SIST EN 60688:2013

SLOVENSKI STANDARD
SIST EN 60688:2013
01-marec-2013
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SIST EN 60688:1995
SIST EN 60688:1995/A1:2001
SIST EN 60688:1995/A2:2002
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Electrical measuring transducers for converting a.c. electrical quantities to analogue or
digital signals (IEC 60688:2012)
Elektrische Messumformer zur Umwandlung von elektrischen Wechselstromgrößen und
Gleichstromgrößen in analoge oder digitale Signale (IEC 60688:2012)
Transducteurs électriques de mesure convertissant les grandeurs électriques
alternatives en signaux analogiques ou numériques (CEI 60688:2012)
Ta slovenski standard je istoveten z: EN 60688:2013
ICS:
17.220.20 0HUMHQMHHOHNWULþQLKLQ Measurement of electrical
PDJQHWQLKYHOLþLQ and magnetic quantities
SIST EN 60688:2013 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN 60688:2013

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SIST EN 60688:2013

EUROPEAN STANDARD
EN 60688

NORME EUROPÉENNE
January 2013
EUROPÄISCHE NORM

ICS 17.220.20 Supersedes EN 60688:1992 + A1:1999 + A2:2001


English version


Electrical measuring transducers for converting A.C. and D.C. electrical
quantities to analogue or digital signals
(IEC 60688:2012)


Transducteurs électriques de mesure Elektrische Messumformer
convertissant les grandeurs électriques zur Umwandlung von elektrischen
alternatives ou continues en signaux Wechselstromgrößen
analogiques ou numériques und Gleichstromgrößen in analoge
(CEI 60688:2012) oder digitale Signale
(IEC 60688:2012)




This European Standard was approved by CENELEC on 2012-11-23. 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, Former Yugoslav Republic of Macedonia, France, Germany,
Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland,
Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom.

CENELEC
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung

Management Centre: Avenue Marnix 17, B - 1000 Brussels


© 2013 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.
Ref. No. EN 60688:2013 E

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SIST EN 60688:2013
EN 60688:2013 - 2 -
Foreword
The text of document 85/421/FDIS, future edition 3 of IEC 60688, 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 60688:2013.

The following dates are fixed:
(dop) 2013-08-23
• latest date by which the document has
to be implemented at national level by
publication of an identical national
standard or by endorsement
• latest date by which the national (dow) 2015-11-23
standards conflicting with the
document have to be withdrawn

This document supersedes EN 60688:1992 + A1:1999 + A2:2001.

EN 60688:2013 includes the following significant technical changes with respect to EN 60688:1992 +
A1:1999 + A2:2001:
- extending the scope to DC quantities;
- extending the scope to harmonics, total harmonic distortion and apparent power;
- adaptation of the requirements for digital transducers;
- updating normative references;
- updating safety requirements with the EN 61010 series;
- updating EMC requirements with EN 61326-1.

Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CENELEC [and/or CEN] shall not be held responsible for identifying any or all such
patent rights.

This standard covers the Principle Elements of the Safety Objectives for Electrical Equipment
Designed for Use within Certain Voltage Limits (LVD - 2006/95/EC).
Endorsement notice
The text of the International Standard IEC 60688:2012 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 NOTE Harmonised as EN 60044-7.
IEC 60044-8 NOTE Harmonised as EN 60044-8.
IEC 60051 Series NOTE Harmonised as EN 60051 Series (not modified).
IEC 60068-2-30 NOTE Harmonised as EN 60068-2-30.
IEC 60359 NOTE Harmonised as EN 60359.
IEC 60770-1 NOTE Harmonised as EN 60770-1.
IEC 60770-2 NOTE Harmonised as EN 60770-2.
IEC 60770-3 NOTE Harmonised as EN 60770-3.

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SIST EN 60688:2013
- 3 - EN 60688:2013
Annex ZA
(normative)

Normative references to international publications
with their corresponding European publications

The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including any amendments) applies.

NOTE  When an international publication has been modified by common modifications, indicated by (mod), the relevant EN/HD
applies.

Publication Year Title EN/HD Year

IEC 60051-1 1997 Direct acting indicating analogue EN 60051-1 1998
electrical measuring instruments
and their accessories -
Part 1: Definitions and general requirements
common to all parts


IEC 60068-2-6 - Environmental testing - EN 60068-2-6 -
Part 2-6: Tests - Test Fc: Vibration
(sinusoidal)


IEC 60068-2-27 - Environmental testing - EN 60068-2-27 -
Part 2-27: Tests - Test Ea and guidance:
Shock


IEC 60255-151 - Measuring relays and protection EN 60255-151 -
equipment -
Part 151: Functional requirements
for over/under current protection


IEC 61010 Series Safety requirements for electrical EN 61010 Series
equipment for measurement, control,
and laboratory use


IEC 61010-1 - Safety requirements for electrical EN 61010-1 -
equipment for measurement, control
and laboratory use -
Part 1: General requirements


IEC 61010-2-030 - Safety requirements for electrical EN 61010-2-030 -
equipment for measurement, control
and laboratory use -
Part 2-030: Particular requirements for
testing and measuring circuits


IEC 61326 Series Electrical equipment for measurement, EN 61326 Series
control and laboratory use -
EMC requirements


IEC 61326-1 - Electrical equipment for measurement, EN 61326-1 -
control and laboratory use -
EMC requirements -
Part 1: General requirements


IEC 61557-12 - Electrical safety in low voltage distribution EN 61557-12 -
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: Performance measuring and
monitoring devices (PMD)


IEC 60417-DB Graphical symbols for use on equipment - -

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SIST EN 60688:2013

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SIST EN 60688:2013



IEC 60688

®


Edition 3.0 2012-10




INTERNATIONAL



STANDARD




NORME



INTERNATIONALE











Electrical measuring transducers for converting A.C. and D.C. 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

PRICE CODE
INTERNATIONALE

CODE PRIX X


ICS 17.220.20 ISBN 978-2-83220-435-1



Warning! Make sure that you obtained this publication from an authorized distributor.

Attention! Veuillez vous assurer que vous avez obtenu cette publication via un distributeur agréé.

® Registered trademark of the International Electrotechnical Commission
Marque déposée de la Commission Electrotechnique Internationale

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SIST EN 60688:2013
– 2 – 60688 © IEC:2012
CONTENTS
FOREWORD . 4
INTRODUCTION . 6
1 Scope . 7
2 Normative references . 8
3 Terms and definitions . 8
3.1 General terms . 8
3.2 Description of transducers according to the measurand . 11
3.3 Description of transducers according to their output load . 12
3.4 Nominal values . 12
3.5 User adjustment . 13
3.6 Influence quantities and reference conditions . 14
3.7 Errors and variations . 14
3.8 Accuracy, accuracy class, class index . 14
4 Class index, permissible limits of intrinsic error, auxiliary supply and reference
conditions . 15
4.1 Transducer general architecture . 15
4.2 Class index . 15
4.3 Class index for transducer used with sensors . 16
4.4 Intrinsic error . 16
4.5 Conditions for the determination of intrinsic error . 16
4.6 Auxiliary supply . 18
4.7 Safety requirements: Clearances and creepage distances . 19
5 Requirements . 19
5.1 Input values . 19
5.2 Analogue output signals . 19
5.3 Output transfer function . 20
5.4 Digital output signals . 23
5.5 Ripple (for analogue outputs) . 23
5.6 Response time . 23
5.7 Variation due to over-range of the measurand . 23
5.8 Limiting value of the output signal . 23
5.9 Limiting conditions of operation . 23
5.10 Limits of the measuring range . 24
5.11 Limiting conditions for storage and transport . 24
5.12 Sealing . 24
5.13 Stability . 24
Tests . 24
6
6.1 General . 24
6.2 Variations due to auxiliary supply voltage . 25
6.3 Variations due to auxiliary supply frequency . 26
6.4 Variations due to ambient temperature . 27
6.5 Variations due to the frequency of the input quantity(ies) . 27
6.6 Variations due to the input voltage . 28
6.7 Variations due to the input current . 29
6.8 Variations due to power factor . 29
6.9 Variation due to output load . 30

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SIST EN 60688:2013
60688 © IEC:2012 – 3 –
6.10 Variations due to distortion of the input quantity(ies) . 30
6.11 Variation due to magnetic field of external origin . 31
6.12 Variation due to unbalanced currents . 32
6.13 Variation due to interaction between measuring elements . 32
6.14 Variation due to self-heating . 33
6.15 Variation due to continuous operation. 33
6.16 Variation due to common mode interference . 34
6.17 Variation due to series mode interference . 34
6.18 Voltage test, insulation tests and other safety requirements . 35
6.19 Impulse voltage tests . 35
6.20 High frequency disturbance test . 36
6.21 Test for temperature rise . 36
6.22 Other tests . 36
7 Marking and information . 36
7.1 Marking on the case . 36
7.2 Markings relating to the reference conditions and nominal ranges of use for
transducers . 37
7.3 Identification of connections and terminals . 38
7.4 Information to be given in a separate document . 38
Bibliography . 40

Figure 1 – Transducer architecture . 15
Figure 2 – Transfer function curves . 22

Table 1 – Relationship between the limits of intrinsic error, expressed as a percentage
of the fiducial value, and the class index . 16
Table 2 – Pre-conditioning . 16
Table 3 – Reference conditions of the influence quantities and tolerances or testing
purposes . 17
Table 4 – Reference conditions relative to the measurand . 18
Table 5 – Usage groups . 25
Table 6 – Examples of marking relating to the reference conditions and nominal range
of use for temperature . 37
Table 7 – Symbols for marking transducers . 38

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SIST EN 60688:2013
– 4 – 60688 © IEC:2012
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________

ELECTRICAL MEASURING TRANSDUCERS
FOR CONVERTING A.C. AND D.C. ELECTRICAL
QUANTITIES TO ANALOGUE OR DIGITAL SIGNALS

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
assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any
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.
International Standard 60688 has been prepared by IEC Technical Committee 85: Measuring
equipment for electrical and electromagnetic quantities.
This third edition cancels and replaces the second edition published in 1992 and its
Amendment 1 (1997) and Amendment 2 (2001). It constitutes a technical revision
This edition includes the following significant technical changes with respect to the previous
edition:
– extending the scope to DC quantities;
– extending the scope to harmonics, total harmonic distortion and apparent power;
– adaptation of the requirements for digital transducers;
– updating normative references;
– updating safety requirements with the IEC 61010 series;
– updating EMC requirements with IEC 61326-1.

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SIST EN 60688:2013
60688 © IEC:2012 – 5 –
The text of this standard is based on the following documents:
FDIS Report on voting
85/421/FDIS 85/436/RVD

Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
In this standard, the following print types are used:
– requirements and definitions: in roman type;
– NOTES: in smaller roman type;
– compliance: in italic type.
The committee has decided that the contents of this publication will remain unchanged until
the stability date indicated on the IEC web site under "http://webstore.iec.ch" in the data
related to the specific publication. At this date, the publication will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.

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SIST EN 60688:2013
– 6 – 60688 © IEC:2012
INTRODUCTION
New transducers can now be equipped with micro-processors that utilize digital data
processing, communication methods and auxiliary sensors. This makes them more complex
than conventional analogue transducers and gives them considerable added value.
The class index system of classification used in this standard is based upon the IEC 60051
series: Direct acting indicating analogue electrical measuring instruments and their
accessories. Under this system, the permitted variations of the output signal due to varying
influence quantities – ambient temperature, voltage, frequency, etc., – are implicit in the clas-
sification.
For those unfamiliar with the class index system, a word of warning is necessary. If, for
example, a transducer is classified as Class 1, it does not mean that the error under practical
conditions of use will be within ±1 % of the actual value of the output or ±1 % of the full output
value. It means that the error should not exceed ±1 % of the fiducial value under closely
specified conditions. If the influence quantities are varied between the limits specified by the
nominal ranges of use, a variation of amount comparable with the value of the class index
may be incurred for each influence quantity.
The permissible error of a transducer under working conditions is the sum of the permissible
intrinsic error and of the permissible variations due to each of the influence quantities.
However, the actual error is likely to be much smaller because not all of the influence
quantities are likely to be simultaneously at their most unfavourable values and some of the
variations may cancel one another. It is important that these facts be taken into consideration
when specifying transducers for a particular purpose.
Furthermore, some of the terms used in this standard are different from those used in
IEC 60051 due to the fundamental differences between indicating instruments and measuring
transducers.
All statements of performance are related to the output which is governed by two basic terms:
– "the nominal value", which may have a positive or a negative sign or both;
– "the span", which is the range of values of the output signal from maximum positive to
maximum negative, if appropriate.

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SIST EN 60688:2013
60688 © IEC:2012 – 7 –
ELECTRICAL MEASURING TRANSDUCERS
FOR CONVERTING A.C. AND D.C. ELECTRICAL
QUANTITIES TO ANALOGUE OR DIGITAL SIGNALS



1 Scope
This International Standard applies to transducers with electrical inputs and outputs for
making measurements of a.c. or d.c. electrical quantities. The output signal may be in the
form of an analogue direct current, an analogue direct voltage or in digital form. In this case,
that part of the transducer utilized for communication purposes will need to be compatible with
the external system.
This standard applies to measuring transducers used for converting electrical quantities such
as the following:
– current,
– voltage,
– active power,
– reactive power,
– power factor,
– phase angle,
– frequency,
– harmonics or total harmonic distortion,
– apparent power
to an output signal.
This standard is not applicable for:
– instrument transformers that comply with IEC 60044 series;
– transmitters for use in industrial process applications that comply with the IEC 60770
series;
– performance measuring and monitoring devices (PMD) that comply with IEC 61557-12.
Within the measuring range, the output signal is a function of the measurand. An auxiliary
supply may be needed.
This standard applies:
a) if the nominal frequency of the input(s) lies between 0 Hz and 1 500 Hz;
b) if a measuring transducer is part of a system for the measurement of a non-electrical
quantity, this standard may be applied to the electrical measuring transducer, if it
otherwise falls within the scope of this standard;
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 International Standard 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;

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SIST EN 60688:2013
– 8 – 60688 © IEC:2012
– to specify accuracy limits and output values for transducers.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and
are indispensable for its application. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any
amendments) applies.
IEC 60051-1:1997, Direct acting indicating analogue electrical measuring instruments and
their accessories – Part 1: Definitions and general requirements common to all parts
IEC 60068-2-6, Environmental testing – Part 2-6: Tests – Test Fc: Vibration (sinusoidal)
IEC 60068-2-27, Environmental testing – Part 2-27: Tests – Test Ea and guidance: Shock
IEC 60255-151, Measuring relays and protection equipment – Part 151: Functional
requirements for over/under current protection
IEC 61010 (all parts), Safety requirements for electrical equipment for measurement, control
and laboratory use
IEC 61010-1, Safety requirements for electrical equipment for measurement, control and
laboratory use – Part 1: General requirements
IEC 61010-2-030, Safety requirements for electrical equipment for measurement, control, and
laboratory use – Part 30 Special requirements for testing and measuring circuits
IEC 61326 (all parts), Electrical equipment for measurement, control and laboratory use –
EMC requirements
IEC 61326-1, Electrical equipment for measurement, control and laboratory use – EMC
requirements – Part 1: General requirements
IEC 61557-12, 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: Perform
...