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1、BRITISH STANDARD BS 5691-3.1: 1995 IEC 216-3-1: 1990 Guide for the determination of thermal endurance properties of electrical insulating materials Part 3: Instructions for calculating thermal endurance characteristics Section 3.1 Calculations using mean values of normally distributed complete data
2、(Implementation of CENELEC HD 611.3.1 S1:1992) UDC 621.315.61:620.193.94 Licensed Copy: sheffieldun sheffieldun, na, Fri Dec 01 14:55:13 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 5691-3.1:1995 This British Standard, having been prepared under the direction of the Electrotechnical Sector Board, w
3、as published under the authority of the Standards Board and comes into effect on 15 November 1995 BSI 12-1999 The following BSI references relate to the work on this standard: Committee reference GEL/15/2 Draft announced in BSI News, April 1995 ISBN 0 580 24483 0 Committees responsible for this Brit
4、ish Standard The preparation of this British Standard was entrusted by Technical Committee GEL/15, Insulating material, to Subcommittee GEL/15/2, Endurance tests, upon which the following bodies were represented: AEA Technology Adhesive Tape Manufacturers Association Association of Manufacturers of
5、Domestic Electrical Appliances British Cable Makers Confederation British Plastics Federation ERA Technology Ltd. University of Manchester Amendments issued since publication Amd. No.DateComments Licensed Copy: sheffieldun sheffieldun, na, Fri Dec 01 14:55:13 GMT+00:00 2006, Uncontrolled Copy, (c) B
6、SI BS 5691-3.1:1995 BSI 12-1999i Contents Page Committees responsibleInside front cover National forewordii Foreword2 Introduction3 1Scope and object3 2Calculation principles3 3Instructions for deriving thermal endurance indices5 Appendix A List of symbols11 Appendix B Worked example12 Appendix C Fr
7、actiles of the 2, t and F distributions15 Appendix D BASIC program for thermal endurance16 Annex ZA (normative) Other international publications quoted in this standard with the references of the relevant European publications25 Figure 1 Thermal endurance graph9 Figure 2 Decision flow chart for ther
8、mal endurance calculations10 Figure B.1 This Thermal Endurance Graph is derived from the data of the Worked Example in Appendix B14 Table I7 Table C.115 Table C.215 Table C.316 List of referencesInside back cover Licensed Copy: sheffieldun sheffieldun, na, Fri Dec 01 14:55:13 GMT+00:00 2006, Uncontr
9、olled Copy, (c) BSI BS 5691-3.1:1995 ii BSI 12-1999 National foreword This Section of BS 5691 has been prepared by Subcommittee GEL/15/2. It implements Harmonization Document HD 611.3.1 S1, which was published by the European Committee for Electrotechnical Standardization (CENELEC). It is identical
10、with IEC 216-3-1:1990 Guide for the determination of thermal endurance properties of electrical insulating materials. Part 3: Instructions for calculating thermal endurance characteristics. Section 1 Calculations using mean values of normally distributed complete data, published by the International
11、 Electrotechnical Commission (IEC). A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Cross
12、-references Publication referred toCorresponding British Standard BS 5691 Guide for the determination of thermal endurance properties of electrical insulating materials HD 611.1 S1:1992 (IEC 216-1:1990) Part 1:1995 General guidelines for ageing procedures and evaluation of test results HD 611.2 S1:1
13、992 (IEC 216-2:1990) Part 2:1995 Choice of test criteria Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, the HD title page, pages 2 to 26, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendm
14、ents incorporated. This will be indicated in the amendment table on the inside front cover. Licensed Copy: sheffieldun sheffieldun, na, Fri Dec 01 14:55:13 GMT+00:00 2006, Uncontrolled Copy, (c) BSI HARMONIZATION DOCUMENT DOCUMENT DHARMONISATION HARMONISIERUNGSDOKUMENT HD 611.3.1 S1 July 1992 UDC 62
15、1.315.61:620.193.94 Descriptors: Insulating material, thermal endurance test, thermal characteristics, calculation, statistical analysis, test results English version Guide for the determination of thermal endurance properties of electrical insulating materials Part 3: Instructions for calculating t
16、hermal endurance characteristics Section 1: Calculations using mean values of normally distributed complete data (IEC 216-3-1:1990) Guide pour la dtermination des proprits dendurance thermique de materiaux isolants lectriques Troisime partie: Instructions pour le calcul des caractristiques denduranc
17、e thermique Section un: Calculs bass sur les valeurs moyennes des rsultats complets normalement distribus (CEI 216-3-1:1990) Leitlinie zur Bestimmung der thermischen Langzeiteigenschaften von Elektroisolierstoffen Teil 3: Vorschriften zur Berechnung der thermischen Langzeitkennwerte Hauptabschnitt 1
18、: Berechnung mit Hilfe von Mittelwerten fr normalverteilte, vollstndige Daten (IEC 216-3-1:1990) This Harmonization Document was approved by CENELEC on 1992-06-16. CENELEC members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for implementation of this
19、Harmonization Document on a national level. Up-to-date lists and bibliographical references concerning national implementation may be obtained on application to the Central Secretariat or to any CENELEC member. This Harmonization Document exists in three official versions (English, French, German).
20、CENELEC members are the national electrotechnical committees of Austria, Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom. CENELEC European Committee for Electrotechnical Standardizat
21、ion Comit Europen de Normalisation Electrotechnique Europisches Komitee fr Elektrotechnische Normung Central Secretariat: rue de Stassart 35, B-1050 Brussels 1992 Copyright reserved to CENELEC members Ref. No. HD 611.3.1 S1:1992 E Licensed Copy: sheffieldun sheffieldun, na, Fri Dec 01 14:55:13 GMT+0
22、0:00 2006, Uncontrolled Copy, (c) BSI BS 5691-3.1:1995 BSI 12-1999 2 Foreword The CENELEC questionnaire procedure, performed for finding out whether or not the International Standard IEC 216-3-1:1990 could be accepted without textual changes, has shown that no common modifications were necessary for
23、 acceptance as a Harmonization Document. The reference document was submitted to the CENELEC members for formal vote and was approved by CENELEC as HD 611.3.1 S1 on 16 June 1992. The following dates were fixed: Annexes designated “normative” are part of the body of the standard. In this standard, An
24、nex ZA is normative. latest date of announcement of the HD at national level(doa) 1992-12-01 latest date of publication of a harmonized national standard(dop) 1993-06-01 latest date of withdrawal of conflicting national standards(dow) 1993-06-01 Licensed Copy: sheffieldun sheffieldun, na, Fri Dec 01
25、 14:55:13 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 5691-3.1:1995 BSI 12-19993 Introduction IEC Publication 216: Guide for the determination of thermal endurance properties of electrical insulating materials, is composed of several parts: Part 1: General guidelines for ageing procedures and eval
26、uation of test results (IEC Publication 216-1); Part 2: Choice of test criteria (IEC Publication 216-2); Part 3: Instructions for calculating thermal endurance characteristics (IEC Publication 216-3); Part 4: Ageing ovens (IEC Publication 216-4); Part 5: Guidelines for application of thermal enduran
27、ce characteristics (IEC Publication 216-5). This Part consists of four sections based upon mean values of normally distributed test results. Further sections may be added to take account of other statistical procedures, for example extreme value statistics for those cases where mean value treatments
28、 are inadequate. However, there is at present insufficient experience to enable these methods to be used in thermal endurance standards. The following sections of Part 3 are in preparation. Each section will consist exclusively of calculation instructions. The relevant statistical theory will be fou
29、nd in the appropriate part of IEC Publication 493. Section 2: Calculation procedures for normally distributed results from destructive test procedures (IEC Publication 216-3-2); Section 3: Calculations for incomplete data: proof test results up to and including the median time to end-point (equal te
30、st groups) (IEC Publication 216-3-3); Section 4: Calculations for relative temperature indices (IEC Publication 216-3-4). 1 Scope and object This part of IEC Publication 216 gives instructions for calculation of thermal endurance characteristics from data obtained in accordance with IEC Publications
31、 216-1 and 216-2. Section 1 gives the main sequence calculation scheme for complete normally distributed data, in accordance with the statistical principles set out in IEC Publication 493-1, to which reference should be made for the mathematical background details. A graphical derivation is also inc
32、luded. Worked examples, a computer program written in “BASIC” and appropriate statistical tables are given in the appendices. 2 Calculation principles 2.1 Statistical principles The calculation procedures and instructions given in Clause 3 are based upon the principles and assumptions set out in IEC
33、 Publication 493-1. The assumptions made may be expressed in simple form as follows (see IEC Publication 493-1, Sub-clause 3.7.1): 1) The relation between the mean of the logarithms of the times taken to reach a given end-point (“mean time to end-point”) and the reciprocal thermodynamic (absolute) a
34、geing temperature is linear. 2) The values of the deviations of the logarithms of the times to end-point from this linear relation are normally distributed with a variance which is independent of the ageing temperature. The best estimates of the coefficients of the linear relationship are obtained b
35、y the method of least squares, and the confidence limits associated with an estimate using this linear relationship are obtained by using the methods of generalized regression analysis. 2.2 Data for analysis 2.2.1 The experimental data are obtained as values of temperature ( C) and time to end-point
36、 (t hours). Each value is transformed to an x or y value: In most cases the number of test specimens at each test temperature is identical, but even if the endurance test is planned with different numbers ni of y values in the temperature groups, the analysis can be carried out as described below. x
37、i= 1/(i + 273) value (i) of reciprocal thermodynamic (absolute) temperature yij= log (tij)a log of value (j) of time in ith ageing group (i) ni= number of y values in group (i) k = number of groups a In principle, calculations may be made using Napierian (base e) or Briggsian (base 10) logarithms, a
38、s long as the choice is consistent throughout. For this reason, the symbol log (y) is used throughout, except in Sub-clause 3.1.4. In order to enable some intermediate results to be comparable with those of the second edition of IEC Publication 216, the computer program (Appendix D) uses logarithms
39、to base 10. Licensed Copy: sheffieldun sheffieldun, na, Fri Dec 01 14:55:13 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 5691-3.1:1995 4 BSI 12-1999 In general, the time to end-point shall be determined for all specimens so that all yij values are available, otherwise the following analysis is not
40、valid. In exceptional cases where one or a few y values are missing for chance reasons, that is, independently of the time to end-point of the specimen, for instance in the case where a specimen is spoiled during handling, it is permissible to carry out the analysis, but the incident should be menti
41、oned in the test report. The values of tij are obtained by direct observation in the case of non-destructive tests or proof tests. In the case of destructive tests they are estimated by the procedures given in IEC Publication 216-3-2. 2.2.2 The data to be used in the common calculation are derived f
42、rom the primary data as follows. For each group of y values, the mean, and variance are calculated 2.3 Statistical tests Three tests are included in the calculation procedure. a) Variance equality (Bartletts 2) test. b) Linearity (F) test. c) Dispersion (confidence interval) test. Tests b) and c) ma
43、y detect deviations from ideal behaviour which are statistically significant but which are too small to have serious practical consequences. Procedures are included to meet these circumstances. 2.3.1 Bartletts 2 test Inequalities of variance, other than major inequalities, are not considered to lead
44、 to serious errors either of temperature index or confidence interval. The value of 2 is calculated, and if this value is greater than that corresponding to a significance level of 0.05, the values of 2 and its significance level are reported. 2.3.2 F-test for linearity The F ratio is the ratio of t
45、he variance of the deviations of the ageing group means from the regression line , see equation (11) to the variance within the ageing groups , see equation (10). A high value of F may result either from high values of the deviations from the regression line or from low values of the variance of dat
46、a within the groups. The F ratio is tested against tabulated values F0 at a significance level of 0.05. In the case of data of very small dispersion, it is possible for a non-linearity to be detected as statistically significant which is of little practical importance. In order that a result may be
47、obtained even where the F test has failed in this way, a procedure is included as follows: a) Increase the value of the variance within the ageing groups () so that the F test gives a result which is just acceptable, that is substitute by an adjusted value ()a = (F/F0), see Sub-clause 3.1.5 b). b) U
48、se this adjusted value to calculate the lower confidence limit of the result, TCa. c) If the lower confidence interval (TI TCa) is found acceptable (TI TCa u 0.6 HIC, see Sub-clause 2.3.3) the non-linearity is deemed to be of no practical importance. 2.3.3 Data dispersion test When the temperature i
49、ndex, its lower confidence limit and the halving interval (TI, TC and HIC respectively) have been calculated, the lower confidence interval (TI TC) is considered acceptable if TI TC u 0.6 HIC In cases where the lower confidence interval exceeds 0.6 HIC by a small margin, still being less than 1.6 HIC, a usable result may yet be obtained (provided F u F0) by calculating an adjusted TIa, that is to say, by subtracting from the calculated TI the amount by which the lower confidence interval exceeds 0.6 HI