IEC 60404-15:2012

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

IEC 60404-15:2012 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.

Matériaux magnétiques - Partie 15: Méthodes 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.

General Information

• Status: Published
• Publication Date: 17-Sep-2012
• ICS: 01 - GENERALITIES. TERMINOLOGY. STANDARDIZATION. DOCUMENTATION
• ICS: 17.220.01 - Electricity. Magnetism. General aspects
• ICS: 29.030 - Magnetic materials
• Technical Committee: TC 68 - Magnetic alloys and steels
• Drafting Committee: WG 2 - TC 68/WG 2
• Current Stage: PPUB - Publication issued
• Start Date: 30-Sep-2012
• Completion Date: 18-Sep-2012

Relations

• Amended By: IEC 60404-15:2012/AMD1:2016 - Amendment 1 - Magnetic materials - Part 15: Methods for the determination of the relative magnetic permeability of feebly magnetic materials
• Effective Date: 05-Sep-2023

Standards Content (Sample)

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
IEC 60404-15:2012

---------------------- Page: 1 ----------------------
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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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– 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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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
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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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– 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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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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– 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

---------------------- Page: 8 ----------------------
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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– 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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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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– 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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60404-15  IEC:2012 – 11 –
ΔH/H is the relative correction of the magnetic field strength, N is the fluxmetric self-

f
demagnetization factor and ΔJ/J is the relative correction of the magnetic polarization.
This is discussed in more detail in Annex A.
4.5 Procedure
4.5.1 The cross-sectional area of the test specimen shall be established from a number of
measurements of each dimension. For a test specimen for the solenoid method, the diameter
or transverse dimensions shall be measured by means of a calibrated micrometer (see 4.3.6)
at approximately 10 mm intervals along the central 40 mm of length. The mean cross-
sectional area, expressed in square metres, shall be calculated from the mean dime
...