SIST EN IEC 61869-99:2023
(Main)Instrument transformers - Part 99: Glossary (IEC 61869-99:2022)
Instrument transformers - Part 99: Glossary (IEC 61869-99:2022)
IEC 61869-99:2022 contains the glossary of specific terminology and definitions used in the field of instrument transformers within the various parts of the series. Unless it is otherwise specified, in this document all periodic electrical quantities are understood to be RMS values.
Messwandler – Teil 99: Glossar (IEC 61869-99:2022)
Transformateurs de mesure - Partie 99: Glossaire (IEC 61869-99:2022)
L'IEC 61869-99:2022 contient le glossaire de la terminologie spécifique et des définitions appliquées au domaine des transformateurs de mesure dans les différentes parties de la série. Sauf indication contraire, dans le présent document toutes les grandeurs électriques périodiques sont comprises comme étant des valeurs efficaces.
Instrumentni transformatorji - 99. del: Slovar (IEC 61869-99:2022)
Standard IEC 61869-99:2022 vsebuje slovar specifičnih izrazov in definicij, ki se uporabljajo na področju instrumentnih transformatorjev v različnih delih skupine standardov. Če ni določeno drugače, se vse periodične električne veličine v tem dokumentu razumejo kot efektivne vrednosti.
General Information
Standards Content (Sample)
SLOVENSKI STANDARD
SIST EN IEC 61869-99:2023
01-februar-2023
Instrumentni transformatorji - 99. del: Slovar (IEC 61869-99:2022)
Instrument transformers - Part 99: Glossary (IEC 61869-99:2022)
Messwandler – Teil 99: Glossar (IEC 61869-99:2022)
Transformateurs de mesure - Partie 99: Glossaire (IEC 61869-99:2022)
Ta slovenski standard je istoveten z: EN IEC 61869-99:2022
ICS:
17.220.20 Merjenje električnih in Measurement of electrical
magnetnih veličin and magnetic quantities
SIST EN IEC 61869-99:2023 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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SIST EN IEC 61869-99:2023
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SIST EN IEC 61869-99:2023
EUROPEAN STANDARD EN IEC 61869-99
NORME EUROPÉENNE
EUROPÄISCHE NORM December 2022
ICS 17.220.20; 01.040.01
English Version
Instrument transformers - Part 99: Glossary
(IEC 61869-99:2022)
Transformateurs de mesure - Partie 99: Glossaire Messwandler - Teil 99: Glossar
(IEC 61869-99:2022) (IEC 61869-99:2022)
This European Standard was approved by CENELEC on 2022-12-13. 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,
Türkiye 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
© 2022 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.
Ref. No. EN IEC 61869-99:2022 E
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SIST EN IEC 61869-99:2023
EN IEC 61869-99:2022 (E)
European foreword
The text of document 38/709/FDIS, future edition 1 of IEC 61869-99, prepared by IEC/TC 38
"Instrument Transformers" was submitted to the IEC-CENELEC parallel vote and approved by
CENELEC as EN IEC 61869-99:2022.
The following dates are fixed:
• latest date by which the document has to be implemented at national (dop) 2023-09-13
level by publication of an identical national standard or by endorsement
• latest date by which the national standards conflicting with the (dow) 2025-12-13
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.
Any feedback and questions on this document should be directed to the users’ national committee. A
complete listing of these bodies can be found on the CENELEC website.
Endorsement notice
The text of the International Standard IEC 61869-99:2022 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 standard indicated:
IEC 60364-1:2005 NOTE Harmonized as HD 60364-1:2008 + A11:2017
IEC 61850-7-4 NOTE Harmonized as EN 61850-7-4
IEC 61850-9-2:2011 NOTE Harmonized as EN 61850-9-2:2011 (not modified)
IEC 61869 (series) NOTE Harmonized as EN IEC 61869 (series)
2
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SIST EN IEC 61869-99:2023
IEC 61869-99
®
Edition 1.0 2022-11
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Instrument transformers –
Part 99: Glossary
Transformateurs de mesure –
Partie 99: Glossaire
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
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ICS 01.040.01; 17.220.20 ISBN 978-2-8322-5852-1
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CONTENTS
FOREWORD . 3
INTRODUCTION . 5
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 6
3.1 Basic terms and definitions . 6
3.2 Instrument transformer types, parts and details . 9
3.3 Current aspects . 16
3.4 Voltage aspects . 18
3.5 Accuracy aspects . 20
3.6 Miscellaneous aspects . 40
Annex A (informative) Indexes . 45
A.1 Alphabetical list of terms . 45
A.2 List of symbols and abbreviated terms in alphabetical order . 50
Bibliography . 54
Table A.1 – Index of terms . 45
Table A.2 – Index of abbreviated terms and symbols . 50
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INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
INSTRUMENT TRANSFORMERS –
Part 99: Glossary
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
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preparation is entrusted to technical committees; any IEC National Committee interested in the subject dealt with
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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
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3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
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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.
IEC 61869-99 has been prepared by IEC technical committee 38: Instrument Transformers. It
is an International Standard.
The text of this International Standard is based on the following documents:
Draft Report on voting
38/709/FDIS 38/711/RVD
Full information on the voting for its approval can be found in the report on voting indicated in
the above table.
The language used for the development of this International Standard is English.
A list of all parts in the IEC 61869 series, published under the general title Instrument
transformers, can be found on the IEC website.
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This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in
accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement, available
at www.iec.ch/members_experts/refdocs. The main document types developed by IEC are
described in greater detail at www.iec.ch/standardsdev/publications.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under 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 document 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.
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INTRODUCTION
Definitions presented in this document are definitions related to the terminology of the
IEC 61869 series and updated in terms of editorial and technical aspects according to the
official decisions of TC 38 (38/619/Q and 38/626/RQ).
TC 38 decided to start this project to develop the IEC 61869-99 Glossary as preliminary work
for revision of IEC 60050-321. The Glossary IEC 61869-99, when published, will be used as a
basis for the update of IEC 60050-321.
Definitions that are listed in this document are valid definitions and should be used for
terminology concerning instrument transformers.
The structure of this Glossary does not follow the order of product families but follows a logical
order based on the hierarchy of concepts: starting from the most general concepts and
continuing with the more specific ones.
For the purpose of better orientation in the arrangement of terminology it is helpful to use the
"Supporting document for IEC 61869-99" which is located at the following link:
https://www.iec.ch/dyn/www/f?p=103:227:::::FSP_ORG_ID:1241
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INSTRUMENT TRANSFORMERS –
Part 99: Glossary
1 Scope
This part of the IEC 61869 series contains the glossary of specific terminology and definitions
used in the field of instrument transformers within the various parts of the series. Unless it is
otherwise specified, in this document all periodic electrical quantities are understood to be RMS
values.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology databases for use in standardization at the following
addresses:
• IEC Electropedia: available at https://www.electropedia.org/
• ISO Online browsing platform: available at https://www.iso.org/obp
NOTE See Annex A for indexes of terms, abbreviated terms, and symbols.
3.1 Basic terms and definitions
3.1.1
instrument transformer
IT
device providing a secondary signal whose instantaneous value is substantially proportional to
the instantaneous value of the primary voltage or current with a defined accuracy and intended
to feed protective, metering or control equipment
3.1.2
current sensor
CS
device providing a secondary signal whose instantaneous value is related to but not proportional
to the instantaneous value of the primary current with a defined accuracy and intended to feed
protective, metering or control equipment
EXAMPLE A Rogowski coil is an example of a current sensor.
3.1.3
primary circuit
external circuit connected to the primary terminals
3.1.4
secondary circuit
external circuit connected to the secondary terminals
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3.1.5
earthed neutral system
system in which the neutral point(s) is(are) connected to earth either solidly or through a
resistance or reactance of sufficiently low value to reduce transient oscillations and to give a
current sufficient for selective earth fault protection
3.1.6
solidly earthed neutral system
system whose neutral point(s) is(are) earthed directly
Note 1 to entry: In low-voltage applications, this corresponds to "TT system" and "TN system" according to
IEC 60364-1.
Note 2 to entry: In some countries (e.g., USA) a line conductor may be earthed instead of the neutral (corner
grounded systems).
[SOURCE: IEC 60050-601:1985, 601-02-25, modified – Note 1 and Note 2 to entry added.]
3.1.7
impedance earthed neutral system
system whose neutral point(s) is(are) earthed through impedances to limit earth fault currents
Note 1 to entry: In low-voltage applications, this corresponds to "IT system" where the neutral conductor is earthed
via an impedance according to IEC 60364-1.
[SOURCE: IEC 60050-601:1985, 601-02-26, modified – Note 1 to entry added.]
3.1.8
resonant earthed neutral system
arc-suppression-coil-earthed neutral system
system in which one or more neutral points are connected to earth through reactances which
approximately compensate the capacitive component of a single-phase-to-earth fault current
Note 1 to entry: With resonant earthing of a system, the residual current in the fault is limited to such an extent that
an arcing fault in air is self-extinguishing.
[SOURCE: IEC 60050-601:1985, 601-02-27, modified – Note 1 to entry added and
"arc-suppression-coil-earthed neutral system" formatted as an admitted term instead of a
preferred term.]
3.1.9
isolated neutral system
system where the neutral point is not intentionally connected to earth, except for high
impedance connections for protection or measurement purposes
Note 1 to entry: In low-voltage applications, this corresponds to an "IT system" according to IEC 60364-1.
[SOURCE: IEC 60050-601:1985, 601-02-24, modified – Note 1 to entry added.]
3.1.10
port
access to a device or network where electromagnetic energy or signals may be supplied or
received or where the device or network variables may be observed or measured
EXAMPLE Auxiliary power supply terminals
[SOURCE: IEC 60050-131:2002, 131-12-60, modified – example added, Note 1 to entry
deleted.]
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3.1.11
channel
digital channel
digital representation describing a single measurement quantity
EXAMPLE Phase current, phase voltage.
Note 1 to entry: Channels are individually rated and may contain a mathematical combination of multiple inputs
(e.g., calculated neutral current).
Note 2 to entry: Multiple channels can be grouped into a single stream and presented at the device digital output.
3.1.12
stream
digital stream
group of channels brought together into a single digital message
Note 1 to entry: All channels in the stream share a common time stamp and a common sample rate in accordance
with IEC 61869-9.
3.1.13
channel group
set of channels with a common specification
Note 1 to entry: For example, set of three phase voltages or currents. All channels in the group share the same set
of rating plate specifications. If the neutral channel shares the same specification as the individual phases, then it is
included in the same group.
3.1.14
electromagnetic compatibility
EMC
ability of equipment or a system to function satisfactorily in its electromagnetic environment
without introducing intolerable electromagnetic disturbances to anything in that environment
[SOURCE: IEC 60050-161:2018, 161-01-07]
3.1.15
steady state
state of a physical system in which the relevant characteristics remain constant with time
Note 1 to entry: A state under periodic conditions is often considered as a steady state.
[SOURCE: IEC 60050-103:2009, 103-05-01]
3.1.16
transient, adj
pertaining to a phenomenon or quantity which passes from one steady state to another
consecutive steady state
Note 1 to entry: The term "transient" is also used as a noun to mean a transient phenomenon or quantity.
[SOURCE: IEC 60050-103:2009, 103-05-02]
3.1.17
normal environmental conditions
basic set of environmental conditions under which a device is intended to operate as specified
3.1.18
special environmental conditions
set of environmental conditions different from normal environmental conditions
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3.1.19
temperature category
range of temperatures of the ambient air or of the cooling medium for which the instrument
transformer has been designed
3.1.20
rated value
value of a quantity used for specification purposes, established for a specified set of operating
conditions of a component, device, equipment, or system
[SOURCE: IEC 60050-151:2001, 151-16-08]
3.2 Instrument transformer types, parts and details
3.2.1
instrument transformer for DC application
instrument transformer designed for
– measuring DC currents and/or DC voltages
– with or without AC components
3.2.2
measuring instrument transformer
instrument transformer intended for measurement applications
3.2.3
protective instrument transformer
instrument transformer intended for protection applications
3.2.4
multipurpose instrument transformer
instrument transformer intended for both measurement and protection applications
3.2.5
current transformer
CT
instrument transformer for current measurement
3.2.6
bushing type current transformer
current transformer without primary conductor and primary insulation of its own which can be
fitted directly over an insulated bushing or conductor
Note 1 to entry: This definition for "bushing type current transformer" is a generic definition that includes the cable
type current transformer as defined in IEV 321-02-04.
[SOURCE: IEC 60050-321:1986, 321-02-02, modified – Note 1 to entry added.]
3.2.7
low-leakage reactance current transformer
current transformer for which measurements made at the secondary terminals (while primary
terminals are open-circuited) are sufficient for an assessment of its protection performance up
to the rated accuracy limit primary current
3.2.8
high-leakage reactance current transformer
current transformer which does not correspond to the definition of low-leakage reactance
current transformer, and for which an additional allowance is made by the manufacturer to take
account of influencing effects which result in additional leakage flux
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3.2.9
voltage transformer
VT
DEPRECATED: PT
instrument transformer for voltage measurement
3.2.10
capacitor voltage transformer
CVT
voltage transformer comprising a capacitor voltage divider and an electromagnetic unit so
designed and interconnected that the secondary voltage of the electromagnetic unit is
substantially proportional to the primary voltage, and differs in phase from it by an angle which
is approximately zero for an appropriate direction of the connections
[SOURCE: IEC 60050-321:1986, 321-03-14, modified – Abbreviated term added as a synonym
and "capacitor divider unit" replaced with "capacitor voltage divider" in the definition.]
3.2.11
earthed voltage transformer
single-phase voltage transformer which is intended to have one of its primary terminals directly
earthed or a three-phase voltage transformer which is intended to have the star-point primary
terminal directly earthed
3.2.12
unearthed voltage transformer
voltage transformer which has all primary terminals insulated from earth to a level
corresponding to its rated insulation level
3.2.13
combined transformer
combined instrument transformer
instrument transformer consisting of current transformer and voltage transformer in the same
enclosure
3.2.14
low-power instrument transformer
LPIT
instrument transformer with no rating assigned to the output power as it is irrelevant
Note 1 to entry: A general block diagram of an LPIT is given in the following image.
In practice some blocks may be omitted or combined, according to the specific technology of the LPIT under
consideration.
3.2.15
low-power current transformer
LPCT
low-power instrument transformer for current measurement
Note 1 to entry: An example block diagram of an LPCT is given in the following image.
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3.2.16
low-power voltage transformer
LPVT
low-power instrument transformer for voltage measurement
Note 1 to entry: An example block diagram of an LPVT is given in the following image.
3.2.17
electronic IT
EIT
LPIT in which signal processing is performed by active electronic components
3.2.18
electronic current transformer
ECT
EIT for current measurement
3.2.19
electronic voltage transformer
EVT
EIT for voltage measurement
3.2.20
voltage divider
device comprising resistors, inductors, capacitors or a combination of these components such
that, between two points of the device, a desired fraction of the voltage applied to the device
as a whole can be obtained
[SOURCE: IEC 60050-312:2001, 312-02-32, modified – The word "transformer" deleted from
the definition.]
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3.2.21
capacitor voltage divider
capacitor stack forming an alternating voltage divider
[SOURCE: IEC 60050-436:1990, 436-02-10]
3.2.22
section
electrically conductive part of an instrument transformer insulated from other similar parts and
equipped with terminals
EXAMPLE Primary or secondary reconnectable windings, shieldings to be externally grounded, temperature
sensors.
3.2.23
high-voltage terminal
terminal intended to be connected to the power line
[SOURCE: IEC 60050-321:1986, 321-03-16]
3.2.24
primary terminal
terminal to which the voltage or current to be measured is applied
3.2.25
secondary terminal
terminal which transmits the secondary signal to measuring instruments, meters and protective
or control devices or similar apparatus
3.2.26
primary winding
winding to which the current or voltage to be transformed is applied
3.2.27
secondary winding
winding intended to be connected with devices for measuring, metering, control and/or
protection applications
3.2.28
selectable-ratio instrument transformer
instrument transformer on which several transformation ratios are obtained by reconnecting the
primary winding sections and/or by means of taps on the secondary winding
Note 1 to entry: Taps are only relevant for windings of inductive current transformers, voltage transformers and
capacitor voltage transformers.
3.2.29
residual voltage winding
winding of a single-phase voltage transformer intended, in a set of three single-phase
transformers, to be used in open-delta connection for the purpose of:
a) producing a residual voltage under earth-fault conditions;
b) damping of relaxation oscillations (ferro-resonances)
3.2.30
enclosure
housing affording the type and degree of protection suitable for the intended application
[SOURCE: IEC 60050-151:2001, 151-13-08]
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3.2.31
low-voltage component
electrical component of an LPIT separated from the primary circuit at the full rated withstand
voltage level
EXAMPLE Examples of low-voltage components are the secondary converter, the merging unit, and the primary
converter if placed at ground level of the high-voltage instrument transformer.
3.2.32
connecting point
individual point of connection between the different low-voltage components
3.2.33
transmitting system
short-distance or long-distance coupling arrangement between primary and secondary parts of
an LPIT intended to transmit the signal
Note 1 to entry: Depending on the LPIT technology used, the transmitting system can also be used for power
transmission.
3.2.34
primary sensing element
electrical, optical or other device belonging to an LPIT transducing the primary signal into a
more suitable signal to be treated by the other components of the LPIT
EXAMPLE Faraday effect electro-optical devices, Hall effect elements, and Pockels effect elements are examples
of primary sensing elements.
3.2.35
primary converter
part of an LPIT that converts the signal coming from one or more primary sensing elements into
a signal suitable for the transmitting system
3.2.36
secondary converter
part of an LPIT that converts the signal transmitted through the transmitting system into a signal
proportional to the primary signal to be used by measuring instruments, meters and protective
or control devices
Note 1 to entry: For an analogue signal, the secondary converter directly supplies measuring instruments, meters,
and protective or control devices. For a digital signal the secondary converter is connected to a merging unit before
supplying the secondary equipment.
3.2.37
auxiliary power supply
external power supply, either AC or DC that powers the equipment through dedicated terminals
separated from the measurement terminals
Note 1 to entry: Auxiliary power supply is intended to feed the primary and/or the secondary power supply.
3.2.38
secondary power supply
power supply circuit that feeds the secondary converter of an LPIT
Note 1 to entry: Secondary power supply can be combined with primary power supply or a power supply of other
instrument transformers and can supply a merging unit if any.
3.2.39
primary power supply
power supply circuit of the primary converter and/or primary sensing element of an LPIT
Note 1 to entry: Primary power supply can be combined with secondary power supply.
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3.2.40
logical device merging unit
logical device in compliance with IEC 61850-7-4 intended to make the time-coherent
combination of logical node
...
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