EN IEC 61869-99:2022

Instrument transformers - Part 99: Glossary

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

Transformateurs de mesure - Partie 99: Glossaire

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

• Status: Published
• Publication Date: 15-Dec-2022
• ICS: 01.040.01 - Generalities. Terminology. Standardization. Documentation (Vocabularies)
• ICS: 17.220.20 - Measurement of electrical and magnetic quantities
• Technical Committee: CLC/TC 38 - Instrument transformers
• Drafting Committee: IEC/TC 38 - IEC_TC_38
• Current Stage: 6060 - Document made available - Publishing
• Start Date: 16-Dec-2022
• Completion Date: 16-Dec-2022
• Ref Project: SIST EN IEC 61869-99:2023 - Instrument transformers - Part 99: Glossary (IEC 61869-99:2022)

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)
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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
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 01.040.01; 17.220.20 ISBN 978-2-8322-5852-1

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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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

in addition to other activities, IEC publishes International Standards, Technical Specifications, Technical Reports,

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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

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4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications

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expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC

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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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IEC 61869-99:2022 © IEC 2022 – 5 –
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

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

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
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
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
...