SIST EN 62059-31-1:2009

Electricity metering equipment - Dependability - Part 31-1: Accelerated reliability testing - Elevated temperature and humidity (IEC 62059-31-1:2008)

This part of IEC 62059 provides one of several possible methods for estimating product life characteristics by accelerated reliability testing. Acceleration can be achieved in a number of different ways. In this particular standard, elevated, constant temperature and humidity is applied to achieve acceleration. The method also takes into account the effect of voltage and current variation. Of course, failures not (or not sufficiently) accelerated by temperature and humidity will not be detected by the application of the test method specified in this standard. Other factors, like temperature variation, vibration, dust, voltage dips and short interruptions, static discharges, fast transient burst, surges, etc. - although they may affect the life characteristics of the meter - are not taken into account in this standard; they may be addressed in future parts of the IEC 62059 series. This standard is applicable to all types of metering equipment for energy measurement, tariffand load control in the scope of IEC TC 13. The method given in this standard may be used for estimating (with given confidence limits) product life characteristics of such equipment prior to and during serial production. This method may also be used to compare different designs.

Elektrizitätszähler - Zuverlässigkeit - Teil 31-1: Zeitraffende Zuverlässigkeitsprüfung - Temperatur und Luftfeuchte erhöht (IEC 62059-31-1:2008)

Equipements de comptage de l'électricité - Sûreté de fonctionnement - Partie 31-1: Essais de fiabilité accélérés - Température et humidité élévées (CEI 62059-31-1:2008)

La CEI 62059-31-1:2008 fournit une méthode, parmi de nombreuses autres, de prévision des caractéristiques de la duré de vie d'un produit au moyen des essais de fiabilité accélérés. Elle utilise une température et une humidité constantes élevées pour parvenir à ladite accélération. La méthode utilisée tient également compte de l'effet de variation de la tension et du courant. Elle s'applique à tous les types d'équipement de comptage de l'énergie et de contrôle des tarifs et de la charge relevant du domaine d'application du comité d'études 13 de la CEI. La méthode décrite dans la présente norme peut être utilisée pour évaluer (avec des limites de confiance données) les caractéristiques de la durée de vie de ces équipements avant et au cours de leur fabrication en série. Cette méthode peut également être employée pour comparer des équipements de conceptions différentes. Le contenu du corrigendum de décembre 2008 a été pris en considération dans cet exemplaire.

Oprema za merjenje električne energije - Zagotovljivost - 31-1. del: Pospešeno preskušanje zanesljivosti - Povišana temperatura in povečana vlažnost (IEC 62059-31-1:2008)

General Information

• Status: Published
• Publication Date: 03-Dec-2008
• ICS: 17.220.20 - Measurement of electrical and magnetic quantities
• ICS: 91.140.50 - Electricity supply systems
• Technical Committee: MEE - Equipment for electrical energy measurement and load control
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 28-Nov-2008
• Due Date: 02-Feb-2009
• Completion Date: 04-Dec-2008
• Ref Project: EN 62059-31-1:2008 - Electricity metering equipment - Dependability - Part 31-1: Accelerated reliability testing - Elevated temperature and humidity

Standards Content (Sample)

SLOVENSKI STANDARD
SIST EN 62059-31-1:2009
01-januar-2009
2SUHPD]DPHUMHQMHHOHNWULþQHHQHUJLMH=DJRWRYOMLYRVWGHO3RVSHãHQR
SUHVNXãDQMH]DQHVOMLYRVWL3RYLãDQDWHPSHUDWXUDLQSRYHþDQDYODåQRVW,(&

Electricity metering equipment - Dependability - Part 31-1: Accelerated reliability testing -
Elevated temperature and humidity (IEC 62059-31-1:2008)
Elektrizitätszähler - Zuverlässigkeit - Teil 31-1: Zeitraffende Zuverlässigkeitsprüfung -
Temperatur und Luftfeuchte erhöht (IEC 62059-31-1:2008)
Equipements de comptage de l'électricité - Sûreté de fonctionnement - Partie 31-1:
Essais de fiabilité accélérés - Température et humidité élévées (CEI 62059-31-1:2008)
Ta slovenski standard je istoveten z: EN 62059-31-1:2008
ICS:
17.220.20 0HUMHQMHHOHNWULþQLKLQ Measurement of electrical
PDJQHWQLKYHOLþLQ and magnetic quantities
91.140.50 Sistemi za oskrbo z elektriko Electricity supply systems
SIST EN 62059-31-1:2009 en,fr
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN 62059-31-1:2009

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SIST EN 62059-31-1:2009

EUROPEAN STANDARD
EN 62059-31-1

NORME EUROPÉENNE
November 2008
EUROPÄISCHE NORM

ICS 29.240; 91.140.50


English version


Electricity metering equipment -
Dependability -
Part 31-1: Accelerated reliability testing -
Elevated temperature and humidity
(IEC 62059-31-1:2008)


Equipements de comptage de l'électricité - Elektrizitätszähler -
Sûreté de fonctionnement - Zuverlässigkeit -
Partie 31-1: Essais de fiabilité accélérés - Teil 31-1: Zeitraffende
Température et humidité élévées Zuverlässigkeitsprüfung -
(CEI 62059-31-1:2008) Temperatur und Luftfeuchte erhöht
(IEC 62059-31-1:2008)




This European Standard was approved by CENELEC on 2008-11-01. 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 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 the Central Secretariat has the same status as the official versions.

CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Cyprus, the
Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,
Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain,
Sweden, Switzerland and the United Kingdom.

CENELEC
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung

Central Secretariat: rue de Stassart 35, B - 1050 Brussels


© 2008 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.
Ref. No. EN 62059-31-1:2008 E

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SIST EN 62059-31-1:2009
EN 62059-31-1:2008 - 2 -
Foreword
The text of document 13/1437A/FDIS, future edition 1 of IEC 62059-31-1, prepared by IEC TC 13,
Electrical energy measurement, tariff- and load control, was submitted to the IEC-CENELEC parallel vote
and was approved by CENELEC as EN 62059-31-1 on 2008-11-01.
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) 2009-08-01
– latest date by which the national standards conflicting
with the EN have to be withdrawn (dow) 2011-11-01
Annex ZA has been added by CENELEC.
__________
Endorsement notice
The text of the International Standard IEC 62059-31-1:2008 was approved by CENELEC as a European
Standard without any modification.
In the official version, for Bibliography, the following notes have to be added for the standards indicated:
IEC 61124 NOTE  Harmonized as EN 61124:2006 (not modified).
IEC 61163-1 NOTE  Harmonized as EN 61163-1:2006 (not modified).
IEC 61164 NOTE  Harmonized as EN 61164:2004 (not modified).
IEC 61709 NOTE  Harmonized as EN 61709:1998 (not modified).
__________

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SIST EN 62059-31-1:2009
- 3 - EN 62059-31-1:2008
Annex ZA
(normative)

Normative references to international publications
with their corresponding European publications

The following referenced 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.

NOTE  When an international publication has been modified by common modifications, indicated by (mod), the relevant EN/HD
applies.

Publication Year Title EN/HD Year

IEC 60050-191 1990 International Electrotechnical Vocabulary - -
(IEV) -
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 61649 2008 Weibull analysis EN 61649 2008


IEC 61703 2001 Mathematical expressions for reliability, EN 61703 2002
availability, maintainability and maintenance
support terms


IEC/TR 62059-11 2002 Electricity metering equipment - - -
Dependability -
Part 11: General concepts


IEC/TR 62059-21 2002 Electricity metering equipment - - -
Dependability -
Part 21: Collection of meter dependability data
from the field


IEC 62059-41 2006 Electricity metering equipment - EN 62059-41 2006
Dependability -
Part 41: Reliability prediction


IEC 62308 2006 Equipment reliability - Reliability assessment EN 62308 2006
methods

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SIST EN 62059-31-1:2009

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SIST EN 62059-31-1:2009
IEC 62059-31-1
Edition 1.0 2008-10
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE


Electricity metering equipment – Dependability –
Part 31-1: Accelerated reliability testing – Elevated temperature and humidity

Equipements de comptage de l'électricité – Sûreté de fonctionnement –
Partie 31-1: Essais de fiabilité accélérés – Température et humidité élevées

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
XC
CODE PRIX
ICS 29.240; 91.140.50 ISBN 2-8318-1002-9
® Registered trademark of the International Electrotechnical Commission
Marque déposée de la Commission Electrotechnique Internationale

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SIST EN 62059-31-1:2009
– 2 – 62059-31-1 © IEC:2008
CONTENTS
FOREWORD.5
INTRODUCTION.7
1 Scope.8
2 Normative references .8
3 Terms and definitions .9
4 Symbols, acronyms and abbreviations.14
5 Description of quantitative accelerated life tests .15
5.1 Introduction .15
5.2 The life distribution.15
5.3 The life-stress model .15
6 The Weibull distribution .16
6.1 Introduction .16
6.2 Graphical representation .16
6.3 Calculation of the distribution parameters.19
6.3.1 Input data to be used.19
6.3.2 Ranking of the time to failure.19
6.3.3 Reliability / unreliability estimates.20
6.3.4 Calculation of the parameters .21
7 The life-stress model .25
7.1 General .25
7.2 Linear equation of the acceleration factor.26
7.3 Calculation of parameters n and E .27
a
8 The quantitative accelerated life testing method .28
8.1 Selection of samples .28
8.2 The steps to check product life characteristics .28
8.3 Procedure for terminating the maximum stress level test .29
8.4 Procedure to collect time to failure data and to repair meters .29
9 Definition of normal use conditions .29
9.1 Introduction .29
9.2 Temperature and humidity conditions .30
9.2.1 Equipment for outdoor installation .30
9.2.2 Equipment for indoor installation .31
9.3 Temperature correction due to variation of voltage and current .31
9.3.1 Definition of the normal use profile of voltage and current .32
9.3.2 Measurement of the meter internal temperature at each current and
voltage .32
9.3.3 Calculation of the meter average internal temperature.32
9.4 Other conditions .34
10 Classification and root cause of failures .34
11 Presentation of the results.34
11.1 Information to be given.34
11.2 Example .35
12 Special cases .35
12.1 Cases of simplification .35
12.1.1 Minor evolution of product design .35

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SIST EN 62059-31-1:2009
62059-31-1 © IEC:2008 – 3 –
12.1.2 Verification of production batches.35
12.2 Cases when additional information is needed .35
12.2.1 The β parameter changes significantly from maximum stress level to
medium or low stress level .35
12.2.2 Fault mode different between stress levels .35
Annex A (informative) Basic statistical background .36
Annex B (informative) The characteristics of the Weibull distribution.38
Annex C (informative, see also draft IEC 62308) Life-stress models .42
Annex D (normative) Rank tables.44
Annex E (normative) Values of the Gamma function Γ(n) .47
Annex F (normative) Calculation of the minimum duration of the maximum stress level
test .48
Annex G (informative) Example.54
Bibliography.84
INDEX .85

Figure 1 – Weibull unreliability representation example with γ = 3 000, β = 1,1, η = 10 000.19
Figure 2 – Example of graphical representation of F(t) in the case of Weibull
distribution.25
Figure 3 – Example of regional climatic conditions.30
Figure 4 – Calculation of average year use conditions .31
Figure A.1 – The probability density function .36
Figure A.2 – The reliability and unreliability functions .37
Figure B.1 – Effect of the β parameter on the Weibull probability density function f (t) .39
Figure B.2 – Effect of the η parameter on the Weibull probability density function f (t) .40
Figure F.1 – Unreliability at normal use conditions .49
Figure F.2 – Unreliability at maximum stress level .50
Figure G.1 – Graphical representation of display failures for each stress level.63
Figure G.2 – Graphical representation of Q2 failures for each stress level .64
Figure G.3 – Graphical representation of U1 failures for each stress level .65
Figure G.4 – Example of climate data .67
Figure G.5 – Graphical representation of all failures at normal use conditions .76
Figure G.6 – Final cumulative distribution with confidence intervals .81
Figure G.7 – Reliability function extrapolated to normal use conditions .82
Figure G.8 – Reliability function extrapolated to normal use conditions (First portion
magnified).83

Table 1 – Construction of ordinate (Y) .17
Table 2 – Construction of abscissa (t-γ) .17
Table 3 – Equations format entered into a spreadsheet .18
Table 4 – Example with γ = 3 000, β = 1,1, η = 10 000 .18
Table 5 – Example of ranking process of times to failure.20
Table 6 – Unreliability estimates by median rank .21
Table 7 – Example of unreliability estimation for Weibull distribution.24

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SIST EN 62059-31-1:2009
– 4 – 62059-31-1 © IEC:2008
Table 8 – Example of 90 % confidence bounds calculation for Weibull distribution.24
Table 9 – Values of the linear equation .27
Table 10 – Example of procedure for temperature correction .33
Table G.1 – Failures logged at 85 °C with RH = 95 % .57
Table G.2 – Failures logged at 85 °C with RH = 85 % .59
Table G.3 – Failures logged at 85 °C with RH = 75 % .60
Table G.4 – Failures logged at 75 °C with RH = 95 % .61
Table G.5 – Failures logged at 65 °C with RH = 95 % .62
Table G.6 – Best fit Weibull distributions for display failures .63
Table G.7 – Best fit Weibull distributions for Q2 failures.64
Table G.8 – Best fit Weibull distributions for U1 failures.65
Table G.9 – Values of the linear equation for display failures.66
Table G.10 – Values of the linear equation for Q2 failures .66
Table G.11 – Values of the linear equation for other failures.66
Table G.12 – Normal use profile of voltage and current.67
Table G.13 – Measurement of the internal temperature.69
Table G.14 – Arrhenius acceleration factors compared to temperature measured at U
n
and 0,1 I , for display failures .70
max
Table G.15 – Arrhenius acceleration factors compared to temperature measured at U
n
and 0,1 I , for Q2 failures.71
max
Table G.16 – Arrhenius acceleration factors compared to temperature measured at U
n
and 0,1 I , for U1 failures .72
max
Table G.17 – Display failures extrapolated to normal use conditions .74
Table G.18 – Q2 failures extrapolated to normal use conditions.75
Table G.19 – U1 failures extrapolated to normal use conditions .76
Table G.20 – Best fit Weibull distributions at normal use conditions.77
Table G.21 – Display failures 90 % confidence bounds calculation .78
Table G.22 – Q2 failures 90 % confidence bounds calculation .79
Table G.23 – U1 failures 90 % confidence bounds calculation .80

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SIST EN 62059-31-1:2009
62059-31-1 © IEC:2008 – 5 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________

ELECTRICITY METERING EQUIPMENT –
DEPENDABILITY –

Part 31-1: Accelerated reliability testing –
Elevated temperature and humidity


FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote
international co-operation on all questions concerning standardization in the electrical and electronic fields. To
this end and in addition to other activities, IEC publishes International Standards, Technical Specifications,
Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC
Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested
in the subject dealt with may participate in this preparatory work. International, governmental and non-
governmental organizations liaising with the IEC also participate in this preparation. IEC collaborates closely
with the International Organization for Standardization (ISO) in accordance with conditions determined by
agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
consensus of opinion on the relevant subjects since each technical committee has representation from all
interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
misinterpretation by any end user.
4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
transparently to the maximum extent possible in their national and regional publications. Any divergence
between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
the latter.
5) IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for any
equipment declared to be in conformity with an IEC Publication.
6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
members of its technical committees and IEC National Committees for any personal injury, property damage or
other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
Publications.
8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 62059-31 has been prepared by IEC technical committee 13:
Electrical energy measurement, tariff- and load control.
The text of this standard is based on the following documents:
FDIS RVD
13/1437A/FDIS 13/1444/RVD

Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.

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SIST EN 62059-31-1:2009
– 6 – 62059-31-1 © IEC:2008
A list of all parts of IEC 62059 series, under the general title Electricity metering equipment –
Dependability, can be found on the IEC website.
The committee has decided that the contents of this publication will remain unchanged until
the maintenance result date indicated on the IEC web site under "http://webstore.iec.ch" in
the data related to the specific publication. At this date, the publication will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.

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SIST EN 62059-31-1:2009
62059-31-1 © IEC:2008 – 7 –
INTRODUCTION
Electricity metering equipment are products designed for high reliability and long life under
normal operating conditions, operating continuously without supervision. To manage metering
assets effectively, it is important to have tools for predicting and estimating life characteristics
of various types.
IEC 62059-41 provides methods for predicting the failure rate – assumed to be constant – of
metering equipment based on the parts stress method.
IEC 62059-31-1 provides a method for estimating life characteristics using temperature and
humidity accelerated testing.
It is practically impossible to obtain data about life characteristics by testing under normal
operating conditions. Therefore, accelerated reliability test methods have to be used.
During accelerated reliability testing, samples taken from a defined population are operated
beyond their normal operating conditions, applying stresses to shorten the time to failure, but
without introducing new failure mechanisms.
The estimation is performed by recording and analysing failures during such accelerated
testing, establishing the failure distribution under the test conditions and, using life stress
models, extrapolating failure distribution under accelerated conditions of use to normal
conditions of use.
The method provides quantitative results with their confidence limits and may be used to
compare life characteristics of products coming from different suppliers or different batches
from the same supplier.

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SIST EN 62059-31-1:2009
– 8 – 62059-31-1 © IEC:2008
ELECTRICITY METERING EQUIPMENT –
DEPENDABILITY –

Part 31-1: Accelerated reliability testing –
Elevated temperature and humidity



1 Scope
This part of IEC 62059 provides one of several possible methods for estimating product life
characteristics by accelerated reliability testing.
Acceleration can be achieved in a number of different ways. In this particular standard,
elevated, constant temperature and humidity is applied to achieve acceleration. The method
also takes into account the effect of voltage and current variation.
Of course, failures not (or not sufficiently) accelerated by temperature and humidity will not be
detected by the application of the test method specified in this standard.
Other factors, like temperature variation, vibration, dust, voltage dips and short interruptions,
static discharges, fast transient burst, surges, etc. – although they may affect the life
characteristics of the meter – are not taken into account in this standard; they may be
addressed in future parts of the IEC 62059 series.
This standard is applicable to all types of metering equipment for energy measurement, tariff-
and load control in the scope of IEC TC 13. The method given in this standard may be used
for estimating (with given confidence limits) product life characteristics of such equipment
prior to and during serial production. This method may also be used to compare different
designs.
2 Normative references
The following referenced 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) – Chapter 191:
Dependability and quality of service
IEC 60300-3-5 Ed. 1.0:2001, Dependability management – Part 3-5: Application guide –
Reliability test conditions and statistical test principles
IEC 61649 Ed 2.0: 2008, Goodness-of-fit tests, confidence intervals and lower confidence
limits for Weibull distributed data
IEC 61703 Ed. 1.0: 2001, Mathematical expressions for reliability, availability, maintainability
and maintenance support terms
IEC/TR 62059-11 Ed 1.0:2002, Electricity metering equipment – Dependability – Part 11:
General concepts
IEC/TR 62059-21 Ed. 1.0:2002, Electricity metering equipment – Dependability – Part 21:
Collection of meter dependability data from the field

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SIST EN 62059-31-1:2009
62059-31-1 © IEC:2008 – 9 –
IEC 62059-41 Ed. 1.0: 2006, Electricity metering equipment – Dependability – Part 41:
Reliability prediction
IEC 62308 Ed. 1.0:2006, Equipment reliability – Reliability assessment methods
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
NOTE 1 Here only those terms relevant to the subject are included, which have not been already included in
IEC 62059-11.
3.1
...