EN IEC 62828-4:2020
(Main)Reference conditions and procedures for testing industrial and process measurement transmitters - Part 4: Specific procedures for level transmitters
Reference conditions and procedures for testing industrial and process measurement transmitters - Part 4: Specific procedures for level transmitters
IEC 62828-4:2020 establishes specific procedures for testing level transmitters used in measuring and control systems for industrial process and machinery control systems. For general test procedures, reference is to be made to IEC 62828-1:2017, applicable to all types of transmitters. Throughout this document, the term "industrial transmitters" covers all types of transmitters used in measuring and control systems for industrial processes and for machinery. The requirements of this document are applicable to all level measurement principles. Detailed description of transmitters is given for two main principles for improved clarity.
Referenzbedingungen und Testmethoden für Industrie- und Prozessmessgrößenumformer - Teil 4: Spezielle Testmethoden für Füllstandmessumformer
Conditions de référence et procédures pour l'essai des transmetteurs de mesure industriels et de processus - Partie 4: Procédures spécifiques pour les transmetteurs de niveau
L'IEC 62828-4:2020 établit les procédures spécifiques d'essai des transmetteurs de niveau utilisés dans les systèmes de mesure et de commande des processus industriels et des systèmes de commande des machines. Pour les procédures d'essais générales, référence doit être faite à l'IEC 62828-1:2017, applicable à tous les types de transmetteurs. Tout au long du présent document, le terme "transmetteurs industriels" couvre tous les types de transmetteurs utilisés dans les systèmes de mesure et de commande des processus industriels et des machines. Les exigences du présent document s'appliquent à tous les principes de mesure du niveau. Par souci de clarté, une description détaillée des transmetteurs est donnée pour deux principes principaux.
Referenčni pogoji in postopki za preskušanje industrijskih in procesnih merilnih oddajnikov - 4. del: Posebni postopki za oddajnike nivoja (IEC 62828-4:2020)
General Information
Standards Content (Sample)
SLOVENSKI STANDARD
01-december-2020
Referenčni pogoji in postopki za preskušanje industrijskih in procesnih merilnih
oddajnikov - 4. del: Posebni postopki za oddajnike nivoja (IEC 62828-4:2020)
Reference conditions and procedures for testing industrial and process measurement
transmitters - Part 4: Specific procedures for level transmitters (IEC 62828-4:2020)
Referenzbedingungen und Testmethoden für Industrie- und
Prozessmessgrößenumformer - Teil 4: Spezielle Testmethoden für
Füllstandmessumformer (IEC 62828-4:2020)
Conditions de référence et procédures pour l'essai des transmetteurs de mesure
industriels et de processus - Partie 4: Procédures spécifiques pour les transmetteurs de
niveau (IEC 62828-4:2020)
Ta slovenski standard je istoveten z: EN IEC 62828-4:2020
ICS:
25.040.40 Merjenje in krmiljenje Industrial process
industrijskih postopkov measurement and control
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
EUROPEAN STANDARD EN IEC 62828-4
NORME EUROPÉENNE
EUROPÄISCHE NORM
September 2020
ICS 17.200.20; 25.040.40
English Version
Reference conditions and procedures for testing industrial and
process measurement transmitters - Part 4: Specific procedures
for level transmitters
(IEC 62828-4:2020)
Conditions de référence et procédures pour l'essai des Referenzbedingungen und Testmethoden für Industrie- und
transmetteurs de mesure industriels et de processus - Prozessmessgrößenumformer - Teil 4: Spezielle
Partie 4: Procédures spécifiques pour les transmetteurs de Testmethoden für Füllstandmessumformer
niveau (IEC 62828-4:2020)
(IEC 62828-4:2020)
This European Standard was approved by CENELEC on 2020-09-22. 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, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, the
Netherlands, Norway, Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and the United Kingdom.
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2020 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.
Ref. No. EN IEC 62828-4:2020 E
European foreword
The text of document 65B/1178(F)/FDIS, future edition 1 of IEC 62828-4, prepared by SC 65B
“Measurement and control devices” of IEC/TC 65 “Industrial-process measurement, control and
automation” was submitted to the IEC-CENELEC parallel vote and approved by CENELEC as
The following dates are fixed:
• latest date by which the document has to be implemented at national (dop) 2021-06-22
level by publication of an identical national standard or by endorsement
• latest date by which the national standards conflicting with the (dow) 2023-09-22
document have to be withdrawn
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CENELEC shall not be held responsible for identifying any or all such patent rights.
Endorsement notice
The text of the International Standard IEC 62828-4:2020 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 60529:1989 NOTE Harmonized as EN 60529:1991 (not modified)
IEC 60947-5-6:1999 NOTE Harmonized as EN 60947-5-6:2000 (not modified)
IEC 61140:2016 NOTE Harmonized as EN 61140:2016 (not modified)
IEC 61298-1:2008 NOTE Harmonized as EN 61298-1:2008 (not modified)
IEC 61298-2:2008 NOTE Harmonized as EN 61298-2:2008 (not modified)
IEC 61298-3:2008 NOTE Harmonized as EN 61298-3:2008 (not modified)
IEC 61987-1:2006 NOTE Harmonized as EN 61987-1:2007 (not modified)
IEC 61987-11:2016 NOTE Harmonized as EN 61987-11:2017 (not modified)
IEC 61987-15 NOTE Harmonized as EN 61987-15
IEC 62683-1:2017 NOTE Harmonized as EN 62683-1:2017 (not modified)
Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications
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.
NOTE 1 Where an International Publication has been modified by common modifications, indicated by (mod), the
relevant EN/HD applies.
NOTE 2 Up-to-date information on the latest versions of the European Standards listed in this annex is available
here: www.cenelec.eu.
Publication Year Title EN/HD Year
IEC 60068-2-6 2007 Environmental testing - Part 2–6: Tests -EN 60068-2-6 2008
Test Fc: Vibration (sinusoidal)
IEC 60068-2-27 2008 Environmental testing - Part 2–27: Tests -EN 60068-2-27 2009
Test Ea and guidance: Shock
IEC 60068-2-64 2008 Environmental testing - Part 2–64: Tests -EN 60068-2-64 2008
Test Fh: Vibration, broadband random
and guidance
IEC 61326-2-3 2012 Electrical equipment for measurement,EN 61326-2-3 2013
control and laboratory use - EMC
requirements - Part 2–3: Particular
requirements - Test configuration,
operational conditions and performance
criteria for transducers with integrated or
remote signal conditioning
IEC 62828-1 2017 Reference conditions and procedures forEN IEC 62828-1 2018
testing industrial and process
measurement transmitters - Part 1:
General procedures for all types of
transmitters
IEC 62828-2 2017 Reference conditions and procedures forEN IEC 62828-2 2018
testing industrial and process
measurement transmitters - Part 2:
Specific procedures for pressure
transmitters
IEC 62828-4 ®
Edition 1.0 2020-08
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Reference conditions and procedures for testing industrial and process
measurement transmitters –
Part 4: Specific procedures for level transmitters
Conditions de reference et procedures pour l'essai des transmetteurs
de mesure industriels et de processus –
Partie 4: Procédures spécifiques pour les transmetteurs de niveau
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 17.200.20; 25.040.40 ISBN 978-2-8322-8757-6
– 2 – IEC 62828-4:2020 © IEC 2020
CONTENTS
FOREWORD . 5
INTRODUCTION . 7
1 Scope . 8
2 Normative references . 8
3 Terms and definitions . 8
3.1 Basic definitions . 9
3.2 Level transmitter definitions . 11
3.2.2 Pressure-based level transmitter definitions . 11
3.2.4 Float level transmitter definitions . 12
3.2.6 Microwave/Radar level transmitter definitions . 12
3.2.7 Optical based level transmitter definitions . 12
3.2.9 Capacitance and admittance level transmitter definitions . 13
3.2.10 Mechanical level transmitter definitions . 13
3.2.11 Electrical resistance level transmitter definitions . 14
3.3 Measurement parameters . 14
3.4 Influence quantity definitions . 14
3.5 Reference to the IEC common data dictionary (CDD) . 15
4 General description of main types of level transmitters . 16
4.1 General . 16
4.2 Pressure-based level transmitters . 16
4.3 Microwave/radar level transmitter . 18
4.3.1 General . 18
4.3.2 Free-space radar level transmitter . 18
4.3.3 Guided-wave radar level transmitter . 19
5 Reference test conditions . 20
5.1 General . 20
5.2 Standard reference test conditions . 20
5.2.1 General . 20
5.2.2 Environmental test conditions . 20
5.2.3 Power supply conditions . 21
5.2.4 Load conditions . 21
5.2.5 Mounting positions for testing . 21
5.3 Reference test conditions for ambient and process quantities influencing
operation . 21
5.3.1 General . 21
5.3.2 Process conditions . 22
5.3.3 Environmental atmospheric conditions . 22
5.3.4 Mechanical vibration . 23
5.3.5 Shock, drop and topple . 23
5.3.6 Power supply . 23
5.3.7 Electromagnetic compatibility (EMC) . 23
5.4 Reference design criteria . 23
5.4.1 General . 23
5.4.2 Enclosure protection against solid, liquid (IP) and impact (IK) . 23
5.4.3 Enclosure protection against corrosive and erosive influences . 23
5.4.4 Electrical safety (insulation resistance, dielectric strength) . 24
5.4.5 Hazardous environment (for application in explosive atmosphere) . 24
IEC 62828-4:2020 © IEC 2020 – 3 –
5.4.6 Functional safety . 24
6 Test procedures . 24
6.1 General . 24
6.1.1 Overview . 24
6.1.2 Specific test setups and procedures . 25
6.2 Type tests at standard reference conditions . 28
6.2.1 General . 28
6.2.2 Accuracy and related factors . 29
6.2.3 Static behaviour . 30
6.2.4 Dynamic behaviour . 31
6.3 Type tests at operating reference test conditions . 31
6.3.1 General . 31
6.3.2 Ambient temperature effects . 31
6.3.3 Ambient relative humidity effects . 32
6.3.4 Vibration effects . 32
6.3.5 Shock, drop and topple . 32
6.3.6 Accelerated operational life test . 32
6.3.7 EMC tests . 32
6.3.8 Further test procedures . 32
6.3.9 Additional test for digital transmitters . 32
6.4 Routine tests. 32
6.5 Acceptance, integration, periodic and maintenance tests . 32
6.5.1 General . 32
6.5.2 Periodical verification . 32
6.5.3 Periodical calibration . 32
7 Test report and technical documentation . 32
7.1 Test report . 32
7.2 Technical documentation . 33
7.3 Total probable error TPE . 33
7.3.1 General . 33
7.3.2 Specific errors . 33
Annex A (informative) Main characteristics for level transmitters . 34
A.1 Properties of level transmitter classes . 34
A.1.1 General . 34
A.1.2 Pressure-based level transmitter . 34
A.1.3 Microwave/Radar level transmitter . 36
A.2 Product properties . 42
A.2.1 Library of properties used in the device classes . 42
A.2.2 Value lists of properties . 46
Annex B (informative) Example for the calculation of the TPE based on 7.3 and the
MRU and MRE . 48
B.1 Overview of the parameters used for the error calculation . 48
B.2 Example test report pressure-based level transmitter . 48
B.2.1 General . 48
B.2.2 Test protocol . 48
B.2.3 DUT characteristics . 48
B.2.4 TPE calculation . 49
B.2.5 MRU calculation . 50
– 4 – IEC 62828-4:2020 © IEC 2020
B.3 Sub test processes . 51
B.3.1 Inaccuracy test . 51
B.3.2 Ambient temperature effect test . 52
B.3.3 Process temperature effect test . 53
B.3.4 Long-term stability test . 54
Bibliography . 56
Figure 1 – Principle diagram of time values and their meanings . 10
Figure 2 – Principles of pressure-based level transmitters . 18
Figure 3 – Free-space radar level transmitter . 19
Figure 4 – Guided-wave radar level transmitter . 20
Figure 5 – Schematic example of a test set-up for pressure PMT . 25
Figure 6 – Typical test set-up for radar level transmitter . 26
Figure 7 –Test setup simulated targets and simulated environment. 27
Figure 8 – Example of test setup for wet test . 28
Table 1 – Environmental test conditions . 21
Table 2 – Influence quantities for the various level measurement principles . 22
Table 3 – Number of measurement cycles and number and position of test points . 24
Table 4 – Example of statement of maximum error. 29
Table A.1 – Pressure-based level transmitter . 34
Table A.2 – Free-space radar level transmitter . 37
Table A.3 – Guided-wave radar level transmitter . 39
Table A.4 – Library of properties used in the device classes . 42
Table A.5 – Value lists of properties . 47
Table B.1 – Abbreviated terms . 48
Table B.2 – DUT characteristics . 49
Table B.3 – TPE calculation . 49
Table B.4 – MRU calculation . 50
Table B.5 – Reference test devices . 51
Table B.6 – Reference test conditions . 51
Table B.7 – Test results . 52
Table B.8 – Reference test equipment . 52
Table B.9 – Reference test conditions . 53
Table B.10 – Test results . 53
Table B.11 – Reference test equipment . 53
Table B.12 – Reference test conditions . 54
Table B.13 – Test results . 54
Table B.14 – Reference test equipment . 55
Table B.15 – Reference test conditions . 55
Table B.16 – Test results . 55
IEC 62828-4:2020 © IEC 2020 – 5 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
REFERENCE CONDITIONS AND PROCEDURES FOR TESTING
INDUSTRIAL AND PROCESS MEASUREMENT TRANSMITTERS –
Part 4: Specific procedures for level transmitters
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 IEC 62828-4 has been prepared by subcommittee 65B: Measurement
and control devices, of IEC technical committee 65: Industrial-process measurement, control
and automation.
The IEC 62828 series cancels and replaces the IEC 60770 series and proposes revisions for
the IEC 61298 series.
The text of this International Standard is based on the following documents:
FDIS Report on voting
65B/1178/FDIS 65B/1182/RVD
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.
– 6 – IEC 62828-4:2020 © IEC 2020
This International Standard is to be used in conjunction with IEC 62828-1:2017.
A list of all parts in the IEC 62828 series, published under the general title Reference conditions
and procedures for testing industrial and process measurement transmitters, 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.
IMPORTANT – The 'colour inside' logo on the cover page of this publication indicates
that it contains colours which are considered to be useful for the correct understanding
of its contents. Users should therefore print this document using a colour printer.
IEC 62828-4:2020 © IEC 2020 – 7 –
INTRODUCTION
Most of the current IEC standards on industrial measurement transmitters are rather old and
were developed having in mind devices based on analogue technologies. Today’s digital
industrial and process measurement transmitters are quite different from those analogue
transmitters: they include more functions and newer interfaces, both towards the computing
section (mostly digital) and towards the measuring section (mostly mechanical). Even if some
standards dealing with digital transmitters already exist, they are not sufficient, since some
aspects of the performance are not covered by appropriate test methods.
In addition, the existing IEC test standards for industrial and process measurement transmitters
are spread over many documents, so that for manufacturers and users it was difficult,
impractical and time-consuming to identify and select all the standards to be applied to a device
measuring a specific process quantity (pressure, temperature, level, flow, etc.).
To help the manufacturers and users, it was decided to review, complete and reorganize the
existing IEC standards on the industrial and process measurement transmitters and to create a
more suitable, effective and comprehensive standard series that provides, in a systematic way,
all the needed specifications and tests for the different industrial and process measurement
transmitters.
To solve the issues mentioned above and to provide an added value for the stakeholders, the
new standard series on industrial and process measurement transmitters covers the following
main aspects:
• applicable normative references;
• specific terms and definitions;
• typical configurations and architectures for the various types of industrial and measurement
transmitters;
• hardware and software aspects;
• interfaces (to the process, to the operator, to the other measurement and control devices);
• physical, mechanical and electrical requirements and relevant tests; clear definition of the
test categories: type tests, acceptance tests and routine tests;
• performances (their specification, tests and verification);
• environmental protection, hazardous areas application, functional safety, etc.;
• structure of the technical documentation.
To cover in a systematic way all the topics to be addressed, the standard series is organized in
several parts. At the time of publication of this document IEC 62828 consists of the following
parts:
• IEC 62828-1: General procedures for all types of transmitters
• IEC 62828-2: Specific procedures for pressure transmitters
• IEC 62828-3: Specific procedures for temperature transmitters
• IEC 62828-4: Specific procedures for level transmitters
• IEC 62828-5: Specific procedures for flow transmitters
In preparing the IEC 62828 series (all parts), many test procedures were taken, with the
necessary improvements, from the IEC 61298 series. As the IEC 61298 series is currently
applicable to all process measurement and control devices, when the IEC 62828 series is
completed, the IEC 61298 series will be revised to harmonize it with the IEC 62828 series,
taking out from its scope the industrial and process measurement transmitters. During the time
when the scope of the IEC 61298 series is being updated, the new IEC 62828 series takes
precedence for industrial and process measurement transmitters.
When the IEC 62828 series is published, the IEC 60770 series will be withdrawn.
– 8 – IEC 62828-4:2020 © IEC 2020
REFERENCE CONDITIONS AND PROCEDURES FOR TESTING
INDUSTRIAL AND PROCESS MEASUREMENT TRANSMITTERS –
Part 4: Specific procedures for level transmitters
1 Scope
This part of IEC 62828 establishes specific procedures for testing level transmitters used in
measuring and control systems for industrial process and machinery control systems. For
general test procedures, reference is to be made to IEC 62828-1:2017, applicable to all types
of transmitters.
Throughout this document, the term "industrial transmitters" covers all types of transmitters
used in measuring and control systems for industrial processes and for machinery.
The requirements of this document are applicable to all level measurement principles.
Detailed description of transmitters is given for two main principles for improved clarity.
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 60068-2-6:2007, Environmental testing – Part 2-6: Tests – Test Fc: Vibration (sinusoidal)
IEC 60068-2-27:2008, Environmental testing – Part 2-27: Tests – Test Ea and guidance: Shock
IEC 60068-2-64:2008, Environmental testing – Part 2-64: Tests – Test Fh: Vibration, broadband
random and guidance
IEC 61326-2-3:2012, Electrical equipment for measurement, control and laboratory use – EMC
requirements – Part 2-3: Particular requirements – Test configuration, operational conditions
and performance criteria for transducers with integrated or remote signal conditioning
IEC 62828-1:2017, Reference conditions and procedures for testing industrial and process
measurement transmitters – Part 1: General procedures for all types of transmitters
IEC 62828-2:2017, Reference conditions and procedures for testing industrial and process
measurement transmitters – Part 2: Specific procedures for pressure transmitters
3 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 62828-1 and the
following 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
IEC 62828-4:2020 © IEC 2020 – 9 –
3.1 Basic definitions
3.1.1
warm-up time
duration between the instant when the power supply is energized and the instant when the
instrument can be used, as specified by the manufacturer
SEE: Figure 1.
[SOURCE: Identifier ABB026 in the IEC common data dictionary.]
3.1.2
settling time
time interval between the step change of an input signal and the instant when the resulting
variation of the output of the signal does not deviate more than 1 % from its final steady state
value
SEE: Figure 1.
[SOURCE: Identifier ABA999 in the IEC common data dictionary.]
3.1.3
output signal
analogue or digital representation of the measurand produced by a transducer
Note 1 to entry: A transmitter is a transducer with standardized output, see IEC 60050-351:2013, 351-56-29.
[SOURCE: IEC 60050-314:2001, 314-04-06, modified – Note 1 to entry has been added.]
– 10 – IEC 62828-4:2020 © IEC 2020
Key
t time
Figure 1 – Principle diagram of time values and their meanings
3.1.4
true value (of a quantity)
value consistent with the definition of a given particular quantity
Note 1 to entry: This term is used in the "true value" approach.
Note 2 to entry: This is a value that would be obtained by a perfect measurement.
Note 3 to entry: True values are by nature indeterminate.
Note 4 to entry: The indefinite article "a", rather than the definite article "the", is used in conjunction with "true
value" because there can be many values consistent with the definition of a given particular quantity.
[SOURCE: IEC 60050-311:2001, 311-01-04]
3.1.5
conventional true value (of a quantity)
value attributed to a particular quantity and accepted, sometimes by convention, as having an
uncertainty appropriate for a given purpose
Note 1 to entry: This term is used in the "uncertainty" approach.
Note 2 to entry: The "conventional true value" is sometimes called "assigned value", "best estimate of the value",
"conventional value" or "reference value". The term "reference value", in this sense, should not be confused with
"reference value" in the sense used in 311-07-01.
Note 3 to entry: Frequently, a large number of results of measurement of a quantity are used to establish a
conventional true value.
IEC 62828-4:2020 © IEC 2020 – 11 –
Note 4 to entry: Traditional definitions, based on the true value approach, treated the conventional true value as a
value approximating to a true value of the quantity such that the difference could be neglected for the purposes for
which that value was used.
[SOURCE: IEC 60050-311:2001, 311-01-06]
3.1.6
zero point for pressure-based level measurement
level at which the medium to be measured is not in contact with the sensing element of the
pressure transmitter.
Note 1 to entry: For an installed pressure-based level transmitter, this means an empty, non-pressurized tank
Note 2 to entry: It represents the lowest possible measurement value which doesn't have to be necessarily the start
of the measuring range as this can be adjusted depending on the application and installation.
Note 3 to entry: Reliable measurements will only be possible with a fully wetted diaphragm.
3.1.7
geometric zero point
vertical centre position of the lower nozzle or flange for side mounting that shall be considered
for mechanical drawings and mounting instructions
Note 1 to entry: The geometric zero point for installation can be different from the zero point for measurement.
SEE: Figure 2 a).
3.2 Level transmitter definitions
3.2.1
level transmitter
transmitter that outputs a signal representative of a level
[SOURCE: Identifier ABA803 in the IEC common data dictionary.]
3.2.2 Pressure-based level transmitter definitions
3.2.2.1
pressure-based level transmitter
level transmitter that uses the pressure exerted by a head of liquid to measure level
Note 1 to entry: Pressure-based level transmitters are often called hydrostatic level transmitters.
[SOURCE: Identifier ABA812 in the IEC common data dictionary.]
3.2.2.2
pressure level transmitter (principle 1)
pressure (hydrostatic) level transmitter that uses gauge pressure to measure level
[SOURCE: Identifier ABA814 in the IEC common data dictionary, modified – "(principle 1)"
added to the term.]
3.2.2.3
differential pressure level transmitter (principle 2)
differential pressure level transmitter (principle 3)
pressure (hydrostatic) level transmitter that uses differential pressure to measure level
[SOURCE: Identifier ABA813 in the IEC common data dictionary, modified – "(principle 2)" and
"(principle 3)" added to the terms.]
– 12 – IEC 62828-4:2020 © IEC 2020
3.2.3
displacer level transmitter
level transmitter that uses the buoyancy of a submerged displacement element to measure level
[SOURCE: Identifier ABA804 in the IEC common data dictionary.]
3.2.4 Float level transmitter definitions
3.2.4.1
float level transmitter
level transmitter that uses a float or a follower to measure level
[SOURCE: Identifier ABA809 in the IEC common data dictionary.]
3.2.4.2
magnetostrictive level transmitter
float level transmitter that uses the magnetostrictive effect to determine the position of the float
[SOURCE: Identifier ABA810 in the IEC common data dictionary.]
3.2.4.3
magnet level transmitters
float level transmitter that uses a magnet and resistors to determine the position of the float
[SOURCE: Identifier ABA811 in the IEC common data dictionary.]
3.2.5
ultrasonic (or sonic) level transmitter
wave level transmitter that uses the travelling time of an ultrasonic (or sonic) beam to measure
level
[SOURCE: Identifier ABA829 in the IEC common data dictionary.]
3.2.6 Microwave/Radar level transmitter definitions
3.2.6.1
free-space radar level transmitter
level transmitter that emits a radar beam by an antenna to measure level by using the time of
flight
3.2.6.2
guided-wave radar level transmitter
level transmitter that emits a high frequency signal guided by a probe to measure level by using
the time of flight
3.2.7 Optical based level transmitter definitions
3.2.7.1
optical-based level transmitter
level transmitter that uses the transmission, reflection or refraction of light by the process
material to measure level
[SOURCE: Identifier ABA820 in the IEC common data dictionary.]
3.2.7.2
optical refraction level transmitter
optical level transmitter that uses the difference between the refractive index of the process
fluid and the material of the sensing element to measure level
IEC 62828-4:2020 © IEC 2020 – 13 –
[SOURCE: Identifier ABA821 in the IEC common data dictionary.]
3.2.7.3
laser level transmitter
wave level transmitter that uses the time of flight of a laser beam to measure level
[SOURCE: Identifier ABA828 in the IEC common data dictionary, modified – In the definition,
"travelling time" replaced with "time of flight".]
3.2.8
nuclear level transmitter
level transmitter that uses the absorption of gamma radiation by process material to measure
level
Note 1 to entry: A nuclear level transmitter is also known as a radiometric or radiation level transmitter.
[SOURCE: Identifier ABA819 in the IEC common data dictionary.]
3.2.9 Capacitance and admittance level transmitter definitions
3.2.9.1
capacitance level transmitter
electrical-based level transmitter that uses dielectric properties of a process material to
measure level
[SOURCE: Identifier ABA806 in the IEC common data dictionary.]
3.2.9.2
admittance level transmitter
electrical-based level transmitter that uses the admittance of a process material to measure
level
[SOURCE: Identifier ABA807 in the IEC common data dictionary.]
3.2.10 Mechanical level transmitter definitions
3.2.10.1
mechanical level transmitter
level transmitter that uses mechanical means to measure level
[SOURCE: Identifier ABA816 in the IEC common data dictionary.]
3.2.10.2
plumb bob level transmitter
level transmitter that uses a wire or tape with a body as sensing element to measure level
[SOURCE: Identifier ABA817 in the IEC common data dictionary.]
3.2.10.3
servo level transmitter
level transmitter that uses a float and a wire fed by a servo motor to measure level
[SOURCE: Identifier ABA818 in the IEC common data dictionary.]
– 14 – IEC 62828-4:2020 © IEC 2020
3.2.11 Electrical resistance level transmitter definitions
3.2.11.1
resistance-tape level transmitter
level transmitter tha
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