SIST EN IEC 61124:2023

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
intensity
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
Ta 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

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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 voting
The 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: 2024

NOTE 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
permission in writing from IEC.

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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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IEC CDV 61124  IEC:2021 – 5 –
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 0
110 risks 17
111 Figure 2 – SPRT diagram and test example . 20
112 Figure 3 – OC curve, P . 21
a
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
e
118 and C.3 test plans . 40
119 Figure B.2 – Operating characteristic P for D.3 and C.3 test plans . 41
a
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 0
125 of m . 60
0
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 0
*
129 Figure F.5 – Using Solver to find T /m in Step {a2} . 64
t 0
*
130 Figure F.6 – Using Solver to find T /m in Step {c2} . 65
t 0
131 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
t
*
133 Figure F.9 – Using Solver to find c and T /m for Clause F.8 . 72
t 0
134 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
0
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
e
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
178

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oSIST prEN IEC 61124:2022
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
189 all national electrotechnical committees (IEC National Committees). The object of IEC is to promote international
190 co-operation on all questions concerning standardization in the electrical and electronic fields. To this end and
191 in addition to other activities, IEC publishes International Standards, Technical Specifications, Technical Reports,
192 Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC Publication(s)”). Their
193 preparation is entrusted to technical committees; any IEC National Committee interested in the subject dealt with
194 may participate in this preparatory work. International, governmental and non-governmental organizations liaising
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196 Standardization (ISO) in accordance with conditions determined by agreement between the two organizations.
197 2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
198 consensus of opinion on the relevant subjects, since each technical committee has representation from all
199 interested IEC National Committees.
200 3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
201 Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
202 Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
203 misinterpretation by any end user.
204 4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
205 transparently to the maximum extent possible in their national and regional publications. Any divergence between
206 any IEC Publication and the corresponding national or regional publication shall be clearly indicated in the latter.
207 5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
208 assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any
209 services carried out by independent certification bodies.
210 6) All users should ensure that they have the latest edition of this publication.
211 7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
212 members of its technical committees and IEC National Committees for any personal injury, property damage or
213 other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
214 expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC Publications.
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:
1
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);

1
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
...