IEC 60404-11:1991

Magnetic materials - Part 11: Method of test for the determination of surface insulation resistance of magnetic sheet and strip

Defines a measurement method for the determination of the characteristics of surface insulation resistance of magnetic sheet and strip. Applicable to magnetic sheet and strip insulated on one or both surfaces and is suitable for manufacturing control in the application of insulation coatings.

Matériaux magnétiques - Partie 11: Méthode d'essai pour la détermination de la résistance d'isolement superficiel des tôles et feuillards magnétiques

Définit une méthode de mesure pour la détermination des caractéristiques de résistance d'isolement superficiel des tôles et feuillards magnétiques. S'applique aux tôles ou feuillards magnétiques isolés sur une ou deux faces et est adaptée au contrôle de fabrication dans le cas d'application de revêtements isolants.

General Information

• Status: Published
• Publication Date: 14-May-2012
• 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: DELPUB - Deleted Publication
• Start Date: 08-Jul-2021
• Completion Date: 30-Nov-2018

Relations

• Amended By: IEC 60404-11:1991/AMD2:2012 - Amendment 2 - Magnetic materials - Part 11: Method of test for the determination of surface insulation resistance of magnetic sheet and strip
• Effective Date: 05-Sep-2023
• Amended By: IEC 60404-11:1991/AMD1:1998 - Amendment 1 - Magnetic materials - Part 11: Method of test for the determination of surface insulation resistance of magnetic sheet and strip
• Effective Date: 05-Sep-2023
• Revised: IEC 60404-11:2021 - Magnetic materials - Part 11: Methods of measurement of the surface insulation resistance of electrical steel strip and sheet
• Effective Date: 05-Sep-2023

Overview

IEC 60404-11:1991 is an international standard developed by the International Electrotechnical Commission (IEC) that specifies a reliable method of test for determining the surface insulation resistance of magnetic sheet and strip materials. This standard is essential for evaluating the surface insulation characteristics of magnetic materials coated on one or both sides, primarily used in electrical and electronic industries. It is beneficial for manufacturing control during the application of insulation coatings on magnetic sheets and strips, ensuring quality and consistency in production processes.

This standard provides a detailed measurement method based on a specialized test apparatus applying multiple contacts to the magnetic sheet surface under controlled voltage and pressure. The measurement of current flow through these contacts allows the assessment of the surface insulation’s effectiveness.

Key Topics

• Test Principle
  The test method assesses surface insulation resistance by applying ten metallic contact buttons on one coated surface of the magnetic sheet or strip. Each button is powered individually using a DC voltage supply under two modes:

  • Mode A: Stabilizes voltage at 500 mV ± 0.5% with current up to 1 A total.
  • Mode B: Stabilizes voltage at 250 mV ± 0.5% with up to 2.5 A current per electrode and uses a potential sensor to reduce contact resistance influence.

• Test Specimen
  The specimen should come from a single sheet or strip segment wider and longer than the contact assembly to ensure representative measurement. Measurement is destructive, so specimens are single-use.

• Apparatus Details
  The apparatus includes:

  • Contact assembly with 10 spring-loaded metallic rods fitted with contact buttons of bronze or stainless steel, each with an area of approximately 64.5 mm².
  • Two spring-loaded twist drills serve as electrical contacts with the metallic substrate by piercing the insulation coating.
  • Stabilized DC power supply, voltmeters, and current measurement resistors ensure accurate current readings with ±2% uncertainty or better.

• Calibration and Validation
  The system calibration involves:

  • Testing on a clean copper sheet to confirm current and voltage requirements.
  • Using carbon paper tests to check the uniformity and pressure application of contact assembly.
  • Applying standard resistors to verify stabilization and current accuracy.

• Force Application
  The total force exerted by the contact assembly on the specimen is carefully measured with an uncertainty of ±5% or better, ensuring consistent contact pressure during tests.

Applications

• Quality Control in Magnetic Material Manufacturing
  Ensuring the quality and uniformity of insulation coatings on magnetic sheets and strips throughout production lines.

• Surface Insulation Characterization
  Providing manufacturers and testing labs with a standardized method to assess surface insulation resistance critical for magnetic core performance in transformers, inductors, and electric motors.

• Material Research and Development
  Facilitating development of new magnetic materials and insulation technologies by offering precise and reproducible test results.

• Compliance and Certification
  Supporting compliance with international safety and performance regulations by verifying insulation reliability in magnetic materials.

Related Standards

• IEC 60404 Series – Covers various parts related to test methods and specifications for magnetic materials, including magnetic measurement and testing protocols.

• ASTM Standards on Electrical Insulation Testing – Complementary standards providing guidelines for testing insulation resistance and dielectric properties in electrical materials.

• ISO Standards on Electrical and Electronic Testing – Broader standards relevant to electrical material testing and quality management that may intersect with IEC 60404-11.

---

Keywords: IEC 60404-11, surface insulation resistance, magnetic sheet, magnetic strip, insulation coating, electrical testing standard, manufacturing control, magnetic materials testing, IEC standard, insulation resistance measurement, magnetic sheet quality, contact assembly, stabilized DC supply, current measurement, test specimen preparation.

Standards Content (Sample)

IEC 60404-11
Edition 1.1 1999-01
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Magnetic materials –
Part 11: Method of test for the determination of surface insulation resistance of
magnetic sheet and strip
Matériaux magnétiques –
Partie 11: Méthode d'essai pour la détermination de la résistance d'isolement
superficiel des tôles et feuillards magnétiques

Copyright © 1999 IEC, Geneva, Switzerland

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.

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et les microfilms, sans l'accord écrit de la CEI ou du Comité national de la CEI du pays du demandeur.

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IEC 60404-11
Edition 1.1 1999-01
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Magnetic materials –
Part 11: Method of test for the determination of surface insulation resistance of
magnetic sheet and strip
Matériaux magnétiques –
Partie 11: Méthode d'essai pour la détermination de la résistance d'isolement
superficiel des tôles et feuillards magnétiques

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
CB
CODE PRIX
ICS 17.220.01; 29.030 ISBN 2-8318-4599-8

– 2 – 60404-11 © CEI:1991+A.1:1998

SOMMAIRE
Pages
AVANT-PROPOS . 4

Articles
1 Objet et domaine d'application. 6

2 Principe de mesure . 6

3 Eprouvette . 8

4 Appareillage. 8
4.1 Ensemble des contacts . 8
4.2 Source de courant. 10
4.3 Mesurage du courant . 10
4.4 Détermination de la force appliquée . 12
5 Calibrage . 12
6 Mode opératoire . 14
7 Evaluation de la résistance d'isolement superficiel. 14
8 Rapport d'essai . 16

60404-11 © IEC:1991+A.1:1998 – 3 –

CONTENTS
Page
FOREWORD . 5

Clause
1 Scope and field of application. 7

2 Principle of measurement. 7

3 Test specimen.9

4 Apparatus . 9
4.1 Contact assembly. 9
4.2 Power supply . 11
4.3 Current measurement . 11
4.4 Determination of applied force. 13
5 Calibration . 13
6 Measuring procedure. 15
7 Evaluation of surface insulation resistance . 15
8 Test report . 17

– 4 – 60404-11 © CEI:1991+A.1:1998

COMMISSION ÉLECTROTECHNIQUE INTERNATIONALE

–––––––––––––
MATÉRIAUX MAGNÉTIQUES –
Partie 11: Méthode d'essai pour la détermination

de la résistance d'isolement superficiel

des tôles et feuillards magnétiques

AVANT-PROPOS
1) La CEI (Commission Electrotechnique Internationale) est une organisation mondiale de normalisation composée
de l'ensemble des comités électrotechniques nationaux (Comités nationaux de la CEI). La CEI a pour objet de
favoriser la coopération internationale pour toutes les questions de normalisation dans les domaines de
l'électricité et de l'électronique. A cet effet, la CEI, entre autres activités, publie des Normes internationales.
Leur élaboration est confiée à des comités d'études, aux travaux desquels tout Comité national intéressé par le
sujet traité peut participer. Les organisations internationales, gouvernementales et non gouvernementales, en
liaison avec la CEI, participent également aux travaux. La CEI collabore étroitement avec l'Organisation
Internationale de Normalisation (ISO), selon des conditions fixées par accord entre les deux organisations.
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sont représentés dans chaque comité d’études.
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comme normes, rapports techniques ou guides et agréés comme tels par les Comités nationaux.
4) Dans le but d'encourager l'unification internationale, les Comités nationaux de la CEI s'engagent à appliquer de
façon transparente, dans toute la mesure possible, les Normes internationales de la CEI dans leurs normes
nationales et régionales. Toute divergence entre la norme de la CEI et la norme nationale ou régionale
correspondante doit être indiquée en termes clairs dans cette dernière.
5) La CEI n’a fixé aucune procédure concernant le marquage comme indication d’approbation et sa responsabilité
n’est pas engagée quand un matériel est déclaré conforme à l’une de ses normes.
6) L’attention est attirée sur le fait que certains des éléments de la présente Norme internationale peuvent faire
l’objet de droits de propriété intellectuelle ou de droits analogues. La CEI ne saurait être tenue pour
responsable de ne pas avoir identifié de tels droits de propriété et de ne pas avoir signalé leur existence.

La présente Norme internationale a été établie par le comité d'études 68 de la CEI: Matériaux
magnétiques tels qu'alliages et aciers.
La présente version consolidée de la CEI 60404-11 comprend la première édition (1991)
[documents 68(BC)69 et 68(BC)76] et son amendement 1 (1998) [documents 68/181/FDIS et

68/186/RVD].
Le contenu technique de cette version consolidée est donc identique à celui de l'édition de
base et à son amendement; cette version a été préparée par commodité pour l'utilisateur.
Elle porte le numéro d'édition 1.1.
Une ligne verticale dans la marge indique où la publication de base a été modifiée par
l'amendement 1.
60404-11 © IEC:1991+A.1:1998 – 5 –

INTERNATIONAL ELECTROTECHNICAL COMMISSION

–––––––––––
MAGNETIC MATERIALS –
Part 11: Method of test for the determination

of surface insulation resistance of

magnetic sheet and strip
FOREWORD
1) The IEC (International Electrotechnical Commission) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of the 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, the IEC publishes International Standards. 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. The 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 the 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 National Committees.
3) The documents produced have the form of recommendations for international use and are published in the form
of standards, technical reports or guides and they are accepted by the National Committees in that sense.
4) In order to promote international unification, IEC National Committees undertake to apply IEC International
Standards transparently to the maximum extent possible in their national and regional standards. Any
divergence between the IEC Standard and the corresponding national or regional standard shall be clearly
indicated in the latter.
5) The IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for any
equipment declared to be in conformity with one of its standards.
6) Attention is drawn to the possibility that some of the elements of this International Standard may be the subject
of patent rights. The IEC shall not be held responsible for identifying any or all such patent rights.

This International Standard has been prepared by IEC technical committee 68: Magnetic alloys
and steels.
This consolidated version of IEC 60404-11 consists of the first edition (1991) [documents
68(CO)69 and 68(CO)76] and its amendment 1 (1998) [documents 68/181/FDIS and 68/186/RVD].

The technical content is therefore identical to the base edition and its amendment and has
been prepared for user convenience.
It bears the edition number 1.1.
A vertical line in the margin shows where the base publication has been modified by
amendment 1.
– 6 – 60404-11 © CEI:1991+A.1:1998

MATÉRIAUX MAGNÉTIQUES –
Partie 11: Méthode d'essai pour la détermination

de la résistance d'isolement superficiel des

tôles et feuillards magnétiques

1 Objet et domaine d'application

La présente Norme internationale a pour objet de définir une méthode de mesure pour la
détermination des caractéristiques de résistance d'isolement superficiel des tôles et feuillards
magnétiques.
Cette méthode est applicable aux tôles ou feuillards magnétiques isolés sur une ou deux faces
et est adaptée au contrôle de fabrication dans le cas d'application de revêtements isolants.
2 Principe de mesure
*
Le principe de mesure s'appuie sur, et inclut, la méthode décrite à l'origine par Franklin qui
permet de caractériser une seule face revêtue à la fois.
L'organisation de l'appareillage est décrite par la figure 1. Dix contacts métalliques de surfaces
déterminées sont appliqués sur une seule face revêtue de la tôle, sous des conditions définies
de tension électrique et de pression.
L'efficacité de l'isolation superficielle est évaluée par la mesure des courants traversant les 10
contacts.
Source
Micro-
d'alimentation
processeur
Affichage
Touches de contact
Foret hélicoïdal
(10 au total)
pour contact
Revêtement
isolant
Eprouvette
IEC  1 595/98
Figure 1 – Organisation de l'appareillage pour la mesure
de la résistance d'isolement superficiel
–––––––––
*
Franklin, R.F., «Measurement and control of interlaminar resistance of laminated magnetic cores», ASTM
Bulletin, n° 144, janvier 1947, p. 57.

60404-11 © IEC:1991+A.1:1998 – 7 –

MAGNETIC MATERIALS –
Part 11: Method of test for the determination

of surface insulation resistance of

magnetic sheet and strip
1 Scope and field of application

This International Standard is intended to define a measurement method for the determination
of the characteristics of surface insulation resistance of magnetic sheet and strip.
This method is applicable to magnetic sheet and strip insulated on one or both surfaces and is
suitable for manufacturing control in the application of insulation coatings.
2 Principle of measurement
The principle of the measurement is based on, and includes, the method originally described by
*
Franklin which characterizes only one coated surface at a time.
The arrangement of the apparatus is shown in figure 1. Ten metallic contacts of fixed area are
applied to one coated surface of the sheet, under specified conditions of voltage and pressure.
The effectiveness of the surface insulation is assessed by the measurement of the currents
through the 10 contacts.
Micro-
Power supply
processor
Display
Contact buttons
Twist drill
(a total of 10)
for contact
Insulation
coating
Test specimen
IEC  1 595/98
Figure 1 – Arrangement of apparatus for the measurement of
surface insulation resistance
–––––––––
*
Franklin, R.F., "Measurement and control of interlaminar resistance of laminated magnetic cores", ASTM
Bulletin, no. 144, January 1947, p. 57.

– 8 – 60404-11 © CEI:1991+A.1:1998

Chaque touche de contact est alimentée individuellement par une source de courant continu
selon une des deux manières constituant les deux modes de mesure en vigueur dans cette

norme, à savoir:
a) Mode A La tension électrique entre l'extrémité des résistances de 5 Ω ± 1 % (voir figure 2)

connectées à la source et les forets de contact est stabilisée à 500 mV ± 0,5 % pour une

plage de courant allant de 0 à 1 A. Les deux forets hélicoïdaux assurent la fonction de

contact avec le substrat pour le passage du courant.

b) Mode B La tension électrique entre chaque touche de contact et les forets de contact est

stabilisée à 250 mV ± 0,5 % pour une plage de courant allant de 0 à 2,5 A en vue de

l'analyse des courants d'électrodes individuels. Les deux forets hélicoïdaux assurent des

fonctions différentes. Un foret fournit le contact avec le substrat pour le passa
...

IEC 60404-11 ®
Edition 1.2 2012-05
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Magnetic materials –
Part 11: Method of test for the determination of surface insulation resistance of
magnetic sheet and strip
Matériaux magnétiques –
Partie 11: Méthode d'essai pour la détermination de la résistance d'isolement
superficiel des tôles et feuillards magnétiques

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 la CEI ou du Comité national de la CEI du pays du demandeur.

Si vous avez des questions sur le copyright de la CEI ou si vous désirez obtenir des droits supplémentaires sur cette

publication, utilisez les coordonnées ci-après ou contactez le Comité national de la CEI de votre pays de résidence.

IEC Central Office Tel.: [phone]
3, rue de Varembé Fax: [phone]
CH-1211 Geneva 20 [e-mail]
Switzerland www.iec.ch
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 corrigenda or an amendment might have been published.

Useful links:
IEC publications search - www.iec.ch/searchpub Electropedia - www.electropedia.org
The advanced search enables you to find IEC publications The world's leading online dictionary of electronic and
by a variety of criteria (reference number, text, technical electrical terms containing more than 30 000 terms and
committee,…). definitions in English and French, with equivalent terms in
It also gives information on projects, replaced and additional languages. Also known as the International
withdrawn publications. Electrotechnical Vocabulary (IEV) on-line.

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A propos de la CEI
La Commission Electrotechnique Internationale (CEI) 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 CEI
Le contenu technique des publications de la CEI est constamment revu. Veuillez vous assurer que vous possédez
l’édition la plus récente, un corrigendum ou amendement peut avoir été publié.

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La recherche avancée vous permet de trouver des Le premier dictionnaire en ligne au monde de termes
publications CEI en utilisant différents critères (numéro de électroniques et électriques. Il contient plus de 30 000
référence, texte, comité d’études,…). termes et définitions en anglais et en français, ainsi que
Elle donne aussi des informations sur les projets et les les termes équivalents dans les langues additionnelles.
publications remplacées ou retirées. Egalement appelé Vocabulaire Electrotechnique
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contactez-nous: [e-mail].
IEC 60404-11 ®
Edition 1.2 2012-05
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Magnetic materials –
Part 11: Method of test for the determination of surface insulation resistance of

magnetic sheet and strip
Matériaux magnétiques –
Partie 11: Méthode d'essai pour la détermination de la résistance d'isolement

superficiel des tôles et feuillards magnétiques

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
CODE PRIX CD
ICS 17.220.01; 29.030 ISBN 978-2-88912-053-6

– 2 – 60404-11 © IEC:1991+A1:1998

+A2:2012
CONTENTS
FOREWORD . 3

1 Scope and field of application . 5

2 Principle of measurement . 5

3 Test specimen . 6

4 Apparatus . 6

4.1 Contact assembly . 6
4.2 Power supply . 7
4.3 Current measurement . 7
4.4 Determination of applied force . 8
5 Calibration . 9
6 Measuring procedure . 9
7 Evaluation of surface insulation resistance . 9
8 Test report . 10

Figure 1 – Arrangement of apparatus for the measurement of surface insulation resistance . 5
Figure 2 – Arrangement of stabilizing circuit: mode A . 8
Figure 3 – Arrangement of stabilizing circuit: mode B . 8

60404-11 © IEC:1991+A1:1998 – 3 –

+A2:2012
INTERNATIONAL ELECTROTECHNICAL COMMISSION

–––––––––––
MAGNETIC MATERIALS –
Part 11: Method of test for the determination

of surface insulation resistance of

magnetic sheet and strip
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
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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.

This International Standard has been prepared by IEC technical committee 68: Magnetic alloys
and steels.
This consolidated version of IEC 60404-11 consists of the first edition (1991) [documents
68(CO)69 and 68(CO)76], its amendment 1 (1998) [documents 68/181/FDIS and 68/186/RVD]
and its amendment 2 (2012) [documents 68/434/FDIS and 68/435/RVD].
The technical content is therefore identical to the base edition and its amendments and has
been prepared for user convenience.

– 4 – 60404-11 © IEC:1991+A1:1998

+A2:2012
It bears the edition number 1.2.

A vertical line in the margin shows where the base publication has been modified by

amendments 1 and 2.
60404-11 © IEC:1991+A1:1998 – 5 –

+A2:2012
MAGNETIC MATERIALS –
Part 11: Method of test for the determination

of surface insulation resistance of

magnetic sheet and strip
1 Scope and field of application
This International Standard is intended to define a measurement method for the determination
of the characteristics of surface insulation resistance of magnetic sheet and strip.
This method is applicable to magnetic sheet and strip insulated on one or both surfaces and is
suitable for manufacturing control in the application of insulation coatings.
2 Principle of measurement
The principle of the measurement is based on, and includes, the method originally described by
*
Franklin which characterizes only one coated surface at a time.
The arrangement of the apparatus is shown in figure 1. Ten metallic contacts of fixed area are
applied to one coated surface of the sheet, under specified conditions of voltage and pressure.
The effectiveness of the surface insulation is assessed by the measurement of the currents
through the 10 contacts.
Micro-
Power supply
processor
Display
Contact buttons
Twist drill
(a total of 10)
for contact
Insulation
coating
Test specimen
IEC  1 595/98
Figure 1 – Arrangement of apparatus for the measurement of
surface insulation resistance
–––––––––
*
Franklin, R.F., "Measurement and control of interlaminar resistance of laminated magnetic cores", ASTM
Bulletin, no. 144, January 1947, p. 57.

– 6 – 60404-11 © IEC:1991+A1:1998

+A2:2012
Each contact button is individually fed from a d.c. power supply in one of the two ways which

constitute the two modes of measurement used in this standard, namely:

a) Mode A The voltage between the supply side of the 5 Ω ± 1 % resistors (see figure 2) and

the drill contacts is stabilized at 500 mV ± 0,5 % over a current range of 0 to 1 A. The two

twist drills perform the function of current return contacts with the substrate.

b) Mode B The voltage between each contact button and the drill contacts is stabilized at

250 mV ± 0,5 % over a current range from 0 to 2,5 A for the analysis of individual electrode

currents. The two twist drills perform different functions. One drill provides the current

return contact with the substrate. The other drill serves as a potential sensor for the voltage

feedback control. This method removes the influence of the variable contact resistance
between the current return drill and the substrate.
The voltage across subsidiary current sensing resistors of low-value, connected in series with
each electrode, but not included within the stabilized voltage, serves to indicate the value of the
current, as shown in figures 2 and 3.
Because the current path is between the contacts and the metallic substrate, this is not a true
measurement of interlaminar resistance. However, this test provides a useful indication of
surface insulation quality.
3 Test specimen
Each test specimen shall be formed from a single sheet or length of strip. The width and length
of the test specimen shall be respectively greater than the width and length of the contact
assembly described in clause 4. This measurement is destructive; the test specimen can only
be used once.
To obtain a representative result, test specimens shall be taken from the full sheet width.
4 Apparatus
4.1 Contact assembly
The test specimen is pressed between a plate and the contact assembly. The contact assembly
consists of 10 vertically-mounted metallic rods which move axially against springs in a
mounting block. These 10 contact rods are normally arranged in two rows. However, for
convenience these 10 contacts can be arranged in one row. Each rod shall be provided with a
contact button of bronze or other suitable material (for example, stainless steel) and shall be
electrically insulated from the mounting frame.

NOTE Articulation of contact buttons improves contact by compensating for minor misalignments.
Each of the 10 contact buttons shall have a contact area of 64,5 mm² ± 1 %, giving a total area
for the 10 buttons of 645 mm² ± 1 %.
Electrical contact with the substrate of the test specimen shall be achieved by means of two
spring-loaded twist drills of about 3 mm diameter which pierce the insulation coating.

60404-11 © IEC:1991+A1:1998 – 7 –

+A2:2012
4.2 Power supply
Mode A: A d.c. power supply capable of maintaining a stabilized voltage of 500 mV across the

electrodes at a current of 0,1 A per electrode (1,0 A total) shall be used.

Mode B: A d.c power supply capable of maintaining a stabilized voltage of 250 mV at a current

of 2,5 A for an individual electrode shall be used. A single supply and a current-sensing

resistor, R can be used and switched to each contact button in turn, or a 10-outlet system can
s,
be used with each electrode fed simultaneously and independently.

4.3 Current measurement
The current flowing through the contact buttons shall be measured with an uncertainty of ± 2%
or better. This can be achieved by inserting a low value (e.g. 0,2 Ω) resistor in the supply to the
contact buttons, at a point outside the connection to the stabilizing circuit, and measuring the
voltage drop across the low value resistor by means of a suitable voltmeter.
The electrical arrangements of the stabilizing circuit and current measurement system are
shown in figures 2 and 3 for modes A and B respectively.

– 8 – 60404-11 © IEC:1991+A1:1998

+A2:2012
Voltmeter
R
s
Feedback voltage
Stabilized d.c.
Output
power supply
U = 0,5 V
5 Ω 5 Ω 5 Ω 5 Ω 5 Ω 5 Ω 5 Ω 5 Ω 5 Ω 5 Ω
Twist drills
Contact buttons
Test specimen
IEC  471/12
Figure 2 – Arrangement of stabilizing circuit: mode A

Voltmeter
R
s
Feedback voltage
Stabilized d.c.
Output
power supply
U = 0,25 V
Current return
Potential sensor
Twist drills
Test specimen Contact buttons
IEC  472/12
Figure 3 – Arrangement of stabilizing circuit: mode B

4.4 Determination of applied force
The total force applied by all of the contacts pressing on the test specimen shall be determined
by any suitable means with an uncertainty of ±5 % or better.

60404-11 © IEC:1991+A1:1998 – 9 –

+A2:2012
5 Calibration
The calibration of the system shall be checked in three ways:

a) The electrodes and drills shall be applied to a clean copper sheet at nominal testing

pressure. The total current passing through the 10 electrodes shall be 1,0 A ± 3 % for

mode A. For mode B the electrode to drill voltage shall be less than 25 mV with a current
of 2,5 A flowing. If this is not the case, the electrodes shall be checked for cleanliness and

the twist drills checked for sharpness and contact resistance.

b) Carbon paper pressed onto white paper by the electrodes at nominal testing pressure shall
give a set of even smudges free from signs of force concentration. Pressure measurement
sheets that could indicate applied pressure as colour density variations can be used instead
of the carbon paper and white paper.
c) Standard resistors of 0,1 Ω, 1 Ω, 10 Ω and 100 Ω connected between the drills and each
electrode in turn shall be used to show that the stabilization is adequate and that the
required current levels can be achieved.
6 Measuring procedure
The test specimen shall be positioned between the baseplate and the 10 contact buttons and a
force of 1 290 N ± 5 % shall be gradually applied. This corresponds to a pressure of 2 N/mm²
for the total contact area of 645 mm².
The stabilized d.c. voltage shall be gradually applied to the electrodes and the total current for
mode A, or each electrode current for mode B, shall be recorded individually or by computer.
If the insulation quality of a single surface is to be evaluated in the test, 10 readings shall be
taken using the 10 contact buttons on 10 separate representative areas of the sheet or on 10
test specimens.
If the insulation quality of both surfaces is to be jointly evaluated in the test then five
applications of the contact buttons shall be made to each surface on five separate
representative areas or test specimens. The same area of the test specimen shall not be used
to test both sides.
7 Evaluation of surface insulation resistance
The recorded currents shall be used to calculate reported values of insulation resistance in the

following ways:
a) For Mode A, the coefficient of surface insulation resistance shall be determined by inserting
the 10 values of the current flowing through the 10 electrodes in parallel (either all from one
surface or five from each of the two coated surfaces) in the following formula:
   
   
U R 0,5
   
C = A −  = 645  − 0,5 (1)
10 10
1 10 1
   
I  I
∑ ∑
A A
   
10 10
 1   1 
– 10 – 60404-11 © IEC:1991+A1:1998

+A2:2012
where
C is the coefficient of surface insulation resistance, in Ω·mm /side

A is the total area of the 10 contact buttons, in mm²

U is the voltage applied to the contacts and 5 Ω resistors, in V

R is the resistance in series with each contact, equal to 5 Ω

I is the measured total electrode current (10 values), in A
A
NOTE If five measurements are taken from each surface, the value C is the coefficient of the surface insulation
resistance of one surface, which represents the mean of the two surfaces of the product.

b) For Mode B, the surface insulation resistance shall
...