IEC 60051-3:2018

IEC 60051-3 ®
Edition 5.0 2018-08
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Direct acting indicating analogue electrical measuring instruments and their
accessories –
Part 3: Special requirements for wattmeters and varmeters

Appareils mesureurs électriques indicateurs analogiques à action directe et
leurs accessoires –
Partie 3: Exigences particulières pour les wattmètres et les varmètres
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IEC 60051-3 ®
Edition 5.0 2018-08
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Direct acting indicating analogue electrical measuring instruments and their

accessories –
Part 3: Special requirements for wattmeters and varmeters

Appareils mesureurs électriques indicateurs analogiques à action directe et

leurs accessoires –
Partie 3: Exigences particulières pour les wattmètres et les varmètres

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 17.220.20 ISBN 978-2-8322-5957-3

– 2 – IEC 60051-3:2018 © IEC 2018
CONTENTS
FOREWORD . 4
INTRODUCTION . 6
1 Scope . 7
2 Normative references . 7
3 Terms and definitions . 7
4 Description, classification and compliance . 7
4.1 Description . 7
4.2 Classification . 8
4.3 Compliance with the requirements of this standard . 8
5 Requirements . 8
5.1 Reference conditions . 8
5.2 Limits of intrinsic uncertainty, fiducial value . 8
5.2.1 Limits of intrinsic uncertainty . 8
5.2.2 Correspondence between intrinsic uncertainty and accuracy class . 8
5.2.3 Fiducial value . 9
5.3 Nominal range of use and variations . 9
5.3.1 Nominal range of use . 9
5.3.2 Limits of variations. 12
5.3.3 Conditions for the determination of variations . 12
5.3.4 Determination of variation due to power factor . 12
5.3.5 Special tests for variations . 12
5.4 Operating uncertainty, overall system uncertainty and variations . 12
5.5 Electrical requirements . 12
5.5.1 Electrical safety requirements . 12
5.5.2 Self-heating . 12
5.5.3 Permissible overloads . 12
5.5.4 Limiting range of temperature . 13
5.5.5 Deviation from zero . 14
5.5.6 Electromagnetic compatibility (EMC) . 14
5.6 Constructional requirements . 14
5.6.1 General constructional requirements . 14
5.6.2 Damping . 14
5.6.3 Sealing to prevent access . 15
5.6.4 Scales . 15
5.6.5 Stopper. 15
5.6.6 Preferred values . 15
5.6.7 Adjusters, mechanical and/or electrical . 15
5.6.8 Effects of vibration and shock . 15
5.6.9 Degrees of protection provided by enclosure . 15
5.6.10 Terminals . 15
6 Information, markings and symbols . 15
6.1 Information . 15
6.2 Markings, symbols and their locations . 15
6.3 Markings relating to the reference values and nominal ranges of use of
influence quantities . 15
6.4 The symbols for marking instruments and accessories . 16

6.5 Markings and symbols for terminals . 16
6.5.1 Requirements for markings . 16
6.5.2 Earthing (grounding) terminals . 16
6.5.3 Measuring circuit terminals . 16
6.5.4 Special markings for terminals . 16
6.6 Instructions for use . 16
7 Package . 16
8 Test rules . 16
Annex A (normative) Nonconformity classification of tests . 17
Bibliography . 18

Table 1 – Reference conditions and tolerances, in addition to those given in Table 2 of
IEC 60051-1:2016, for testing purposes relating to the influence quantities . 8
Table 2 – Limits of the nominal range of use and permissible variations in addition to
those given in Table 3 of IEC 60051-1:2016 . 10
Table 3 – Overloads of short duration . 13
Table A.1 – Nonconformity classification of tests . 17

– 4 – IEC 60051-3:2018 © IEC 2018
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
DIRECT ACTING INDICATING ANALOGUE ELECTRICAL
MEASURING INSTRUMENTS AND THEIR ACCESSORIES –

Part 3: Special requirements for wattmeters and varmeters

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
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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
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6) All users should ensure that they have the latest edition of this publication.
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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 60051-3 has been prepared by IEC technical committee 85:
Measuring equipment for electrical and electromagnetic quantities.
This fifth edition cancels and replaces the fourth edition published in 1984 and
Amendment 1:1994. This edition constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) updating of content in line with new editions of IEC 60051-1 and IEC 60051-9;
b) addition of Annex A to specify the nonconformity classification of test items.

The text of this International Standard is based on the following documents:
CDV Report on voting
85/556/CDV 85/579A/RVC
Full information on the voting for the approval of this International Standard can be found in
the report on voting indicated in the above table.
This document has been drafted in accordance with the ISO/IEC Directives, Part 2.
This International Standard is to be used in conjunction with IEC 60051-1:2016.
A list of all parts in the IEC 60051 series, published under the general title Direct acting
indicating analogue electrical measuring instruments and their accessories, 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 "http://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.
– 6 – IEC 60051-3:2018 © IEC 2018
INTRODUCTION
IEC 60051 is published in separate parts according to the following structure and under the
general title: Direct acting indicating analogue electrical measuring instruments and their
accessories.
Part 1: Definitions and general requirements common to all parts
Part 2: Special requirements for ammeters and voltmeters
Part 3: Special requirements for wattmeters and varmeters
Part 4: Special requirements for frequency meters
Part 5: Special requirements for phase meters, power factor meters and synchroscopes
Part 6: Special requirements for ohmmeters (impedance meters) and conductance meters
Part 7: Special requirements for multi-function instruments
Part 8: Special requirements for accessories
Part 9: Recommended test methods
IEC 60051-3 is not complete in itself and is read in conjunction with IEC 60051-1.
All of these parts are arranged in the same format and a standard relationship between
subject and clause number is maintained throughout these parts. This arrangement will assist
the reader of IEC 60051 to distinguish information relating to the different types of instruments.

DIRECT ACTING INDICATING ANALOGUE ELECTRICAL
MEASURING INSTRUMENTS AND THEIR ACCESSORIES –

Part 3: Special requirements for wattmeters and varmeters

1 Scope
This part of IEC 60051 applies to direct acting indicating wattmeters and varmeters having an
analogue display.
NOTE For multi-function instruments, see IEC 60051-7.
It also applies to:
• non-interchangeable accessories (as defined in 3.1.23 of IEC 60051-1:2016) used with
wattmeters and varmeters;
• a combination of the instruments and the accessories provided that the adjustments have
been made for the combination;
• direct acting indicating electrical measuring instruments whose scale marks do not
correspond directly to their electrical input quantity, provided that the relationship between
them is known;
• instruments and accessories having electronic devices in their measuring and/or auxiliary
circuits.
This document does not apply to:
– special purpose instruments which are covered by their own IEC standards;
– special purpose devices which are covered by their own IEC standards when they are
used as accessories.
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 60051-1:2016, Direct acting indicating analogue electrical measuring instruments and
their accessories – Part 1: Definitions and general requirements common to all parts
IEC 60051-9, Direct acting indicating analogue electrical measuring instruments and their
accessories – Part 9: Recommended test methods
3 Terms and definitions
See IEC 60051-1:2016.
4 Description, classification and compliance
4.1 Description
See IEC 60051-1:2016.
– 8 – IEC 60051-3:2018 © IEC 2018
4.2 Classification
See IEC 60051-1:2016.
4.3 Compliance with the requirements of this standard
See IEC 60051-1:2016.
5 Requirements
5.1 Reference conditions
See IEC 60051-1:2016; the reference value of the influence quantities should be as given in
Table 2 of IEC 60051-1:2016 and Table 1.
Table 1 – Reference conditions and tolerances, in addition to those
given in Table 2 of IEC 60051-1:2016, for testing purposes
relating to the influence quantities
Influence quantity Reference conditions unless otherwise Tolerance permitted for testing
marked purposes, applicable for a single
a
reference value
Voltage component of the Rated voltage or any voltage within the ±2 % of the rated value
measured power reference range
Current component of the Any current up to the rated current or up to –
measured power the upper limit of the reference range
Frequency of voltage and Instruments using Reference frequency ±0,1 % of the reference frequency
current components of the phase shifting
measured power devices
Other instruments 45 Hz to 65 Hz ±2 % of the reference frequency
b
Power factor PF = 1 or rated value 0,01 lagging or leading
c d
Phase balance (for polyphase Symmetrical voltages and currents
instruments)
a
This tolerance applies when a single reference value is specified in this table or is marked by the
manufacturer. For a reference range, no tolerance is allowed.
b
Power factor for varmeters. Positive sign for lagging (inductive), negative sign for leading (capacitive).
c
The difference between any two line-to-line voltages and between any two line-to-neutral voltages shall not
exceed 1 % of the average (line-to-line and line-to-neutral voltages, respectively).
Each of the currents in the phases shall differ by not more than 1 % from the average of the currents.
The angles between each of the currents and the corresponding phase-to-neutral voltages shall differ by not
more than 2°.
d
Single-phase testing of polyphase instruments is acceptable if permitted by the manufacturer.

5.2 Limits of intrinsic uncertainty, fiducial value
5.2.1 Limits of intrinsic uncertainty
See IEC 60051-1:2016.
5.2.2 Correspondence between intrinsic uncertainty and accuracy class
See IEC 60051-1:2016.
5.2.3 Fiducial value
5.2.3.1 The fiducial value for a wattmeter or varmeter corresponds to the following.
5.2.3.2 The upper limit of the measuring range for the following:
• instruments with the mechanical and/or electrical zero at one end of the scale;
• instruments with the mechanical zero outside the scale irrespective of the position of the
electrical zero;
• instruments with the electrical zero outside the scale irrespective of the position of the
mechan-ical zero.
The class index for these wattmeters or varmeters is marked using Symbol E-1 given in
Table 6 of IEC 60051-1:2016 (see Clause 6 of IEC 60051-1:2016).
5.2.3.3 The sum of the absolute values of the upper and lower limit of the measuring
range when both the mechanical and the electrical zeros are displaced within the scale.
The class index for these wattmeters or varmeters is marked using Symbol E-1 given in
Table 6 of IEC 60051-1:2016 (see Clause 6 of IEC 60051-1:2016).
5.2.3.4 The span for an instrument whose scale marks do not correspond directly to its
electrical input quantity.
The class index for these wattmeters or varmeters is marked using Symbol E-10 given in
Table 6 of IEC 60051-1:2016 (see Clause 6 of IEC 60051-1:2016).
This does not apply to a wattmeter or varmeter designed to be used in conjunction with one or
more shunt(s), series resistor(s) (impedance(s)) or (an) instrument transformer(s). These
instruments are treated in accordance with 5.2.3.2 or 5.2.3.3 as appropriate.
5.3 Nominal range of use and variations
5.3.1 Nominal range of use
See IEC 60051-1:2016; the limits of the nominal range of use for influence quantities shall be
as given in Table 3 of IEC 60051-1:2016 and Table 2.

– 10 – IEC 60051-3:2018 © IEC 2018

Table 2 – Limits of the nominal range of use and permissible variations
in addition to those given in Table 3 of IEC 60051-1:2016
Influence quantity Limits of the nominal range of use Permissible variation expressed
unless otherwise marked
Distortion of AC voltage or Distortion factor Instruments using phase shifting 5 % 100 %
current components of the devices
measured power
Other instruments 20 %
a b
Peak factor 1 to 3 200 %
Frequency of AC voltage and Instruments using Reference frequency ± 1 % or lower limit of 100 %
current components of the phase shifting reference range - 1 % and upper limit of
measured power devices reference range + 1 %
Other instruments Reference frequency ± 10 % or lower limit
of reference range - 10 % and upper limit
of reference range + 10 %
Voltage components of the measured power Reference voltage ± 15 % or lower limit of 100 %
reference range - 15 % and upper limit of
reference range + 15 %
Power factor for wattmeters Class indices 0,3 and Any: lagging or leading 100 %
smaller
c
Class indices 0,5 and lagging (inductive)
Phase angle 0° . 60°
greater
Power factor for varmeters Class indices 0,3 and Any: lagging or leading 100 %
smaller
c
Class indices 0,5 and Phase angle 0° . 60° lagging (inductive)
greater
Phase balance (for polyphase instruments) Disconnection of one current component of 200 %
the measured power
Interaction between measuring elements of polyphase Disconnection of one voltage component of 200 %
d
instruments the measured power

Influence quantity Limits of the nominal range of use Permissible variation expressed
unless otherwise marked
Magnetic field of external origin 0,4kA/m Class indices Class indices
0,3 and smaller 0,5 and greater
Electrodynamic 3 % of the fiducial 6 % of the fiducial
e e
instruments if not values values
static and/or not
having a magnetic
screen
Ferrodynamic 1,5 % of the fiducial 3 % of the fiducial
e e
instruments if not
values values
static and/or not
having a magnetic
screen
All other instruments 0,75 % of the fiducial 1,5 % of the fiducial
e e
values values
a
For instruments having electronic devices in their measuring circuits.
b
The permissible variation due to a peak factor of other than (corresponding to a sine wave) is included in the permissible variation due to distortion of the measured
power.
For instruments having a peak factor capability greater than 3, the manufacturer shall state:
1) the instrument peak factor capability producing a variation of 100 % of the class index;
2) the upper and lower limits of the frequency response (bandwidth) to 0,707 times the indication at the reference frequency;
3) the effective maximum rate of change of internal instrument AC amplifier response (slew rate), expressed in volts per second using appropriate SI prefixes.
Peak factor relates to the total peak factor capability of the instrument and includes both the peak factor due to a distorted waveform and the peak factor due to spurious
impulses (which may be random or harmonically related to the fundamental frequency) containing negligible average power.
c
Inductive power factor unless otherwise agreed between manufacturer and user.
d
It may sometimes be impossible to carry out a test for interaction between the measuring elements due to interconnection of the current and/or voltage circuits.
e
Not as a percentage of the class index.

– 12 – IEC 60051-3:2018 © IEC 2018
5.3.2 Limits of variations
See IEC 60051-1:2016.
5.3.3 Conditions for the determination of variations
See IEC 60051-1:2016.
5.3.4 Determination of variation due to power factor
The power factor shall be lagging for instruments of class indices 0,5 and greater. For
instruments of class indices 0,3 and smaller, the test shall be carried out using both lagging
and leading power factors. The test shall be carried out with PF = 0.
For the recommended test, see IEC 60051-9.
5.3.5 Special tests for variations
Special tests using combinations of the components of the measured quantity may be carried
out when considered necessary by agreement between manufacturer and user.
5.4 Operating uncertainty, overall system uncertainty and variations
See IEC 60051-1:2016.
5.5 Electrical requirements
5.5.1 Electrical safety requirements
See IEC 60051-1:2016.
5.5.2 Self-heating
See IEC 60051-1:2016.
5.5.3 Permissible overloads
5.5.3.1 Continuous overload
For the recommended test, see IEC 60051-9.
Wattmeters and varmeters, together with their non-interchangeable accessory (if any), except
for instruments fitted with a non-locking switch, shall be subjected to a continuous overload of
120 % of the rated values of current and voltage sequentially, the other value being
maintained at its rated value. The duration of each application shall be 2 h.
After having cooled to the reference temperature, the instrument, together with its non-inter-
changeable accessory (if any), shall comply with its accuracy requirements; however, the
overload shall not be repeated.
The continuous overload test shall be carried out under reference conditions except for
current and voltage. The test shall be carried out with PF = 1.
5.5.3.2 Overloads of short duration
5.5.3.2.1 For the recommended test, see IEC 60051-9.
Wattmeters and varmeters, together with their non-interchangeable accessory (if any), shall
be subjected to overloads of short duration.

However, these requirements do not apply to:
– thermocouple instruments;
– instruments having a freely suspended moving element.
5.5.3.2.2 The values of current and voltage for the overloads of short duration shall be the
product of the relevant factor given in Table 3 and the value of the upper limit of the nominal
range of use for current and voltage unless other values are stated by the manufacturer. The
power factor (reactive power factor) shall be at its reference value.
Table 3 – Overloads of short duration
Current factor Voltage factor Number of Duration of each Interval between
overloads overload successive
overloads
(s)
(s)
Class indices 0,5 and smaller
1 2 1 5 –
2 1 5 0,5 15
Class indices 1 and greater
10 1 9 0,5 60
10 1 1 5 –
1 2 1 5 –
When two or three series of tests are specified, all the tests should be carried out in the order given. The
overloads of short duration are applied simultaneously to all the measuring elements of polyphase wattmeters
and varmeters.
5.5.3.2.3 The full duration of each overload shall be applied except when an automatic cut-
out (fuse) fitted to the instrument has interrupted the circuit in less than the time specified in
Table 3.
The automatic cut-out shall be reset (or the fuse replaced) before the application of the next
overload.
5.5.3.2.4 After having been subjected to the overloads of short duration and after having
cooled to the reference temperature, wattmeters and varmeters whose mechanical zero is
within the scale, together with their non-interchangeable accessory (if any), shall comply with
both of the following requirements:
a) the deviation of the index from the zero scale mark, expressed as a percentage of the
scale length, shall not exceed the following value:
1) 0,5 for instruments of class indices 0,5 and smaller,
2) the class index for instruments of class indices 1 and greater;
b) the wattmeter or varmeter, together with its non-interchangeable accessory (if any), after
adjustment of the zero (if necessary) shall comply with the accuracy requirements;
however, the overloads shall not be repeated.
A wattmeter or varmeter whose mechanical zero is outside the scale is considered to have
complied with these requirements if, after having cooled to the reference temperature, it has
errors not exceeding those relating to its class index; however, the overloads shall not be
repeated.
5.5.4 Limiting range of temperature
See IEC 60051-1:2016.
– 14 – IEC 60051-3:2018 © IEC 2018
5.5.5 Deviation from zero
5.5.5.1 General
For the recommended test, see IEC 60051-9.
If a wattmeter or varmeter has a zero position marked on the scale, it shall be tested for
deviation from zero.
The test shall be carried out under reference conditions.
5.5.5.2 All circuits energized
After a period of energization of 30 s at the upper limit of the measuring range, the deviation
of the index from the zero scale mark, expressed as a percentage of the scale length, shall
not exceed a value corresponding to 50 % of the class index.
5.5.5.3 Voltage circuit(s) only energized
With only the voltage circuit(s) energized, the deviation of the index from the zero scale mark
shall not exceed a value corresponding to 100 % of the class index.
5.5.6 Electromagnetic compatibility (EMC)
See IEC 60051-1:2016.
5.6 Constructional requirements
5.6.1 General constructional requirements
See IEC 60051-1:2016.
5.6.2 Damping
5.6.2.1 General
See IEC 60051-1:2016.
5.6.2.2 Overshoot
See IEC 60051-1:2016.
5.6.2.3 Response time
See IEC 60051-1:2016.
However, the requirements of 5.6.2.2 of IEC 60051-1:2016 do not apply to the following types
of wattmeters and varmeters:
• thermal instruments;
• instruments having a freely suspended moving element;
• instruments having a material pointer longer than 150 mm;
• instruments in which the power (active or reactive) corresponding to the upper limit of the
measuring range is less than 10 W or 10 var;
• special purpose instruments where other response times may be required. Such
instruments will be the subject of agreement between manufacturer and user.

5.6.2.4 Impedance of the external measuring circuit
See IEC 60051-1:2016.
5.6.3 Sealing to prevent access
See IEC 60051-1:2016.
5.6.4 Scales
See IEC 60051-1:2016.
5.6.5 Stopper
See IEC 60051-1:2016.
5.6.6 Preferred values
The upper limit of the measuring range for wattmeters and varmeters shall preferably be one
of the following values:
1, 1,2, 1,5, 2, 2,5, 3, 4, 5, 6, 7,5, 8
or their decimal multiples and sub-multiples.
For multi-range instruments, at least one of the ranges shall preferably comply with this
requirement.
5.6.7 Adjusters, mechanical and/or electrical
See IEC 60051-1:2016.
5.6.8 Effects of vibration and shock
See IEC 60051-1:2016.
5.6.9 Degrees of protection provided by enclosure
See IEC 60051-1:2016.
5.6.10 Terminals
See IEC 60051-1:2016.
6 Information, markings and symbols
6.1 Information
See IEC 60051-1:2016.
6.2 Markings, symbols and their locations
See IEC 60051-1:2016.
6.3 Markings relating to the reference values and nominal ranges of use of influence
quantities
See IEC 60051-1:2016.
– 16 – IEC 60051-3:2018 © IEC 2018
6.4 The symbols for marking instruments and accessories
See IEC 60051-1:2016.
6.5 Markings and symbols for terminals
6.5.1 Requirements for markings
See IEC 60051-1:2016.
6.5.2 Earthing (grounding) terminals
See IEC 60051-1:2016.
6.5.3 Measuring circuit terminals
See IEC 60051-1:2016.
6.5.4 Special markings for terminals
6.5.4.1 General
All terminals shall be marked to ensure that they can be uniquely identified.
6.5.4.2 Single element instruments
Wattmeters and varmeters having only two current terminals and two voltage terminals shall
have the current and voltage terminals easily distinguishable. The current terminal which is
normally associated with a particular voltage terminal shall be identified by both of them being
marked with a common sign.
6.5.4.3 Polyphase instruments
For all polyphase wattmeters and varmeters, a connection diagram shall be provided,
preferably affixed to the case.
The identification of a terminal on the instrument and on the connection diagram shall be
identical.
The connection diagram shall show the intended interconnection of the elements of the
instrument with the external circuit.
6.6 Instructions for use
See IEC 60051-1:2016.
7 Package
See IEC 60051-1:2016.
8 Test rules
See IEC 60051-1:2016.
The recommended nonconformity classification of tests is given in Annex A.
The method of acceptance inspection may be agreed between the manufacturer and the
customer.
Annex A
(normative)
Nonconformity classification of tests
The recommended nonconformity classification of tests is listed in Table A.1.
Table A.1 – Nonconformity classification of tests
Test Nonconformity class
Limits of intrinsic uncertainty (5.2.1) A
Limits of variations (5.3.2) B
Electrical safety requirements (5.5.1) A
Self-heating (5.5.2) B
Permissible overloads (5.5.3) B
Limiting range of temperature (5.5.4) B
Deviation from zero (5.5.5) B
Electromagnetic compatibility (EMC) (5.5.6) B
Damping (5.6.2) B
Adjusters, mechanical and/or electrical (5.6.7) B
Effects of vibration and shock (5.6.8) B
Degrees of protection provided by enclosure (5.6.9) B
Terminals (5.6.10) B
– 18 – IEC 60051-3:2018 © IEC 2018
Bibliography
IEC 60051-7, Direct acting indicating analogue electrical measuring instruments and their
accessories – Part 7: Special requirements for multi-function instruments

___________
– 20 – IEC 60051-3:2018 © IEC 2018
SOMMAIRE
AVANT-PROPOS . 22
INTRODUCTION . 24
1 Domaine d'application . 25
2 Références normatives . 25
3 Termes et définitions . 25
4 Description, classification et conformité . 26
4.1 Description . 26
4.2 Classification . 26
4.3 Conformité aux exigences de la présente norme . 26
5 Exigences . 26
5.1 Conditions de référence . 26
5.2 Limites de l'incertitude intrinsèque, valeur de repère . 27
5.2.1 Limites de l'incertitude intrinsèque . 27
5.2.2 Correspondance entre l'incertitude intrinsèque et la classe d'exactitude . 27
5.2.3 Valeur de repère . 27
5.3 Domaine nominal d'utilisation et variations . 27
5.3.1 Domaine nominal d'utilisation . 27
5.3.2 Limites des variations . 30
5.3.3 Conditions à respecter pour la détermination des variations . 30
5.3.4 Détermination de la variation due au facteur de puissance . 30
5.3.5 Essais spéciaux pour les variations . 30
5.4 Incertitude de fonctionnement, incertitude globale du système et variations . 30
5.5 Exigences électriques . 30
5.5.1 Exigences de sécurité électrique . 30
5.5.2 Autoéchauffement . 30
5.5.3 Surcharges admissibles . 30
5.5.4 Limites de la plage de températures . 32
5.5.5 Ecart de zéro . 32
5.5.6 Compatibilité électromagnétique (CEM) . 32
5.6 Exigences de construction . 32
5.6.1 Exigences générales de construction . 32
5.6.2 Amortissement . 32
5.6.3 Plombage destiné à interdire l'accès à l'intérieur de l'appareil. 33
5.6.4 Echelles . 33
5.6.5 Butoir . 33
5.6.6 Valeurs préférentielles .
...