IEC 60404-11:2021
(Main)Magnetic materials - Part 11: Methods of measurement of the surface insulation resistance of electrical steel strip and sheet
Magnetic materials - Part 11: Methods of measurement of the surface insulation resistance of electrical steel strip and sheet
IEC 60404-11:2021 is applicable to electrical steel strip and sheet insulated by coating on one or both sides.
The object of this document is to define the general principles and technical details of the measurement of the surface insulation resistance of electrical steel strip and sheet.
NOTE This test is suitable for manufacturing and quality control in the application of insulation coatings.
This edition includes the following significant technical changes with respect to the previous edition:
Method B has been deleted and the measurement of individual currents through each contact button is enabled by Method A;
an improved arrangement of the test apparatus and the voltage stabilizing circuit for Method A, “Arrangement B”, is introduced.
an alternative layout using two pairs of contact assemblies in opposing position of the test specimen is introduced;
the restriction: “The same area of the test specimen shall not be used to test both sides.” has been deleted.
Matériaux magnétiques - Partie 11: Méthodes de mesurage de la résistance d'isolement superficiel des bandes et tôles en acier électrique
L'IEC 60404-11:2021 s'applique aux bandes et tôles en acier électrique isolées par un revêtement sur une seule face ou sur les deux faces.
Le présent document a pour objet de définir les principes généraux et les éléments techniques pour le mesurage de la résistance d'isolement superficiel des bandes et tôles en acier électrique.
NOTE Cet essai convient à la fabrication et au contrôle de la qualité dans l'application des revêtements isolants.
Cette édition inclut les modifications techniques majeures suivantes par rapport à l'édition précédente:
la Méthode B a été supprimée, et la Méthode A permet de mesurer les courants qui traversent chaque touche de contact;
un montage amélioré, "Montage B", a été ajouté pour l'appareillage d'essai et le circuit de stabilisation de tension de la Méthode A;
une variante de montage, qui utilise deux paires d'ensembles de contacts situés en position opposée à l'éprouvette, a été introduite;
la restriction "Une même portion de l'éprouvette ne doit pas être utilisée pour caractériser les deux faces" a été supprimée.
General Information
Relations
Standards Content (Sample)
IEC 60404-11 ®
Edition 2.0 2021-07
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Magnetic materials –
Part 11: Methods of measurement of the surface insulation resistance of
electrical steel strip and sheet
Matériaux magnétiques –
Partie 11: Méthodes de mesurage de la résistance d'isolement superficiel des
bandes et tôles en acier électrique
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form
or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from
either IEC or IEC's member National Committee in the country of the requester. If you have any questions about IEC
copyright or have an enquiry about obtaining additional rights to this publication, please contact the address below or
your local IEC member National Committee for further information.
Droits de reproduction réservés. Sauf indication contraire, aucune partie de cette publication ne peut être reproduite
ni utilisée sous quelque forme que ce soit et par aucun procédé, électronique ou mécanique, y compris la photocopie
et les microfilms, sans l'accord écrit de l'IEC ou du Comité national de l'IEC du pays du demandeur. Si vous avez des
questions sur le copyright de l'IEC ou si vous désirez obtenir des droits supplémentaires sur cette publication, utilisez
les coordonnées ci-après ou contactez le Comité national de l'IEC de votre pays de résidence.
IEC Central Office Tel.: +41 22 919 02 11
3, rue de Varembé info@iec.ch
CH-1211 Geneva 20 www.iec.ch
Switzerland
About the IEC
The International Electrotechnical Commission (IEC) is the leading global organization that prepares and publishes
International Standards for all electrical, electronic and related technologies.
About IEC publications
The technical content of IEC publications is kept under constant review by the IEC. Please make sure that you have the
latest edition, a corrigendum or an amendment might have been published.
IEC publications search - webstore.iec.ch/advsearchform IEC online collection - oc.iec.ch
The advanced search enables to find IEC publications by a Discover our powerful search engine and read freely all the
variety of criteria (reference number, text, technical publications previews. With a subscription you will always
committee, …). It also gives information on projects, replaced have access to up to date content tailored to your needs.
and withdrawn publications.
Electropedia - www.electropedia.org
IEC Just Published - webstore.iec.ch/justpublished
The world's leading online dictionary on electrotechnology,
Stay up to date on all new IEC publications. Just Published
containing more than 22 000 terminological entries in English
details all new publications released. Available online and
and French, with equivalent terms in 18 additional languages.
once a month by email.
Also known as the International Electrotechnical Vocabulary
(IEV) online.
IEC Customer Service Centre - webstore.iec.ch/csc
If you wish to give us your feedback on this publication or
need further assistance, please contact the Customer Service
Centre: sales@iec.ch.
A propos de l'IEC
La Commission Electrotechnique Internationale (IEC) est la première organisation mondiale qui élabore et publie des
Normes internationales pour tout ce qui a trait à l'électricité, à l'électronique et aux technologies apparentées.
A propos des publications IEC
Le contenu technique des publications IEC est constamment revu. Veuillez vous assurer que vous possédez l’édition la
plus récente, un corrigendum ou amendement peut avoir été publié.
Recherche de publications IEC - IEC online collection - oc.iec.ch
webstore.iec.ch/advsearchform Découvrez notre puissant moteur de recherche et consultez
La recherche avancée permet de trouver des publications IEC gratuitement tous les aperçus des publications. Avec un
en utilisant différents critères (numéro de référence, texte, abonnement, vous aurez toujours accès à un contenu à jour
comité d’études, …). Elle donne aussi des informations sur adapté à vos besoins.
les projets et les publications remplacées ou retirées.
Electropedia - www.electropedia.org
IEC Just Published - webstore.iec.ch/justpublished
Le premier dictionnaire d'électrotechnologie en ligne au
Restez informé sur les nouvelles publications IEC. Just
monde, avec plus de 22 000 articles terminologiques en
Published détaille les nouvelles publications parues.
anglais et en français, ainsi que les termes équivalents dans
Disponible en ligne et une fois par mois par email.
16 langues additionnelles. Egalement appelé Vocabulaire
Electrotechnique International (IEV) en ligne.
Service Clients - webstore.iec.ch/csc
Si vous désirez nous donner des commentaires sur cette
publication ou si vous avez des questions contactez-nous:
sales@iec.ch.
IEC 60404-11 ®
Edition 2.0 2021-07
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Magnetic materials –
Part 11: Methods of measurement of the surface insulation resistance of
electrical steel strip and sheet
Matériaux magnétiques –
Partie 11: Méthodes de mesurage de la résistance d'isolement superficiel des
bandes et tôles en acier électrique
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 17.220.01; 29.030 ISBN 978-2-8322-9942-5
– 2 – IEC 60404-11:2021 © IEC 2021
CONTENTS
FOREWORD . 3
1 Scope . 5
2 Normative references . 5
3 Terms and definitions . 5
4 Principle of measurement . 5
5 Test specimen . 7
6 Test apparatus . 8
6.1 Contact assembly . 8
6.2 Power supply . 8
6.3 Current measurement . 8
6.4 Applied force. 8
7 Verification . 9
8 Measurement procedure . 9
9 Evaluation of surface insulation resistance . 10
10 Uncertainty . 10
11 Test report . 11
Bibliography . 12
Figure 1 – Fundamental arrangement of the test apparatus (schematic) . 6
Figure 2 – Schematic arrangements of the test apparatus and the voltage stabilizing
circuit . 6
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
MAGNETIC MATERIALS –
Part 11: Methods of measurement of the surface
insulation resistance of electrical steel strip and sheet
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.
IEC 60404-11 has been prepared by IEC technical committee 68: Magnetic alloys and steels.
It is an International Standard.
This second edition cancels and replaces the first edition published in 1991, Amendment 1:1998
and Amendment 2:2012. This edition constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) Method B has been deleted and the measurement of individual currents through each
contact button is enabled by Method A;
b) an improved arrangement of the test apparatus and the voltage stabilizing circuit for
Method A, “Arrangement B”, is introduced.
c) an alternative layout using two pairs of contact assemblies in opposing position of the test
specimen is introduced;
– 4 – IEC 60404-11:2021 © IEC 2021
d) the restriction: “The same area of the test specimen shall not be used to test both sides.”
has been deleted.
The text of this International Standard is based on the following documents:
CDV Report on voting
68/665/CDV 68/681/RVC
Full information on the voting for its approval can be found in the report on voting indicated in
the above table.
The language used for the development of this International Standard is English.
This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in
accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement, available
at www.iec.ch/members_experts/refdocs. The main document types developed by IEC are
described in greater detail at www.iec.ch/standardsdev/publications.
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 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.
MAGNETIC MATERIALS –
Part 11: Methods of measurement of the surface
insulation resistance of electrical steel strip and sheet
1 Scope
This part of IEC 60404 is applicable to electrical steel strip and sheet insulated by coating on
one or both sides.
The object of this document is to define the general principles and technical details of the
measurement of the surface insulation resistance of electrical steel strip and sheet.
NOTE This test is suitable for manufacturing and quality control in the application of insulation coatings.
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.
ISO/IEC Guide 98-3, Uncertainty of measurement – Part 3: Guide to the expression of
uncertainty in measurement (GUM:1995)
3 Terms and definitions
No terms and definitions are listed in this document.
ISO and IEC maintain terminological database 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
4 Principle of measurement
The principle of the measurement is based on, and includes, the method originally described
by Franklin [1] which characterizes one coated surface at a time.
The fundamental arrangement of the test apparatus is shown in Figure 1. Ten metallic contact
buttons of fixed area are applied to one coated surface of the test specimen, under specified
conditions of voltage and pressure.
The effectiveness of the surface insulation is assessed by the measurement of currents flowing
through the 10 contact buttons.
___________
1 Numbers in square brackets refer to the Bibliography.
– 6 – IEC 60404-11:2021 © IEC 2021
Figure 1 – Fundamental arrangement of the test apparatus (schematic)
A power supply feeds each contact button with a stabilized DC voltage, and the currents through
the 10 contact buttons are measured.
The arrangements of the test apparatus and the voltage stabilizing circuit are shown in Figure 2.
a) Arrangement A
b) Arrangement B
Figure 2 – Schematic arrangements of the test apparatus
and the voltage stabilizing circuit
Ten contact buttons are applied to one coated surface of the test specimen. 5 Ω resistors of
±1 % precision are connected in series with each contact button as shown in Figure 2. Two
conductive twist drills contact electrically with the metallic substrate under the insulation coating.
The voltage between the supply side of the 5 Ω resistors and the twist drills is stabilized at DC
0,5 V with a relative tolerance of ±0,5 % over a current range from 0 A to 1,0 A.
The two twist drills may be placed at each end of the contact buttons and applied to the same
side of the test specimen.
In Arrangement A, the two twist drills perform the function of current return contacts with the
metallic substrate [see Figure 2 a)].
In Arrangement B, the two twist drills perform different functions [see Figure 2 b)]. One drill
provides the current return contact with the metallic substrate. The other drill serves as a
potential sensor for the voltage feedback control. This feedback control removes the influence
of the contact resistance between the current return drill and the metallic substrate.
NOTE The contribution of the contact resistance on the measurement is significant when measuring a relatively low
surface insulation resistance.
Arrangement B is recommended when measuring a relatively low surface insulation resistance.
The total current flowing through the insulation coating between the 10 contact buttons and the
metallic substrate in parallel connection is measured (see Figure 2).
The value of the total current shall be determined by measuring the voltage drop across the
current sensing resistor R connected in series with the current circuit. The current sensing
s
resistor shall not be included within the voltage stabilizing circuit.
The individual contact button currents may be analysed by measuring the individual voltage
drops across each 5 Ω resistor.
Because the current path is between the contact buttons and the metallic substrate, this test is
not a true measurement of interlaminar resistance, in which the current path is between two
metallic substrates of adjacent sheets. However, this test provides a useful index of the quality
of the surface insulation resistance.
5 Test specimen
The test specimen shall be a length of strip or a sheet. The width and length of the test specimen
shall be greater than the width and length of the contact assembly (see 6.1).
The test specimen shall be representative for the material to be tested. The surfaces shall be
clean and free from powder, dust and oil, etc. which may be the result of handling of the test
specimen. Measurements shall be performed at room temperature of (23 ± 5) °C.
This measurement is destructive, the surface of the test specimen where the contact assembly
touched shall not be used again.
NOTE To obtain a representative result, several test specimens can be taken evenly across the full width of the
strip or sheet.
– 8 – IEC 60404-11:2021 © IEC 2021
6 Test apparatus
6.1 Contact assembly
The contact assembly consists of 10 vertically mounted contact rods and two twist drills of
approximately 3 mm in diameter. These 10 contact rods shall be able to move individually and
axially against springs in a mounting block. The contact rods shall press on the surface of the
test specimen with the same force. In order to achieve electrical contact with the metallic
substrate, the two twist drills shall be rotated when pressed on the test specimen. The twist
drills shall pierce the insulation coating but shall not pierce through the test specimen.
The 10 contact rods shall be arranged in one or two rows.
Each rod shall be provided with a contact button of bronze or other equivalent low resistive
material with sufficient hardness (for example, stainless steel). The contact buttons shall be
electrically insulated from the mounting block.
Each of the 10 contact buttons shall have a contact area of 64,5 mm with a relative tolerance
of ±1 %, giving a total area for the 10 buttons of 645 mm with a relative tolerance of ±1 %.
Each contact button shall press on the test specimen uniformly over the whole contact area and
shall avoid concentrating the force at the edge of the contact button.
NOTE 1 A force concentration at the edge of the contact button can destroy the insulation coating and cause a
direct contact between the contact button and the metallic substrate. Therefore, misalignments of the contact buttons
can cause an erroneous large current through the contact buttons. Articulated joints which allow the contact buttons
to follow the surface of the test specimen improve the contacts by compensating for minor misalignments.
NOTE 2 In case the purchaser and the manufacturer agree to use a different contact button size, e.g. 100 mm , for
each contact button (e.g. total area of 1 000 mm ), the measured values differ from the values measured with contact
2 2
buttons of the standard size of 64,5 mm for each contact button (total area of 645 mm ).
The test specimen shall be pressed between a baseplate and the contact assembly.
Alternatively, the test specimen may be pressed between pairs of contact assemblies
(arrangement of the 10 contact buttons each) of the same dimensions in opposing positions
provided that the comparability of the results can be demonstrated. This arrangement allows
successive measurement of both sides of the test specimen without turning over the test
specimen.
6.2 Power supply
The power supply shall be capable of maintaining a stabilized voltage of DC 0,5 V with a relative
tolerance of ±0,5 % over a current range from 0 A to 1,0 A.
6.3 Current measurement
The total current flowing through the contact buttons shall be measured with an uncertainty
of ±0,5 % or better.
The value of the total current shall be determined by measuring the voltage drop across the
of a low resistance value (e.g. 0,2 Ω) by means of a suitable
current sensing resistor R
s
voltmeter (see Figure 2).
NOTE An ammeter with a low internal resistance value can be used instead of the resistor R and the voltmeter.
s
6.4 Applied force
A pressure of 2 N/mm with a relative tolerance of ±5 % shall be applied to each of the 10
contact buttons pressing on the test specimen. This corresponds to a force of 1 290 N with a
relative tolerance of ±5 % for the total contact area of 645 mm .
7 Verification
The system shall be verified in four ways:
a) The 10 contact buttons and 2 twist drills shall be applied to a clean and flat copper sheet at
the nominal testing pressure. The total current flowing through the 10 contact buttons shall
be between 0,97 A and 1,00 A. If this is not the case, the cleanliness of the contact buttons
and the contact resistance between the power supply and the copper sheet shall be
checked.
b) Standard resistors of 0,1 Ω, 1 Ω, 10 Ω and 100 Ω connected between the twist drills and
each contact button in turn may be used in order to show that the stabilization of voltage is
adequate and that the required current levels can be achieved.
c) The total force applied to all the 10 contact buttons pressing on the base plate or the 10
contact buttons in opposing positions shall be verified by any suitable means, e.g. load cells,
with an uncertainty of ±5 % or better.
d) Pressure measurement sheets, that can indicate applied pressure as colour density
variations, shall be pressed between the 10 contact buttons and a flat plate at the nominal
testing pressure. In the case of measurements performed with two sets of contact buttons
in opposite positions (see 6.1), a plate equipped with pressure measurement sheets on both
sides shall be inserted between the pairs of contact assemblies for the purpose of such
verification. The 10 marks shall be even and free from signs of force concentration. Carbon
paper pressed on white paper by the contact buttons can be used instead of the pressure
measurement sheet. Contact buttons giving uneven marks shall be replaced with new ones
ensuring even pressure.
8 Measurement procedure
The test specimen shall be positioned between the 10 contact buttons and the baseplate.
Alternatively, the test specimen shall be positioned between two sets of 10 contact buttons in
opposing positions (see 6.1).
The force of 1 290 N shall be gradually applied to the 10 contact buttons pressing on the test
specimen.
The voltage of DC 0,5 V shall be applied across the supply side of the 5 Ω resistors and the
twist drills. The total current I shall be recorded directly or by a micro-processor (see Figure 1).
A
If the surface insulation resistance of one coated surface of the test specimen is to be evaluated
in the test, the total current I shall be taken from 10 separate representative areas, on the
A
same surface of one or several test specimens, and the average value of the total current
I
A
shall be calculated for the 10 values.
If the surface insulation resistance of both coated surfaces of the test specimen is to be
evaluated in the test, the total current I shall be taken from 5 separate representative areas,
A
each on both surfaces of one or several test specimens, and the average value of the total
current shall be calculated from the 10 values.
I
A
As an alternative, upon agreement between the purchaser and the manufacturer, two sides of
the test specimen may be evaluated separately by adding the total currents I from the 5
A
measurements per side separately and calculating the average values of the total current
I
A
of each side separately.
Care shall be taken so that the contact buttons are not placed on any marks of the contact
buttons and the drills from previous measurements. It is particularly important to avoid the drill
marks from measuring the first side when measuring the opposite side.
– 10 – IEC 60404-11:2021 © IEC 2021
9 Evaluation of surface insulation resistance
The average value of the total current shall be calculated by averaging the 10 recorded
I
A
values of the total current I (either all from the same surface or 5 each from two surfaces)
A
using Formula (1):
(1)
I = I
AA∑
where
I is the total current, in A;
A
is the average value of the total current I , in A.
I
A
A
In the alternative case that the two sides of the specimen are evaluated separately, Formula (1)
is applied to each surface by replacing 10 by 5.
C is the coefficient of surface insulation resistance for one coated surface of the test specimen.
If 5 measurements are taken each from both coated surfaces, the value C is the coefficient of
the surface insulation resistance per one coated surface in Ω mm /side, which represents the
mean of both coated surfaces. Twice the value C corresponds to the coefficient of interlaminar
resistance in Ω mm /sheet for both coated surfaces.
In the case of one coated surface, it is only possible to calculate the coefficient of the surface
insulation resistance per one coated surface in Ω mm /side.
NOTE The described procedure in ASTM A717 [2] produces a surface insulation resistivity which corresponds to
twice the value of C.
The coefficient of surface insulation resistance C shall be determined using Formula (2).
U R 0,5
c
CA= ⋅− =645⋅ − 0,5 (2)
II10
AA
where
C is the coefficient of surface insulation resistance, in Ω·mm /side;
A is the total area of the 10 contact buttons, equal to 645 mm ;
U is the voltage applied across the supply side of the 5 Ω resistors and the twist drills, equal
to 0,5 V;
is the resistance of the resistors in series with each contact butt
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.
Loading comments...