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 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 edition includes the following significant technical changes with respect to the previous edition:  
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;
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;
the method of test for compressibility has been modified to match to the method of test for stacking factor specified in IEC 60404-13;
the concept of "resistance grades" has been removed;
the clamping pressure to be used at temperature ratings above 500 °C has been reduced to (0,01 ± 0,001) N/mm2;
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.

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

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:  
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;
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;
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;
le concept de "niveaux de résistance" a été supprimé;
la pression de serrage à utiliser à des températures assignées supérieures à 500 °C a été réduite à (0,01 ± 0,001) N/mm2;
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.

General Information

• Status: Published
• Publication Date: 09-Feb-2023
• ICS: 17.220.01 - Electricity. Magnetism. General aspects
• ICS: 29.030 - Magnetic materials
• Technical Committee: TC 68 - Magnetic alloys and steels
• Drafting Committee: WG 2 - TC 68/WG 2
• Current Stage: PPUB - Publication issued
• Start Date: 15-Mar-2023
• Completion Date: 10-Feb-2023

Standards Content (Sample)

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

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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

– 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

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
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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 t
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