EN IEC 61557-12:2022

SLOVENSKI STANDARD
01-marec-2022
Nadomešča:
SIST EN 61557-12:2008
Električna varnost v nizkonapetostnih razdelilnih sistemih za izmenične napetosti
do 1 kV in enosmerne napetosti do 1,5 kV - Oprema za preskušanje, merjenje ali
nadzorovanje zaščitnih ukrepov - 12. del: Naprave za merjenje in nadzorovanje
moči (PMD) (IEC 61557-12:2018)
Electrical safety in low voltage distribution systems up to 1 000 V a.c. and 1 500 V d.c. -
Equipment for testing, measuring or monitoring of protective measures - Part 12: Power
metering and monitoring devices (PMD) (IEC 61557-12:2018)
Elektrische Sicherheit in Niederspannungsnetzen bis AC 1 000 V und DC 1 500 V -
Geräte zum Prüfen, Messen oder Überwachen von Schutzmaßnahmen - Teil 12: Geräte
zur Energiemessung und -überwachung (PMD) (IEC 61557-12:2018)
Sécurité électrique dans les réseaux de distribution basse tension jusqu'à 1 000 V c.a. et
1 500 V c.c. - Dispositifs de contrôle, de mesure ou de surveillance de mesures de
protection - Partie 12: Dispositifs de comptage et de surveillance du réseau électrique
(PMD) (IEC 61557-12:2018)
Ta slovenski standard je istoveten z: EN IEC 61557-12:2022
ICS:
17.220.20 Merjenje električnih in Measurement of electrical
magnetnih veličin and magnetic quantities
29.080.01 Električna izolacija na Electrical insulation in
splošno general
29.240.01 Omrežja za prenos in Power transmission and
distribucijo električne energije distribution networks in
na splošno general
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD EN IEC 61557-12

NORME EUROPÉENNE
EUROPÄISCHE NORM
January 2022
ICS 17.220.20; 29.080.01; 29.240.01 Supersedes EN 61557-12:2008 and all of its
amendments and corrigenda (if any)
English Version
Electrical safety in low voltage distribution systems up to 1 000 V
AC and 1 500 V DC - Equipment for testing, measuring or
monitoring of protective measures - Part 12: Power metering and
monitoring devices (PMD)
(IEC 61557-12:2018)
Sécurité électrique dans les réseaux de distribution basse Elektrische Sicherheit in Niederspannungsnetzen bis AC 1
tension jusqu'à 1 000 V c.a. et 1 500 V c.c. - Dispositifs de 000 V und DC 1 500 V - Geräte zum Prüfen, Messen oder
contrôle, de mesure ou de surveillance de mesures de Überwachen von Schutzmaßnahmen - Teil 12: Geräte zur
protection - Partie 12: Dispositifs de comptage et de Energiemessung und -überwachung (PMD)
surveillance du réseau électrique (PMD) (IEC 61557-12:2018)
(IEC 61557-12:2018)
This European Standard was approved by CENELEC on 2021-11-10. 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 CEN-CENELEC
Management Centre 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 CEN-CENELEC Management Centre has the
same status as the official versions.
CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus, the Czech Republic,
Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, the
Netherlands, Norway, Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and the United Kingdom.

European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2022 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.
Ref. No. EN IEC 61557-12:2022 E

European foreword
The text of document 85/644/FDIS, future edition 2 of IEC 61557-12, prepared by IEC/TC 85
"Measuring equipment for electrical and electromagnetic quantities" was submitted to the IEC-
CENELEC parallel vote and approved by CENELEC as EN IEC 61557-12:2022.
The following dates are fixed:
• latest date by which the document has to be implemented at national (dop) 2022-08-10
level by publication of an identical national standard or by endorsement
• latest date by which the national standards conflicting with the (dow) 2026-11-10
document have to be withdrawn
This document supersedes EN 61557-12:2008 and all of its amendments and corrigenda (if any).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CENELEC shall not be held responsible for identifying any or all such patent rights.
This document has been prepared under a Standardization Request given to CENELEC by the
European Commission and the European Free Trade Association, and supports essential
requirements of EU Directive(s) / Regulation(s).
For the relationship with EU Directive(s) / Regulation(s), see informative Annex ZZ, which is an
integral part of this document.
Any feedback and questions on this document should be directed to the users’ national committee. A
complete listing of these bodies can be found on the CENELEC website.
Endorsement notice
The text of the International Standard IEC 61557-12:2018 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 60044-7:1999 NOTE Harmonized as EN 60044-7:2000 (not modified)
IEC 60044-8:2002 NOTE Harmonized as EN 60044-8:2002 (not modified)
IEC 60051 (series) NOTE Harmonized as EN IEC 60051 (series)
IEC 60071-1:2006 NOTE Harmonized as EN 60071-1:2006 (not modified)
IEC 60359:2001 NOTE Harmonized as EN 60359:2002 (not modified)
IEC 60364-6 NOTE Harmonized as HD 60364-6
IEC 60364-8-1 NOTE Harmonized as HD 60364-8-1
IEC 61000-4-5 NOTE Harmonized as EN 61000-4-5
IEC 61000-4-7:2002 NOTE Harmonized as EN 61000-4-7:2002 (not modified)
IEC 61000-4-15 NOTE Harmonized as EN 61000-4-15
IEC 61010-2-030 NOTE Harmonized as EN IEC 61010-2-030
IEC 61010-2-031 NOTE Harmonized as EN 61010-2-031
IEC 61010-2-032 NOTE Harmonized as EN IEC 61010-2-032
IEC 61140:2001 NOTE Harmonized as EN 61140:2002 (not modified)
IEC 61557-2:2007 NOTE Harmonized as EN 61557-2:2007 (not modified)
IEC 61557-3:2007 NOTE Harmonized as EN 61557-3:2007 (not modified)
IEC 61557-4:2007 NOTE Harmonized as EN 61557-4:2007 (not modified)
IEC 61557-5:2007 NOTE Harmonized as EN 61557-5:2007 (not modified)
IEC 61557-7:2007 NOTE Harmonized as EN 61557-7:2007 (not modified)
IEC 61557-8:2014 NOTE Harmonized as EN 61557-8:2015 (not modified)
IEC 61557-9:2014 NOTE Harmonized as EN 61557-9:2015 (not modified)
IEC 61557-13:2011 NOTE Harmonized as EN 61557-13:2011 (not modified)
IEC 61869-2:2012 NOTE Harmonized as EN 61869-2:2012 (not modified)
IEC 61869-3:2011 NOTE Harmonized as EN 61869-3:2011 (not modified)
IEC 62020 NOTE Harmonized as EN 62020
IEC 62052-11:2003 NOTE Harmonized as EN 62052-11:2003 (not modified)
IEC 62053 (series) NOTE Harmonized as EN 62053 (series)
IEC 62053-21:2003 NOTE Harmonized as EN 62053-21:2003 (not modified)
IEC 62053-22:2003 NOTE Harmonized as EN 62053-22:2003 (not modified)
IEC 62053-23:2003 NOTE Harmonized as EN 62053-23:2003 (not modified)
IEC 62053-24:2014 NOTE Harmonized as EN 62053-24:2015 (not modified)
IEC 62586 (series) NOTE Harmonized as EN 62586-2:2017/A1 (series)
IEC 62586-1 NOTE Harmonized as EN 62586-1
ISO 50001 NOTE Harmonized as EN ISO 50001
Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements 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 1  Where an International Publication has been modified by common modifications, indicated by (mod),
the relevant EN/HD applies.
NOTE 2  Up-to-date information on the latest versions of the European Standards listed in this annex is available
here: www.cenelec.eu.
Publication Year Title EN/HD Year
IEC 60068-2-1 - Environmental testing - Part 2-1: Tests - EN 60068-2-1 -
Test A: Cold
IEC 60068-2-2 - Environmental testing - Part 2-2: Tests - EN 60068-2-2 -
Test B: Dry heat
IEC 60068-2-30 - Environmental testing - Part 2-30: Tests - EN 60068-2-30 -
Test Db: Damp heat, cyclic (12 h + 12 h
cycle)
IEC 60529 - Degrees of protection provided by - -
enclosures (IP Code)
IEC 61000-4-30 2015 Electromagnetic compatibility (EMC) - Part EN 61000-4-30 2015
4-30: Testing and measurement techniques
- Power quality measurement methods
IEC 61010-1 2010 Safety requirements for electrical equipment EN 61010-1 2010
for measurement, control, and laboratory
use - Part 1: General requirements
+ A1 (mod) 2016 + A1 2019
IEC 61010-2-030 2017 Safety requirements for electrical equipment EN IEC 61010-2-030 2021
for measurement, control, and laboratory
use - Part 2-030: Particular requirements for
equipment having testing or measuring
circuits
- - + A11 2021
IEC 61326-1 2012 Electrical equipment for measurement, EN 61326-1 2013
control and laboratory use - EMC
requirements - Part 1: General requirements
IEC 62053-31 1998 Electricity metering equipment (a.c.) - EN 62053-31 1998
Particular requirements - Part 31: Pulse
output devices for electromechanical and
electronic meters (two wires only)
Annex ZZ
(informative)
Relationship between this European standard and the safety
objectives of Directive 2014/35/EU [2014 OJ L96] aimed to be
covered
This European Standard has been prepared under a Commission’s standardization request relating to
harmonized standards in the field of the Low Voltage Directive, M/511, to provide one voluntary means
of conforming to safety objectives of Directive 2014/35/EU of the European Parliament and of the
Council of 26 February 2014 on the harmonization of the laws of the Member States relating to the
making available on the market of electrical equipment designed for use within certain voltage limits
[2014 OJ L96].
Once this standard is cited in the Official Journal of the European Union under that Directive,
compliance with the normative clauses of this standard given in Table ZZ.1 confers, within the limits of
the scope of this standard, a presumption of conformity with the corresponding safety objectives of
that Directive, and associated EFTA regulations.
Table ZZ.1 — Correspondence between this European standard and Annex I of Directive
2014/35/EU [2014 OJ L96]
Safety objectives of Directive Clause(s) / subclause(s) of Remarks / Notes
2014/35/EU (Annex I) this EN
1. General conditions
1 (a) the essential characteristics, 1; 2; 3; 4; 5; 6
the recognition and observance of
which will ensure that electrical
equipment will be used safely and in
applications for which it was made,
shall be marked on the electrical
equipment, or, if this is not possible,
on an accompanying document
1 (b) the electrical equipment, 1; 2; 3; 4; 5; 6
together with its component parts,
shall be made in such a way as to
ensure that it can be safely and
properly assembled and connected
1 (c) the electrical equipment shall Same as those covering
be so designed and manufactured as safety objectives 2 a) to 2 d)
to ensure that protection against the and 3 a) to 3 c) in addition to
hazards set out in points 2 and 3 is the clauses 1; 3; 4
assured, providing that the
equipment is used in applications for
which it was made and is adequately
maintained
2. Protection against hazards arising from the electrical equipment
Measures of a technical nature shall be laid down in accordance with point 1, in order to ensure that:
2 (a) persons and domestic animals 4.9; 4.10; 6.1; 6.2; 6.3
are adequately protected against the
danger of physical injury or other
harm which might be caused by
direct or indirect contact
2 (b) temperatures, arcs or radiation 4.9; 4.10; 6.1; 6.2; 6.3
which would cause a danger, are not
produced
2 (c) persons, domestic animals and 4.9; 4.10; 6.1; 6.2; 6.3
property are adequately protected
against non-electrical dangers
caused by the electrical equipment
which are revealed by experience
2 (d) the insulation is suitable for 4.9; 4.10; 6.1; 6.2; 6.3
foreseeable conditions
3. Protection against hazards which may be caused by external influences on the electrical
equipment
Technical measures shall be laid down in accordance with point 1, in order to ensure that the electrical
equipment:
3 (a) meets the expected mechanical 4.9; 4.10; 6.1; 6.2; 6.3
requirements in such a way that
persons, domestic animals and
property are not endangered
3 (b) is resistant to non-mechanical 4.9; 4.10; 6.1; 6.2; 6.3
influences in expected environmental
conditions, in such a way that
persons, domestic animals and
property are not endangered
3 (c) does not endanger persons, 4.10; 5.2; 5.3; 6.1; 6.2; 6.3
domestic animals and property in
foreseeable conditions of overload
WARNING 1 — Presumption of conformity stays valid only as long as a reference to this European
standard is maintained in the list published in the Official Journal of the European Union. Users of this
standard should consult frequently the latest list published in the Official Journal of the European
Union.
WARNING 2 — Other Union legislation may be applicable to the product(s) falling within the scope of
this standard.
IEC 61557-12 ®
Edition 2.0 2018-10
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Electrical safety in low voltage distribution systems up to 1 000 V AC and

1 500 V DC. – Equipment for testing, measuring or monitoring of protective

measures –
Part 12: Power metering and monitoring devices (PMD)

Sécurité électrique dans les réseaux de distribution basse tension jusqu’à

1 000 V c.a. et 1 500 V c.c. – Dispositifs de contrôle, de mesure ou de

surveillance de mesures de protection –

Partie 12: Dispositifs de comptage et de surveillance du réseau électrique (PMD)

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 17.220.20; 29.080.01; 29.240.01 ISBN 978-2-8322-6077-7

– 2 – IEC 61557-12:2018 © IEC 2018
CONTENTS
FOREWORD . 7
INTRODUCTION . 9
1 Scope . 10
2 Normative references. 11
3 Terms, definitions and notations. 11
3.1 General definitions . 11
3.2 Definitions related to uncertainty and performance . 13
3.3 Definitions related to electric phenomena . 17
3.4 Definitions related to measurement techniques . 20
3.5 Notations . 21
3.5.1 Functions . 21
3.5.2 Symbols and abbreviations . 21
3.5.3 Indices . 22
4 Requirements . 22
4.1 General requirements . 22
4.2 PMD general architecture . 22
4.3 Classification of PMD . 23
4.4 Structure of PMD. 24
4.4.1 Structure of PMD related to sensors . 24
4.4.2 Requirements for self-powered PMD . 24
4.5 List of applicable performance classes . 25
4.6 Operating and reference conditions for PMD . 25
4.6.1 Reference conditions . 25
4.6.2 Rated operating conditions . 26
4.7 Start-up conditions . 28
4.8 Requirements for PMD functions . 28
4.8.1 General requirements . 28
4.8.2 Active power (P) and active energy (E ) measurements . 29
a
4.8.3 Reactive power (Q , Q ) and reactive energy (E , E ) measurements . 35
A V rA rV
4.8.4 Apparent power (S , S ) and apparent energy (E , E )
A V apA apV
measurements . 38
4.8.5 Frequency (f) measurements . 40
4.8.6 RMS phase current (I) and neutral current (I , I ) measurements . 41
N Nc
4.8.7 RMS voltage (U) measurements . 45
4.8.8 Power factor (PF , PF ) measurements . 47
A V
4.8.9 Short term flicker (P ) and long term flicker (P ) measurements . 47
st lt
4.8.10 Voltage dip (U ) and voltage swell (U ) measurements . 48
dip swl
4.8.11 Voltage interruption (U ) measurements . 53
int
4.8.12 Transient overvoltage (U ) measurements . 54
tr
4.8.13 Voltage unbalance (U , U ) measurements . 54
nb nba
4.8.14 Voltage harmonics (U ) and voltage THD (THD and THD-R )
h u u
measurements . 55
4.8.15 Current unbalance (I , I ) measurements . 56
nb nba
4.8.16 Current harmonics (I ) and current THD (THD and THD-R )
h i i
measurements . 57

IEC 61557-12:2018 © IEC 2018 – 3 –
4.8.17 Minimum, maximum, peak, three-phases average and demand
measurements . 58
4.9 General mechanical requirements . 58
4.9.1 Vibration requirements . 58
4.9.2 IP requirements . 58
4.10 Safety requirements . 59
4.10.1 Protection against electrical hazards . 59
4.10.2 Protection against mechanical hazards . 60
4.10.3 Protection against other hazards . 60
4.11 EMC requirements . 60
4.11.1 Immunity . 60
4.11.2 Emission . 60
4.12 Inputs and/or outputs . 60
4.12.1 General . 60
4.12.2 Analog outputs . 60
4.12.3 Pulse outputs . 61
4.12.4 Control outputs . 61
4.12.5 Analog inputs . 61
4.12.6 Pulse and control inputs . 61
5 Marking and operating instructions . 61
5.1 General . 61
5.2 Marking . 61
5.3 Operating, installation and maintenance instructions . 62
5.3.1 General . 62
5.3.2 General characteristics . 62
5.3.3 Essential characteristics . 62
6 Tests . 64
6.1 General . 64
6.2 Type tests of PMD . 65
6.2.1 General . 65
6.2.2 Tests of intrinsic uncertainty . 65
6.2.3 Tests of variation of uncertainty with influence quantities . 65
6.2.4 Test of temperature influence . 65
6.2.5 Active power . 66
6.2.6 Apparent power . 68
6.2.7 Power factor . 69
6.2.8 Common mode voltage rejection test . 69
6.2.9 Frequency. 69
6.2.10 Measurement of voltage harmonics and THD . 70
u
6.2.11 Measurement of current harmonics and THD . 70
i
6.2.12 Dips and swells . 71
6.2.13 Voltage interruptions . 71
6.2.14 Outputs tests . 71
6.2.15 Climatic tests . 72
6.2.16 EMC tests . 73
6.2.17 Start-up tests . 73
6.2.18 Gapless measurement test . 73
6.2.19 Safety tests . 73
6.3 Routine tests . 73

– 4 – IEC 61557-12:2018 © IEC 2018
6.3.1 Protective bonding test . 73
6.3.2 Dielectric strength test . 74
6.3.3 Uncertainty test . 74
Annex A (informative) Metering, measuring and monitoring applications . 75
A.1 Applications on demand side and supply side . 75
A.2 Link between applications, devices and standards . 75
Annex B (informative) Definitions of electrical parameters . 77
B.1 General . 77
B.2 Definitions in the presence of a neutral . 77
B.3 Power measurement in three-phase three-wire systems using the two-
wattmeter method . 81
B.3.1 General . 81
B.3.2 Total active power . 82
B.3.3 Total vector reactive power using quadrature phase shift definition . 82
B.3.4 Total vector reactive power using Budeanu’s definition . 83
B.4 Additional relationships in case of sinusoidal voltage . 83
Annex C (informative) Convention about the sign of the power factor . 84
C.1 General . 84
C.2 Convention for power factor (consumer perspective) . 84
C.3 Convention for power factor (producer reference frame) . 85
Annex D (normative) Definitions of minimum, maximum, peak and demand values . 87
D.1 Demand quantities . 87
D.1.1 General . 87
D.1.2 Power demand . 87
D.1.3 Current demand . 87
D.1.4 Thermal current demand (or bi-metal current demand) . 87
D.1.5 Specified intervals for demand calculation . 87
D.2 Peak demand quantities . 88
D.3 Three-phase average quantities . 88
D.4 Maximum and minimum quantities . 88
Annex E (informative) Intrinsic uncertainty and operating uncertainty . 89
E.1 General . 89
E.2 Operating uncertainty calculation . 89
Annex F (informative) Recommended sensor classes for the different kinds of PMD . 91
F.1 General considerations . 91
F.2 Specific case of an active power and energy measurement, achieved by a
PMD associated with an external current sensor or/and a voltage sensor . 91
F.3 List of functions affected by uncertainty of external sensors . 91
Annex G (informative) Notion of measurement uncertainty . 93
G.1 General considerations . 93
G.2 Computing the expanded uncertainty . 93
G.2.1 General . 93
G.2.2 Estimated standard deviation . 93
G.2.3 Expanded uncertainty . 94
G.3 Determining the measurement uncertainty . 95
G.3.1 Systematic error . 95
G.3.2 Measurement uncertainty . 95
G.4 Using the measurement uncertainty as a pass/fail criterion . 96

IEC 61557-12:2018 © IEC 2018 – 5 –
G.4.1 Intrinsic uncertainty tests . 96
G.4.2 Tests with influence quantities . 96
G.4.3 Overall pass/fail criterion . 96
Bibliography . 98

Figure 1 – PMD generic measurement chain . 23
Figure 2 – Description of different types of PMD . 24
Figure 3 – Relationship between ambient air temperature and relative humidity . 28
Figure 4 – Waveform for odd harmonics influence test on active power measurement . 66
Figure 5 – Spectral content for odd harmonics influence test on active power
measurement . 67
Figure 6 – Waveform for sub-harmonics influence test on active power measurement . 68
Figure 7 – Spectral content for sub-harmonics influence test on active power

measurement . 68
Figure 8 – Common mode voltage influence testing . 69
Figure 9 – Waveform for harmonics influence test on frequency measurement . 70
Figure A.1 – Simplified overview of measurement applications on supply side and
demand side . 75
Figure B.1 – Arithmetic and vector apparent powers in sinusoidal situation . 81
Figure B.2 – Three-phase circuit without neutral . 82
Figure C.1 – Formatting of power factor with a consumer perspective . 84
Figure C.2 – Convention for power factor with a producer perspective . 85
Figure D.1 – Thermal current demand . 87
Figure D.2 – Fixed block interval . 88
Figure D.3 – Sliding block interval . 88
Figure E.1 – Different kinds of uncertainties . 89
Figure E.2 – Flowchart for the determination of the operating uncertainty . 90
Figure G.1 – Illustration of the notion of measurement uncertainty . 95
Figure G.2 – Overview of the uncertainty test procedure . 97

Table 1 – Functional classification of PMD with minimal required functions . 23
Table 2 – Structure of PMD . 24
Table 3 – List of applicable performance classes . 25
Table 4 – Reference conditions for testing . 26
Table 5 – Rated operating temperatures for portable equipment . 26
Table 6 – Rated operating temperatures for fixed installed equipment . 27
Table 7 – Humidity and altitude operating conditions . 27
Table 8 – Intrinsic uncertainty table for active power and active energy measurement . 30
Table 9 – Influence quantities for active power and active energy measurement (1 of 3) . 31
Table 10 – Minimum test period . 34
Table 11 – Starting current for active power and active energy measurement . 35
Table 12 – Intrinsic uncertainty table for reactive power and reactive energy
measurement . 35
Table 13 – Influence quantities for reactive power and reactive energy measurement . 36
Table 14 – Minimum test period . 37

– 6 – IEC 61557-12:2018 © IEC 2018
Table 15 – Starting current for reactive energy measurement . 38
Table 16 – Intrinsic uncertainty table for apparent power and apparent energy
measurement . 38
Table 17 – Influence quantities for apparent power and apparent energy measurement . 39
Table 18 – Intrinsic uncertainty table for frequency measurement . 40
Table 19 – Influence quantities for frequency measurement . 41
Table 20 – Rated range of operation for phase current measurement . 41
Table 21 – Rated range of operation for neutral current (calculated or measured) . 42
Table 22 – Intrinsic uncertainty table for phase current . 42
Table 23 – Intrinsic uncertainty table for neutral current measurement . 42
Table 24 – Intrinsic uncertainty table for neutral current calculation . 43
Table 25 – Influence quantities for phase current and neutral current measurement . 44
Table 26 – Rated range of operation for RMS voltage measurement . 45
Table 27 – Intrinsic uncertainty table for RMS voltage measurement . 45
Table 28 – Influence quantities for RMS voltage measurement . 46
Table 29 – Intrinsic uncertainty table for power factor measurement . 47
Table 30 – Intrinsic uncertainty table for flicker measurement . 48
Table 31 – Rated range of operation for voltage dips and swells measurement . 50
Table 32 – Intrinsic uncertainty table for voltage dips and swells measurement . 51
Table 33 – Influence quantities for dips and swells measurement . 52
Table 34 – Intrinsic uncertainty table for voltage interruption measurement . 54
Table 35 – Intrinsic uncertainty table for transient overvoltage measurement . 54
Table 36 – Intrinsic uncertainty table for voltage unbalance measurement . 55
Table 37 – Rated range of operation for voltage harmonics measurement . 55
Table 38 – Intrinsic uncertainty table for voltage harmonics measurement . 55
Table 39 – Intrinsic uncertainty table for voltage THD or THD-R measurement . 56
u u
Table 40 – Intrinsic uncertainty table for current unbalance measurement . 56
Table 41 – Rated range of operation for current harmonics measurement . 57
Table 42 – Intrinsic uncertainty table for current harmonics measurement . 57
Table 43 – Intrinsic uncertainty table for current THD and THD-R measurement . 57
i i
Table 44 – Minimum IP requirements for PMD . 58
Table 45 – PMD specification form . 63
Table 46 – Characteristics specification template . 64
Table A.1 – Main measurement applications . 76
Table B.1 – Definition of symbols . 77
Table B.2 – Calculation definitions for electrical parameters . 78
Table C.1 – Conventions for the sign of Power factor with a Consumer perspective . 85
Table C.2 – Conventions for the sign of power factor with a producer perspective . 86
Table F.1 – PMD SD associated with current sensor or PMD DS associated with
voltage sensor or PMD SS associated with voltage and current sensors . 91
Table F.2 – List of functions affected by uncertainty of external sensors . 92
Table G.1 – Correction factor C(N) for sample size N . 94

IEC 61557-12:2018 © IEC 2018 – 7 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
ELECTRICAL SAFETY IN LOW VOLTAGE DISTRIBUTION
SYSTEMS UP TO 1 000 V AC AND 1 500 V DC. –
EQUIPMENT FOR TESTING, MEASURING OR
MONITORING OF PROTECTIVE MEASURES –

Part 12: Power metering and monitoring devices (PMD)

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 itself does not provide any attestation of conformity. Independent certification bodies provide conformity
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6) All users should ensure that they have the latest edition of this publication.
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members of its technical committees
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