1、 IEC TR 60493-3 Edition 1.0 2017-05 TECHNICAL REPORT Guidelines for the statistical analysis of ageing test data Part 3: Minimum specimen numbers at different test conditions with given experimental data IEC TR 60493-3:2017-05(en) colour inside THIS PUBLICATION IS COPYRIGHT PROTECTED Copyright 2017
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11、ing test data Part 3: Minimum specimen numbers at different test conditions with given experimental data INTERNATIONAL ELECTROTECHNICAL COMMISSION ICS 29.035.01 ISBN 978-2-8322-4299-5 Registered trademark of the International Electrotechnical Commission Warning! Make sure that you obtained this publ
12、ication from an authorized distributor. colour inside 2 IEC TR 60493-3:2017 IEC 2017 CONTENTS FOREWORD . 3 INTRODUCTION . 5 1 Scope 6 2 Normative references 6 3 Terms, definitions, symbols and conventions . 6 3.1 Terms and definitions 6 3.2 Symbols 6 3.3 Conventions 7 4 Assumptions 7 5 General consi
13、derations 8 6 Probability calculation based on normal distributions . 10 6.1 General . 10 6.2 Calculations 10 6.3 Estimated life at 90 C (temperature difference is set to be 40 C) 12 6.3.1 Ideal case with = 0,05, 0,1, 0,2, 0,3 12 6.3.2 Test sample numbers of 20, 10, 5, 3 with = 0,05 . 13 6.3.3 Test
14、sample numbers of 20, 10, 5, 3 with = 0,3 . 14 6.4 Estimated life at 50 C (temperature difference is set to be 80 C) 15 6.4.1 Ideal case with = 0,05, 0,1, 0,2, 0,3 15 6.4.2 Test sample numbers of 20, 10, 5, 3 with = 0,05 . 16 6.4.3 Test sample numbers of 20, 10, 5, 3 with = 0,3 . 17 Figure 1 Ageing
15、time versus survival ratio . 9 Figure 2 Arrhenius plot of failure time or scatter 9 Figure 3 Temperature dependence of t 10 Figure 4 Estimated life at 90 C for the ideal case 13 Figure 5 Test sample numbers of 20, 10, 5, 3 with = 0,05 14 Figure 6 Test sample numbers of 20, 10, 5, 3 with = 0,3 . 15 F
16、igure 7 Estimated life at 50 C for the ideal case 16 Figure 8 Test sample numbers of 20, 10, 5, 3 with = 0,05 17 Figure 9 Test sample numbers of 20, 10, 5, 3 with = 0,3 . 18 Table 1 Symbols 7 IEC TR 60493-3:2017 IEC 2017 3 INTERNATIONAL ELECTROTECHNICAL COMMISSION _ GUIDELINES FOR THE STATISTICAL AN
17、ALYSIS OF AGEING TEST DATA Part 3: Minimum specimen numbers at different test conditions with given experimental data FOREWORD 1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising all national electrotechnical committees (IEC National Comm
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28、task of IEC technical committees is to prepare International Standards. However, a technical committee may propose the publication of a Technical Report when it has collected data of a different kind from that which is normally published as an International Standard, for example “state of the art“.
29、IEC TR 60493-3, which is a Technical Report, has been prepared by IEC technical committee 112: Evaluation and qualification of electrical insulating materials and systems. The text of this Technical Report is based on the following documents: Enquiry draft Report on voting 112/384/DTR 112/389/RVDTR
30、4 IEC TR 60493-3:2017 IEC 2017 Full information on the voting for the approval of this Technical Report can be found in the report on voting indicated in the above table. This document has been drafted in accordance with the ISO/IEC Directives, Part 2. A list of all parts in the IEC 60493 series, pu
31、blished under the general title Guidelines for the statistical analysis of ageing test data, can be found on the IEC website. Future standards in this series will carry the new general title as cited above. Titles of existing standards in this series will be updated at the time of the next edition.
32、The committee has decided that the contents of this document will remain unchanged until the stability date indicated on the IEC website under “http:/webstore.iec.ch“ in the data related to the specific document. At this date, the document will be reconfirmed, withdrawn, replaced by a revised editio
33、n, or amended. A bilingual version of this publication may be issued at a later date. IMPORTANT The colour inside logo on the cover page of this publication indicates that it contains colours which are considered to be useful for the correct understanding of its contents. Users should therefore prin
34、t this document using a colour printer. IEC TR 60493-3:2017 IEC 2017 5 INTRODUCTION The objective of this document is to clarify how a statistical analysis can be done even with a small number of samples. When the scatter of data is sufficiently small, a statistical analysis should be possible. Gene
35、rally, a statistical analysis applies to a larger number of samples similar to ordinary cases. On the other hand, this document may be useful in clarifying how the scatter of a small number of data points can be used to estimate “lifetime“ when the number of specimens is limited (e.g. around five) a
36、nd there are few ageing conditions (e.g. two or three conditions). Therefore, the aim is to document, for a small group of specimens with limited scatter of data, whether or not it is possible to estimate characteristics such as lifetime within a certain statistical error. If such a simulation were
37、available, it would be very helpful for users. Manufacturers, for example, may prefer a new simplified, accelerated test method as an alternative to their current traditional test methods. A new test method would be easier and less expensive, especially if the specimens were small in size (dimension
38、), although it may not be as suitable for large specimen sizes or expensive materials or devices (such as motors). It would be very welcome if a statistical treatment method of this type, applying to a smaller number of specimens, were defined. Though inappropriate cases are anticipated, this docume
39、nt deals with cases where such statistical treatment is appropriate. 6 IEC TR 60493-3:2017 IEC 2017 GUIDELINES FOR THE STATISTICAL ANALYSIS OF AGEING TEST DATA Part 3: Minimum specimen numbers at different test conditions with given experimental data 1 Scope This part of IEC 60493 clarifies how a st
40、atistical analysis can be done with a small number of samples. This document will be useful when the accelerated test method is difficult to carry out, for example in cases where the dimensions of test specimens (including test devices) are very large in scale or the cost of test specimens is high.
41、Testing is facilitated by enabling users to reduce the number of test specimens. 2 Normative references The following documents are referred to in the text in such a way that some or all of their content constitutes requirements of this document. For dated references, only the edition cited applies.
42、 For undated references, the latest edition of the referenced document (including any amendments) applies. IEC 60493-1, Guide for the statistical analysis of ageing test data Part 1: Methods based on mean values of normally distributed test results IEC TR 60493-2, Guide for the statistical analysis
43、of ageing test data Part 2: Validation of procedures for statistical analysis of censored normally distributed data IEC 62539, Guide for the statistical analysis of electrical insulation breakdown data 3 Terms, definitions, symbols and conventions 3.1 Terms and definitions For the purposes of this d
44、ocument, the terms and definitions given in IEC 60493-1, IEC TR 60493-2, and IEC 62539 apply. ISO and IEC maintain terminological databases for use in standardization at the following addresses: IEC Electropedia: available at http:/www.electropedia.org/ ISO Online browsing platform: available at htt
45、p:/www.iso.org/obp 3.2 Symbols In this document, the following symbols are used. IEC TR 60493-3:2017 IEC 2017 7 Table 1 Symbols A pre-factor in equation to express rate constant A*, c/A pre-factor in equation to express lifetime c criterion of degradation k rate constant of degradation mean of lifet
46、ime R ideal gas constant (= 8,31 J K -1 mol -1 ) standard deviation istandard deviation of lifetime at temperature i Hstandard deviation of lifetime at high temperature Mstandard deviation of lifetime at medium temperature Lstandard deviation of lifetime at low temperature T absolute temperature, in
47、 K t time t Hlifetime at high temperature t ilifetime at temperature i t Mlifetime at medium temperature t Llifetime at low temperature lifetime (time to criterion) U activation energy of a chemical reaction, in eV or J mol -13.3 Conventions In this document, (Greek tau) means lifetime in use, t (lo
48、wer case) means lifetime upon accelerated ageing and T (upper case) means temperature. Subscripts H, M and L mean high, medium and low temperatures, respectively (see Table 1). Lifetime uat temperature T uis to be estimated. The scatter of ushall be below a criterion, where the criterion is decided
49、by the user. Through an accelerated test, ucan be derived with t Hat T H , t Mat T Mand t Lat T L , where T H T M T L T u. t H , t Mand t Lhave their own scatter. Generally, they may differ from each other. For convenience, scatter shall be assumed to be equal to the first step. This document aims to clarify how small the scatter of t H , t Mand t Lneeds to be in order to keep the scatter of ubelow the criterion. This d
