1、BRITISH STANDARD BS EN 61164:2004 Reliability growth Statistical test and estimation methods The European Standard EN 61164:2004 has the status of a British Standard ICS 03.120.01; 03.120.30 BS EN 61164:2004 This British Standard was published under the authority of the Standards Policy and Strategy
2、 Committee on 2 September 2004 BSI 2 September 2004 ISBN 0 580 44365 5 National foreword This British Standard is the official English language version of EN 61164:2004. It is identical with IEC 61164:2004. It supersedes BS 5760-17:1995 which is withdrawn. The UK participation in its preparation was
3、 entrusted to Technical Committee DS/1, Dependability and terotechnology, which has the responsibility to: A list of organizations represented on this committee can be obtained on request to its secretary. Cross-references The British Standards which implement international or European publications
4、referred to in this document may be found in the BSI Catalogue under the section entitled “International Standards Correspondence Index”, or by using the “Search” facility of the BSI Electronic Catalogue or of British Standards Online. This publication does not purport to include all the necessary p
5、rovisions of a contract. Users are responsible for its correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. aid enquirers to understand the text; present to the responsible international/European committee any enquiries on the interpretat
6、ion, or proposals for change, and keep the UK interests informed; monitor related international and European developments and promulgate them in the UK. Summary of pages This document comprises a front cover, an inside front cover, the EN title page, pages 2 to 55 and a back cover. The BSI copyright
7、 notice displayed in this document indicates when the document was last issued. Amendments issued since publication Amd. No. Date CommentsEUROPEAN STANDARD EN 61164 NORME EUROPENNE EUROPISCHE NORM April 2004 CENELEC European Committee for Electrotechnical Standardization Comit Europen de Normalisati
8、on Electrotechnique Europisches Komitee fr Elektrotechnische Normung Central Secretariat: rue de Stassart 35, B - 1050 Brussels 2004 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members. Ref. No. EN 61164:2004 E ICS 03.120.01; 03.120.30 English ver
9、sion Reliability growth - Statistical test and estimation methods (IEC 61164:2004) Croissance de la fiabilit - Tests et mthodes destimation statistiques (CEI 61164:2004) Zuverlssigkeitswachstum - Statistische Prf- und Schtzverfahren (IEC 61164:2004) This European Standard was approved by CENELEC on
10、2004-04-01. CENELEC members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national standards may
11、be obtained on application to the Central Secretariat or to any CENELEC member. This European Standard exists in three official versions (English, French, German). A version in any other language made by translation under the responsibility of a CENELEC member into its own language and notified to t
12、he Central Secretariat has the same status as the official versions. CENELEC members are the national electrotechnical committees of Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, N
13、etherlands, Norway, Poland, Portugal, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom. EN 66112:4400 - - 2 Foreword The text of document 56/920/FDIS, future edition 2 of IEC 61164, prepared by IEC TC 56, Dependability, was submitted to the IEC-CENELEC parallel vote and was approved
14、 by CENELEC as EN 61164 on 2004-04-01. This European Standard should be used in conjunction with EN 61014:2003. The following dates were fixed: latest date by which the EN has to be implemented at national level by publication of an identical national standard or by endorsement (dop) 2005-01-01 late
15、st date by which the national standards conflicting with the EN have to be withdrawn (dow) 2007-04-01 Annex ZA has been added by CENELEC. _ Endorsement notice The text of the International Standard IEC 61164:2004 was approved by CENELEC as a European Standard without any modification. _ Page2 EN6116
16、4:2004 2 66114 IE2:C400(E) CONTENTS 1 Scope.6 2 Normative references .6 3 Terms and definitions .6 4 Symbols .7 5 Reliability growth models in design and test .10 6 Reliability growth models used for systems/products in design phase.12 6.1 Modified power law model for planning of reliability growth
17、in product design phase12 6.1.1 General .12 6.1.2 Planning model for the reliability growth during the product design period13 6.1.3 Tracking the achieved reliability growth .14 6.2 Modified Bayesian IBM-Rosner model for planning reliability growth in design phase15 6.2.1 General .15 6.2.2 Data requ
18、irements .15 6.2.3 Estimates of reliability growth and related parameters .16 6.2.4 Tracking reliability growth during design phase17 7 Reliability growth planning a tracking in the product reliability growth testing17 7.1 Continuous reliability growth models .17 7.1.1 The power law model.17 7.1.2 T
19、he fixed number of faults model.18 7.2 Discrete reliability growth model19 7.2.1 Model description 19 7.2.2 Estimation .21 8 Use of the power law model in planning reliability improvement test programmes.22 9 Statistical test and estimation procedures for continuous power law model.22 9.1 Overview.2
20、2 9.2 Growth tests and parameter estimation .22 9.2.1 Case 1 Time data for every relevant failure.22 9.2.2 Case 2 Time data for groups of relevant failures.25 9.3 Goodness-of-fit tests .26 9.3.1 General .26 9.3.2 Case 1 Time data for every relevant failure.26 9.3.3 Case 2 Time data for groups of rel
21、evant failures.27 9.4 Confidence intervals on the shape parameter28 9.4.1 General .28 9.4.2 Case 1 Time data for every relevant failure.28 9.4.3 Case 2 Time data for groups of relevant failures.29 9.5 Confidence intervals on current MTBF.30 9.5.1 General .30 9.5.2 Case 1 Time data for every relevant
22、 failure.30 9.5.3 Case 2 Time data for groups of relevant failures.31 9.6 Projection technique32 Annex A (informative) Examples for planning and analytical models used in design and test phase of product development 36 Page3 EN61164:200466114 IEC:0204(E) 3 A.1 Reliability growth planning in product
23、design phase.36 A.1.1 Power law planning model example .36 A.1.2 Construction of the model and monitoring of reliability growth36 A.2 Example of Bayesian reliability growth model for the product design phase.39 A.3 Failure data for discrete trials41 A.4 Examples of reliability growth through testing
24、41 A.4.1 Introduction .41 A.4.2 Current reliability assessments42 A.4.3 Projected reliability estimates 43 Annex B (informative) The power law reliability growth model Background information .49 B.1 The Duane postulate .49 B.2 The power law model 49 B.3 Modified power law model for planning of relia
25、bility growth in product design phase50 B.4 Modified Bayesian IBM-Rosner model for planning reliability growth in the design phase.51 Annex ZA (normative) Normative references to international publications with their corresponding European publications .54 Figure 1 Planned improvement of the average
26、 failure rate or reliability 11 Figure A.1 Planned and achieved reliability growth Example.39 Figure A.2 Planned reliability growth using Bayesian reliability growth model.40 Figure A.3 Scatter diagram of expected and observed test times at failure based on data of Table A.2 with power law model47 F
27、igure A.4 Observed and estimated accumulated failures/accumulated test time based on data of Table A.2 with power law model.48 Table 1 Categories of reliability growth models with clause references 12 Table 2 Critical values for Cramr-von Mises goodness-of-fit test at 10 % level of significance.33 T
28、able 3 Two-sided 90 % confidence intervals for MTBF from Type I testing .34 Table 4 Two-sided 90 % confidence intervals for MTBF from Type II testing 35 Table A.1 Calculation of the planning model for reliability growth in design phase .38 Table A.2 Complete data All relevant failures and accumulate
29、d test times for Type I test 45 Table A.3 Grouped data for Example 3 derived from Table A.2 45 Table A.4 Complete data for projected estimates in Example 4 All relevant failures and accumulated test times 46 Table A.5 Distinct types of Category B failures, from Table A.4, with failure times, time of
30、 first occurrence, number observed and effectiveness factors.46 Page4 EN61164:2004 4 66114 IE2:C400(E) INTRODUCTION This International Standard describes the power law reliability growth model and related projection model and gives step-by-step directions for their use. There are several reliability
31、 growth models available, the power law model being one of the most widely used. This standard provides procedures to estimate some or all of the quantities listed in Clauses 4, 6 and 7 of IEC 61014. Two types of input are required. The first one is for reliability growth planning through analysis a
32、nd design improvements in the design phase in terms of the design phase duration, initial reliability, reliability goal, and planned design improvements, along with their expected magnitude. The second input, for reliability growth in the project validation phase, is for a data set of accumulated te
33、st times at which relevant failures occurred, or were observed, for a single system, and the time of termination of the test, if different from the time of the final failure. It is assumed that the collection of data as input for the model begins after the completion of any preliminary tests, such a
34、s environmental stress screening, intended to stabilize the products initial failure intensity. Model parameters estimated from previous test results may be used to plan and predict the course of future reliability growth programmes, provided the conditions are similar. Some of the procedures may re
35、quire computer programs, but these are not unduly complex. This standard presents algorithms for which computer programs should be easy to construct. Page5 EN61164:200466114 IEC:0204(E) 5 RELIABILITY GROWTH STATISTICAL TEST AND ESTIMATION METHODS 1 Scope This International Standard gives models and
36、numerical methods for reliability growth assess- ments based on failure data, which were generated in a reliability improvement programme. These procedures deal with growth, estimation, confidence intervals for product reliability and goodness-of-fit tests. 2 Normative references The following refer
37、enced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. IEC 60050(191):1990, International Electrotechnical Vocabulary (IEV)
38、 Chapter 191: Dependability and quality of service IEC 60300-3-5:2001, Dependability management Part 3-5: Application guide Reliability test conditions and statistical test principles IEC 60605-4, Equipment reliability testing Part 4: Statistical procedures for exponential distribution Point estimat
39、es, confidence intervals, prediction intervals and tolerance intervals IEC 60605-6, Equipment reliability testing Part 6: Tests for the validity of the constant failure rate or constant failure intensity assumptions IEC 61014:2003, Programmes for reliability growth 3 Terms and definitions For the pu
40、rposes of this document, the terms and definitions of IEC 60050(191) and IEC 61014, together with the following terms and definitions, apply. 3.1 reliability goal desired level of reliability that the product should have at the end of the reliability growth programme 3.2 initial reliability reliabil
41、ity that is estimated for the product in earlier design stages before any potential failure modes or their causes have been mitigated by the design improvement 3.3 reliability growth model for the design phase mathematical model that takes into consideration potential design improvements, and their
42、magnitude to express mathematically reliability growth from start to finish during the design period Page6 EN61164:2004 6 66114 IE2:C400(E) 3.4 average product failure rate average product failure rate calculated from its reliability as estimated for a predetermined time period NOTE The change in th
43、is failure rate as a function of time is a result of the modifications of the product design. 3.5 delayed modification corrective modification, which is incorporated into the product at the end of a test NOTE A delayed modification is not incorporated during the test. 3.6 improvement effectiveness f
44、actor fraction by which the intensity of a systematic failure is reduced by means of corrective modification 3.7 type I test time-terminated test reliability growth test which is terminated at a predetermined time, or test with data available through a time which does not correspond to a failure 3.8
45、 type II test failure-terminated test reliability growth test which is terminated upon the accumulation of a specified number of failures, or test with data available through a time which corresponds to a failure 4 Symbols For the purposes of this standard, the following symbols apply. a) For 6.1, c
46、lauses A.1 and B.3: T product lifetime such as mission, warranty period or operational time () T R 0initial product reliability 0 a initial average failure rate of product in design period () t d number of design modifications at any time during the design period D reliability growth rate resultant
47、from fault mitigation D total number of implemented design improvements D t total duration of the design period available for the design improvements t time variable during the design period from 0 to D t () t a average failure rate of product as a function of time during the design period () D aG t
48、 goal average failure rate at the end of the design period D t () T R Greliability goal of the product to be attained during design period () T t R , reliability of product as a function of time and design improvements Page7 EN61164:200466114 IEC:0204(E) 7 b) For 6.2, clauses A.2 and B.4: () T R Gre
49、liability goal of the product to be attained during design period D t total duration of the design period D reliability growth rate during design period NS rate of non-systematic (or residual) failures D total number of predicted or implemented design improvements within design period to address weaknesses K total number of distinct classes of fault i k
