SIST EN IEC 60404-12:2023

Magnetic materials - Part 12: Methods of test for the assessment of the thermal endurance of surface insulation coatings on electrical steel strip and sheet (IEC 60404-12:2023)

This part of IEC 60404 is applicable to surface insulation coatings on electrical steel strip and
sheet classified in IEC 60404-1-1.
This document defines the general principles and technical details of the tests for the
assessment of the thermal endurance of surface insulation coatings on electrical steel strip and
sheet.
The assessment is made by evaluating the change of a specified property of the surface
insulation coating due to a heat treatment at a specified temperature up to 850 °C for a specified
duration time up to 2 500 h. The specified property is measured at an ambient temperature of
(23 ± 5) °C both without heat treatment and after heat treatment.
This document is applicable to the following properties of surface insulation coatings:
– adhesion;
– surface insulation resistance;
– stacking factor.
This document is not applicable to other properties of surface insulation coatings, e.g. welding
properties, or to other effects, e.g. discoloration and off-gassing, which can be caused by
exposure to elevated temperatures.
NOTE Some of the tests take a very long time to perform and therefore they are often not appropriate for acceptance
tests of material supplied on a specific order.

Magnetische Werkstoffe - Teil 12: Prüfverfahren zur Bewertung der thermischen Beständigkeit von Oberflächenisolierbeschichtungen auf Elektroband und -blech (IEC 60404-12:2023)

Matériaux magnétiques - Partie 12: Méthodes d’essai pour l'évaluation de l’endurance thermique des revêtements isolants superficiels des bandes et tôles en acier électrique (IEC 60404-12:2023)

L’IEC 60404-12:2023 s'applique aux revêtements isolants superficiels des bandes et tôles en acier électrique classées dans l’IEC 60404-1-1.
Le présent document définit les principes généraux et les éléments techniques des essais relatifs à l’évaluation de l’endurance thermique des revêtements isolants superficiels des bandes et tôles en acier électrique.
L'évaluation consiste à apprécier la variation d’une propriété spécifiée du revêtement isolant superficiel du fait d’un traitement thermique à une température spécifiée allant jusqu’à 850 °C pendant une durée spécifiée maximale de 2 500 h. La propriété spécifiée est mesurée à une température ambiante de (23 ± 5) °C sans traitement thermique et après un traitement thermique.
Cette édition inclut les modifications techniques majeures suivantes par rapport à l'édition précédente:

   
1. la méthode d'essai d’adhérence a été modifiée afin de correspondre à la méthode d’essai de pliage spécifiée dans l’ISO 1519, qui utilise un mandrin cylindrique d’un diamètre de 32 mm en lieu et place du mandrin d’un diamètre de 30 mm spécifié dans la première édition;

   
2. la méthode d’essai de résistance d'isolation interlaminaire a été modifiée afin de correspondre à la méthode spécifiée dans l’IEC 60404-11 et l’essai de Franklin modifié a été supprimé;

   
3. la méthode d’essai de compressibilité a été modifiée afin de correspondre à la méthode d’essai du facteur de foisonnement spécifiée dans l’IEC 60404-13;

   
4. le concept de "niveaux de résistance" a été supprimé;

   
5. la pression de serrage à utiliser à des températures assignées supérieures à 500 °C a été réduite à (0,01 ± 0,001) N/mm2;

   
6. L’essai d’exposition continue a fait l’objet d’un accord entre le fabricant et l’acheteur et la procédure a été déplacée vers une Annexe A informative.

Magnetni materiali - 12. del: Metode preskušanja za oceno toplotne vzdržljivosti površinskih izolacijskih premazov na električnih jeklenih trakovih in pločevinah (IEC 60404-12:2023)

Ta del standarda IEC 60404 se uporablja za površinske izolacijske premaze na električnih jeklenih trakovih in
pločevini, ki so razvrščeni v standardu IEC 60404-1-1.
Ta dokument določa splošna načela in tehnične podrobnosti preskusov za
ocenjevanje toplotne vzdržljivosti površinskih izolacijskih premazov na električnih jeklenih trakovih in
pločevini.
Ocena je izvedena z oceno sprememb določene lastnosti površinskega
izolacijskega premaza zaradi toplotne obdelave pri določeni temperaturi do 850 °C in določenem trajanju
do 2500 ur. Določena lastnost se meri pri temperaturi okolja
(23 ± 5) °C tako v primeru brez toplotne obdelave kot po toplotni obdelavi.
Ta dokument se uporablja za naslednje lastnosti površinskih izolacijskih premazov:
– adhezija;
– površinska izolacijska upornost;
– skladni faktor.
Ta dokument se ne uporablja za druge lastnosti površinskih izolacijskih premazov, npr. varilne
lastnosti, ali druge učinke, npr. razbarvanje in uhajanje plinov, ki so lahko posledica
izpostavljenosti povišanim temperaturam.
OPOMBA: Izvedba nekaterih preskusov vzame veliko časa, zato pogosto niso ustrezni za preskuse sprejemljivosti materiala, dobavljenega s posebnim naročilom.

General Information

• Status: Published
• Public Enquiry End Date: 14-Apr-2022
• Publication Date: 05-Apr-2023
• ICS: 17.220.01 - Electricity. Magnetism. General aspects
• 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: 29-Mar-2023
• Due Date: 03-Jun-2023
• Completion Date: 06-Apr-2023
• Ref Project: EN IEC 60404-12:2023 - Magnetic materials - Part 12: Methods of test for the assessment of the thermal endurance of surface insulation coatings on electrical steel strip and sheet

Standards Content (Sample)

SLOVENSKI STANDARD
SIST EN IEC 60404-12:2023
01-maj-2023
Magnetni materiali - 12. del: Metode preskušanja za oceno toplotne vzdržljivosti
površinskih izolacijskih premazov na električnih jeklenih trakovih in pločevinah
(IEC 60404-12:2023)
Magnetic materials - Part 12: Methods of test for the assessment of the thermal
endurance of surface insulation coatings on electrical steel strip and sheet (IEC 60404-
12:2023)
Magnetische Werkstoffe - Teil 12: Prüfverfahren zur Bewertung der thermischen
Beständigkeit von Oberflächenisolierbeschichtungen auf Elektroband und -blech (IEC
60404-12:2023)
Matériaux magnétiques - Partie 12: Méthodes d’essai pour l'évaluation de l’endurance
thermique des revêtements isolants superficiels des bandes et tôles en acier électrique
(IEC 60404-12:2023)
Ta slovenski standard je istoveten z: EN IEC 60404-12:2023
ICS:
17.220.20 Merjenje električnih in Measurement of electrical
magnetnih veličin and magnetic quantities
29.030 Magnetni materiali Magnetic materials
SIST EN IEC 60404-12:2023 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN IEC 60404-12:2023

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SIST EN IEC 60404-12:2023


EUROPEAN STANDARD EN IEC 60404-12

NORME EUROPÉENNE

EUROPÄISCHE NORM March 2023
ICS 29.030; 17.220.01

English Version
Magnetic materials - Part 12: Methods of test for the assessment
of the thermal endurance of surface insulation coatings on
electrical steel strip and sheet
(IEC 60404-12:2023)
Matériaux magnétiques - Partie 12: Méthodes d'essai pour Magnetische Werkstoffe - Teil 12: Prüfverfahren zur
l'évaluation de l'endurance thermique des revêtements Bewertung der thermischen Beständigkeit von
isolants superficiels des bandes et tôles en acier électrique Oberflächenisolierbeschichtungen auf Elektroband und -
(IEC 60404-12:2023) blech
(IEC 60404-12:2023)
This European Standard was approved by CENELEC on 2023-03-17. 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, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, the
Netherlands, Norway, Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Türkiye and the United Kingdom.


European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2023 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.
 Ref. No. EN IEC 60404-12:2023 E

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SIST EN IEC 60404-12:2023
EN IEC 60404-12:2023 (E)
European foreword
The text of document 68/698/CDV, future edition 2 of IEC 60404-12, prepared by IEC/TC 68
"Magnetic alloys and steels" was submitted to the IEC-CENELEC parallel vote and approved by
CENELEC as EN IEC 60404-12:2023.
The following dates are fixed:
• latest date by which the document has to be implemented at national (dop) 2023-12-17
level by publication of an identical national standard or by endorsement
• latest date by which the national standards conflicting with the (dow) 2026-03-17
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 shall not be held responsible for identifying any or all such patent rights.
Any feedback and questions on this document should be directed to the users’ national committee. A
complete listing of these bodies can be found on the CENELEC website.
Endorsement notice
The text of the International Standard IEC 60404-12:2023 was approved by CENELEC as a European
Standard without any modification.
In the official version, for Bibliography, the following note has to be added for the standard indicated:
IEC 60216-1 NOTE Approved as EN 60216-1
2

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SIST EN IEC 60404-12:2023
EN IEC 60404-12:2023 (E)
Annex ZA
(normative)

Normative references to international publications
with their corresponding European publications
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.
NOTE 1  Where an International Publication has been modified by common modifications, indicated by (mod),
the relevant EN/HD applies.
NOTE 2  Up-to-date information on the latest versions of the European Standards listed in this annex is available
here: www.cencenelec.eu.
Publication Year Title EN/HD Year
IEC 60050-121 - International Electrotechnical Vocabulary - - -
Part 121: Electromagnetism
IEC 60050-221 - International Electrotechnical Vocabulary. - -
Chapter 221: Magnetic materials and
components
IEC 60404-1-1 - Magnetic materials - Part 1-1: - -
Classification - Surface insulations of
electrical steel sheet, strip and laminations
IEC 60404-11 - Magnetic materials - Part 11: Method of - -
test for the determination of surface
insulation resistance of magnetic sheet
and strip
IEC 60404-13 - Magnetic materials - Part 13: Methods of EN IEC 60404-13 -
measurement of resistivity, density and
stacking factor of electrical steel strip and
sheet
ISO 1519 - Paints and varnishes - Bend test EN ISO 1519 -
(cylindrical mandrel)

3

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SIST EN IEC 60404-12:2023

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SIST EN IEC 60404-12:2023



IEC 60404-12

®


Edition 2.0 2023-02




INTERNATIONAL



STANDARD




NORME


INTERNATIONALE











Magnetic materials –

Part 12: Methods of test for the assessment of the thermal endurance of surface

insulation coatings on electrical steel strip and sheet



Matériaux magnétiques –

Partie 12: Méthodes d’essai pour l'évaluation de l’endurance thermique des


revêtements isolants superficiels des bandes et tôles en acier électrique













INTERNATIONAL

ELECTROTECHNICAL

COMMISSION


COMMISSION

ELECTROTECHNIQUE


INTERNATIONALE




ICS 17.220.01; 29.030 ISBN 978-2-8322-6445-4




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 IEC 60404-12:2023
– 2 – IEC 60404-12:2023 © IEC 2023
CONTENTS
FOREWORD . 3
INTRODUCTION . 5
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 7
4 General principles . 7
4.1 General . 7
4.2 Preparation of clamped stacks of test specimens . 7
4.2.1 Procedure of stacking test specimens . 7
4.2.2 Clamping stacks for temperature ratings up to 500 °C . 7
4.2.3 Clamping stacks for temperature ratings above 500 °C . 8
4.3 Heat treatment . 8
4.3.1 For time ratings up to 2 500 h . 8
4.3.2 For continuous exposure . 9
5 Standard temperature/time performance designations T/t . 9
6 Method of the test for adhesion . 9
6.1 General . 9
6.2 Test specimens . 9
6.3 Procedure of test . 9
6.4 Test report . 10
7 Method of the test for surface insulation resistance . 10
7.1 General . 10
7.2 Test specimens . 10
7.3 Procedure of test . 10
7.4 Test report . 11
8 Method of the test for stacking factor . 11
8.1 General . 11
8.2 Test specimen . 11
8.3 Procedure of test . 11
8.4 Test report . 11
Annex A (informative) Method of test for the assessment of the thermal endurance for
continuous exposure to elevated temperatures . 12
A.1 General . 12
A.2 Procedure of test . 12
A.3 Temperature/time performance designations T/t for continuous exposure . 12
Bibliography . 13

Figure 1 – Example of clamped stack for 100 mm square test specimens . 8

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SIST EN IEC 60404-12:2023
IEC 60404-12:2023 © IEC 2023 – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________

MAGNETIC MATERIALS –

Part 12: Methods of test for the assessment of the thermal endurance
of surface insulation coatings on 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 60404-12 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 1992. This edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) the method of test for adhesion has been modified to match to the method of bend test
specified in ISO 1519 using a cylindrical mandrel of 32 mm in diameter instead of the 30 mm
diameter mandrel specified in the first edition;
b) the method of test for interlaminar insulation resistance has been modified to match to the
method specified in IEC 60404-11 and the modified Franklin test has been removed;
c) the method of test for compressibility has been modified to match to the method of test for
stacking factor specified in IEC 60404-13;

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SIST EN IEC 60404-12:2023
– 4 – IEC 60404-12:2023 © IEC 2023
d) the concept of "resistance grades" has been removed;
e) the clamping pressure to be used at temperature ratings above 500 °C has been reduced
2
to (0,01 ± 0,001) N/mm ;
f) the testing for continuous exposure has been made a subject to an agreement between the
manufacturer and the purchaser and the procedure has been moved to an informative
Annex A.
The text of this International Standard is based on the following documents:
Draft Report on voting
68/698/CDV 68/720/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/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.

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SIST EN IEC 60404-12:2023
IEC 60404-12:2023 © IEC 2023 – 5 –
INTRODUCTION
The surface insulation coatings on electrical steel strip and sheet are sometimes exposed to
elevated temperatures in service or during processing by the purchaser. Therefore, the thermal
endurance of the surface insulation coating is important.
Physicochemical models postulated for the aging processes lead to the almost universal
assumption of the Arrhenius equations to describe the rate of aging (see Annex A of this
document and IEC 60216-1).
Since the measurement of
...

SLOVENSKI STANDARD
oSIST prEN IEC 60404-12:2022
01-april-2022
Magnetni materiali - 12. del: Metode preskušanja za oceno toplotne vzdržljivosti
površinskih izolacijskih premazov na električnih jeklenih trakovih in pločevinah
Magnetic materials - Part 12: Methods of test for the assessment of thermal endurance
of surface insulation coatings on electrical steel strip and sheet
Matériaux magnétiques - Partie 12: Guide aux méthodes de caractérisation de la tenue
en température de l'isolation interlaminaire
Ta slovenski standard je istoveten z: prEN IEC 60404-12:2022
ICS:
17.220.20 Merjenje električnih in Measurement of electrical
magnetnih veličin and magnetic quantities
29.030 Magnetni materiali Magnetic materials
oSIST prEN IEC 60404-12:2022 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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oSIST prEN IEC 60404-12:2022

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oSIST prEN IEC 60404-12:2022
68/698/CDV

COMMITTEE DRAFT FOR VOTE (CDV)
PROJECT NUMBER:
IEC 60404-12 ED2
DATE OF CIRCULATION: CLOSING DATE FOR VOTING:
2022-01-21 2022-04-15
SUPERSEDES DOCUMENTS:
68/679/CD, 68/694/CC

IEC TC 68 : MAGNETIC ALLOYS AND STEELS
SECRETARIAT: SECRETARY:
Germany Mr Richard Daniel Knobloch
OF INTEREST TO THE FOLLOWING COMMITTEES: PROPOSED HORIZONTAL STANDARD:


Other TC/SCs are requested to indicate their interest, if
any, in this CDV to the secretary.
FUNCTIONS CONCERNED:
EMC ENVIRONMENT QUALITY ASSURANCE SAFETY
SUBMITTED FOR CENELEC PARALLEL VOTING NOT SUBMITTED FOR CENELEC PARALLEL VOTING
Attention IEC-CENELEC parallel voting
The attention of IEC National Committees, members of
CENELEC, is drawn to the fact that this Committee Draft
for Vote (CDV) is submitted for parallel voting.
The CENELEC members are invited to vote through the
CENELEC online voting system.

This document is still under study and subject to change. It should not be used for reference purposes.
Recipients of this document are invited to submit, with their comments, notification of any relevant patent rights of
which they are aware and to provide supporting documentation.

TITLE:
Magnetic materials - Part 12: Methods of test for the assessment of thermal endurance of
surface insulation coatings on electrical steel strip and sheet

PROPOSED STABILITY DATE: 2028

NOTE FROM TC/SC OFFICERS:
This document was prepared by the Project Leader together with the Project Team on the basis of the
second CD, 68/679/CD, and the related observations presented in 68/694/CC. The Chair decided to
proceed to the CDV according to the high degree of consensus achieved.

Copyright © 2021 International Electrotechnical Commission, IEC. All rights reserved. It is permitted to
download this electronic file, to make a copy and to print out the content for the sole purpose of preparing National
Committee positions. You may not copy or "mirror" the file or printed version of the document, or any part of it, for
any other purpose without permission in writing from IEC.

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oSIST prEN IEC 60404-12:2022
IEC CDV 60404-12 © IEC 2021 2 68/698/CDV

1 CONTENTS
2
3 FOREWORD . 3
4 INTRODUCTION . 5
5 1 Scope . 6
6 2 Normative references . 6
7 3 Terms and definitions . 7
8 4 General principles . 7
9 4.1 General . 7
10 4.2 Preparation of clamped stacks of test specimens . 7
11 4.2.1 Procedure of stacking test specimens . 7
12 4.2.2 Clamping stacks for temperature ratings up to 500 °C . 8
13 4.2.3 Clamping stacks for temperature ratings above 500 °C . 8
14 4.3 Heat treatment . 8
15 4.3.1 For time ratings up to 2 500 hours . 8
16 4.3.2 For continuous exposure . 9
17 5 Standard temperature/time performance designations . 9
18 6 Method of the test for adhesion . 9
19 6.1 General . 9
20 6.2 Test specimens . 9
21 6.3 Procedure of test . 9
22 6.4 Test report . 10
23 7 Method of the test for surface insulation resistance . 10
24 7.1 General . 10
25 7.2 Test specimens . 10
26 7.3 Procedure of test . 10
27 7.4 Test report . 10
28 8 Method of the test for stacking factor . 11
29 8.1 General . 11
30 8.2 Test specimen . 11
31 8.3 Procedure of test . 11
32 8.4 Test report . 11
33 Annex A (informative) Method of test for the assessment of the thermal endurance for
34 continuous exposure to elevated temperatures . 12
35 A.1 General . 12
36 A.2 Test procedure . 12
37 A.3 Temperature/time performance designations for continuous exposure . 12
38 Bibliography . 13
39
40 Figure 1 – Example of clamped stack for 100 mm square test specimens . 8
41
42

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oSIST prEN IEC 60404-12:2022
IEC CDV 60404-12 © IEC 2021 3 68/698/CDV

43 INTERNATIONAL ELECTROTECHNICAL COMMISSION
44 ___________
45
46 MAGNETIC MATERIALS –
47
48 Part 12: Methods of test for the assessment of the thermal endurance of
49 surface insulation coatings on electrical steel strip and sheet
50
51
52 FOREWORD
53 1) The IEC (International Electrotechnical Commission) is a world-wide organization for standardization
54 comprising all national electrotechnical committees (IEC National Committees). The object of the IEC is to
55 promote international cooperation on all questions concerning standardization in the electrical and electronic
56 fields. To this end and in addition to other activities, the IEC publishes International Standards, Technical
57 Specifications, Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to
58 as “IEC Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee
59 interested in the subject dealt with may participate in this preparatory work. International, governmental and
60 non-governmental organizations liaising with the IEC also participate in this preparation. The IEC collaborates
61 closely with the International Organization for Standardization (ISO) in accordance with conditions determined
62 by agreement between the two organizations.
63 2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an
64 international consensus of opinion on the relevant subjects since each technical committee has representation
65 from all interested IEC National Committees.
66 3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
67 Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
68 Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
69 misinterpretation by any end user.
70 4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
71 transparently to the maximum extent possible in their national and regional publications. Any divergence
72 between any IEC Publication and the corresponding national or regional publication shall be clearly indicated
73 in the latter.
74 5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
75 assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any
76 services carried out by independent certification bodies.
77 6) All users should ensure that they have the latest edition of this publication.
78 7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
79 members of its technical committees and IEC National Committees for any personal injury, property damage
80 or other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
81 expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
82 Publications.
83 8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
84 indispensable for the correct application of this publication.
85 9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
86 patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
87 IEC 60404-12 has been prepared by IEC technical committee 68: Magnetic alloys and steels.
88 It is an International Standard.
89 This second edition cancels and replaces the first edition published in 1992. This edition
90 constitutes a technical revision.
91 This edition includes the following significant technical changes with respect to the previous
92 edition:
93 a) the method of test for adhesion has been modified to match to the method of bend test
94 specified in ISO 1519:2011 using a cylindrical mandrel of 32 mm in diameter instead of the
95 30 mm diameter mandrel specified in the previous edition of this document;

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96 b) the method of test for interlaminar insulation resistance has been modified to match to the
97 method specified in IEC 60404-11 and the modified Franklin test has been removed;
98 c) the method of test for compressibility has been modified to match to the method of test for
99 stacking factor specified in IEC 60404-13;
100 d) the concept of “resistance grades” has been removed;
101 e) the clamping pressure to be used at temperature ratings above 500 °C has been reduced to
2
102 (0,01 ± 0,001) N/mm .
103 f) The testing for continuous exposure has been made a subject to an agreement between the
104 manufacturer and the purchaser and the procedure has been moved to an informative Annex
105 A.
106 The text of this International Standard is based on the following documents:
FDIS Report on voting
68/XX/FDIS 68/XX/RVD
107
108 Full information on the voting for the approval of this standard can be found in the Voting
109 Reports indicated in the above table.
110 The language used for the development of this International Standard is English.
111 This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in
112 accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement, available
113 at www.iec.ch/members_experts/refdocs. The main document types developed by IEC are
114 described in greater detail at http://www.iec.ch/standardsdev/publications.
115 A list of all parts in the IEC 60404 series, published under the general title Magnetic materials,
116 can be found on the IEC website.
117 The committee has decided that the contents of this document will remain unchanged until the
118 stability date indicated on the IEC website under "webstore.iec.ch" in the data related to the
119 specific document. At this date, the document will be
120  reconfirmed,
121  withdrawn,
122  replaced by a revised edition, or
123  amended.
124
125 The National Committees are requested to note that for this document the stability date
126 is 2028.
127 THIS TEXT IS INCLUDED FOR THE INFORMATION OF THE NATIONAL COMMITTEES AND WILL BE DELETED
128 AT THE PUBLICATION STAGE.
129
130

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131 INTRODUCTION
132 The surface insulation coatings on electrical steel strip and sheet are sometimes exposed to
133 elevated temperatures in service or during processing by the purchaser. Therefore, the thermal
134 endurance of the surface insulation coating is important.
135 Physicochemical models postulated for the aging processes lead to the almost universal
136 assumption of the Arrhenius equations to describe the rate of aging (see Annex A and IEC
137 60216-1:2013).
138 Since the measurement of the properties of surface insulation coatings at elevated
139 temperatures is expensive and time-consuming, the thermal endurance of a coating is usually
140 assessed by evaluating a specified coating property before and after a heat treatment.
141

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142 MAGNETIC MATERIALS –
143
144 Part 12: Methods of test for the assessment of the thermal endurance of
145 surface insulation coatings on electrical steel strip and sheet
146
147
148
149 1 Scope
150 This part of IEC 60404 is applicable to surface insulation coatings on electrical steel strip and
151 sheet classified in IEC 60404-1-1.
152 The purpose of this document is to define the general principles and technical details of the
153 tests for the assessment of the thermal endurance of surface insulation coatings on electrical
154 steel strip and sheet.
155 The assessment is made by evaluating the change of a specified property of the surface
156 insulation coating due to a heat treatment at a specified temperature up to 850 °C and a
157 specified duration time up to 2 500 h. The specified property is measured at an ambient
158 temperature of (23 ± 5) °C both without heat treatment and after heat treatment.
159 This document is applicable to the following properties of surface insulation coatings:
160 – adhesion;
161 – surface insulation resistance;
162 – stacking factor.
163 This document is not applicable to other properties of surface insulation coatings, e.g. welding
164 properties, or to other effects e.g. discoloration and off-gassing, which can be caused by
165 exposure to elevated temperatures.
166 NOTE Some of the tests take a very long time to perform and therefore they may not be suitable for acceptance tests of material
167 supplied on a specific order.
168
169 2 Normative references
170 The following documents are referred to in the text in such a way that some or all of their content
171 constitutes requirements of this document. For dated references, only the edition cited applies.
172 For undated references, the latest edition of the referenced document (including any
173 amendments) applies.
174 IEC 60050-121, International Electrotechnical Vocabulary – Part 121: Electromagnetism
175 IEC 60050-131, International Electrotechnical Vocabulary – Part 131: Circuit theory
176 IEC 60050-221, International Electrotechnical Vocabulary – Chapter 221: Magnetic materials
177 and components
178 IEC 60404-1-1, Magnetic materials – Part 1-1: Classification – Surface insulations of electrical
179 steel sheet, strip and lami
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