Electricity metering equipment (AC) - Acceptance inspection - Part 11: General acceptance inspection methods

IEC 62058-11:2008 specifies the general acceptance inspection methods which apply to newly manufactured electricity meters produced and supplied in lots of 50 and above.
This publication is of high relevance for Smart Grid.

Equipement de comptage de l'électricite (c.a.) - Contrôle de réception - Partie 11: Méthodes générales de contrôle de réception

La CEI 62058-11:2008 spécifie les méthodes générales de contrôle de réception qui s'appliquent aux compteurs électriques neufs et livrés par lots de 50 et plus.

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Status
Published
Publication Date
17-Sep-2008
Current Stage
PPUB - Publication issued
Start Date
18-Sep-2008
Completion Date
18-Sep-2008
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IEC 62058-11
Edition 1.0 2008-09
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Electricity metering equipment (AC) – Acceptance inspection –
Part 11: General acceptance inspection methods
Equipement de comptage de l'électricite (c.a.) – Contrôle de réception –
Partie 11: Méthodes générales de contrôle de réception
IEC 62058-11:2008
---------------------- Page: 1 ----------------------
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---------------------- Page: 2 ----------------------
IEC 62058-11
Edition 1.0 2008-09
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Electricity metering equipment (AC) – Acceptance inspection –
Part 11: General acceptance inspection methods
Equipement de comptage de l'électricite (c.a.) – Contrôle de réception –
Partie 11: Méthodes générales de contrôle de réception
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
CODE PRIX
ICS 17.220; 91.140.50 ISBN 2-8318-9988-5
® Registered trademark of the International Electrotechnical Commission
Marque déposée de la Commission Electrotechnique Internationale
---------------------- Page: 3 ----------------------
– 2 – 62058-11 © IEC:2008
CONTENTS

FOREWORD...........................................................................................................................6

INTRODUCTION.....................................................................................................................8

1 Scope...............................................................................................................................9

2 Normative references .......................................................................................................9

3 Terms and definitions .......................................................................................................9

3.1 Sources of data .....................................................................................................10

3.2 Types of sampling .................................................................................................11

3.3 Specifications, values and test results...................................................................11

3.4 Types of inspection ...............................................................................................12

3.5 Types of acceptance sampling inspection..............................................................14

3.6 Acceptance sampling inspection system aspects...................................................15

3.7 Acceptance criteria................................................................................................16

3.8 Types of operating characteristic curves................................................................18

3.9 Terms relating to operating characteristics ............................................................18

3.10 Outgoing quality concepts .....................................................................................21

3.11 Other terms ...........................................................................................................21

4 Symbols and abbreviations.............................................................................................22

4.1 Symbols ................................................................................................................22

4.2 Acronyms ..............................................................................................................23

5 General ..........................................................................................................................23

5.1 The objectives of acceptance inspection ...............................................................23

5.2 Acceptance sampling plans, schemes and systems ...............................................24

5.3 Practical and economic advantages of using standard sampling plans ..................24

5.4 Agreement between the parties .............................................................................25

5.5 Selection of sampling schemes and sampling plans ..............................................26

5.6 Considerations influencing a selection...................................................................27

5.6.1 Long and short production runs .................................................................27

5.6.2 Lot-by-lot inspection ..................................................................................28

5.6.3 Isolated lot inspection................................................................................28

5.6.4 Attributes versus variables ........................................................................28

5.6.5 Single and double sampling.......................................................................29

5.6.6 “s” method and “σ” method.........................................................................29

5.7 Nonconformity and nonconforming items ...............................................................29

5.8 Classification of nonconformities ...........................................................................29

5.9 Operating characteristic (OC) curve ......................................................................30

5.10 Producer’s risks (PR) and consumer’s risk (CR) ....................................................30

5.11 AQL, PRQ, LQ and CRQ .......................................................................................31

5.12 Switching rules for normal, tightened and reduced inspection................................31

5.13 Inspection level .....................................................................................................32

5.14 Sample size code letter .........................................................................................32

5.15 Place of inspection ................................................................................................33

5.16 Submission of product for acceptance inspection ..................................................33

5.17 Drawing of samples ...............................................................................................33

5.18 Acceptability of lots ...............................................................................................34

6 100 % inspection ............................................................................................................34

6.1 Application of the method ......................................................................................34

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62058-11 © IEC:2008 – 3 –

6.2 Lot sizes and acceptance numbers........................................................................34

6.3 Acceptance and non-acceptance ...........................................................................35

7 Lot-by-lot inspection by attributes ...................................................................................35

7.1 Application of the method ......................................................................................35

7.2 Drawing of samples ...............................................................................................36

7.3 Inspection level .....................................................................................................36

7.4 Sampling plans......................................................................................................36

7.4.1 Obtaining a sampling plan .........................................................................36

7.4.2 Single sampling plans................................................................................36

7.4.3 Double sampling plans ..............................................................................39

7.4.4 Determination of acceptability....................................................................40

7.5 Normal, tightened and reduced inspection (see also 5.12).....................................41

7.5.1 Start and continuation of inspection...........................................................41

7.5.2 Normal to tightened ...................................................................................41

7.5.3 Tightened to normal...................................................................................42

7.5.4 Normal to reduced .....................................................................................42

7.5.5 Reduced to normal ....................................................................................43

7.5.6 Discontinuation and resumption of inspection ............................................43

7.6 Operating characteristic (OC) curves.....................................................................43

7.7 Process average ...................................................................................................46

7.8 Average outgoing quality (AOQ) ............................................................................46

7.9 Average outgoing quality limit (AOQL)...................................................................46

7.10 Consumer’s risk (CR) ............................................................................................47

7.11 Producer’s risk (PR) ..............................................................................................49

8 Isolated lot inspection.....................................................................................................50

8.1 Application of the method ......................................................................................50

8.2 Procedures specified.............................................................................................50

8.2.1 Procedure A ..............................................................................................50

8.2.2 Procedure B ..............................................................................................50

8.3 Limiting quality ......................................................................................................50

8.4 Procedure A ..........................................................................................................50

8.5 Procedure B ..........................................................................................................53

8.6 Rules for acceptance and non-acceptance ............................................................55

9 Skip-lot inspection ..........................................................................................................55

9.1 Application of the method ......................................................................................55

9.2 Manufacturer qualification .....................................................................................56

9.3 Product qualification..............................................................................................56

9.4 Detailed procedures ..............................................................................................57

10 Lot-by-lot inspection by variables ...................................................................................57

10.1 Application of the method ......................................................................................57

10.2 Choice between the “s” and the “σ” methods..........................................................57

10.3 Standard plans ......................................................................................................58

10.4 Preliminary operations...........................................................................................58

10.5 Standard multivariate “s” method procedures for independent quality

characteristics with combined control ....................................................................

10.5.1 General methodology ................................................................................58

10.5.2 Sampling plans..........................................................................................59

10.5.3 Description of the procedure......................................................................60

10.5.4 Simplified exact formula for the “s” method with sample size 4 ..................61

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10.5.5 Approximate procedure for the “s” method for n > 5 ...................................61

10.6 Standard multivariate “σ” method procedures for independent quality

characteristics with combined control ....................................................................64

10.6.1 General methodology ................................................................................64

10.6.2 Sampling plans..........................................................................................65

10.6.3 Description of the procedure......................................................................65

10.7 Procedure during continuing inspection .................................................................66

10.8 Normality and outliers............................................................................................66

10.8.1 Normality...................................................................................................66

10.8.2 Outliers .....................................................................................................66

10.9 Records ................................................................................................................66

10.9.1 Control charts............................................................................................66

10.9.2 Lots that are not accepted .........................................................................66

10.10 Normal, tightened and reduced inspection (see also 5.12) ..................................66

10.11 Discontinuation and resumption of inspection .....................................................67

10.12 Switching between the “s” and “σ” methods .........................................................68

10.12.1 Estimating the process standard deviation ..............................................68

10.12.2 State of statistical control ........................................................................68

10.12.3 Switching from the “s” method to the “σ” method ......................................68

10.12.4 Switching from the “σ” method to the “s” method ......................................69

10.13 Consumer protection ..........................................................................................69

10.14 Operating characteristic curves ..........................................................................69

10.15 Consumer’s risk (CR) .........................................................................................72

10.16 Producer’ risk (PR) .............................................................................................74

Annex A (normative) Random numbers................................................................................76

Annex B (normative) Procedure for obtaining s or σ .............................................................79

Bibliography..........................................................................................................................80

Figure 1 – Selection procedure of sampling schemes and plans ...........................................

Figure 2 – Outline of switching rules .....................................................................................32

Figure 3 – OC curves for AQL = 1,0, single sampling plans, normal inspection .....................44

Figure 4 – OC curves for AQL = 1,0, single sampling plans, tightened inspection .................44

Figure 5 – OC curves for single sampling plans, Ac=0 ..........................................................45

Figure 6 – Operating characteristic curves for single sampling plans for non-critical

nonconformities, procedure B ...............................................................................................54

Figure 7 – OC curves for normal inspection, AQL = 1,0.........................................................69

Figure 8 – OC curves for tightened inspection, AQL = 1,0.....................................................70

Figure 9 – OC curves for reduced inspection, AQL = 1,0.......................................................71

Table 1 – Acceptance number Ac for 100 % inspection .........................................................34

Table 2 – Single sampling plans for normal, tightened and reduced inspection, AQL = 1,0...37

Table 3 – Example with lot size = 80, inspection level II........................................................37

Table 4 – Example with lot size = 400, inspection level II......................................................38

Table 5 – Example with lot size = 800, inspection level III.....................................................38

Table 6 – Single sampling plans for critical nonconformities Ac = 0.......................................39

Table 7 – Double sampling plans for normal, tightened and reduced inspection, AQL = 1,0 .40

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62058-11 © IEC:2008 – 5 –

Table 8 – Calculation of switching scores .............................................................................43

Table 9 – Tabulated values of OC curves for single sampling, AQL = 1,0 plans ....................45

Table 10 – Tabulated values of OC curves for single sampling, normal inspection,

accept zero sampling plans...................................................................................................46

Table 11 – Average Outgoing Quality Limit (AOQL) at AQL = 1,0..........................................47

Table 12 – Average Outgoing Quality Limit (AOQL) for Ac = 0 sampling plans, normal

inspection .............................................................................................................................47

Table 13 – Consumer’s risk quality (CRQ): AQL = 1,0 plans .................................................48

Table 14 – Consumer’s risk quality (CRQ): Accept zero plans...............................................48

Table 15 – Producer’s risk (PR): AQL = 1,0 ..........................................................................49

Table 16 – Producer’s risk (PR): Accept zero plans ..............................................................49

Table 17 – Sampling plans for non-critical nonconformities, procedure A, LQ = 5,0 .............51

Table 18 – Sampling plans for critical nonconformities, procedure A.....................................52

Table 19 – Probability of acceptance for accept zero plans...................................................52

Table 20 – Single sampling plans for non-critical nonconformities, procedure B, LQ = 5,0 ....54

Table 21 – Equivalent sample sizes for single and double sampling......................................55

Table 22 – Equivalent acceptance numbers for single and double sampling..........................55

Table 23 – Sample sizes for the “s” method and the “σ” method with AQL = 1,0 ....................58

Table 24 – Sampling plans for the “s” method .......................................................................60

Table 25 – Values of a .........................................................................................................62

Table 26 – Sampling plans for the “σ” method.......................................................................65

Table 27 – Supplementary acceptability constants for qualifying towards reduced

inspection .............................................................................................................................67

Table 28 – Values of c for upper control limit on the sample standard deviation ..................68

Table 29 – Tabulated values of OC curves for normal inspection, AQL = 1,0 ........................70

Table 30 – Tabulated values of OC curves for tightened inspection, AQL = 1,0.....................71

Table 31 – Tabulated values of OC curves for reduced inspection, AQL = 1,0.......................72

Table 32 – Consumer’s risk quality (CRQ): “s” method ..........................................................73

Table 33 – Consumer’s risk quality (CRQ): “σ” method .........................................................73

Table 34 – Producer’s risk (PR): “s” method..........................................................................74

Table 35 – Producer’s risk (PR): “σ” method .........................................................................74

Table A.1 – Random numbers...............................................................................................76

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– 6 – 62058-11 © IEC:2008
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
ELECTRICITY METERING EQUIPMENT (AC) –
ACCEPTANCE INSPECTION –
Part 11: General acceptance inspection methods
FOREWORD

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International Standard IEC 62058-11 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 Report on voting
13/1430/FDIS 13/1438/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.

A list of all parts of IEC 62058 series, published under the general title Electricity metering

equipment (AC) – Acceptance inspection, can be found on the IEC website.

This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.

---------------------- Page: 8 ----------------------
62058-11 © IEC:2008 – 7 –

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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– 8 – 62058-11 © IEC:2008
INTRODUCTION
This part of IEC 62058 descri
...

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