IEC 60404-16:2018

IEC 60404-16 ®
Edition 1.0 2018-03
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Magnetic materials –
Part 16: Methods of measurement of the magnetic properties of Fe-based
amorphous strip by means of a single sheet tester

Matériaux magnétiques –
Partie 16: Méthodes de mesure des propriétés magnétiques des bandes en
alliage amorphe à base de fer à l'aide de l'essai sur tôle unique

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IEC 60404-16 ®
Edition 1.0 2018-03
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Magnetic materials –
Part 16: Methods of measurement of the magnetic properties of Fe-based

amorphous strip by means of a single sheet tester

Matériaux magnétiques –
Partie 16: Méthodes de mesure des propriétés magnétiques des bandes en

alliage amorphe à base de fer à l'aide de l'essai sur tôle unique

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 17.220.20; 29.030 ISBN 978-2-8322-5426-4

– 2 – IEC 60404-16:2018 © IEC 2018
CONTENTS
FOREWORD . 4
INTRODUCTION . 6
1 Scope . 7
2 Normative references . 7
3 Terms and definitions . 7
4 General principles . 8
4.1 Principle of the method . 8
4.2 Test specimen . 9
4.3 Test apparatus . 9
4.3.1 General . 9
4.3.2 Yoke . 10
4.3.3 Windings . 10
4.3.4 Air flux compensation . 11
4.3.5 Magnetic shielding . 11
4.4 Power supply . 11
4.5 Measuring instruments . 12
4.6 Digital sampling technique . 12
5 Measurement procedure . 13
5.1 Principle of measurement. 13
5.2 Preparation of measurement . 13
5.3 Adjustment of power supply . 14
6 Determination of characteristics . 14
6.1 Determination of the magnetic polarization . 14
6.2 Determination of the magnetic field strength . 15
6.3 Determination of the specific total loss . 15
6.4 Determination of the specific apparent power . 16
7 Reproducibility . 16
Annex A (informative) Requirements of the single sheet tester for Fe-based
amorphous strip . 17
A.1 Shape of test specimen . 17
A.2 H coil method . 17
A.3 Yoke . 17
A.4 Wirings . 17
A.5 Non-inductive precision resistor . 18
A.6 Magnetic shielding . 18
A.7 Method for checking the stability of the installed H coil from time to time . 18
Annex B (informative) Digital sampling technique for the determination of the
magnetic properties and numerical air flux compensation . 19
B.1 General . 19
B.2 Technical details and requirements . 19
B.3 Calibration aspects . 22
B.4 Numerical air flux compensation . 22
Annex C (informative) Sinusoidal waveform control of the magnetic polarization by
digital means . 24
Bibliography . 26

Figure 1 – Schematic diagram of the test apparatus. 8
Figure 2 – Circuit of the wattmeter method with H coil mode . 9
Figure 3 – Yoke dimensions . 10
Figure 4 – Circuit of the wattmeter method with H coil mode adopting the digital
sampling technique . 12

– 4 – IEC 60404-16:2018 © IEC 2018
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
MAGNETIC MATERIALS –
Part 16: Methods of measurement of the magnetic properties of
Fe-based amorphous strip by means of a single sheet tester

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
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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 60404-16 has been prepared by IEC technical committee 68:
Magnetic alloys and steels.
The text of this International Standard is based on the following documents:
CDV Report on voting
68/570/CDV 68/583A/RVC
Full information on the voting for the approval of this International Standard can be found in
the report on voting indicated in the above table.
This document has been drafted in accordance with the ISO/IEC Directives, Part 2.
A list of all parts in the IEC 60404 series, published under the general title Magnetic materials,
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 "http://webstore.iec.ch" in the data related to
the specific document. At this date, the document will be
 reconfirmed,
 withdrawn,
 replaced by a revised edition, or
 amended.
The contents of the corrigendum of Novembre 2018 have been included in this copy.

– 6 – IEC 60404-16:2018 © IEC 2018
INTRODUCTION
A method of measuring the magnetic properties of Fe-based amorphous strip is required to
grade what is regarded as a promising material to reduce energy loss in transformer cores
and, consequently, to reduce global warming.
Fe-based amorphous strip is produced by a rapidly-solidifying, direct-casting process. The
strip is intended primarily for the construction of wound cores of distribution transformers for
commercial power frequency (50 Hz and 60 Hz) applications.
After appropriate heat treatment, the strip exhibits a significantly lower value of specific total
loss compared to grain-oriented electrical steel strip. It is associated with low hysteresis loss
due to low magnetic anisotropy and low eddy current loss due to high resistivity and reduced
thickness. However, significant deterioration can occur by applying stress on the strip due to
the large magnetostriction and low magnetic anisotropy characteristics of the material.
Therefore, a method of measurement of the magnetic properties of Fe-based amorphous strip
by means of a single sheet tester (SST) is required, independent of IEC 60404-3 [1] , which is
specified for electrical steel sheets.
The almost exclusively applied wattmeter method is used also in this standard. However, the
widely used version with the determination of the magnetic field strength from the magnetizing
current (“MC method”) is not applicable to this kind of material, because the influence of the
yokes on the loss measurement is significantly greater for the thinner and magnetically softer
test specimen of this material. Thus, the wattmeter method with H coil mode (“H coil method”)
has been included for the magnetic field determination. International round robin tests of SST
and Fe-based amorphous test specimens have been carried out, resulting in a suitable
configuration of the SST for amorphous material. The single-yoke concept was adopted in
order to avoid the effect of the impact of the upper yoke caused by the high magneto-elastic
sensitivity of the material.
___________
Numbers in square brackets refer to the Bibliography.

MAGNETIC MATERIALS –
Part 16: Methods of measurement of the magnetic properties of
Fe-based amorphous strip by means of a single sheet tester

1 Scope
This part of IEC 60404 is applicable to Fe-based amorphous strips specified in IEC 60404-8-
11 for the measurement of AC magnetic properties at frequencies up to 400 Hz.
The object of this part is to define the general principles and technical details of the
measurement of the magnetic properties of Fe-based amorphous strips by means of a single
sheet tester.
The single sheet tester is applicable to test specimens obtained from Fe-based amorphous
strips of any quality. The AC magnetic characteristics are determined for a sinusoidal induced
voltage, for specified peak values of magnetic polarization and for a specified frequency.
The measurements are made at an ambient temperature of (23 ± 5) °C on test specimens
which have first been demagnetized.
NOTE 1 The single sheet tester specified in this document is appropriate for other materials which have magnetic
properties and physical characteristics similar to those of Fe-based amorphous strip, such as nano-crystalline soft
magnetic strip. The single sheet tester for electrical steel sheets is specified in IEC 60404-3.
NOTE 2 Throughout this document the term “magnetic polarization” is used as described in IEC 60050-121. In
some standards of the IEC 60404 series, the term “magnetic flux density” is used.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their
content constitutes requirements of this document. For dated references, only the edition
cited applies. For undated references, the latest edition of the referenced document (including
any amendments) applies.
IEC 60050-121, International Electrotechnical Vocabulary – Part 121: Electromagnetism
IEC 60050-221, International Electrotechnical Vocabulary – Chapter 221: Magnetic materials
and components
IEC 60404-8-11, Magnetic materials – Part 8-11: Specifications for individual materials –
Fe-based amorphous strip delivered in the semi-processed state
3 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 60050-121 and
IEC 60050-221 apply.
ISO and IEC maintain terminological databases for use in standardization at the following
addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp

– 8 – IEC 60404-16:2018 © IEC 2018
4 General principles
4.1 Principle of the method
This document applies the wattmeter method with H coil mode for the determination of the
magnetic field strength (“H coil method”). The flux closure is made by a single “U”-shaped
yoke.
The test specimen comprises a Fe-based amorphous strip, which is placed inside the
following two windings:
– an exterior primary winding (magnetizing winding);
– an interior secondary winding (induced voltage winding).
A H coil that detects the magnetic field strength at the surface of the test specimen is placed
under the test specimen.
The flux closure is made by a single vertical “U” shaped yoke, the cross-section of which is
very large compared with that of the test specimen (see Figure 1).
Windings
Test specimen
Yoke
IEC
Figure 1 – Schematic diagram of the test apparatus
NOTE 1 Double yokes are unsuitable because the influence of the loading of an upper yoke on the test specimen
is significant due to the large magnetostriction of the material. However, the upper yoke can be placed on the lower
yoke in the absence of the test specimen to demagnetize yokes and to measure the power loss in the yokes.
The circuit diagram of Figure 2 illustrates the principle of the wattmeter method with H coil
mode. The single sheet tester and the measuring instruments shall be connected as shown in
Figure 2.
NOTE 2 Figure 2 also sets out the fundamentals of the widely used digital sampling technique, where the
instrument functions are realised partly, or fully, through evaluating software. For the application of the digital
sampling technique, see 4.6 and Annex B. Figure 2 does not show the feed-back circuit for the waveform control of
the induced secondary voltage (see 4.4 and Annex C).

N N
1 2
V
Hz
W
dH
H
dt ⇒ H
∫
dt
IEC
Key
~ power supply
Hz frequency meter
N primary winding
N secondary winding
H H coil
V voltmeter
integrator
W wattmeter
Figure 2 – Circuit of the wattmeter method with H coil mode
NOTE 3 The voltage induced in the H coil, U (t), can be used for the air flux compensation in different ways (see
H
4.3.4 and Clause B.4) and for the digital sinusoidal waveform control of the induced secondary voltage, U (t) (see
5.3 and Annex C) .
4.2 Test specimen
The test specimen shall be sampled in accordance with IEC 60404-8-11.
NOTE Nominal widths of Fe-based amorphous strip are 142,2 mm, 170,2 mm and 213,4 mm (see IEC 60404-8-
11).
The length of the test specimen shall be no less than 280 mm, which is the outside dimension
of the distance across the pole faces of the yoke. Although the part of the specimen situated
outside the pole faces has no great influence on the measurement, this part shall not be
longer than is necessary to facilitate insertion and removal of the test specimen.
The test specimen shall be cut to length from Fe-based amorphous strip without the formation
of excessive burrs or mechanical distortion. The test specimen shall be plane and rectangular.
The test specimen shall be prepared by a magnetic anneal in a DC magnetic field directed
parallel to the casting direction according to the instructions of the manufacturer. The test
specimen shall be flat during the treatment.
Care shall be taken in handling the test specimen after the treatment in order to avoid raising
fragments of the strip or creating mechanical stresses in the test specimen because the
material is usually brittle after heat treatment.
4.3 Test apparatus
4.3.1 General
The test apparatus comprises the windings and the yoke (see Figure 1).

– 10 – IEC 60404-16:2018 © IEC 2018
Care shall be taken to ensure that temperature changes are kept below a level likely to
produce stress in the test specimen due to the distribution of thermal expansion or contraction.
4.3.2 Yoke
The yoke is in the form of a letter U built by using soft ferrite (see Figure 3). It should have a
low magnetic remanence, a low reluctance and a specific total loss as low as possible.
NOTE 1 Lower quality of yoke materials can lead to poor measurement quality and to misleading results of the
magnetic properties of the test specimen accordingly (see Annex A).
Dimensions in millimetres
IEC
Figure 3 – Yoke dimensions
The yoke shall have pole faces having a width of 20 mm ± 1 mm.
The two pole faces of the yoke shall be as flat as possible and coplanar to within 0,1 mm.
Also, the yoke shall be rigid in order to avoid creating mechanical stresses in the test
specimen.
The height of the yoke shall be between 80 mm and 120 mm. The yoke shall have a width of
220 mm ± 1 mm and an inside length of 240 mm ± 1 mm (see Figure 3).
Other yoke dimensions may be used provided that comparability of the results can be
demonstrated.
NOTE 2 The power loss dissipated in the yoke can be measured by making a magnetic closure circuit consisting
of the yoke and a matching upper yoke that are wound with primary and secondary windings; 25 turns are sufficient
for each winding.
There shall be a specimen support, which is made of non-conductive and non-magnetic
materials, between the vertical limbs of the yokes. The surface of the support, on which the
test specimen is supported, shall be in the same plane with the pole faces so that the test
specimen can contact the pole faces with minimum air gaps.
NOTE 3 If there are steps between the surface of the test support plane and the pole faces, deteriorated magnetic
properties are measured.
4.3.3 Windings
The primary winding shall be at least 230 mm in length. The secondary winding shall be
120 mm ± 1 mm in length and centred in the primary winding. The primary and secondary
windings shall be wound on a non-conducting, non-magnetic and rectangular former. The
dimensions of the former shall be as follows:
– length for winding: 235 mm ± 5 mm;
– internal height: 3 mm ± 1 mm;
– external height: ≤ 15 mm; the value of 12 mm is recommended.
<0,1
The primary winding can be made up of a single continuous and uniform winding taking up the
whole length. One example of the winding is made up of 220 turns of copper wire 1 mm in
diameter taking up the whole length, wound in one or more layers.
The secondary winding shall be made up of a single continuous and uniform winding taking up
the length of 120 mm ± 1 mm, wound in one layer. The number of turns on the secondary
winding depends on the characteristics of the measuring instruments.
The H coil shall have the same length as the secondary winding and be centred in the primary
winding. The H coil shall be wound on a non-conducting, non-magnetic and rectangular plate.
The width of the plate shall be 120 mm ± 1 mm and the height of the plate shall be
3 mm ± 0,2 mm.
The H coil shall be embedded in the specimen support plate and the distance between the
upper surface of the support plate and the upper surface of the H coil shall be 1 mm ± 0,2 mm.
The area-turns of the H coil shall be calibrated in a uniform field using a solenoid coil of a
diameter and length large enough to obtain a uniform field over the volume of the H coil.
4.3.4 Air flux compensation
Compensation of the effect of air flux on the induced secondary voltage shall be made.
This can be achieved, for example, by the numerical air flux compensation method (see
Clause B.4).
4.3.5 Magnetic shielding
A simple magnetic shielding of the single sheet tester is recommended to weaken sufficiently
the effects of geomagnetic and other external magnetic fields in order to avoid unexpected
magnetization of the test apparatus (see Annex A).
4.4 Power supply
The power supply should consist of a computer-controlled arbitrary signal generator and a
power amplifier, or an instrument integrating both of these functions (see Figure 4).
The arbitrary signal generator shall synthesize a signal of magnetizing waveform, amplitude
and frequency data, which are programmed externally. A low pass filter should be inserted
between the arbitrary signal generator and the power amplifier to prevent aliasing at the
measuring instruments.
The frequency shall be measured with an accuracy of ±0,1 % or better.
The waveform of the induced secondary voltage shall be maintained as sinusoidal as possible.
It is preferable not only to maintain the form factor of the induced secondary voltage to within
1,111 with a relative tolerance of ±1 %, but also to suppress harmonic contents in the induced
secondary voltage to as low as possible. This can be achieved by various means, using
analogue feedback control or by digital means described in Annex C.
The power amplifier shall be of low internal impedance and shall be highly stable in terms of
voltage and frequency, being with sufficiently low voltage noise. During the measurement, the
voltage and frequency shall be maintained constant within ±0,2 %.
The power amplifier should be a bipolar type with low noise and wide ranges of frequency and
voltage.
– 12 – IEC 60404-16:2018 © IEC 2018
4.5 Measuring instruments
The measuring instruments shall meet the following specifications: The power shall be
measured with an accuracy of ±0,5 % or better at the actual power factor and crest factor.
The voltages shall be measured with an accuracy of ±0,5 % or better.
4.6 Digital sampling technique
The fundamental circuit of the digital sampling technique, almost exclusively used for this kind
of measurement, is shown in Figure 4, in this case employing the H coil combined with the
integrator for the determination of the magnetic field strength (for technical details see also
Annex B). The measuring instrument is usually composed of preamplifiers, a digitizer and a
digital signal calculator, and provides the functions of the wattmeter and voltmeter shown in
Figure 2 in the software.
T
1 dJ
(H )dt ⇒ P
∫
T dt
N1 N2
Hz
U dt ⇒ H(t)
H
∫
H
U dt ⇒ J(t)
∫
Measuring instrument
IEC
Key
~ power supply
Hz frequency meter
N primary winding
N secondary winding
H H coil
U (t) voltage induced in the secondary winding
U (t) voltage induced in the H coil

H
H-integrator function of software
J-integrator function of software
wattmeter and voltmeter functions of software
T
Figure 4 – Circuit of the wattmeter method with H coil mode adopting
the digital sampling technique
NOTE 1 The numerical air flux compensation, J = B - µ x H, is not presented in Figure 4 but is included in the
software, see 4.3.4. Figure 4 does also not show the possible analogue feed-back circuit for the waveform control
of the induced secondary voltage (see 4.4). The waveform control can also be managed by digital means (see the
paragraph before the last one in 4.6 and Annex C).
The following signals shall be measured:
U (t) U (t)
H 2
– the voltage induced in the secondary winding, U (t);
– the voltage induced in the H coil, U (t);
H
The data set of signals U (t) and U (t) sampled over one period of magnetization provides the
H 2
complete information for one measurement.
The magnetic field strength H(t), the magnetic polarization J(t), the specific total loss P and
s
the specific apparent power S shall be calculated from U (t) and U (t) by the function of the
s H 2
field measuring devices and the wattmeter in the measuring instrument, see Clause 6.
The measuring instrument using the digital sampling technique is comprised of calibrated
preamplifiers for each signal channel, a calibrated digitizer and a digital signal calculator. The
measuring instrument has two independent signal channels corresponding to U (t) and U (t)
2 H
working simultaneously with a sampling clock that is synchronized with the readout clock of
the arbitrary signal generator. Unsynchronized sampling is also used; however, a higher
sampling rate is then required to achieve the same accuracy (see Annex B).
The signal channels shall have sufficiently high input impedance (typically > 1 MΩ in parallel
with about 100 pF) to avoid the load on the secondary winding. The phase shift difference
between the channels shall be sufficiently small even at the lowest power factor.
The digital signal calculator calculates the magnetic properties through the evaluating
software.
The digital signal calculator may create the digital feedback signal to feed into the arbitrary
signal generator for the sinusoidal waveform control of the magnetic polarization by digital
means (see Annex C).
The instrument specifications established in 4.5 shall also be applied to the digital sampling
technique.
NOTE 2 For the technical details and requirements of the digital sampling technique, see Annex B.
5 Measurement procedure
5.1 Principle of measurement
The apparatus and the windings shall be connected as shown in Figure 2 or Figure 4, as
applicable.
If the digital sampling technique is employed, the voltage induced in the secondary winding
U (t) and the voltage induced in the H coil U (t) shall be measured as time functional signals.
2 H
The magnetic field strength H(t), the magnetic polarization J(t), the specific total loss P and
s
the specific apparent power S shall be calculated from U (t) and U (t).
s H 2
NOTE For the technical details and requirements of the digital sampling technique, see Annex B.
5.2 Preparation of measurement
The length of the test specimen and its mass shall be measured with an accuracy of ±0,1 %.
The test specimen shall be loaded and centred on the longitudinal and transverse axes of the
windings.
The cross-sectional area of the test specimen shall be calculated from Formula (1).

– 14 – IEC 60404-16:2018 © IEC 2018
m
(1)
A
l
m
where
A is the cross-sectional area of the test specimen, in square metres;
is the mass of the test specimen, in kilograms;
m
l is the length of the test specimen, in metres;
 is the density of the test material, in kilograms per cubic metre.
m
Prior to measurement, the test specimen shall be carefully demagnetized from well above the
value of magnetic field strength to be measured, by slowly reducing the corresponding
magnitude of the alternating magnetizing current to zero.
5.3 Adjustment of power supply
ˆ
In practice, single or grouped peak values of magnetic polarization and magnetic field
J
ˆ
strength are set at a specified frequency.
H
For the measurements of the specific total loss P , the specific apparent power S , r.m.s.
s s
~
ˆ
value of magnetic field strength and the peak value of the magnetic field strength , the
H H
ˆ
peak value of magnetic polarization J shall be set by adjusting the power supply.

ˆ
For the measurement of the peak value of magnetic polarization J , the peak value of
ˆ
magnetic field strength H shall be set.
ˆ ˆ
The values of H and shall be calculated from U (t) and U (t) measured over one or several
J
H 2
periods of magnetization respectively, using formulas corresponding to Formulas (2) and (3),
respectively.
ˆ ˆ
The output of the power supply shall be slowly increased until or has reached the desired
J H
value. The output of the power supply shall not decrease during the measurement.
The waveform of the induced secondary voltage U (t) should be checked to ensure that only
the fundamental component is present. In addition, the shape of the hysteresis loop
composed of H(t) and J(t) should be checked to ensure that a symmetrical loop is presented.
6 Determination of characteristics
6.1 Determination of the magnetic polarization
The magnetic polarization J (t) shall be calculated from Formula (2).
t Tt

11
(2)
J(tU)()ddU ()dt



NA T
2000


where
J(t) is the magnetic polarization, in teslas;
N is the number of turns of the secondary winding;
A is the cross-sectional area of the test specimen, in square metres;
U (t) is the induced secondary voltage, in volts;
τ is an auxiliary time variable.

The second term in the brackets of Formula (2) is the time average over the length of a period
which compensates for the integration constant.
6.2 Determination of the magnetic field strength
The magnetic field strength H(t) shall be calculated from Formula (3).
t Tt


11
Ht()U()ddU()dt (3)


HH


 NA T

0HH
000

where
H(t) is the magnetic field strength, in amperes per metre;
7
 is the magnetic constant (4   10 henrys per metre);
(N A ) is the area-turns of the H coil, in square metres;
H H
U (t) is the voltage induced in the H coil, in volts;
H
τ is an auxiliary time variable.
The second term in the brackets of Formula (3) is the time average over the length of a period
which compensates for the integration constant.
NOTE For the determination of the area-turns of H coil, see 4.3.3.
6.3 Determination of the specific total loss
The specific total loss P , corresponds to the area of the hysteresis loop formed by the
s
magnetic field strength H(t) and the magnetic polarization J(t), and shall be calculated from
Formula (4).
T T
f
f dJ(t)
(4)
P  H(t) dt H(t)U (t)dt
s 2c
 
 dt  N A
m t0 m 2 t0
where
P is the specific total loss of the test specimen, in watts per kilogram;
s
 is the conventional density of the test material, in kilograms per cubic metre;
m
f is the frequency of the magnetization, in hertz;
T is the magnetizing period where T = 1 / f , in seconds;
N is the number of turns of the secondary winding;
A is the cross-sectional area of the test specimen, in square metres;
H(t) is the magnetic field strength, in amperes per metre;
J(t) is the magnetic polarization, in teslas;
U (t) is the air flux compensated induced secondary voltage, in volts.
2c
NOTE 1 For the air flux compensation, J = B - µ x H, see 4.3.4.
T
dJ(t)
NOTE 2 In the first integral of Formula (4), , B was replaced by J because the contribution of the
H(t) dt

dt
t0
T
dH(t)
air flux, the integral , is zero.
H(t) dt

dt
t0
– 16 – IEC 60404-16:2018 © IEC 2018
6.4 Determination of the specific apparent power
The specific apparent power S shall be calculated from Formula (5).
s
1 ~ ~
(5)
S = 2πf H ⋅ J
s
ρ
m
where
S is the specific apparent power of the test specimen, in volt-amperes per kilogram;
s
f is the frequency of the magnetization, in hertz;
ρ is the conventional density of the test material, in kilograms per cubic metres;
m
~
H is the r.m.s. value of magnetic field strength , in amperes per metre;
H (t)
~
J is the r.m.s. value of magnetic polarization , in teslas.
J (t)
7 Reproducibility
The reproducibility of this method using the test apparatus defined above is characterized by
a relative standard deviation of 3 % or less for the specific total loss at 1,3 T and 1,4 T, about
1 % for the peak value of magnetic polarization at 80 A/m, and about 6 % for the specific
apparent power at 1,3 T and 1,4 T.

Annex A
(informative)
Requirements of the single sheet tester for Fe-based amorphous strip
A.1 Shape of test specimen
The test specimen should be kept flat in the test apparatus. The magnetic properties of
Fe-based amorphous strip can be deteriorated significantly with a small deformation of its
shape because of the high magnetoelastic sensitivity of the material.
The test method using a toroidal test specimen in accordance with IEC 60404-6 [2] is
unsuitable because a small change in diameter of the test specimen is usually unavoidable
and then deteriorated magnetic properties may be obtained.
A.2 H coil method
The wattmeter method with the determination of the magnetic field strength from the
magnetizing current (“MC method”), measures magnetic properties including the effects of the
yoke. Thus, this combination is unsuitable for thin and low loss materials such as Fe-based
amorphous strip. In contrast, the wattmeter method with H coil mode (“H coil method”),
measures only the magnetic properties of test specimen at the area apart from the pole faces
of yoke. Therefore, the loss values measured using the MC method are usually indicated
higher than the values when the H coil method is used.
To apply the H coil method, a key point is to connect one terminal of the signal from the H coil
and one terminal of the signal from the secondary winding as shown in Figure 4. It results in
an effective reduction of high frequency noise on the signal of the H coil. Larger area-turns of
the H coil and amplification of the H coil signal by a high quality preamplifier with low noise
and low phase shift are also key points. A preamplifier powered by a clean DC power source
is preferential in order to be free from power frequency noise.
Synchronous averaging of the signals over several periods is effective to remove noise on the
signals except the noise of power frequency when the frequency of the magnetization is the
same as the power frequency.
A.3 Yoke
The yoke material has low magnetic remanence and low values of specific total loss at low
magnetization to reduce DC bias of magnetization of the test specimen. Soft ferrite is suitable
for the yoke material.
A single yoke is more suitable than double yokes. The magnetic properties of Fe-based
amorphous strip are very sensitive to stress. The upper yoke will apply stress in the parts of
the test specimen near the pole faces of the yokes, and, as a result, the magnetic properties
become deteriorated. Moreover, the large magnetostriction of Fe-based amorphous material
causes compressive stress in the material if both ends of the test specimen are clamped
between the pole faces of the yokes. These effects
...