BS EN 61810-2:2017
$189.07
Electromechanical elementary relays – Reliability
| Published By | Publication Date | Number of Pages |
| BSI | 2017 | 48 |
This part of IEC 61810 covers test conditions and provisions for the evaluation of endurance tests using appropriate statistical methods to obtain reliability characteristics for relays.
This document applies to electromechanical elementary relays considered as non-repaired items (i.e. items which are not repaired after failure).
The lifetime of a relay is usually expressed in number of cycles (CTF). Therefore, whenever the terms “time” or “duration” are used in IEC 61649 , they carry the meaning “cycles”. However, with a given frequency of operation, the number of cycles can be transformed into respective times (e.g. times to failure (TTF)).
The failure criteria and the resulting characteristics of elementary relays describing their reliability in normal use are specified in this document. A relay failure occurs when the specified failure criteria are met.
As the failure rate for elementary relays cannot be considered as constant, particularly due to wear-out mechanisms, the cycles to failure of tested items typically show a Weibull distribution. This document provides numerical and graphical methods to calculate approximate values for the two-parameter Weibull distribution, as well as lower confidence limits and a method for confirmation of reliability values with the WeiBayes method.
This document does not cover procedures for electromechanical elementary relays where enhanced requirements for the verification of reliability apply.
Such reliability test procedures are specified in IEC 61810‑2‑1 . In particular, when electromechanical elementary relays are intended to be incorporated in safety-related control systems of machinery in accordance with IEC 62061 and ISO 13849‑1 , IEC 61810‑2‑1 defines procedures for the manufacturer to provide B 10D values.
Electromechanical elementary relays with forcibly guided (mechanically linked) contacts according to IEC 61810‑3 offer the possibility of a high diagnostic coverage according to 4.5.3 of ISO 13849‑1:2015 .
PDF Catalog
| PDF Pages | PDF Title |
|---|---|
| 2 | National foreword |
| 7 | English CONTENTS |
| 9 | FOREWORD |
| 11 | INTRODUCTION |
| 12 | 1 Scope 2 Normative references 3 Terms and definitions |
| 15 | 3.21 Terms and definitions related to tests 4 General considerations |
| 16 | 5 Test conditions 5.1 Sample items |
| 17 | 5.2 Environmental conditions 5.3 Operating conditions |
| 18 | 5.4 Test equipment 6 Failure criteria 7 Output data 8 Analysis of output data 9 Presentation of reliability measures |
| 20 | Annex A (normative) Data analysis A.1 General A.2 Abbreviations A.3 Symbols and definitions |
| 21 | A.4 Weibull distribution |
| 22 | A.5 Procedure A.5.1 Graphical methods |
| 23 | Figures Figure A.1 – An example of Weibull probability paper |
| 25 | Figure A.2 – An example of cumulative hazard plotting paper Figure A.3 – Plotting of data points and drawing of a straight line |
| 26 | Figure A.4 – Estimation of distribution parameters |
| 27 | A.5.2 Numerical methods |
| 28 | A.5.3 Confidence Intervals |
| 30 | A.5.4 WeiBayes Approach |
| 31 | Tables Table A.1 – Confidence levels for WeiBayes without failures |
| 33 | Annex B (informative) Example of data analysis B.1 Graphical methods case study (cumulative hazard plot) B.1.1 General B.1.2 Procedure of cumulative hazard plot Table B.1 – Worksheet for cumulative hazard analysis |
| 35 | B.1.3 Example applied to life test data Figure B.1 – Estimation of distribution parameters |
| 36 | Table B.2 – Example worksheet |
| 37 | Figure B.2 – Cumulative hazard plots |
| 38 | B.2 Numerical methods case study (Weibull probability) B.2.1 General B.2.2 Distribution parameters B.2.3 Mean cycles to failure (MCTF) Table B.3 – First twenty failures in this example |
| 39 | B.2.4 Value of B10 B.2.5 Mean time to failure (MTTF) B.3 Confidence intervals case study B.3.1 General B.3.2 Interval estimation of β |
| 40 | B.3.3 Interval estimation of η B.3.4 Lower confidence limit for B10 |
| 41 | B.3.5 Lower confidence limit for R B.4 WeiBayes case study |
| 42 | Figure B.3 – Type test versus WeiBayes analysed periodic test |
| 43 | Annex C (informative) Statistical tables C.1 Table of gamma function C.2 Fractiles of the normal distribution Table C.1 – Values of the gamma function |
| 44 | Table C.2 – Fractiles of the normal distribution |
| 45 | Annex D (informative) Success run – Test without failures D.1 General D.2 Confidence level and minimum reliability |
| 46 | D.3 Example Table D.1 – Number of samples and life cycles |
| 47 | Bibliography |
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BS EN 61810-2:2017 – TC:2020 Edition
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