IEC 62539:2007

INTERNATIONAL IEC
STANDARD 62539
First edition
2007-07
IEEE 930
Guide for the statistical analysis of electrical
insulation breakdown data
Reference number
IEC 62539(E):2007
IEEE Std 930-2004
All rights reserved. IEEE is a registered trademark in the U.S. Patent & Trademark Office, owned by the Institute of
Electrical and Electronics Engineers, Inc.
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 the publisher.
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.

IEC Central Office The Institute of Electrical and Electronics Engineers, Inc
3, rue de Varembé 3 Park Avenue
CH-1211 Geneva 20 US-New York, NY10016-5997
Switzerland USA
Email: inmail@iec.ch Email: stds-info@ieee.org
Web: www.iec.ch Web: www.ieee.org

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also gives information on projects, withdrawn and replaced publications.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: csc@iec.ch
Tel.: +41 22 919 02 11
Fax: +41 22 919 03 00
INTERNATIONAL IEC
STANDARD 62539
First edition
2007-07
IEEE 930
Guide for the statistical analysis of electrical
insulation breakdown data
© IEEE 2007   Copyright - all rights reserved
IEEE is a registered trademark in the U.S. Patent & Trademark Office, owned by the Institute of Electrical and Electronics Engineers, Inc.
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
The Institute of Electrical and Electronics Engineers, Inc, 3 Park Avenue, New York, NY 10016-5997, USA
Telephone: +1 732 562 3800 Telefax: +1 732 562 1571 E-mail: stds-info@ieee.org Web: www.standards.ieee.org
Commission Electrotechnique Internationale
International Electrotechnical Commission
МеждународнаяЭлектротехническаяКомиссия

–2 – IEC 62539:2007(E)
IEEE 930-2004(E)
CONTENTS
FOREWORD .4
IEEE Introduction .7
1. Scope. 8
2. References. 8
3. Steps required for analysis of breakdown data . 9
3.1 Data acquisition . 9
3.2 Characterizing data using a probability function . 10
3.3 Hypothesis testing.11
4. Probability distributions for failure data.12
4.1 The Weibull distribution.12
4.2 The Gumbel distribution.13
4.3 The lognormal distribution .13
4.4 Mixed distributions .13
4.5 Other terminology.14
5. Testing the adequacy of a distribution .14
5.1 Weibull probability data .14
5.2 Use of probability paper for the three-parameter Weibull distribution .15
5.3 The shape of a distribution plotted on Weibull probability paper .16
5.4 A simple technique for testing the adequacy of the Weibull distribution .16
6. Graphical estimates of Weibull parameters . 17
7. Computational techniques for Weibull parameter estimation . 17
7.1 Larger data sets . 17
7.2 Smaller data sets . 18
8. Estimation of Weibull percentiles. 19
9. Estimation of confidence intervals for the Weibull function. 19
9.1 Graphical procedure for complete and censored data. 20
9.2 Plotting confidence limits . 21
10. Estimation of the parameter and their confidence limits of the log-normal function. 21
10.1 Estimation of lognormal parameters. 21
10.2 Estimation of confidence intervals of log-normal parameters. 22
11. Comparison tests. 22
11.1 Simplified method to compare percentiles of Weibull distributions . 23
12. Estimating Weibull parameters for a system using data from specimens . 23
Published by IEC under licence from IEEE. © 2004 IEEE. All rights reserved.

IEEE 930-2004(E)
Annex A (informative) Least squares regression. 24
Annex B (informative) Bibliography. 48
Annex C (informative) List of participants. 49
Published by IEC under licence from IEEE. © 2004 IEEE. All rights reserved.

– 4 – IEC 62539:2007(E)
IEEE 930-2004(E)
INTERNATIONAL ELECTROTECHNICAL COMMISSION
___________
GUIDE FOR THE STATISTICAL ANALYSIS OF ELECTRICAL INSULATION
BREAKDOWN DATA
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) 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/IEEE 62539 has been processed through Technical Committee
112: Evaluation and qualification of electrical insulating materials and systems.
The text of this standard is based on the following documents:
IEEE Std FDIS Report on voting
930 (2004) 112/59/FDIS 112/69A/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.
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.
Published by IEC under licence from IEEE. © 2004 IEEE. All rights reserved.

IEEE 930-2004(E)
IEC/IEEE Dual Logo International Standards
This Dual Logo International Standard is the result of an agreement between the IEC and the Institute of
Electrical and Electronics Engineers, Inc. (IEEE). The original IEEE Standard was submitted to the IEC for
consideration under the agreement, and the resulting IEC/IEEE Dual Logo International Standard has been
published in accordance with the ISO/IEC Directives.
IEEE Standards documents are developed within the IEEE Societies and the Standards Coordinating
Committees of the IEEE Standards Association (IEEE-SA) Standards Board. The IEEE develops its standards
through a consensus development process, approved by the American National Standards Institute, which
brings together volunteers representing varied viewpoints and interests to achieve the final product. Volunteers
are not necessarily members of the Institute and serve without compensation. While the IEEE administers the
process and establishes rules to promote fairness in the consensus development process, the IEEE does not
independently evaluate, test, or verify the accuracy of any of the information contained in its standards.
Use of an IEC/IEEE Dual Logo International Standard is wholly voluntary. The IEC and IEEE disclaim liability for
any personal injury, property or other damage, of any nature whatsoever, whether special, indirect,
consequential, or compensatory, directly or indirectly resulting from the publication, use of, or reliance upon
this, or any other IEC or IEEE Standard document.
The IEC and IEEE do not warrant or represent the accuracy or content of the material contained herein, and
expressly disclaim any express or implied warranty, including any implied warranty of merchantability or fitness
for a specific purpose, or that the use of the material contained herein is free from patent infringement.
IEC/IEEE Dual Logo International Standards documents are supplied “AS IS”.
The existence of an IEC/IEEE Dual Logo International Standard does not imply that there are no other ways to
produce, test, measure, purchase, market, or provide other goods and services related to the scope of the
IEC/IEEE Dual Logo International Standard. Furthermore, the viewpoint expressed at the time a standard is
approved and issued is subject
...