kSIST FprEN IEC 61124:2022
(Main)Reliability testing - Compliance tests for constant failure rate and constant failure intensity
Reliability testing - Compliance tests for constant failure rate and constant failure intensity
This International Standard gives a number of optimized test plans, the corresponding border lines and characteristics. In addition the algorithms for designing test plans using a spreadsheet program are also given, together with guidance on how to choose test plans.
This standard specifies procedures to test whether an observed value of
- failure rate,
- failure intensity,
- mean operating time to failure (MTTF),
- mean operating time between failures (MTBF),
conforms to a given requirement.
It is assumed, except where otherwise stated, that during the accumulated test time, the times to failure or the operating times between failures are independent and identically exponentially distributed. This assumption implies that the failure rate or failure intensity is assumed to be constant.
Four types of test plans are described as follows:
- truncated sequential probability ratio test (SPRT);
- fixed time/failure terminated test (FTFT);
- fixed calendar time terminated test without replacement;
- combined test.
This standard does not cover guidance on how to plan, perform, analyse and report a test. This information can be found in IEC 60300-3-5.
This standard does not describe test conditions. This information can be found in IEC 60605-2 and in IEC 60300-3-5.
Prüfungen der Funktionsfähigkeit - Prüfpläne für konstante Ausfallrate und konstante Ausfalldichte
Essais de fiabilité - Plan d'essais de conformité d'un taux de défaillance constant et d'une intensité de défaillance constante
L'IEC 61124:2023 spécifie un certain nombre de plans d’essai optimisés, ainsi que les limites et caractéristiques correspondantes. De plus, les algorithmes pour concevoir des plans d’essai à l’aide d’une feuille de calcul sont également fournis, avec des recommandations relatives au choix de ces plans.
Le présent document spécifie les procédures utilisées pour vérifier qu’une valeur observée:
- d’un taux de défaillance;
- d’une intensité de défaillance;
- d’un temps moyen de fonctionnement avant défaillance (MTTF);
- d’un temps moyen de fonctionnement entre défaillances (MTBF).
est conforme à une exigence donnée.
Il est présumé, sauf spécification contraire, que pendant le temps d’essai cumulé, les temps de fonctionnement avant défaillance ou les temps de fonctionnement entre défaillances sont indépendants et suivent une distribution identique et exponentielle. Cette hypothèse implique que le taux de défaillance ou l’intensité de défaillance est présumé constant.
Preskušanje zanesljivosti - Ustreznostni preskusi za konstantno pogostost odpovedi in konstantno intenzivnost odpovedi
General Information
Relations
Standards Content (Sample)
SLOVENSKI STANDARD
oSIST prEN IEC 61124:2022
01-januar-2022
Preskušanje zanesljivosti - Ustreznostni preskusi za konstantno pogostost
odpovedi in konstantno intenzivnost odpovedi
Reliability testing - Compliance tests for constant failure rate and constant failure
intensityPrüfungen der Funktionsfähigkeit - Prüfpläne für konstante Ausfallrate und konstante
AusfalldichteEssais de fiabilité - Plan d'essais de conformité d'un taux de défaillance constant et
d'une intensité de défaillance constanteTa slovenski standard je istoveten z: prEN IEC 61124:2021
ICS:
03.120.01 Kakovost na splošno Quality in general
19.020 Preskuševalni pogoji in Test conditions and
postopki na splošno procedures in general
21.020 Značilnosti in načrtovanje Characteristics and design of
strojev, aparatov, opreme machines, apparatus,
equipment
oSIST prEN IEC 61124:2022 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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oSIST prEN IEC 61124:2022
56/1928/CDV
COMMITTEE DRAFT FOR VOTE (CDV)
PROJECT NUMBER:
IEC 61124 ED4
DATE OF CIRCULATION: CLOSING DATE FOR VOTING:
2021-10-29 2022-01-21
SUPERSEDES DOCUMENTS:
56/1859/CD, 56/1877C/CC
IEC TC 56 : DEPENDABILITY
SECRETARIAT: SECRETARY:
United Kingdom Mr Amit Patel
OF INTEREST TO THE FOLLOWING COMMITTEES: PROPOSED HORIZONTAL STANDARD:
Other TC/SCs are requested to indicate their interest, if any,
in this CDV to the secretary.
FUNCTIONS CONCERNED:
EMC ENVIRONMENT QUALITY ASSURANCE SAFETY
SUBMITTED FOR CENELEC PARALLEL VOTING NOT SUBMITTED FOR CENELEC PARALLEL VOTING
Attention IEC-CENELEC parallel votingThe attention of IEC National Committees, members of
CENELEC, is drawn to the fact that this Committee Draft for
Vote (CDV) is submitted for parallel voting.
The CENELEC members are invited to vote through the
CENELEC online voting system.
This document is still under study and subject to change. It should not be used for reference purposes.
Recipients of this document are invited to submit, with their comments, notification of any relevant patent rights of which they
are aware and to provide supporting documentation.TITLE:
Reliability testing - Compliance tests for constant failure rate and constant failure intensity
PROPOSED STABILITY DATE: 2024NOTE FROM TC/SC OFFICERS:
Copyright © 2021 International Electrotechnical Commission, IEC. All rights reserved. It is permitted to download this
electronic file, to make a copy and to print out the content for the sole purpose of preparing National Committee positions.
You may not copy or "mirror" the file or printed version of the document, or any part of it, for any other purpose without
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oSIST prEN IEC 61124:2022
IEC CDV 61124 IEC:2021 – 3 –
1 Contents
2 FOREWORD ........................................................................................................................... 7
3 INTRODUCTION ..................................................................................................................... 9
4 1 Scope ............................................................................................................................ 11
5 2 Normative references .................................................................................................... 11
6 3 Terms, definitions, abbreviations and symbols ............................................................... 12
7 Terms and definitions............................................................................................ 12
8 Abbreviations and symbols ................................................................................... 12
9 Abbreviations................................................................................................. 12
10 Symbols ........................................................................................................ 12
11 4 General requirements and area of application................................................................ 14
12 Requirements and characteristics ......................................................................... 14
13 Applicability to replaced and repaired items .......................................................... 14
14 Types of test plans................................................................................................ 14
15 General ......................................................................................................... 14
16 Advantages and disadvantages of the different test plan types ...................... 15
17 5 General test procedure .................................................................................................. 17
18 Test conditions ..................................................................................................... 17
19 General characteristics of the test plans ............................................................... 18
20 Data to be recorded .............................................................................................. 18
21 Calculation of accumulated test time, T ................................................................ 18
22 Number of failures ................................................................................................ 19
23 6 Truncated sequential probability ratio test (SPRT) plans ................................................ 19
24 General ................................................................................................................. 19
25 Common test procedure ........................................................................................ 19
26 Decision criteria .................................................................................................... 19
27 Operating characteristic curve (OC) ...................................................................... 20
28 Expected accumulated test time to decision (ETT) ................................................ 21
29 Overview of test plans........................................................................................... 22
30 7 Fixed time/failure terminated test plans – Fixed duration (to acceptance) test
31 plans ............................................................................................................................. 24
32 General ................................................................................................................. 24
33 Common test procedure ........................................................................................ 25
34 Decision criteria .................................................................................................... 25
35 Test plans ............................................................................................................. 25
36 8 Design of alternative time/failure terminated test plans (FTFT) ...................................... 26
37 General ................................................................................................................. 26
38 Design procedures ................................................................................................ 26
39 Common FTFT procedure ..................................................................................... 27
40 Decision criteria .................................................................................................... 27
41 9 Calendar time/failure terminated test plans (FTFT) for non-replaced items .................... 27
42 General ................................................................................................................. 27
43 Common test procedure ........................................................................................ 27
44 Decision criteria .................................................................................................... 28
45 Use of Table 5 of IEC 61123:2019 for fixed calendar time tests ............................ 28
46 General ......................................................................................................... 28
47 Procedure when the test time is given ........................................................... 28
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48 Procedure when the number of items is given ................................................ 29
49 10 Combined test plans ...................................................................................................... 29
50 General ................................................................................................................. 29
51 Common test procedure ........................................................................................ 29
52 Decision criteria .................................................................................................... 29
53 Test plans ............................................................................................................. 30
54 11 Performing the test and presenting the results ............................................................... 31
55 Annex A (normative) Tables for border lines of SPRT plans (types A and C) ........................ 32
56 A.1 Symbols ................................................................................................................ 32
57 A.2 Border lines .......................................................................................................... 32
58 A.3 Example of the SPRT plan from Clause 6. ............................................................ 35
59 Annex B (normative) Tables and graphs for combined test plans (type D) ............................ 37
60 B.1 General ................................................................................................................. 37
61 B.2 Test plans D.3 and C.3 (α = β = 10 %, D = 1,7 ) ..................................................... 39
62 Annex C (informative) Extension of the set of SPRT type A tests ......................................... 42
63 C.1 Symbols ................................................................................................................ 42
64 C.2 Extension of the set of type A tests (through interpolation by α and β ) ................. 42
65 Annex D (informative) Approximation of operating characteristic for type A SPRT by
66 Wald’s formula............................................................................................................... 45
67 D.1 Symbols ................................................................................................................ 45
68 D.2 Approximations of OC in this standard .................................................................. 45
69 D.3 Approximation of OC for type A SPRT by Wald’s formula ...................................... 45
70 D.4 Construction of the approximated OC curve using a spreadsheet .......................... 46
71 Annex E (informative) Mathematical references and examples for fixed time/failure
72 terminated test plans (FTFT) ......................................................................................... 49
73 E.1 Symbols ................................................................................................................ 49
74 E.2 Mathematical references ....................................................................................... 49
75 E.2.1 General ......................................................................................................... 49
76 E.2.2 Mathematical references ................................................................................ 49
77 E.2.3 Design procedure {a} ..................................................................................... 51
78 E.2.4 Design procedure {b} ..................................................................................... 52
79 E.2.5 Design procedure {c} ..................................................................................... 52
80 E.2.6 Design procedure {d} ..................................................................................... 53
81 E.3 Examples of FTFT design using test plans B ........................................................ 53
82 E.3.1 Example 1 ..................................................................................................... 53
83 E.3.2 Example 2 ..................................................................................................... 54
84 E.4 Test OC approximation using formula for FTFT ..................................................... 55
85 Annex F (informative) Examples of FTFT design using a spreadsheet program .................... 56
86 F.1 General ................................................................................................................. 56
87 F.2 Finding the test border lines using optimization on the example of the design
88 procedure {b} ........................................................................................................ 59
89 F.3 ETT and OC curves .............................................................................................. 60
90 F.4 Example of design FTFT by procedure {a} ............................................................ 62
91 F.5 Example of design FTFT by procedure {c} ............................................................. 64
92 F.6 Example of design FTFT by procedure {d} ............................................................ 66
93 F.7 Example of a test with replacement of failed items ................................................ 69
94 F.8 Evaluation of an approximate OC for non-FTFT plans using a spreadsheet ........... 69
95 Annex G (informative) Examples and mathematical references for the calendar time
96 terminated test plans ..................................................................................................... 74
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97 G.1 Examples .............................................................................................................. 74
98 G.1.1 Example 1 ..................................................................................................... 74
99 G.1.2 Example 2 ..................................................................................................... 74
100 G.2 Mathematical background ..................................................................................... 74
101 Annex H (informative) Derivation and mathematical reference for the optimized test
102 plans of GOST R 27 402 [12] ......................................................................................... 76
103 H.1 Symbols ................................................................................................................ 76
104 H.2 Test plan types and terminology ........................................................................... 77
105 H.3 General introduction ............................................................................................. 77
106 H.4 Procedure used for developing the optimized test plans ........................................ 78
107 12 Bibliography .................................................................................................................. 84
108* *
109 Figure 1 – Relative ETT (T /m ) and MaxTT (T /m ) of various tests with the same
e 0 t 0110 risks 17
111 Figure 2 – SPRT diagram and test example .......................................................................... 20
112 Figure 3 – OC curve, P ....................................................................................................... 21
113 Figure 4 – SPRT – Curve of expected accumulated test time to decision (ETT) .................... 22
114 Figure 5 – Example of a decision graph for combined test plan (type D) and for SPRT
115 type C ................................................................................................................................... 30
116 Figure A.1 – Decision graph of SPRT plan ............................................................................ 33
117 Figure B.1 – Expected accumulated test time to acceptance decision, T (+) for D.3
118 and C.3 test plans ................................................................................................................. 40
119 Figure B.2 – Operating characteristic P for D.3 and C.3 test plans ...................................... 41
120 Figure D.1 – Approximation of OC for type A SPRT using Wald’s formulae ........................... 46
121 Figure E.1 – Example 1. Expected accumulated test time to decision (ETT) of tests B.2
122 and A.25 ............................................................................................................................... 54
123 Figure E.2 – Example 1. Operating characteristics of tests B.2 and A.25 .............................. 54
124 Figure F.1 – Using Solver to find T /m - accumulated test truncation time in term
t 0125 of m .................................................................................................................................... 60
126 Figure F.2 – ETT plotted from the spreadsheet calculations .................................................. 61
127 Figure F.3 – OC curve plotted from the spreadsheet calculations .......................................... 61
128 Figure F.4 – Using Solver to find T /m and c in Step {a1}..................................................... 63
t 0129 Figure F.5 – Using Solver to find T /m in Step {a2} ............................................................. 64
t 0130 Figure F.6 – Using Solver to find T /m in Step {c2} ............................................................. 65
t 0131 Figure F.7 – Using Solver to find D and c in Step {d1} ........................................................... 67
132 Figure F.8 – Using Solver to find D and T in Step {d2} ........................................................ 68
133 Figure F.9 – Using Solver to find c and T /m for Clause F.8 ................................................ 72
t 0134 Figure F.10 – OC approximated by formula for FTFT (example from Clause F.8) .................. 73
135 Figure H.1 – Test plan types and terminology ....................................................................... 77
136 Figure H.2 – Principle of test plans ....................................................................................... 79
137 Figure H.3 – Partitioning of the test plan graph ..................................................................... 79
138 Figure H.4 – Interior nodes and border nodes ....................................................................... 79
139 Figure H.5 – Paths to the accept line .................................................................................... 80
140 Figure H.6 – Paths to the reject line ...................................................................................... 80
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141 Figure H.7 – Probabilities of paths transfer between nodes ................................................... 81
142 Figure H.8 – The recurrent element – Two cases .................................................................. 83
143 Table 1 – Advantages and disadvantages for the different test plan types ............................. 16
144 Table 2 – OC curve ............................................................................................................... 20
145 Table 3 – Relative ETT vs. m/m ........................................................................................... 21
146 Table 4 – Overview of type A SPRT plans ............................................................................. 23
147 Table 5 – Overview of type C SPRT plans ............................................................................ 24
148 Table 6 – Type B FTFT plans ................................................................................................ 26
149 Table 7 – Overview of type D combined plans ....................................................................... 30
150 Table A.1 – Constants for border line formulae and their coordinates for type A SPRT
151 plans .................................................................................................................................... 34
152 Table A.2 – Constants for border line formulae and their coordinates for type C SPRT
153 plans .................................................................................................................................... 35
154 Table A.3 – Example for SPRT using test plan A.41 (with example data) .............................. 36
155 Table B.1 – Combined test plans in Annex B ........................................................................ 37
156 Table B.2 – Type D test plans – Accept and reject lines ........................................................ 38
157 Table B.3 – Expected accumulated test time to acceptance decision, T (+), for D and
158 C test plans .......................................................................................................................... 39
159 Table B.4 – Accept and reject lines for D.3 and C.3 test plans .............................................. 40
160 Table C.1 – Example for interpolation by α and β ................................................................. 44
161 Table D.1 – Spreadsheet set-up for construction of the OC curve by Wald ............................ 47
162 Table D.2 – Formulae embedded in the spreadsheet ............................................................ 48
163 Table E.1 – List of the typical FTFT design procedures ......................................................... 51
164 Table F.1 – Set-up of the spreadsheet with embedded formulae ........................................... 57
165 Table F.2 – Formulae embedded in the spreadsheet ............................................................. 58
166 Table F.3 – Fragment from Table 6 ....................................................................................... 59
167 Table F.4 – Set-up 1 of the spreadsheet for example by procedure {a} ................................. 62
168 Table F.5 – Set-up 2 of the spreadsheet for example by procedure {a} ................................. 63
169 Table F.6 – Set-up 3 (final solution) for example by procedure {a} ........................................ 64
170 Table F.7 – Set-up 2 for example by procedure {c} ............................................................... 65
171 Table F.8 – Set-up 3 (final solution) for example by procedure {c} ........................................ 66
172 Table F.9 – Set-up 1 of the spreadsheet for example by procedure {d} ................................. 67
173 Table F.10 – Set-up 2 of the spreadsheet for example by procedure {d} ............................... 68
174 Table F.11 – Set-up 3 (final solution) for example by procedure {d} ...................................... 69
175 Table F.12 – Set-up of the spreadsheet with embedded formulae for Clause F.8 .................. 71
176 Table F.13 – Set-up 1 of the spreadsheet for Clause F.8 ...................................................... 71
177 Table F.14 – Set-up 2 of the spreadsheet for example from Clause F.8 ................................ 72
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IEC CDV 61124 IEC:2021 – 7 –
179 INTERNATIONAL ELECTROTECHNICAL COMMISSION
180 ____________
181
182 RELIABILITY TESTING –
183 COMPLIANCE TESTS FOR CONSTANT FAILURE RATE
184 AND CONSTANT FAILURE INTENSITY
185
186
187 FOREWORD
188 1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
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209 services carried out by independent certification bodies.210 6) All users should ensure that they have the latest edition of this publication.
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215 8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
216 indispensable for the correct application of this publication.217 9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of patent
218 rights. IEC shall not be held responsible for identifying any or all such patent rights.
219 International Standard IEC 61124 has been prepared by IEC technical committee 56:
220 Dependability.221 This fourth edition of IEC 61124 cancels and replaces the third edition, published in 2012, and
222 constitutes a technical revision.223 The main changes with respect to the previous edition are as follows:
224 a) The truncated sequential probability ratio test (SPRT) [1, 2, 3] has been significantly
225 developed in recent years [4, 5, 6]. In this edition, type A test plans (optimally truncated
226 SPRT) have been significantly changed, as follows:227 – the tests are significantly truncated (the maximal test time is low) without substantially
228 increasing the expected accumulated test time to decision (ETT);229 – the true producer’s and consumer’s risks (α', β') are given and are very close to the
230 nominal values;231 – the range of the test parameters is wide (risks and discrimination ratio);
Numbers in square brackets refer to the bibliography.
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232 – the test plans include various risk ratios (not restricted to equal risks only);
233 – the values of ETT are accurate and given in the relevant region (for practical use);
234 – guidelines for extension of the tests set (using accurate interpolation) are included.
235 b) Other ready-to-use test plans (types B, C, D) are not changed, only the form of
236 presentation of the data on their border lines and the characteristics has been changed.
237 This form is made unified for all types of test plans, which helps the comparison of
238 different plans and, accordingly, to facilitate the selection of the most appropriate.
239 c) FTFT design procedures, to extend the set of test plans B, are significantly changed and
240 make the design accurate and simple. The implementation of this design is given on a
241 spreadsheet program. A unified approach to the calculation of the operational
242 characteristics of all types of test plans is introduced.243 The text of this standard is based on the following documents:
FDIS Report on voting
XX/XXXX/FDIS XX/XXXX/RVD
244
245 Full information on the vo
...
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