1,2 0,309 3 6,2 %

ΔH/H is the relative correction of the magnetic field strength and N is the magnetometric

m
self-demagnetization factor.
This is discussed in more detail in Annex A.
4.3.4 Flux integrator. The flux integrator shall be an electronic charge integrator or similar
device, calibrated with an uncertainty of ± 0,5 % or better.
4.3.5 Current measuring device. The current measuring device shall consist of a calibrated
resistor connected in series with the magnetizing circuit and a calibrated digital voltmeter.
The magnetizing current shall be determined from the measurement of the voltage developed
across the resistor. The combined uncertainties of the resistor and voltmeter shall be such
that the magnetizing current can be determined with an uncertainty of ± 0,2 % or better.
Alternatively, an ammeter calibrated with an equivalent uncertainty can be used.
4.3.6 Micrometer. The micrometer for measuring the transverse dimensions of the test
specimen for the solenoid method shall be calibrated. For the magnetic moment method, the
volume is required and appropriate dimensional measurements shall be made.
4.4 Test specimen for the solenoid method
The test specimen shall consist of a round or rectangular bar, or a number of strips or wires
2
having a total cross-sectional area of at least 100 mm . The maximum cross-sectional area
shall be determined by the diameter of the central aperture of the search coil. Allowance shall
be made for the easy insertion and withdrawal of the test specimen without disturbing the
position of the search coil.
To avoid significant errors introduced by self-demagnetization, the length to equivalent
diameter ratio of the test specimen shall be not less than 10:1. When corrections for self-
demagnetization are required see Annex A.
For example, values are given in Table 3 for a rod of circular cross section with an aspect
ratio of 10:1, a diameter of 30 mm and a search coil with an effective average diameter of
52,2 mm. The relative corrections to the applied magnetic field strength and the magnetic
polarization for different relative magnetic permeabilities due to self-demagnetization are
shown.
Table 3 – Circular cross section rod with an aspect ratio of 10:1
µ N ∆H/H ∆J/J
r f
1,000 1 0,004 927 0,000 % 1,49 %
1,007 0,004 931 0,003 % 1,49 %
1,2 0,005 054 0,101 % 1,53 %
2 0,005 541 0,554 % 1,68 %

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SIST EN 60404-15:2013
60404-15  IEC:2012 – 11 –
ΔH/H is the relative cor
...