IEC 60051-4:2018

IEC 60051-4 ®
Edition 5.0 2018-08
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Direct acting indicating analogue electrical measuring instruments and their
accessories title –
Part 4: Special requirements for frequency meters

Appareils mesureurs électriques indicateurs analogiques à action directe et
leurs accessoires –
Partie 4: Exigences particulières pour les fréquencemètres

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IEC 60051-4 ®
Edition 5.0 2018-08
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Direct acting indicating analogue electrical measuring instruments and their

accessories title –
Part 4: Special requirements for frequency meters

Appareils mesureurs électriques indicateurs analogiques à action directe et

leurs accessoires –
Partie 4: Exigences particulières pour les fréquencemètres

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 17.220.20 ISBN 978-2-8322-5958-0

– 2 – IEC 60051-4:2018 © 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
5 Requirements . 7
5.1 Reference conditions . 7
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 . 8
5.3 Nominal range of use and variations . 8
5.3.1 Nominal range of use . 8
5.3.2 Limits of variations . 9
5.3.3 Conditions for the determination of variations . 9
5.4 Operating uncertainty, overall system uncertainty and variations . 9
5.5 Electrical requirements . 9
5.5.1 Electrical safety requirements . 9
5.5.2 Self-heating . 9
5.5.3 Permissible overloads . 9
5.5.4 Limiting range of temperature . 10
5.5.5 Deviation from zero . 10
5.5.6 Electromagnetic compatibility (EMC) . 11
5.6 Constructional requirements . 11
5.6.1 General constructional requirements . 11
5.6.2 Damping . 11
5.6.3 Sealing to prevent access . 11
5.6.4 Scales . 11
5.6.5 Stopper. 11
5.6.6 Preferred values . 11
5.6.7 Adjusters, mechanical and/or electrical . 11
5.6.8 Effects of vibration and shock . 11
5.6.9 Degrees of protection provided by enclosure . 11
5.6.10 Terminals . 11
6 Information, markings and symbols . 11
6.1 Information . 11
6.2 Markings, symbols and their locations . 12
6.3 Markings relating to the reference values and nominal ranges of use of
influence quantities . 12
6.4 The symbols for marking instruments and accessories . 12
6.5 Markings and symbols for terminals . 12
6.5.1 Requirements for markings . 12
6.5.2 Earthing (grounding) terminals . 12
6.5.3 Measuring circuit terminals . 12
6.5.4 Special markings for terminals . 12

6.6 Instructions for use . 12
7 Package . 12
8 Test rules . 12
Annex A (normative) Nonconformity classification of tests . 13

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 . 9
Table 3 – Overloads of short duration for frequency meters . 10
Table A.1 – Nonconformity classification of tests . 13

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

Part 4: Special requirements for frequency meters

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,
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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-
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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
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
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between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
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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 60051-4 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. 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
85/557/CDV 85/580B/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 60051-4:2018 © 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 60051-4 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 TITLE –

Part 4: Special requirements for frequency meters

1 Scope
This part of IEC 60051 applies to direct acting indicating analogue frequency meters of the
following types:
• pointer-type frequency meters (as defined in 3.2.11 of IEC 60051-1:2016);
• vibrating-reed frequency meters (as defined in 3.2.12 of IEC 60051-1:2016).
This document also applies to non-interchangeable accessories (as defined in 3.1.23 of
IEC 60051-1:2016) used with frequency meters.
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
See IEC 60051-1:2016.
5 Requirements
5.1 Reference conditions
See Table 1.
– 8 – IEC 60051-4:2018 © IEC 2018
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 condition unless Tolerance permitted for testing
otherwise marked purposes, applicable for a single
a
reference value
Voltage of AC measured quantity Nominal value or any voltage within ±2 % of the nominal value
the nominal range)
a
For a nominal range, no tolerance is allowed.

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 General
The fiducial value for a frequency meter corresponds to:
a) The upper limit of the measuring range.
b) For vibrating-reed frequency meters that have several rows of reeds, each row is
considered to be a separate range, and each row has its own fiducial value that is the
upper limit of the measuring range of that row.
5.2.3.2 Special requirements for vibrating reed frequency meters
For vibrating reed frequency meters, the following shall also apply:
a) The difference between the nominal frequencies of two adjacent reeds shall not exceed
twice the limit of the permissible intrinsic uncertainty.
b) With a uniform rate of change of frequency, reeds shall reach their maximum amplitudes
of vibration in the sequence implied by their nominal frequencies.
c) The uncertainty is taken as the greatest value of the frequency differences:
1) between the nominal frequency for each reed and the frequency at which that reed has
its maximum amplitude of vibration, or
2) between the mean of the nominal frequencies of any two adjacent reeds and the
frequency at which these reeds have the same amplitude of vibration.
5.3 Nominal range of use and variations
5.3.1 Nominal range of use
See Table 2.
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 Permissible variation expressed
use unless otherwise marked as a percentage of the class
index
Voltage of measured quantity Nominal voltage ±15 % or lower 100 %
limit of nominal range -15 % and
upper limit of nominal range +15 %
Distortion of voltage of measured 15 % 100 %
quantity
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.
5.4 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
Frequency meters, together with their non-interchangeable accessory(ies), if any,
except for instruments fitted with a non-locking switch, shall be subjected to a
continuous voltage overload of 120 % of the nominal voltage or 120 % of the upper limit
of the nominal range for a period of 2 h.
After having cooled to its reference temperature, the frequency meter, together with its
non-interchangeable accessory(ies), 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
the voltage, at any frequency within the measuring range.
For the recommended test, see IEC 60051-9.
5.5.3.2 Overloads of short duration
non-interchangeable accessory(ies), if any, shall be
Frequency meters together with their
subjected to voltage overloads of short duration.

– 10 – IEC 60051-4:2018 © IEC 2018
The values of voltage for the overloads of short duration shall be the product of the
relevant factor given in Table 3 and the value of the nominal voltage or the upper limit of the
nominal range for voltage, unless other values are stated by the manufacturer.
The full duration of each overload shall be applied except when an automatic circuit breaker
(or fuse) fitted to the instrument has interrupted the circuit in less than the time specified
in Table 3 .
The automatic circuit breaker shall be reset (or the fuse replaced) before the application
of the next overload.
Table 3 – Overloads of short duration for frequency meters
Voltage factor Number of overloads Duration of each Interval between
overload successive overloads
(s) (s)
Class indices 0,3 and smaller
2 5 1 15
Class indices 0,5 and greater
2 9 0,5 60
2 1 5 –
Where two series of tests are specified, they should both be carried out, in the order given.

After having been subjected to the overloads of short duration and after having cooled to
the reference temperature, the frequency meter together with its non-interchangeable
accessory(ies), if any, shall comply with its accuracy requirements; however, the
overloads shall not be repeated.
The short duration overload test shall be carried out under reference conditions, except for
the voltage, at any frequency within the measuring range.
For the recommended tests, see IEC 60051-9.
5.5.4 Limiting range of temperature
See IEC 60051-1:2016.
5.5.5 Deviation from zero
The requirements of 5.5.5 do not apply to vibrating reed frequency meters.
If a frequency meter has a setting mark (zero scale mark) on the scale, it shall be tested for
return to that mark when de-energized.
The test shall be carried out under reference conditions.
After a period of energization of 30 s at the upper limit of the measuring range, the deviation
of the index from the setting mark (zero scale mark), expressed as a percentage of the scale
not exceed a value corresponding to 50 % of the class index.
length, shall
For the recommended test, see IEC 60051-9.

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
The requirements of IEC 60051-1:2016 do not apply to vibrating-reed frequency meters
and, for pointer-type frequency meters only, the requirements of 5.6.2.2 and 5.6.2.3 of
IEC 60051-1:2016 apply.
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 values of frequency and voltage are to be agreed between manufacturer and user.
5.6.7 Adjusters, mechanical and/or electrical
Frequency meters having a mechanical zero position on the scale shall have a setting mark
(zero scale mark) at that position.
Frequency meters not having a determinate mechanical zero (e.g. quotient-meters) or
having a mechanical zero that is outside the scale shall not be provided with an accessible
zero adjuster.
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 Termin
...