IEC 60688:2021

Electrical measuring transducers for converting AC and DC electrical quantities to analogue or digital signals

IEC 60688:2021 applies to transducers with electrical inputs and outputs for making measurements of AC or DC electrical quantities. The output signal can be in the form of an analogue direct current, an analog direct voltage or in digital form.
This document applies to measuring transducers used for converting electrical quantities such as
– current,
– voltage,
– active power,
– reactive power,
– power factor,
– phase angle,
– frequency,
– harmonics or total harmonic distortion, and
– apparent power
to an output signal.
This document is not applicable for
– instrument transformers that complies with IEC 61869 (all parts),
– transmitters for use in industrial process application that complies with IEC 60770 (all parts), and
– performance measuring and monitoring devices (PMD) that comply with IEC 61557 12:2018.
Within the measuring range, the output signal is a function of the measurand. An auxiliary supply can be needed.
This document applies
a) if the nominal frequency of the input(s) lies between 0 Hz and 1 500 Hz,
b) to the electrical measuring transducer if it is part of a system for the measurement of a non-electrical quantity, and if it otherwise falls within the scope of this document, and
c) to transducers for use in a variety of applications such as telemetry and process control and in one of a number of defined environments.
This document is intended:
– to specify the terminology and definitions relating to transducers whose main application is in industry,
– to unify the test methods used in evaluating transducer performance, and
– to specify accuracy limits and output values for transducers.
IEC 60688:2021 cancels and replaces the third edition published in 2012. This edition constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous edition:
a) updating normative references;
b) additional requirements for specific transducers used for LV monitoring applications;
c) creation of interface coding to ease selection by the end-user.

Transducteurs électriques de mesure convertissant les grandeurs électriques alternatives ou continues en signaux analogiques ou numériques

L'IEC 60688:2021 s'applique aux transducteurs à grandeurs d'entrées et de sorties électriques destinés à mesurer des grandeurs électriques alternatives ou continues. Le signal de sortie peut être sous la forme d’un courant continu analogique ou d’une tension continue analogique ou d’un signal numérique.
Le présent document s'applique aux transducteurs de mesure destinés à convertir des grandeurs électriques, telles que:
– le courant,
– la tension,
– la puissance active,
– la puissance réactive,
– le facteur de puissance,
– l’angle de phase,
– la fréquence,
– les harmoniques ou la distorsion harmonique totale, et
– la puissance apparente
en signal de sortie.
Le présent document ne s’applique pas:
– aux transformateurs de mesure conformes à la série IEC 61869,
– aux transmetteurs utilisés dans le processus industriel conformes à la série IEC 60770, et
– aux dispositifs de mesure et de surveillance des performances (PMD – performance measuring and monitoring device) conformes à l’IEC 61557-12:2018.
Dans l’étendue de mesure, le signal de sortie varie en fonction du mesurande. Une alimentation auxiliaire peut être nécessaire.
Le présent document s'applique:
a) si la fréquence nominale de la ou des grandeurs d'entrée est comprise entre 0 Hz et 1 500 Hz;
b) à un transducteur de mesure électrique appartenant à une chaîne de mesure d'une grandeur non électrique, et si, par ailleurs, celui-ci relève du domaine d'application du présent document, et
c) aux transducteurs destinés à une utilisation générale, par exemple à la télémesure, à la commande de processus et dans un des nombreux environnements spécifiés.
Le présent document a pour objet:
– de spécifier la terminologie et les définitions relatives aux transducteurs dont l'application principale relève du domaine de l'industrie,
– d'unifier les méthodes d'essai utilisées pour évaluer les performances des transducteurs, et
– de spécifier les limites de précision et les valeurs de sortie des transducteurs.
L'IEC 60688:2021 annule et remplace la troisième édition parue en 2012. Cette édition constitue une révision technique.
Cette édition inclut les modifications techniques majeures suivantes par rapport à l'édition précédente:
a) mise à jour des références normatives;
b) exigences supplémentaires pour les transducteurs spécifiques utilisés pour les applications de surveillance de la BT (basse tension)
c) création d'un codage d'interface pour faciliter la sélection par l'utilisateur final.

General Information

• Status: Published
• Publication Date: 15-Sep-2021
• ICS: 17.220.20 - Measurement of electrical and magnetic quantities
• Technical Committee: TC 85 - Measuring equipment for electrical and electromagnetic quantities
• Drafting Committee: WG 20 - TC 85/WG 20

Relations

• Revises: IEC 60688:2012 - Electrical measuring transducers for converting A.C. and D.C. electrical quantities to analogue or digital signals
• Effective Date: 05-Sep-2023
• Revised: IEC 60688:2024 - Electrical measuring transducers for converting AC and DC electrical quantities to analogue or digital signals
• Effective Date: 05-Sep-2023
• Revises: IEC 60688:2012/COR1:2013 - Corrigendum 1 - Electrical measuring transducers for converting A.C. and D.C. electrical quantities to analogue or digital signals
• Effective Date: 05-Sep-2023

Standards Content (Sample)

IEC 60688 ®
Edition 4.0 2021-09
REDLINE VERSION
INTERNATIONAL
STANDARD
colour
inside
Electrical measuring transducers for converting AC and DC electrical quantities
to analogue or digital signals

All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form
or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from
either IEC or IEC's member National Committee in the country of the requester. If you have any questions about IEC
copyright or have an enquiry about obtaining additional rights to this publication, please contact the address below or
your local IEC member National Committee for further information.

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Switzerland
About the IEC
The International Electrotechnical Commission (IEC) is the leading global organization that prepares and publishes
International Standards for all electrical, electronic and related technologies.

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IEC 60688 ®
Edition 4.0 2021-09
REDLINE VERSION
INTERNATIONAL
STANDARD
colour
inside
Electrical measuring transducers for converting AC and DC electrical quantities

to analogue or digital signals

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 17.220.20 ISBN 978-2-8322-1029-1

– 2 – IEC 60688:2021 RLV © IEC 2021
CONTENTS
FOREWORD . 9
INTRODUCTION . 11
1 Scope . 12
2 Normative references. 13
3 Terms and definitions . 13
3.1 General terms . 14
3.2 Terms describing transducers according to the measurand . 17
3.3 Terms describing transducers according to their output load . 18
3.4 Nominal values . 18
3.5 User adjustment Terms describing transducers with provisions to be
adjusted by users . 19
3.6 Influence quantities and reference conditions . 20
3.7 Errors and variations . 20
3.8 Accuracy, accuracy class, class index . 21
4 Class index, permissible limits of intrinsic error, auxiliary supply and reference
conditions General . 21
4.1 Transducer general architecture . 21
4.2 Classification of transducers (TRD) . 22
5 Requirements for TRD1 . 22
5.1 Safety requirements: clearances and creepage distances . 22
5.2 EMC requirements . 22
5.2.1 Immunity . 22
5.2.2 Emission . 23
5.3 Class index requirements . 23
5.3.1 Class index . 23
5.3.2 Class index for transducer used with sensors . 23
5.3.3 Intrinsic error . 23
5.4 Conditions for the determination of intrinsic error . 23
5.5 Auxiliary supply . 25
5.5.1 General . 25
5.5.2 DC supply . 25
5.5.3 AC supply . 25
5.6 Input values . 26
5.6.1 General . 26
5.6.2 Adjustment ranges . 26
5.6.3 Preferred nominal values . 26
5.7 Analogue output signals . 26
5.7.1 General . 26
5.7.2 Output current . 26
5.7.3 Compliance voltage . 26
5.7.4 Maximum output voltage . 26
5.7.5 Interference risk of output current . 27
5.7.6 Output voltage . 27
5.8 Output transfer function . 27
5.9 Digital output signals . 30
5.10 Ripple (for analogue outputs) . 30

5.11 Response time . 30
5.12 Variation due to over-range of the measurand . 30
5.13 Limiting value of the output signal . 30
5.14 Limiting conditions of operation . 31
5.15 Limits of the measuring range . 31
5.16 Limiting conditions for storage and transport . 31
5.17 Sealing . 31
5.18 Stability . 31
6 Tests for TRD1 . 31
6.1 General . 31
6.1.1 Determination of variations . 31
6.1.2 Environmental conditions . 32
6.1.3 Computations . 32
6.2 Variations due to auxiliary supply voltage . 32
6.2.1 Application . 32
6.2.2 Procedure . 32
6.2.3 Computation . 33
Permissible variations . 33
6.3 Variations due to auxiliary supply frequency . 33
6.3.1 Application . 33
6.3.2 Procedure . 33
6.3.3 Computation . 33
6.3.4 Permissible variations . 34
6.4 Variations due to ambient temperature . 34
6.4.1 Application . 34
6.4.2 Procedure . 34
6.4.3 Computation . 34
6.4.4 Permissible variations . 34
6.5 Variations due to the frequency of the input quantity(ies) . 35
6.5.1 Application . 35
6.5.2 Procedure . 35
6.5.3 Computation . 35
6.5.4 Permissible variations . 35
6.6 Variations due to the input voltage . 35
6.6.1 Application . 35
6.6.2 Procedure . 35
6.6.3 Computation . 36
6.6.4 Permissible variations . 36
6.7 Variations due to the input current . 36
6.7.1 Application . 36
6.7.2 Procedure . 36
6.7.3 Computation . 36
6.7.4 Permissible variations . 36
6.8 Variations due to power factor . 37
6.8.1 Application . 37
6.8.2 Procedure . 37
6.8.3 Computation . 37
6.8.4 Permissible variations . 37
6.9 Variation due to output load . 38

– 4 – IEC 60688:2021 RLV © IEC 2021
6.9.1 Application . 38
6.9.2 Procedure .
...

IEC 60688 ®
Edition 4.0 2021-09
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Electrical measuring transducers for converting AC and DC electrical quantities
to analogue or digital signals

Transducteurs électriques de mesure convertissant les grandeurs électriques
alternatives ou continues en signaux analogiques ou numériques

All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form
or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from
either IEC or IEC's member National Committee in the country of the requester. If you have any questions about IEC
copyright or have an enquiry about obtaining additional rights to this publication, please contact the address below or
your local IEC member National Committee for further information.

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utilisée sous quelque forme que ce soit et par aucun procédé, électronique ou mécanique, y compris la photocopie et
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les coordonnées ci-après ou contactez le Comité national de l'IEC de votre pays de résidence.

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3, rue de Varembé [e-mail]
CH-1211 Geneva 20 www.iec.ch
Switzerland
About the IEC
The International Electrotechnical Commission (IEC) is the leading global organization that prepares and publishes
International Standards for all electrical, electronic and related technologies.

About IEC publications
The technical content of IEC publications is kept under constant review by the IEC. Please make sure that you have the
latest edition, a corrigendum or an amendment might have been published.

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and French, with equivalent terms in 18 additional languages.
a month by email.
Also known as the International Electrotechnical Vocabulary

(IEV) online.
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IEC 60688 ®
Edition 4.0 2021-09
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Electrical measuring transducers for converting AC and DC electrical quantities

to analogue or digital signals

Transducteurs électriques de mesure convertissant les grandeurs électriques

alternatives ou continues en signaux analogiques ou numériques

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 17.220.20 ISBN 978-2-8322-1009-1

– 2 – IEC 60688:2021 © IEC 2021
CONTENTS
FOREWORD . 9
INTRODUCTION . 11
1 Scope . 12
2 Normative references. 13
3 Terms and definitions . 13
3.1 General terms . 13
3.2 Terms describing transducers according to the measurand . 15
3.3 Terms describing transducers according to their output load . 17
3.4 Nominal values . 17
3.5 Terms describing transducers with provisions to be adjusted by users . 18
3.6 Influence quantities and reference conditions . 18
3.7 Errors and variations . 19
3.8 Accuracy, accuracy class, class index . 19
4 General . 19
4.1 Transducer general architecture . 19
4.2 Classification of transducers (TRD) . 20
5 Requirements for TRD1 . 20
5.1 Safety requirements: clearances and creepage distances . 20
5.2 EMC requirements . 20
5.2.1 Immunity . 20
5.2.2 Emission . 21
5.3 Class index requirements . 21
5.3.1 Class index . 21
5.3.2 Class index for transducer used with sensors . 21
5.3.3 Intrinsic error . 21
5.4 Conditions for the determination of intrinsic error . 21
5.5 Auxiliary supply . 23
5.5.1 General . 23
5.5.2 DC supply . 23
5.5.3 AC supply . 23
5.6 Input values . 24
5.6.1 General . 24
5.6.2 Adjustment ranges . 24
5.6.3 Preferred nominal values . 24
5.7 Analogue output signals . 24
5.7.1 General . 24
5.7.2 Output current . 24
5.7.3 Compliance voltage . 24
5.7.4 Maximum output voltage . 24
5.7.5 Interference risk of output current . 24
5.7.6 Output voltage . 25
5.8 Output transfer function . 25
5.9 Digital output signals . 27
5.10 Ripple (for analogue outputs) . 27
5.11 Response time . 28
5.12 Variation due to over-range of the measurand . 28

5.13 Limiting value of the output signal . 28
5.14 Limiting conditions of operation . 28
5.15 Limits of the measuring range . 28
5.16 Limiting conditions for storage and transport . 28
5.17 Sealing . 29
5.18 Stability . 29
6 Tests for TRD1 . 29
6.1 General . 29
6.1.1 Determination of variations . 29
6.1.2 Environmental conditions . 29
6.1.3 Computations . 30
6.2 Variations due to auxiliary supply voltage . 30
6.2.1 Application . 30
6.2.2 Procedure . 30
6.2.3 Computation . 30
6.2.4 Permissible variations . 31
6.3 Variations due to auxiliary supply frequency . 31
6.3.1 Application . 31
6.3.2 Procedure . 31
6.3.3 Computation . 31
6.3.4 Permissible variations . 31
6.4 Variations due to ambient temperature . 32
6.4.1 Application . 32
6.4.2 Procedure . 32
6.4.3 Computation . 32
6.4.4 Permissible variations . 32
6.5 Variations due to the frequency of the input quantity(ies) . 32
6.5.1 Application .
...