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BS EN IEC 61123:2020

BS EN IEC 61123:2020

$198.66

Reliability testing. Compliance test plans for success ratio

Published By Publication Date Number of Pages
BSI 2020 54
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IEC 61123:2019 is intended to define a procedure to verify if a reliability of an item/system complies with the stated requirements. The requirement is assumed to be specified as the percentage of success (success ratio) or the percentage of failures (failure ratio). This document can be used where a number of items are tested (number of trials performed) and classified as passed or failed. It can also be used where one or a number of items are tested repeatedly. The procedures are based on the assumption that the probability of success or failure is the same from trial to trial (statistically independent events). Plans for fixed trial/failure terminated tests as well as truncated sequential probability ratio tests (SPRTs) are included. This document contains extensive tables with ready-to-use SPRT plans and their characteristics for equal and non-equal risks for supplier and customer. In the case of the reliability compliance tests for constant failure rate/intensity, IEC 61124 applies. This second edition cancels and replaces the first edition published in 1991. This edition constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition: The sequential probability ratio test (SPRT) [1, 2][1] has been significantly developed in recent years [3, 4, 5]. This edition contains shorter and accurate tests, a wide range of test plans, and significant additional characteristic data, as follows: the tests are significantly truncated (the maximum trial numbers are low) without substantially increasing the expected number of trials to decision (ENT); the true producer’s and consumer’s risks (?‘, ?‘) are given and very close to the nominal (?, ?); the range of the test parameters is wide (failure ratio, risks and discrimination ratio); the test plans include various risk ratios (not restricted to equal risks only); the values of ENT are accurate and given in the relevant region (for practical use); guidelines for extension of the test sets (interpolation and extrapolation) are included. In Annex C, the use of the cumulative binomial distribution function of Excel that simplifies the procedure of designing has been added (Clause C.3). Keywords: verify if a reliability of an item/system complies with the stated requirements

PDF Catalog

PDF Pages PDF Title
2 undefined
5 Annex ZA(normative)Normative references to international publicationswith their corresponding European publications
6 English
CONTENTS
8 FOREWORD
10 INTRODUCTION
12 1 Scope
2 Normative references
3 Terms, definitions, abbreviated terms and symbols
3.1 Terms and definitions
13 3.2 Abbreviated terms and symbols
3.2.1 Abbreviated terms
3.2.2 Symbols
14 4 General requirements and area of application
4.1 Reliability requirement
4.2 Repair and replacement
4.3 Types of test plans
4.3.1 General
4.3.2 Features of the test plan types
15 4.4 General test procedure
4.5 General decision criteria
Figures
Figure 1 – Expected and maximal number of trials for SPRT and FTFT with the same risks
16 Tables
Table 1 – Overview – Maximal number of trials and expected number of trials at p0 for SPRT and FTFT
17 5 Truncated sequential probability ratio test plans (SPRT)
5.1 Characteristics
5.2 Decision criteria
Table 2 – Range of the test parameters
18 5.3 Operating characteristic curve (OC)
Figure 2 – SPRT diagram
Table 3 – OC curve
19 5.4 Expected number of trials to decision (ENT)
Figure 3 – OC curve
Figure 4 – SPRT – Curve of expected number of trials to decision (ENT)
Table 4 – ENT (ne) versus true failure ratio (p)
20 6 Fixed trial/failure terminated test plans (FTFT)
6.1 Characteristics
6.2 Decision criteria
Table 5 – Fixed trial/failure terminated test plans
21 7 Design of fixed trial/failure terminated test plans
7.1 Characteristics
7.2 Approach
22 7.3 Common case
7.4 Other cases
7.5 Example of application
7.6 Procedure to determine D and c or n and c
7.6.1 Figure and table readings
23 7.6.2 Use of figures and tables
7.7 Decision criteria
Figure 5 – Principal layout of Tables E.1 to E.3
24 Annex A (informative)Additional information on sequential test plans
A.1 Example
Figure A.1 – Example of a truncated sequential test
25 A.2 Extension of the test set (through interpolation and extrapolation)
A.2.1 General
A.2.2 Extrapolation for p0 < 0,001
A.2.3 Interpolation
27 Table A.1 – Example for interpolation by α and β
28 Annex B (informative)Design of fixed trial/failure terminated test plans − Examples
B.1 Use of figures and tables
B.2 Case where number of events, n, is not known, but is predictable
30 Annex C (informative)Design of fixed trial/failure terminated test plans –Mathematical procedures and formulas
C.1 General
C.2 Symbols
C.3 Computation
C.3.1 Determination of D versus n
31 C.3.2 Determination of n and c versus p0, D, α, β
C.3.3 Test without failures – Determination of n and D versus p0, α, β
32 C.3.4 Determination of OC curves
C.3.5 Determination of inverse OC curves
33 C.4 Accuracy
C.5 Tables of cumulative normal distribution and its Inverse
Table C.1 – Cumulative normal distribution for fixed uγ values
34 Table C.2 – Inverse cumulative normal distribution for fixed 1 − γ values
35 Annex D (normative)Truncated sequential test plans
Table D.1 – Truncated sequential test plans
44 Annex E (informative)Design of fixed trial/failure terminated test plans – Figures and tables to determine D and c or n and c
Figure E.1 – Discrimination ratio, D, versus number of events, n for p0 = 0,05
45 Figure E.2 – Discrimination ratio, D, versus number of events, n for p0 = 0,10
46 Figure E.3 – Discrimination ratio, D, versus number of events, n for p0 = 0,15
47 Table E.1 – Acceptable number of failures, c, versus number of events, n for p0 = 0,05 (1 of 2)
49 Table E.2 – Acceptable number of failures, c, versus number of events, n for p0 = 0,10 (1 of 2)
51 Table E.3 – Acceptable number of failures, c, versus number of events, n for p0 = 0,15 (1 of 2)
53 Bibliography

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BS EN IEC 61123:2020
$198.66