IEC 61858:2008

Electrical insulation systems - Thermal evaluation of modifications to an established wire-wound EIS

IEC 61858:2008 lists the required test procedures for qualification of modifications of an established electrical insulation system (EIS) with respect to its thermal classification. This standard is applicable to EIS used in wire-wound electrotechnical devices. The test procedures are comparative in that the performance of a candidate EIS is compared to that of a reference EIS, which has proven service experience in accordance with IEC 60505 or has been evaluated by one of the procedures given in the IEC 61857 series. This third edition cancels and replaces the second edition, published in 2004 by IEC TC 98: Electrical insulation systems (EIS). It constitutes an editorial revision.

Systèmes d'isolation électriques - Evaluation thermique des modifications apportées à un système d'isolation électrique éprouvé à enroulements à fil

La CEI 61858:2008 indique les procédures d'essai requises pour la qualification des modifications qui ont été apportées à un système d'isolation électrique éprouvé (SIE), pour ce qui concerne sa classification thermique. Cette norme s'applique aux systèmes d'isolation électrique existant dans les dispositifs électrotechniques à enroulements à fils. Les procédures d'essai se font par comparaison des performances d'un système d'isolation électrique candidat avec celles d'un système d'isolation électrique de référence dont l'expérience en service a été démontrée conformément à la CEI 60505, ou qui a été évalué par une des procédures décrites dans la série 61857. Cette troisième édition annule et remplace la seconde édition, publiée en 2004 par le comité d'études 98 de la CEI: Systèmes d'isolation électrique (SIE). Elle constitue une révision rédactionnelle.

General Information

• Status: Replaced
• Publication Date: 24-Jul-2008
• ICS: 29.080.30 - Insulation systems
• Technical Committee: TC 112 - Evaluation and qualification of electrical insulating materials and systems
• Drafting Committee: WG 6 - TC 112/WG 6
• Current Stage: DELPUB - Deleted Publication
• Completion Date: 12-Feb-2014

Relations

• Replaced By: IEC 61858-1:2014 - Electrical insulation systems - Thermal evaluation of modifications to an established electrical insulation system (EIS) - Part 1: Wire-wound winding EIS
• Effective Date: 05-Sep-2023
• Revises: IEC 61858:2004 - Electrical insulation systems - Thermal evaluation of modifications to an established wire-wound EIS
• Effective Date: 05-Sep-2023

Standards Content (Sample)

IEC 61858
Edition 3.0 2008-07
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Electrical insulation systems – Thermal evaluation of modifications to an
established wire-wound EIS
Systèmes d’isolation électriques – Evaluation thermique des modifications
apportées à un système d’isolation électrique éprouvé à enroulements à fil

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
3, rue de Varembé
CH-1211 Geneva 20
Switzerland
Email: [e-mail]
Web: 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.
ƒ Catalogue of IEC publications: www.iec.ch/searchpub
The IEC on-line Catalogue enables you to search by a variety of criteria (reference number, text, technical committee,…).
It also gives information on projects, withdrawn and replaced publications.
ƒ IEC Just Published: www.iec.ch/online_news/justpub
Stay up to date on all new IEC publications. Just Published details twice a month all new publications released. Available
on-line and also by email.
ƒ Electropedia: www.electropedia.org
The world's leading online dictionary of electronic and electrical terms containing more than 20 000 terms and definitions
in English and French, with equivalent terms in additional languages. Also known as the International Electrotechnical
Vocabulary online.
ƒ Customer Service Centre: www.iec.ch/webstore/custserv
If you wish to give us your feedback on this publication or need further assistance, please visit the Customer Service
Centre FAQ or contact us:
Email: [e-mail]
Tel.: [phone]
Fax: [phone]
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.
ƒ Catalogue des publications de la CEI: www.iec.ch/searchpub/cur_fut-f.htm
Le Catalogue en-ligne de la CEI vous permet d’effectuer des recherches en utilisant différents critères (numéro de référence,
texte, comité d’études,…). Il donne aussi des informations sur les projets et les publications retirées ou remplacées.
ƒ Just Published CEI: www.iec.ch/online_news/justpub
Restez informé sur les nouvelles publications de la CEI. Just Published détaille deux fois par mois les nouvelles
publications parues. Disponible en-ligne et aussi par email.
ƒ Electropedia: www.electropedia.org
Le premier dictionnaire en ligne au monde de termes électroniques et électriques. Il contient plus de 20 000 termes et
définitions en anglais et en français, ainsi que les termes équivalents dans les langues additionnelles. Egalement appelé
Vocabulaire Electrotechnique International en ligne.
ƒ Service Clients: www.iec.ch/webstore/custserv/custserv_entry-f.htm
Si vous désirez nous donner des commentaires sur cette publication ou si vous avez des questions, visitez le FAQ du
Service clients ou contactez-nous:
Email: [e-mail]
Tél.: [phone]
Fax: [phone]
IEC 61858
Edition 3.0 2008-07
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Electrical insulation systems – Thermal evaluation of modifications to an
established wire-wound EIS
Systèmes d’isolation électriques – Evaluation thermique des modifications
apportées à un système d’isolation électrique éprouvé à enroulements à fil

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
R
CODE PRIX
ICS 29.080.30 ISBN 2-8318-9946-X
– 2 – 61858 © IEC:2008
CONTENTS
FOREWORD.3
INTRODUCTION.5
1 Scope.6
2 Normative references .6
3 Terms and definitions .7
4 General considerations.8
5 Evaluation of the change of thickness of an EIM.10
5.1 Samples .10
5.2 Acceptance .10
6 Substitution of winding wire .10
6.1 General .10
6.2 Substitution of enamel.10
6.3 Substitution of conductor material .10
6.4 Alternate winding wire .10
7 Substitution of impregnating resin/varnish .11
7.1 Thermal class determination.11
7.2 Evaluation .11
7.2.1 Thermal classes equal or better.11
7.2.2 One thermal class lower .11
7.2.3 Other criteria .11
8 Substitution with other EIM.11
8.1 Technically equivalent materials.11
8.2 Previous evaluation .12
8.3 Other.12
9 Evaluation of additions .12
9.1 Addition of an impregnating resin/varnish .12
9.2 Addition of other components .12
10 Single-point thermal ageing test .12
10.1 Test objects.12
10.2 Establishing the EIS relative thermal endurance index (EIS RTE).12
10.3 Interpretation of results .13
Annex A (normative) Classes of winding wire.14
Annex B (normative) Compatibility test procedure.15
Bibliography.18

Figure 1 – Overview of evaluation methods.9

Table 1 – Thermal ageing test methods for resin/varnishes.11
Table A.1 – Winding wire types.14

61858 © IEC:2008 – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
ELECTRICAL INSULATION SYSTEMS –
THERMAL EVALUATION OF MODIFICATIONS TO
AN ESTABLISHED WIRE-WOUND EIS
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 provides no marking procedure to indicate its approval and cannot be rendered responsible for any
equipment declared to be in conformity with an IEC Publication.
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 61858 has been prepared by IEC technical committee 112:
Evaluation and qualification of electrical insulating materials and systems.
This third edition cancels and replaces the second edition, published in 2004 by IEC TC 98:
Electrical insulation systems (EIS). It constitutes an editorial revision.
The text of this standard is based on the following documents:
CDV Report on voting
112/90/CDV 112/98/RVC
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.

– 4 – 61858 © IEC:2008
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.
61858 © IEC:2008 – 5 –
INTRODUCTION
This International Standard describes procedures for the evaluation of changes to an
established electrical insulation system (EIS) for wire-wound electrotechnical devices and the
effect of these changes on the thermal classification of the established EIS.
General principles f
...