IEC 60426:2007
(Main)Electrical insulating materials - Determination of electrolytic corrosion caused by insulating materials - Test methods
Electrical insulating materials - Determination of electrolytic corrosion caused by insulating materials - Test methods
IEC 60426:2007 determines the ability of insulating materials to produce electrolytic corrosion on metals being in contact with them under the influence of electric stress, high humidity and elevated temperature. The effect of electrolytic corrosion is assessed in one test by using consecutively two methods:
- visual semi-quantitative method consisting in comparing visually the corrosion appearing on the anode and cathode metal strips, with those given in the reference figures. This method consists of the direct visual assessment of the degree of corrosion of two copper strips, acting as anode and cathode respectively, placed in contact with the tested insulating material under a d.c. potential difference at specified environmental conditions. The degree of corrosion is assessed by visually comparing the corrosion marks on the anode and cathode metal strips with those shown in the reference figures;
- quantitative method, which involves the tensile strength measurement, carried out on the same anode and cathode metal strips after visual inspection.
An additional quantitative test method for determining electrolytic corrosion, which involves tensile strength measurement of copper wire, is described in the informative Annex C.
Matériaux isolants électriques - Détermination de la corrosion électrolytique en présence de matériaux isolants - Méthodes d'essais
La CEI 60426:2007 détermine la capacité des matériaux isolants à produire une corrosion électrolytique sur des métaux en contact avec eux, sous l'influence de contraintes électriques, d'une forte humidité et de températures élevées. L'effet de la corrosion électrolytique est apprécié d'après un seul essai, en utilisant successivement les deux méthodes suivantes:
- une méthode visuelle semi-quantitative qui consiste à comparer visuellement la corrosion qui apparaît sur les bandes métalliques pour l'anode et la cathode, à celles des figures de référence. Cette méthode consiste en l'appréciation visuelle directe du degré de corrosion de deux lames de cuivre, servant respectivement d'anode et de cathode, mises en contact avec le matériau isolant en essai et soumises dans des conditions d'environnement spécifiées à une différence de potentiel en courant continu. Le degré de corrosion est évalué en comparant visuellement les marques de corrosion constatées sur les bandes métalliques anode et cathode, à celles des figures de référence;
- une méthode quantitative, qui met en jeu des mesures de résistance à la traction, effectuées sur les mêmes bandes métalliques pour l'anode et la cathode, après inspection visuelle.
Une méthode d'essai quantitative supplémentaire en vue de déterminer la corrosion électrolytique, qui met en jeu des mesures de la résistance à la traction de fils de cuivre, est décrite dans l'Annexe informative C.
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INTERNATIONAL IEC
STANDARD 60426
Second edition
2007-01
Electrical insulating materials –
Determination of electrolytic corrosion
caused by insulating materials –
Test methods
Reference number
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60000 series. For example, IEC 34-1 is now referred to as IEC 60034-1.
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INTERNATIONAL IEC
STANDARD 60426
Second edition
2007-01
Electrical insulating materials –
Determination of electrolytic corrosion
caused by insulating materials –
Test methods
© IEC 2007 ⎯ Copyright - all rights reserved
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 the publisher.
International Electrotechnical Commission, 3, rue de Varembé, PO Box 131, CH-1211 Geneva 20, Switzerland
Telephone: +41 22 919 02 11 Telefax: +41 22 919 03 00 E-mail: inmail@iec.ch Web: www.iec.ch
PRICE CODE
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International Electrotechnical Commission
МеждународнаяЭлектротехническаяКомиссия
For price, see current catalogue
– 2 – 60426 © IEC:2007(E)
CONTENTS
FOREWORD.4
INTRODUCTION.6
1 Scope.7
2 Normative references .7
3 Terms and definitions .7
4 General description of the test method .8
5 Test specimens .8
5.1 General .8
5.2 Cut surfaces of rigid materials (blocks, plates, sheets or semi-finished
materials) .9
5.3 Cast, moulding, injection and pressed materials .9
5.4 Cut surfaces of flexible films, foils and thin sheets.9
5.5 Adhesive tapes.10
5.6 Flexible sleeving and tubing .10
5.7 Lacquers and insulating varnishes.10
5.8 Cleanliness of contact surfaces .10
5.9 Number of test specimens .11
6 Test strips .11
6.1 General .11
6.2 Preparation of the test strips .11
6.3 Cleanliness of test strips .12
7 Test device.12
8 Test conditions .14
9 Test procedure .14
10 Evaluation .14
10.1 General evaluation .14
10.2 Visual inspection of the test strips .15
10.3 Tensile strength of test strips .15
11 Evaluation of corrosion on copper strips .16
12 Test report.17
Annex A (normative) Tables for the evaluation of corrosion on brass and aluminium
strips .18
Annex B (informative) Notes on visual evaluation .20
Annex C (informative) Copper wire tensile strength method .21
Figure 1 – Test specimen of rigid material, for example textile laminate.8
Figure 2 – Test specimen of flexible material, for example flexible films, foils etc.10
Figure 3 – Test strip.12
Figure 4 – Test device for determining electrolytic corrosion.13
Figure C.1 – Apparatus for determining electrolytic corrosion of rigid insulating material .23
Figure C.2 – Apparatus for determining electrolytic corrosion of flexible insulating material .23
60426 © IEC:2007(E) – 3 –
Table 1 – Degrees of corrosion of copper strips .16
Table A.1 – Degrees of corrosion of brass strips.18
Table A.2 – Degrees of corrosion of aluminium strips .19
– 4 – 60426 © IEC:2007(E)
INTERNATIONAL ELECTROTECHNICAL COMMISSION
___________
ELECTRICAL INSULATING MATERIALS −
DETERMINATION OF ELECTROLYTIC CORROSION CAUSED BY
INSULATING MATERIALS −
TEST METHODS
FOREWORD
1) The International Electrotechnical Commission (IEC) 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, 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 National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
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Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
misinterpretation by any end user.
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between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
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8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 60426 has been prepared by IEC technical committee 112:
Evaluation and qualification of electrical insulating materials and systems.
This second edition cancels and replaces the first edition, published in 1973, and constitutes
a technical revision.
The main changes with respect to the previous edition are listed below:
• experience has indicated the need for improved description of the experimental method. It
describes a revised procedure for the visual and tensile strength test method that
overcomes the limitations of the first edition;
• one older method of the first edition has partly been maintained in the informative annex.
60426 © IEC:2007(E) – 5 –
The text of this standard is based on the following documents:
FDIS Report on voting
112/45/FDIS 112/55/RVD
Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
A bilingual version of this publication may be issued at a later date.
The committee has decided that the contents of this publication will remain unchanged until
the maintenance result date indicated on the IEC web site under “http://webstore.iec.ch” in the
data related to the specific publication. At this date, the publication will be
• reconfirmed;
• withdrawn;
• replaced by a revised edition, or
• amended.
– 6 – 60426 © IEC:2007(E)
INTRODUCTION
Electrical insulating materials at high atmospheric humidity and under influence of electric
stress may cause corrosion of metal parts being in contact with them. Such electrolytic
corrosion is dependent upon the composition of the insulating material and the character of
the metal; it is influenced by temperature, relative humidity, nature of the voltage and the time
of exposure. Direct voltage produces much more rapid and extensive corrosion than alterna-
ting voltage. Corrosion is more pronounced at the positive electrode.
Not only copper but also most other metals, except the noble metals such as platinum or gold,
are subject to electrolytic corrosion. Electrolytic corrosion, however, is usually determined
with insulating materials in contact with copper, brass or aluminium. Copper, however, is a
basic metal and most frequently used in electrotechnical, teletechnical and electronic
equipment, especially for current conducting parts and therefore it was chosen as a basic test
metal. Other metals may be used when needed for special purposes, but the results may
differ from those described in this method.
Electrolytic corrosion may cause open-circuit failure in electrical conductors and devices. It
may promote low resistance leakage path across or through electrical insulation and the
products of corrosion may otherwise interfere with the operation of electrical devices, i.e. may
prevent operation of contacts, etc.
Electronic equipment operating under conditions of high humidity and elevated temperature
may be particula
...
IEC 60426 ®
Edition 2.0 2007-01
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Electrical insulating materials – Determination of electrolytic corrosion caused
by insulating materials – Test methods
Matériaux isolants électriques – Détermination de la corrosion électrolytique en
présence de matériaux isolants – Méthodes d’essais
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IEC 60426 ®
Edition 2.0 2007-01
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Electrical insulating materials – Determination of electrolytic corrosion caused
by insulating materials – Test methods
Matériaux isolants électriques – Détermination de la corrosion électrolytique en
présence de matériaux isolants – Méthodes d’essais
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
U
CODE PRIX
ICS 17.220.99; 29.035.01 ISBN 978-2-88910-192-4
– 2 – 60426 © IEC:2007
CONTENTS
FOREWORD.4
INTRODUCTION.6
1 Scope.7
2 Normative references .7
3 Terms and definitions .7
4 General description of the test method .8
5 Test specimens .8
5.1 General .8
5.2 Cut surfaces of rigid materials (blocks, plates, sheets or semi-finished
materials) .9
5.3 Cast, moulding, injection and pressed materials .9
5.4 Cut surfaces of flexible films, foils and thin sheets.9
5.5 Adhesive tapes.10
5.6 Flexible sleeving and tubing .10
5.7 Lacquers and insulating varnishes.10
5.8 Cleanliness of contact surfaces .10
5.9 Number of test specimens .11
6 Test strips .11
6.1 General .11
6.2 Preparation of the test strips .11
6.3 Cleanliness of test strips .12
7 Test device.12
8 Test conditions .14
9 Test procedure .14
10 Evaluation .14
10.1 General evaluation .14
10.2 Visual inspection of the test strips .15
10.3 Tensile strength of test strips .15
11 Evaluation of corrosion on copper strips .16
12 Test report.17
Annex A (normative) Tables for the evaluation of corrosion on brass and aluminium
strips .18
Annex B (informative) Notes on visual evaluation .20
Annex C (informative) Copper wire tensile strength method .21
Figure 1 – Test specimen of rigid material, for example textile laminate.8
Figure 2 – Test specimen of flexible material, for example flexible films, foils etc.10
Figure 3 – Test strip.12
Figure 4 – Test device for determining electrolytic corrosion.13
Figure C.1 – Apparatus for determining electrolytic corrosion of rigid insulating material .23
Figure C.2 – Apparatus for determining electrolytic corrosion of flexible insulating material .23
60426 © IEC:2007 – 3 –
Table 1 – Degrees of corrosion of copper strips .16
Table A.1 – Degrees of corrosion of brass strips.18
Table A.2 – Degrees of corrosion of aluminium strips .19
– 4 – 60426 © IEC:2007
INTERNATIONAL ELECTROTECHNICAL COMMISSION
___________
ELECTRICAL INSULATING MATERIALS –
DETERMINATION OF ELECTROLYTIC CORROSION
CAUSED BY INSULATING MATERIALS –
TEST METHODS
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.
International Standard IEC 60426 has been prepared by IEC technical committee 112:
Evaluation and qualification of electrical insulating materials and systems.
This second edition cancels and replaces the first edition, published in 1973, and constitutes
a technical revision.
The main changes with respect to the previous edition are listed below:
• experience has indicated the need for improved description of the experimental method. It
describes a revised procedure for the visual and tensile strength test method that
overc
...
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