IEC TR 60493-2-2010 Guide for the statistical analysis of ageing test data - Part 2 Validation of procedures for statistical analysis of censored normally distr.pdf

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12、 of a different kind from that which is normally published as an International Standard, for example “state of the art“. IEC 60493-2 which is a technical report, has been prepared by IEC technical committee 112: Evaluation and qualification of electrical insulating materials and systems. TR 60493-2

13、IEC:2010(E) 5 The text of this technical report is based on the following documents: Enquiry draft Report on voting 112/140/DTR 112/145/RVC 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 publication has

14、 been drafted in accordance with the ISO/IEC Directives, Part 2. This publication contains attached files in the form of a CD-ROM. These files are intended to be used as a complement and do not form an integral part of the standard. A list of all parts of the IEC 60493 series, published under the ge

15、neral title Guide for the statistical analysis of ageing test data, can be found on the IEC website. The committee has decided that the contents of this publication will remain unchanged until the stability date indicated on the IEC web site under “http:/webstore.iec.ch“ in the data related to the s

16、pecific publication. At this date, the publication will be reconfirmed, withdrawn, replaced by a revised edition, or amended. A bilingual version of this publication may be issued at a later date. 6 TR 60493-2 IEC:2010(E) INTRODUCTION Procedures for estimating ageing properties are described in spec

17、ific test procedures, or are covered by the general documents on test procedures for ageing tests with a specific environmental stress (e.g. temperature, radiation, partial discharges). In many cases, a certain property is determined as a function of time at different ageing stresses, and a time to

18、failure based on a chosen end-point criterion is found at each ageing stress. A plot of time to failure versus ageing stress may be used to obtain an estimate of the time to failure for similar specimens exposed to a specified stress, or to obtain an estimate of the value of stress which will cause

19、failure in a specified time. The physical and chemical laws governing the ageing phenomena may often lead to the assumption that a linear relationship exists between the property examined and the ageing time at fixed ageing stresses, or between certain mathematical functions of property and ageing t

20、ime, e.g. square root or logarithm. The relationships between property values, ageing time, ageing and ageing exposure temperature are determined by mathematical procedures known as analysis of variance, analysis of covariance and regression analysis. In some cases, the property values cannot be det

21、ermined because of time or property measurement limitations. Such data are referred to as “censored data”. The mathematical procedures are well known and accepted as valid for complete (uncensored) data. This technical report describes the work done to validate the procedures for censored data. TR 6

22、0493-2 IEC:2010(E) 7 GUIDE FOR THE STATISTICAL ANALYSIS OF AGEING TEST DATA Part 2: Validation of procedures for statistical analysis of censored normally distributed data 1 Scope This part of IEC 60493 provides an account of the work done in designing and validating the statistical procedures for o

23、perations on censored groups of normally distributed data. The relationship to similar operations on complete (uncensored) data is examined, and it is shown that “mixed” or wholly uncensored data groups may be analysed in the same way as wholly censored ones. Attention is drawn to the effect of some

24、 variation of group size and extent of censoring, as well as the effect of non-uniform data group sizes. 2 Normative references IEC 60216-3, Electrical insulating materials Thermal endurance properties Part 3: Instructions for calculating thermal endurance characteristics IEC 60216-5, Electrical ins

25、ulating materials Thermal endurance properties Part 5: Determination of relative thermal endurance index (RTE) of an insulating material IEC 60216-6, Electrical insulating materials Thermal endurance properties Part 6: Determination of thermal endurance indices (TI and RTE) of an insulating material

26、 using the fixed time frame method IEC 60493-1, Guide for the statistical analysis of ageing test data. Part 1: Methods based on mean values of normally distributed test results 3 Terms, definitions and symbols 3.1 Definitions For the purposes of this document, the following terms and definitions ap

27、ply. 3.1.1 ordered data a set of data arranged in sequence so that in the appropriate direction through the sequence each member is greater than or equal to its predecessor. NOTE “Ascending order“ in this report implies that the data is ordered in this way, the first being the smallest. 3.1.2 order-statistic each individual value in a set of ordered data identified by its numerical position in the sequence