IEC 62057-1:2023

IEC 62057-1 ®
Edition 1.0 2023-03
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Electrical energy meters – Test equipment, techniques and procedures –
Part 1: Stationary meter test units (MTUs)

Compteurs d'énergie électrique – Équipements, techniques et procédures
d'essai –
Partie 1: Bancs d'essai stationnaires des compteurs d'énergie électrique (MTU)

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IEC 62057-1 ®
Edition 1.0 2023-03
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Electrical energy meters – Test equipment, techniques and procedures –

Part 1: Stationary meter test units (MTUs)

Compteurs d'énergie électrique – Équipements, techniques et procédures

d'essai –
Partie 1: Bancs d'essai stationnaires des compteurs d'énergie électrique (MTU)

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 17.220.20; 91.140.50 ISBN 978-2-8322-6437-9

– 2 – IEC 62057-1:2023 © IEC 2023
CONTENTS
FOREWORD . 7
1 Scope . 9
2 Normative references . 9
3 Terms and definitions . 10
3.1 Definitions related to the elements of the MTU . 11
3.2 Definitions of active, reactive and apparent power . 12
3.3 Definitions related to influence quantities . 15
3.4 Definitions related to accuracy . 16
3.5 Definitions related to testing. 17
4 Meter test units and automated meter test units. 18
5 Meter accuracy test methods . 19
5.1 General . 19
5.2 Energy comparison method . 19
5.3 Power–time measurement method (wattmeter method with register reading) . 20
5.4 Pulse comparison method . 20
6 Standard electrical values. 21
6.1 Mains supply . 21
6.2 Output values and ranges of the test circuits . 22
6.2.1 Test voltage circuit . 22
6.2.2 Test current circuit . 22
6.2.3 Phase angle . 23
6.2.4 Frequency . 23
6.2.5 Harmonics . 24
6.3 Standard meter . 24
6.3.1 Accuracy class . 24
6.3.2 Standard electrical values . 24
6.4 Magnetic field of the MTU . 25
6.5 Electrical and mechanical values for the scanning head(s) . 25
6.6 Error calculation system . 26
6.6.1 Functional requirements . 26
6.6.2 Parameters . 26
7 Constructional requirements of the MTU . 26
7.1 General requirements . 26
7.2 Source and standard meter . 26
7.3 Meter mounting system . 27
7.3.1 General . 27
7.3.2 Terminals . 27
8 Information and marking requirements . 28
8.1 General . 28
8.2 Labels, signs and signals . 29
8.3 Information for selection . 30
8.3.1 General . 30
8.3.2 General information . 30
8.3.3 Information related to standard meters . 30
8.3.4 Information related to sources, error calculation systems and frequency
generators . 31

8.3.5 Information related to the ICTs and MSVTs . 31
8.3.6 For the communication interfaces and error calculation systems . 31
8.4 Information for installation and commissioning . 32
8.4.1 General . 32
8.4.2 Dimensions and mass . 32
8.4.3 Connection . 32
8.4.4 Protection – Protective class and earthing . 32
8.4.5 Self-consumption . 33
8.5 Information for use . 33
8.5.1 General . 33
8.5.2 Display, push buttons and other controls . 33
8.5.3 Connection to user’s equipment . 33
8.5.4 External protection devices . 33
8.5.5 Cleaning . 33
8.5.6 Information for maintenance . 33
9 Climatic conditions for the MTU . 34
9.1 Normal environmental conditions . 34
9.2 Extreme environmental conditions. 34
9.3 Temperature limits and resistance to heat . 34
10 Electrical requirements of the MTU . 35
10.1 Influence of mains supply. 35
10.2 Insulation . 35
10.2.1 General . 35
10.2.2 Clearances and creepage distances . 35
10.2.3 Verification of clearances and creepage distances . 35
10.2.4 AC voltage test . 35
11 Electromagnetic compatibility . 36
11.1 General requirements and performance criteria . 36
11.2 General test conditions . 37
11.2.1 General . 37
11.2.2 Test of immunity to electrostatic discharges. 37
11.2.3 Test of immunity of electromagnetic RF Fields . 37
11.2.4 Immunity to power frequency magnetic fields of external origin . 38
11.2.5 Test of immunity to fast transient bursts . 38
11.2.6 Test of immunity to surges . 38
11.2.7 Test of immunity to conducted disturbances, induced by RF (radio
frequency) fields . 38
11.2.8 Radio interference suppression . 39
12 Standard meter . 39
12.1 General . 39
12.2 Accuracy requirements under reference conditions . 39
12.3 Limits of error due to influence quantities . 40
12.4 Accuracy tests in the presence of harmonics . 42
th
12.4.1 Test with 5 harmonic in the current and voltage . 42
12.4.2 Tests of the influence of odd and sub-harmonics . 42
13 Software requirements . 42
13.1 Application . 42
13.2 Identification . 42

– 4 – IEC 62057-1:2023 © IEC 2023
13.3 Protection . 42
13.4 Functional requirements . 43
13.5 Control and supervision of the MTU by the software . 43
13.6 Creation, protection and storage of test programs . 44
13.7 Protection and storage of test results and test protocols . 44
13.8 Documentation of the software . 44
13.9 Software logs . 44
14 Accuracy requirements and tests . 45
14.1 General . 45
14.2 Test methods for determination of the MTU accuracy . 45
14.3 Test points – Selection of voltage and current ranges . 46
14.4 Accuracy requirements . 47
14.4.1 Limits of maximum permissible error . 47
14.4.2 Correction of the error δW of the MTU . 47
14.4.3 Mean value and repeatability of the measurements . 48
14.5 Check of measurement results of the MTU . 49
14.5.1 Basic measurements of the MTU . 49
14.5.2 Maintenance measurement of the MTU . 49
14.6 Tests and testing procedures . 49
14.6.1 Type tests . 49
14.6.2 Routine tests . 49
14.6.3 Acceptance test . 51
14.6.4 Commissioning test . 51
Annex A (informative) Symbols according to IEC 60417 . 52
Annex B (normative) Reference conditions . 53
Annex C (informative) Test circuits and test signals for testing in the presence of
harmonics . 54
C.1 General . 54
C.2 Phase fired control (odd harmonics) . 54
C.3 Burst control (sub-harmonics) . 56
Annex D (informative) Calculation of errors and the associated expanded
measurement uncertainty . 58
D.1 General . 58
D.2 Degrees of freedom and sensitivity coefficient . 58
D.3 Method for the determination of the standard measurement uncertainty . 59
D.3.1 Type A . 59
D.3.2 Type B . 60
D.4 Examples for the calculation of the measurement uncertainty . 61
D.4.1 Measuring principle . 61
D.4.2 Model equation . 61
D.4.3 Measurement uncertainty budget considering the specification for the
working standard . 62
D.4.4 Measurement uncertainty budget considering the error of the working

standard . 65
D.5 Indication of the measurement uncertainty . 67
Annex E (informative) Guidelines for overall laboratory setup . 68
E.1 General . 68
E.2 General conditions . 68
E.3 Quality of mains supply . 68

E.4 Reference standard . 69
Annex F (normative) Multi-secondary voltage transformer . 70
F.1 General . 70
F.2 Definitions. 70
F.3 Application . 70
F.4 Technical requirements . 71
F.5 Total accuracy of MTU with MSVT . 72
Annex G (normative) Isolating current transformer (ICT) . 73
G.1 General . 73
G.2 Definitions. 73
G.3 Application . 73
G.4 Technical requirements . 74
G.5 Wiring and terminals . 74
G.6 Total accuracy of MTU with ICT . 74
Bibliography . 76

Figure C.1 – Test circuit diagram (informative) . 54
Figure C.2 – Phase fired waveform . 55
Figure C.3 – Informative distribution of harmonic content of phase fired waveform (the
Fourier analysis is not complete) . 55
Figure C.4 – Burst fired waveform . 56
Figure C.5 – Informative distribution of harmonics (the Fourier analysis is not
complete) . 57
Figure D.1 – Measuring setup of the meter test arrangement . 61
Figure F.1 – Testing of single-phase meters with closed link between the voltage and
current circuits (variant 1) . 71
Figure F.2 – Testing of single-phase meters with closed link between the voltage and
current circuits (variant 2) . 71
Figure G.1 – Testing of three-phase meters with closed link between the voltage and

current circuits . 73

Table 1 – Mains power supply condition . 22
Table 2 – Test voltage circuit for each phase . 22
Table 3 – Test current circuit for each phase . 23
Table 4 – Setting of phase angle between each phase voltage and current circuit . 23
Table 5 – Setting of frequency . 23
Table 6 – Setting of harmonics. 24
Table 7 – Standard electrical values for the standard meter . 25
Table 8 – Electrical and mechanical values for the scanning head(s) . 25
Table 9 – Parameters for the error calculation system. 26
Table 10 – Information requirements . 28
Table 11 – Climatic conditions . 34
Table 12 – Surface temperature limits . 34
Table 13 – AC voltage tests . 36
Table 14 – Limits of variation of error of standard meters during immunity test . 37
Table 15 – Relative error limits for the standard meter . 40

– 6 – IEC 62057-1:2023 © IEC 2023
Table 16 – Influence quantities . 41
Table 17 – Recommended accuracy class of reference standard meter . 46
Table 18 – Basic measurement table (recommended test points) . 46
Table 19 – Limits of maximum permissible error (δW ) of the complete MTU related
max
to DUT . 47
Table 20 – Limits of permissible values of standard deviation of MTU . 48
Table A.1 – Symbols which may be used on metering equipment . 52
Table B.1 – Reference conditions . 53
Table D.1 – Coverage factors k for different effective degrees of freedom V . 59
eff
Table D.2 – List 1 of quantities . 63
Table D.3 – Readings 1 of the DUT . 63
Table D.4 – Reading 1 of the standard meter . 64
Table D.5 – Measurement uncertainty budget 1 . 64
Table D.6 – List 2 of quantities . 65
Table D.7 – Readings 2 of the DUT . 65
Table D.8 – Reading 2 of the standard meter . 66
Table D.9 – Measurement uncertainty budget 2 . 67
Table E.1 – Mains supply quality . 69
Table F.1 – Technical requirements of MSVTs . 72
Table F.2 – Maximum permissible limits of error of MTU with MSVT . 72
Table G.1 – Technical requirements of ICT . 74
Table G.2 – Maximum permissible limits of error of MTU with ICT . 75

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
ELECTRICAL ENERGY METERS –
TEST EQUIPMENT, TECHNIQUES AND PROCEDURES –

Part 1: Stationary meter test units (MTUs)

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
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preparation is entrusted to technical committees; any IEC National Committee interested in the subject dealt with
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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
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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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services carried out by independent certification bodies.
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.
IEC 62057-1 has been prepared by IEC technical committee 13: Electrical energy measurement
and control. It is an International Standard.
The text of this International Standard is based on the following documents:
Draft Report on voting
13/1879/FDIS 13/1886/RVD
Full information on the voting for its approval can be found in the report on voting indicated in
the above table.
The language used for the development of this International Standard is English.

– 8 – IEC 62057-1:2023 © IEC 2023
This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in
accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement, available
at www.iec.ch/members_experts/refdocs. The main document types developed by IEC are
described in greater detail at www.iec.ch/publications.
A list of all parts in the IEC 62057 series, published under the general title Electrical energy
meters – Test equipment, techniques and procedures, can be found on the IEC website.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under webstore.iec.ch in the data related to the
specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
ELECTRICAL ENERGY METERS –
TEST EQUIPMENT, TECHNIQUES AND PROCEDURES –

Part 1: Stationary meter test units (MTUs)

1 Scope
This part of IEC 62057 applies to stationary meter test units (MTUs) permanently installed in
laboratories, used for testing and calibration of electricity meters, in particular for their type test,
acceptance test and verification test. It covers the requirements for automatic MTUs for indoor
laboratory application and applies to newly manufactured MTUs to test electricity meters on
50 Hz or 60 Hz networks with an AC voltage up to 600 V (phase to neutral).
If meters are intended for system voltages not specified in this document, special requirements
are agreed between the manufacturer and the purchaser.
This document also defines the kind of tests to perform as type tests / routine tests / acceptance
tests and commissioning tests for MTUs.
It does not apply to:
• portable reference meters and portable sources;
• electricity meters;
• data interfaces to the meter and test procedures of data interface;
• transformer operated MTUs;
• personal computers supplied together with the MTU.
2 Normative references
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.
IEC 60417, Graphical symbols for use on equipment (available at http://www.graphical-
symbols.info/equipment)
IEC 60617, Graphical symbols for diagrams (available at http://std.iec.ch/iec60617)
IEC 60664-1:2020, Insulation coordination for equipment within low-voltage systems – Part 1:
Principles, requirements and tests
IEC 60721-3-2:2018, Classification of environmental conditions – Part 3-2: Classification of
groups of environmental parameters and their severities – Transportation and handling
IEC 60721-3-3:2019, Classification of environmental conditions – Part 3-3: Classification of
groups of environmental parameters and their severities – Stationary use at weatherprotected
locations
– 10 – IEC 62057-1:2023 © IEC 2023
IEC 61010-031:2015, Safety requirements for electrical equipment for measurement, control
and laboratory use – Part 031: Safety requirements for hand-held probe assemblies for
electrical measurement and test
IEC 61010-031:2015/AMD1:2018
IEC 61010-1:2010, Safety requirements for electrical equipment for measurement, control, and
laboratory use – Part 1: General requirements
IEC 61010-1:2010/AMD1:2016
IEC 61140:2016, Protection against electric shock – Common aspects for installation and
equipment
IEC 61326-1:2020, Electrical equipment for measurement, control and laboratory use – EMC
requirements – Part 1: General requirements
IEC 62052-11:2020, Electricity metering equipment – General requirements, tests and test
conditions – Part 11: Metering equipment
IEC 62052-31:2015, Electricity metering equipment (AC) – General requirements, tests and test
conditions – Part 31: Product safety requirements and tests
IEC 62053 (all parts), Electricity metering equipment
CISPR 11:2015, Industrial, scientific and medical equipment – Radio-frequency disturbance
characteristics – Limits and methods of measurement
CISPR 11:2015/AMD1:2016
CISPR 11:2015/AMD2:2019
EN 50160, Voltage characteristics of electricity supplied by public electricity networks
EN 50470 (all parts), Electricity metering equipment (a.c.)
ISO 3864-1:2011, Graphical symbols – Safety colours and safety signs – Part 1: Design
principles for safety signs and safety markings
ISO 7000, Graphical symbols for use on equipment – Registered symbols (available at
http://www.graphical-symbols.info/equipment)
ISO 13732-1:2006, Ergonomics of the thermal environment – Methods for the assessment of
human responses to contact with surfaces – Part 1: Hot surfaces
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following
addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp

3.1 Definitions related to the elements of the MTU
3.1.1
device under test
DUT
meter intended to measure active and/or reactive energy by integrating active and/or reactive
power with respect to time
Note 1 to entry: For the definition of various types of energy meters and their elements, see IEC 62052-11:2020,
IEC 62053-21:2020, IEC 62053-22:2020, IEC 62053-23:2020, and IEC 62053-24:2020.
3.1.2
meter test unit
MTU
assembly of sources, frequency generator, reference or working standard, and error calculation
and indication system to supply the required test signals to the DUT and to measure, calculate
and display the error of the DUT
3.1.3
automatic meter test unit
AMTU
MTU which conducts, controls and monitors the desired function(s) or activity(ies) of meter
testing through computer-controlled software
3.1.4
source
part of the MTU that generates test voltage signals and current signals with the appropriate
frequency, magnitude, and with the appropriate phase angles between currents and voltages
Note 1 to entry: These test signals shall be independent from the mains input in the specified operating range.
Note 2 to entry: The test signals are based on the command(s) received from the test software or controller.
3.1.5
reference standard meter
reference standard
meter used to measure the unit of electrical energy and power
Note 1 to entry: The reference standard meter is designed and operated to obtain the highest accuracy and stability
in a controlled laboratory environment.
Note 2 to entry: A reference standard meter shall be traceable to national or international primary standards.
3.1.6
working standard meter
working standard
meter used to measure the unit of electrical energy and power, for use in MTUs
Note 1 to entry: The working standard meter shall be calibrated against the reference standard (meter).
Note 2 to entry: An MTU can also be fitted with a reference standard used for day to day calibration of DUTs of
high accuracy (reference standard used as the working standard).
3.1.7
standard meter
common term for the reference standard according to 3.1.5 or the working standard in
accordance with 3.1.6
3.1.8
error calculation system
device or a group of devices to count pulses, or read energy values and to compare, calculate
and indicate the relative error of the DUTs

– 12 – IEC 62057-1:2023 © IEC 2023
Note 1 to entry: The default error calculation system receives pulses from the scanning heads or from the pulse
outputs of the DUTs and compares these with pulses received from the standard meter.
3.1.9
output terminal
terminal from which the test voltages and currents are applied to the DUTs
3.1.10
maximum output power of the source
output power corresponding to the highest load applied at the output terminals of a source
Note 1 to entry: It shall be expressed in VA and shall be defined separately for the test voltage and test current
sources.
3.1.11
S
output stability of source
value or relative error of the output quantity of the source indicating that the output quantity
may likely vary within this number when all other parameters such as supply voltage, etc., are
in accordance with reference conditions (Annex B)
Note 1 to entry: The output stability (S) for voltage, current, power and frequency test output shall be separately
defined in % and is given in Formula (1).
max mT( ), m (T), . m (T) − min mT( ), m (T), . m (T)
{ } { }
12 N 12 N
S ⋅100 %
(1)
1 N
⋅ mT
( )
∑ k
k=1
N
where:
S is the stability of the test output;
th
m (T) is the N measured value with integration period T inside a successive sequence of measurements;
N
th
m (T) is the k value, k = 1…N inside this sequence;
k
N is the number of values inside this sequence;
T is the integration period;
max is the largest value in a sequence of elements {m (T), m (T), . m (T)};
1 2 N
min is the smallest value in a sequence of elements {m (T), m (T), . m (T)}.
1 2 N
The output stability (S ) of the phase angle between output values shall be separately defined in ° (degrees) and
abs
is given in Formula (2).
S = max {m (T), m (T), . m (T)} − min{m (T), m (T), . m (T)}
(2)
abs 1 2 N 1 2 N
Note 2 to entry: The purchaser and the manufacturuer may mutually agree for the integration period T and the
values N of the measuring sequence.
3.2 Definitio
...