SIST EN 61869-2:2013
(Main)Instrument transformers - Part 2: Additional requirements for current transformers
Instrument transformers - Part 2: Additional requirements for current transformers
IEC 61869-2:2012 is applicable to newly manufactured inductive current transformers for use with electrical measuring instruments and/or electrical protective devices having rated frequencies from 15 Hz to 100 Hz. This International Standard is to be used in conjunction with, and is based on, IEC 61869-1:2007. This International Standard cancels and replaces the first edition of IEC 60044-1, published in 1996, and its Amendment 1 (2000) and Amendment 2 (2002), and the first edition of IEC 60044-6, published in 1992. Additionally it introduces technical innovations in the standardization and adaptation of the requirements for current transformers for transient performance.
Messwandler - Teil 2: Zusätzliche Anforderungen für Stromwandler
Transformateurs de mesure - Partie 2: Exigences supplémentaires concernant les transformateurs de courant
La CEI 61869-2:2012 s'applique aux transformateurs inductifs de courant fabriqués récemment et destinés à être utilisés avec des appareils de mesure électriques et/ou des dispositifs électriques de protection présentant une fréquence assignée comprise entre 15 Hz et 100 Hz. Cette Norme Internationale doit être utilisée conjointement avec la CEI 61869-1:2007, sur laquelle elle est basée. Cette Norme Internationale annule et remplace la première édition de la CEI 60044-1, publiée en 1996, et son Amendement 1 (2000) et Amendement 2 (2002), et la première édition de la CEI 60044-6 (1992). De plus, elle introduit des innovations techniques dans la normalisation et l'adaptation des exigences des transformateurs de courant pour réponse en régime transitoire.
Instrumentni transformatorji - 2. del: Dodatne zahteve za tokovne transformatorje
Ta del standarda IEC 61869 se uporablja za nove induktivne tokovne transformatorje, ki se uporabljajo v električnih merilnih instrumentih in/ali električnih zaščitnih napravah z naznačenimi frekvencami od 15 Hz do 100 Hz.
General Information
Relations
Standards Content (Sample)
SLOVENSKI STANDARD
01-marec-2013
1DGRPHãþD
SIST EN 60044-6:2001
Instrumentni transformatorji - 2. del: Dodatne zahteve za tokovne transformatorje
Instrument transformers - Part 2: Additional requirements for current transformers
Messwandler - Teil 2: Zusätzliche Anforderungen für Stromwandler
Transformateurs de mesure - Partie 2: Exigences supplémentaires concernant les
transformateurs de courant
Ta slovenski standard je istoveten z: EN 61869-2:2012
ICS:
17.220.20 0HUMHQMHHOHNWULþQLKLQ Measurement of electrical
PDJQHWQLKYHOLþLQ and magnetic quantities
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
EUROPEAN STANDARD
EN 61869-2
NORME EUROPÉENNE
November 2012
EUROPÄISCHE NORM
ICS 17.220.20 Supersedes EN 60044-1:1999 + A1:2000 + A2:2003, EN 60044-6:1999
English version
Instrument transformers -
Part 2: Additional requirements for current transformers
(IEC 61869-2:2012)
Transformateurs de mesure - Messwandler -
Partie 2: Exigences supplémentaires Teil 2: Zusätzliche Anforderungen für
concernant les transformateurs de courant Stromwandler
(CEI 61869-2:2012) (IEC 61869-2:2012)
This European Standard was approved by CENELEC on 2012-10-23. 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
© 2012 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.
Ref. No. EN 61869-2:2012 E
Foreword
The text of document 38/435/FDIS, future edition 1 of IEC 61869-2, prepared by IEC/TC 38, "Instrument
transformers" was submitted to the IEC-CENELEC parallel vote and approved by CENELEC as
The following dates are fixed:
(dop) 2013-07-23
• 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) 2015-10-23
standards conflicting with the
document have to be withdrawn
This document supersedes EN 60044-1:1999 + A1:2000 + A2:2003 and EN 60044-6:1999.
Additionally it introduces technical innovations in the standardization and adaptation of the requirements
for current transformers for transient performance.
This Part 2 is to be used in conjunction with, and is based on, EN 61869-1:2009, General Requirements –
however the reader is encouraged to use its most recent edition.
This Part 2 follows the structure of EN 61869-1:2009 and supplements or modifies its corresponding
clauses.
When a particular clause/subclause of Part 1 is not mentioned in this Part 2, that clause/subclause
applies as far as is reasonable. When this standard states “addition”, “modification” or “replacement”, the
relevant text in Part 1 is to be adapted accordingly.
For additional clauses, subclauses, figures, tables, annexes or notes, the following numbering system is
used:
– clauses, subclauses, tables, figures and notes that are numbered starting from 201 are additional to
those in Part 1;
– additional annexes are lettered 2A, 2B, etc.
Annex ZZ of EN 61869-1 is not applicable for this part of the series.
An overview of the planned set of standards at the date of publication of this document is given below.
The updated list of standards prepared by IEC TC38 is available at the website: www.iec.ch; the updated
list of standards prepared by IEC TC38 and approved by CENELEC is available at the website:
www.cenelec.eu.
- 3 - EN 61869-2:2012
PRODUCT FAMILY STANDARDS PRODUCT PRODUCTS OLD
STANDARD STANDARD
ADDITIONAL REQUIREMENTS FOR 60044-1
61869-2
CURRENT TRANSFORMERS
ADDITIONAL REQUIREMENTS FOR 60044-2
61869-3
INDUCTIVE VOLTAGE TRANSFORMERS
ADDITIONAL REQUIREMENTS FOR 60044-3
61869-4
COMBINED TRANSFORMERS
ADDITIONAL REQUIREMENTS FOR 60044-5
61869-5
CAPACITIVE VOLTAGE TRANSFORMERS
61869-1
ADDITIONAL REQUIREMENTS FOR 60044-7
61869-6 61869-7
GENERAL
ELECTRONIC VOLTAGE TRANSFORMERS
REQUIREMENTS ADDITIONAL
GENERAL
FOR INSTRUMENT
ADDITIONAL REQUIREMENTS FOR 60044-8
61869-8
REQUIREMENT
TRANSFORMERS
ELECTRONIC CURRENT TRANSFORMERS
FOR ELECTRONIC
INSTRUMENT
TRANSFORMERS DIGITAL INTERFACE FOR INSTRUMENT
61869-9
AND LOW POWER TRANSFORMERS
STAND ALONE
SENSORS
ADDITIONAL REQUIREMENTS FOR LOW-
61869-10
POWER STAND-ALONE CURRENT SENSORS
ADDITIONAL REQUIREMENTS FOR LOW 60044-7
61869-11
POWER STAND ALONE VOLTAGE SENSOR
ADDITIONAL REQUIREMENTS FOR
61869-12
COMBINED ELECTRONIC INSTRUMENT
TRANSFORMER OR COMBINED STAND
ALONE SENSORS
STAND ALONE MERGING UNIT
61869-13
Since the publication of EN 60044-6 (Requirements for protective current transformers for transient
performance) in 1999, the area of application of this kind of current transformers has been extended. As a
consequence, the theoretical background for the dimensioning according to the electrical requirements
has become much more complex. In order to keep this standard as user-friendly as possible, the
explanation of the background information will be transferred to the Technical Report IEC/TR 61869-100,
which is now in preparation.
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 61869-2:2012 was approved by CENELEC as a European
Standard without any modification.
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.
Addition to Annex ZA of EN 61869-1:2009:
Publication Year Title EN/HD Year
IEC 61869-1 (mod) 2007 Instrument transformers - EN 61869-1 2009
Part 1: General requirements
IEC 61869-2 ®
Edition 1.0 2012-09
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Instrument transformers –
Part 2: Additional requirements for current transformers
Transformateurs de mesure –
Partie 2: Exigences supplémentaires concernant les transformateurs de courant
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
CODE PRIX XB
ICS 17.220.20 ISBN 978-2-83220-293-7
– 2 – 61869-2 © IEC:2012
CONTENTS
FOREWORD . 5
1 Scope . 8
2 Normative references . 8
3 Terms and definitions . 8
3.1 General definitions . 8
3.3 Definitions related to current ratings . 9
3.4 Definitions related to accuracy . 10
3.7 Index of abbreviations . 18
5 Ratings . 20
5.3 Rated insulation levels . 20
5.3.2 Rated primary terminal insulation level . 20
5.3.5 Insulation requirements for secondary terminals . 20
5.3.201 Inter-turn insulation requirements . 20
5.5 Rated output . 20
5.5.201 Rated output values . 20
5.5.202 Rated resistive burden values . 20
5.6 Rated accuracy class . 21
5.6.201 Measuring current transformers . 21
5.6.202 Protective current transformers . 22
5.6.203 Class assignments for selectable-ratio current transformers . 26
5.201 Standard values for rated primary current . 26
5.202 Standard values for rated secondary current . 27
5.203 Standard values for rated continuous thermal current . 27
5.204 Short-time current ratings . 27
5.204.1 Rated short-time thermal current (I ) . 27
th
5.204.2 Rated dynamic current (I ) . 27
dyn
6 Design and construction . 27
6.4 Requirements for temperature rise of parts and components . 27
6.4.1 General . 27
6.13 Markings . 27
6.13.201 Terminal markings . 27
6.13.202 Rating plate markings . 28
7 Tests . 30
7.1 General . 30
7.1.2 Lists of tests . 30
7.2 Type tests . 31
7.2.2 Temperature-rise test . 31
7.2.3 Impulse voltage withstand test on primary terminals . 33
7.2.6 Tests for accuracy . 33
7.2.201 Short-time current tests . 35
7.3 Routine tests . 36
7.3.1 Power-frequency voltage withstand tests on primary terminals . 36
7.3.5 Tests for accuracy . 36
7.3.201 Determination of the secondary winding resistance (R ) . 38
ct
7.3.202 Determination of the secondary loop time constant (T ) . 38
s
61869-2 © IEC:2012 – 3 –
7.3.203 Test for rated knee point e.m.f. (E ) and exciting current at E . 39
k k
7.3.204 Inter-turn overvoltage test . 39
7.4 Special tests . 40
7.4.3 Measurement of capacitance and dielectric dissipation factor . 40
7.4.6 Internal arc fault test . 40
7.5 Sample tests . 41
7.5.1 Determination of the remanence factor . 41
7.5.2 Determination of the instrument security factor (FS) of
measuring current transformers . 41
Annex 2A (normative) Protective current transformers classes P, PR . 42
Annex 2B (normative) Protective current transformer classes for transient
performance . 47
Annex 2C (normative) Proof of low-leakage reactance type . 63
Annex 2D (informative) Technique used in temperature rise test of oil-immersed
transformers to determine the thermal constant by an experimental estimation . 64
Annex 2E (informative) Alternative measurement of the ratio error (ε) . 66
Annex 2F (normative) Determination of the turns ratio error . 68
Figure 201 – Duty cycles . 15
Figure 202 – Primary time constant T . 16
P
Figure 203 – Secondary linked flux for different fault inception angles γ . 17
Figure 2A.1 – Vector Diagram . 42
Figure 2A.2 – Error triangle . 43
Figure 2A.3 – Typical current waveforms . 44
Figure 2A.4 – Basic circuit for 1:1 current transformer . 44
Figure 2A.5 – Basic circuit for current transformer with any ratio. 45
Figure 2A.6 – Alternative test circuit . 45
Figure 2B.1 – Short-circuit current for two different fault inception angles . 48
Figure 2B.2 – ψ (t) as the curve of the highest flux values, considering all relevant
max
fault inception angles γ . 48
Figure 2B.3 – Relevant time ranges for calculation of transient factor . 49
Figure 2B.4 – Determination of K
in time range 1 at 50 Hz for T = 1,8 s . 50
tf s
Figure 2B.5 – Determination of K in time range 1 at 60 Hz for T = 1,5 s . 50
tf s
Figure 2B.6 – Determination of K in time range 1 at 16,7 Hz for T = 5.5 s . 50
tf s
Figure 2B.7 – Limiting the magnetic flux by considering core saturation . 52
Figure 2B.8 – Basic circuit . 53
Figure 2B.9 – Determination of remanence factor by hysteresis loop . 55
Figure 2B.10 – Circuit for d.c. method . 56
Figure 2B.11 – Time-amplitude and flux-current diagrams . 56
Figure 2B.12 – Recordings with shifted flux base line . 57
Figure 2B.13 – Circuit for capacitor discharge method . 58
Figure 2B.14 – Typical records for capacitor discharge method . 59
Figure 2B.15 – Measurement of error currents . 60
Figure 2D.1 – Graphical extrapolation to ultimate temperature rise . 65
Figure 2E.1 – Simplified equivalent circuit of the current transformer . 66
– 4 – 61869-2 © IEC:2012
Table 201 – Limits of ratio error and phase displacement for measuring current
transformers (classes 0,1 to 1). 21
Table 202 – Limits of ratio error and phase displacement for measuring current
transformers (classes 0,2S and 0,5S) . 22
Table 203 – Limits of ratio error for measuring current transformers (classes 3 and 5) . 22
Table 204 – Characterisation of protective classes . 23
Table 205 – Error limits for protective current transformers class P and PR . 23
Table 206 – Error limits for TPX, TPY and TPZ current transformers. 25
Table 207 – Specification Methods for TPX, TPY and TPZ current transformers . 26
Table 208 – Marking of terminals . 28
Table 10 – List of tests . 31
61869-2 © IEC:2012 – 5 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
INSTRUMENT TRANSFORMERS –
Part 2: Additional requirements for current transformers
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 closely 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.
This International Standard IEC 61869-2 Ed.1.0 has been prepared by committee 38:
Instrument transformers.
This first edition of IEC 61869-2 cancels and replaces the first edition of IEC 60044-1,
published in 1996, and its Amendment 1 (2000) and Amendment 2 (2002), and the first edition
of IEC 60044-6, published in 1992. Additionally it introduces technical innovations in the
standardization and adaptation of the requirements for current transformers for transient
performance.
The text of this standard is based on the following documents:
FDIS Report on voting
38/435/FDIS 38/437/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.
– 6 – 61869-2 © IEC:2012
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
A list of all the parts in the IEC 61869 series, published under the general title Instrument
transformers, can be found on the IEC website.
This Part 2 is to be used in conjunction with, and is based on, IEC 61869-1:2007, General
Requirements – however the reader is encouraged to use its most recent edition.
This Part 2 follows the structure of IEC 61869-1:2007 and supplements or modifies its
corresponding clauses.
When a particular clause/subclause of Part 1 is not mentioned in this Part 2, that
clause/subclause applies as far as is reasonable. When this standard states “addition”,
“modification” or “replacement”, the relevant text in Part 1 is to be adapted accordingly.
For additional clauses, subclauses, figures, tables, annexes or notes, the following numbering
system is used:
– clauses, subclauses, tables, figures and notes that are numbered starting from 201 are
additional to those in Part 1;
– additional annexes are lettered 2A, 2B, etc.
An overview of the planned set of standards at the date of publication of this document is
given below. The updated list of standards issued by IEC TC38 is available at the website:
www.iec.ch.
61869-2 © IEC:2012 – 7 –
PRODUCT FAMILY STANDARDS PRODUCT PRODUCTS OLD
STANDARD STANDARD
ADDITIONAL REQUIREMENTS FOR 60044-1
61869-2
CURRENT TRANSFORMERS 60044-6
ADDITIONAL REQUIREMENTS FOR 60044-2
61869-3
INDUCTIVE VOLTAGE TRANSFORMERS
ADDITIONAL REQUIREMENTS FOR 60044-3
61869-4
COMBINED TRANSFORMERS
ADDITIONAL REQUIREMENTS FOR 60044-5
61869-5
CAPACITIVE VOLTAGE TRANSFORMERS
ADDITIONAL REQUIREMENTS FOR 60044-7
61869-6 61869-7
61869-1:2007
ELECTRONIC VOLTAGE
TRANSFORMERS
ADDITIONAL
GENERAL
GENERAL
REQUIREMENTS
REQUIREMENT ADDITIONAL REQUIREMENTS FOR 60044-8
61869-8
FOR
ELECTRONIC CURRENT
FOR
INSTRUMENT
TRANSFORMERS
ELECTRONIC
TRANSFORMERS
INSTRUMENT
TRANSFORMERS
DIGITAL INTERFACE FOR INSTRUMENT
61869-9
AND LOW
TRANSFORMERS
POWER STAND
ALONE
ADDITIONAL REQUIREMENTS FOR LOW-
61869-10
SENSORS
POWER STAND-ALONE CURRENT
SENSORS
ADDITIONAL REQUIREMENTS FOR LOW 60044-7
61869-11
POWER STAND ALONE VOLTAGE
SENSOR
ADDITIONAL REQUIREMENTS FOR
61869-12
COMBINED ELECTRONIC INSTRUMENT
TRANSFORMER OR COMBINED STAND
ALONE SENSORS
STAND ALONE MERGING UNIT
61869-13
Since the publication of IEC 60044-6 (Requirements for protective current transformers for
transient performance) in 1992, the area of application of this kind of current transformers has
been extended. As a consequence, the theoretical background for the dimensioning according
to the electrical requirements has become much more complex. In order to keep this standard
as user-friendly as possible, the explanation of the background information will be transferred
to the Technical Report IEC 61869-100 TR, which is now in preparation.
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.
– 8 – 61869-2 © IEC:2012
INSTRUMENT TRANSFORMERS –
Part 2: Additional requirements for Current Transformers
1 Scope
This part of IEC 61869 is applicable to newly manufactured inductive current transformers for
use with electrical measuring instruments and/or electrical protective devices having rated
frequencies from 15 Hz to 100 Hz.
2 Normative references
Clause 2 of IEC 61869-1:2007 is applicable with the following additions:
IEC 61869-1:2007, Instrument Transformers – Part 1: General requirements
3 Terms and definitions
For the purposes of this document, the terms and definitions in IEC 61869-1:2007 apply with
the following additions:
3.1 General definitions
3.1.201
current transformer
instrument transformer in which the secondary current, under normal conditions of use, is
substantially proportional to the primary current 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, 321-02-01]
3.1.202
measuring current transformer
current transformer intended to transmit an information signal to measuring instruments and
meters
[SOURCE: IEC 60050-321:1986, 321-02-18]
3.1.203
protective current transformer
a current transformer intended to transmit an information signal to protective and control
devices
[SOURCE: IEC 60050-321: 1986, 321-02-19)
3.1.204
class P protective current transformer
protective current transformer without remanent flux limit, for which the saturation behaviour
in the case of a symmetrical short-circuit is specified
3.1.205
class PR protective current transformer
protective current transformer with remanent flux limit, for which the saturation behaviour in
the case of a symmetrical short-circuit is specified
61869-2 © IEC:2012 – 9 –
3.1.206
class PX protective current transformer
protective current transformer of low-leakage reactance without remanent flux limit for which
knowledge of the excitation characteristic and of the secondary winding resistance, secondary
burden resistance and turns ratio, is sufficient to assess its performance in relation to the
protective relay system with which it is to be used
3.1.207
class PXR protective current transformer
protective current transformer with remanent flux limit for which knowledge of the excitation
characteristic and of the secondary winding resistance, secondary burden resistance and
turns ratio, is sufficient to assess its performance in relation to the protective relay system
with which it is to be used
Note 1 to entry: An increasingly number of situations occur where low DC currents are continuously flowing through
current transformers. Therefore, in order to stop the current transformer from saturating, current transformers with
air gaps, but with the same performance as Class PX, are used.
Note 2 to entry: The air gaps for remanence reduction do not necessarily lead to a high-leakage reactance current
transformer (see Annex 2C).
3.1.208
class TPX protective current transformer for transient performance
protective current transformer without remanent flux limit, for which the saturation behaviour
in case of a transient short-circuit current is specified by the peak value of the instantaneous
error
3.1.209
class TPY protective current transformer for transient performance
protective current transformer with remanent flux limit, for which the saturation behaviour in
case of a transient short-circuit current is specified by the peak value of the instantaneous
error
3.1.210
class TPZ protective current transformer for transient performance
protective current transformer with a specified secondary time-constant, for which the
saturation behaviour in case of a transient short-circuit current is specified by the peak value
of the alternating error component
3.1.211
selectable-ratio current transformer
current transformer on which several transformation ratios are obtained by reconnecting the
primary winding sections and / or by means of taps on the secondary winding
3.3 Definitions related to current ratings
3.3.201
rated primary current
I
pr
value of the primary current on which the performance of the transformer is based
[SOURCE: IEC 60050-321:1986, 321-01-11, modified title, synonym and definition]
3.3.202
rated secondary current
I
sr
value of the secondary current on which the performance of the transformer is based
[SOURCE: IEC 60050-321:1986, 321-01-15, modified title, synonym and definition]
– 10 – 61869-2 © IEC:2012
3.3.203
rated short-time thermal current
I
th
maximum value of the primary current which a transformer will withstand for a specified short
time without suffering harmful effects, the secondary winding being short-circuited
[SOURCE: IEC 60050-321:1986, 321-02-22]
3.3.204
rated dynamic current
I
dyn
maximum peak value of the primary current which a transformer will withstand, without being
damaged electrically or mechanically by the resulting electromagnetic forces, the secondary
winding being short-circuited
[SOURCE: IEC 60050-321:1986, 321-02-24]
3.3.205
rated continuous thermal current
I
cth
value of the current which can be permitted to flow continuously in the primary winding, the
secondary winding being connected to the rated burden, without the temperature rise
exceeding the values specified
[SOURCE: IEC 60050-321:1986, 321-02-25]
3.3.206
rated primary short-circuit current
I
psc
r.m.s. value of the a.c. component of a transient primary short-circuit current on which the
accuracy performance of a current transformer is based
Note 1 to entry: While I is related to the thermal limit, I is related to the accuracy limit. Usually, I is smaller
th psc psc
than I .
th
3.3.207
exciting current
I
e
r.m.s. value of the current taken by the secondary winding of a current transformer, when a
sinusoidal voltage of rated frequency is applied to the secondary terminals, the primary and
any other windings being open-circuited
[SOURCE: IEC 60050-321:1986, 321-02-32]
3.4 Definitions related to accuracy
3.4.3
ratio error
ε
Definition 3.4.3 of IEC 61869-1:2007 is applicable with the addition of the following note:
Note 201 to entry: The current ratio error, expressed in per cent, is given by the formula:
k I −I
r s p
ε = ×100 %
I
p
where
k is the rated transformation ratio;
r
I is the actual primary current;
p
I is the actual secondary current when I is flowing, under the conditions of measurement.
s p
An explicative vector diagram is given in 2A.1.
61869-2 © IEC:2012 – 11 –
3.4.4
phase displacement
Δϕ
The definition 3.4.4 of IEC 61869-1:2007 is applicable with the addition of the following note:
Note 1 to entry: An explicative vector diagram is given in 2A.1.
3.4.201
rated resistive burden
R
b
rated value of the secondary connected resistive burden in ohms
3.4.202
secondary winding resistance
R
ct
actual secondary winding d.c. resistance in ohms corrected to 75 ºC or such other
temperature as may be specified
Note 1 to entry: R is an actual value. It shall not be confused with the upper limit for R , which can be specified
ct ct
otherwise.
3.4.203
composite error
ε
c
under steady-state conditions, the r.m.s. value of the difference between
a) the instantaneous values of the primary current, and
b) the instantaneous values of the actual secondary current multiplied by the rated
transformation ratio,
the positive signs of the primary and secondary currents corresponding to the convention for
terminal markings
Note 1 to entry: The composite error ε is generally expressed as a percentage of the r.m.s. values of the primary
c
current:
T
(k i − i ) dt
r s p
∫
T
ε = ×100 %
c
I
p
where
k is the rated transformation ratio;
r
I is the r.m.s. value of the primary current;
p
i is the instantaneous value of the primary current;
p
i is the instantaneous value of the secondary current;
s
T is the duration of one cycle.
For further explanation, refer to 2A.4.
[SOURCE: IEC 60050-321:1986, 321-02-26, modified note to entry]
3.4.204
rated instrument limit primary current
I
PL
value of the minimum primary current at which the composite error of the measuring current
transformer is equal to or greater than 10 %, the secondary burden being equal to the rated
burden
[SOURCE: IEC 60050-321:1986, 321-02-27]
– 12 – 61869-2 © IEC:2012
3.4.205
instrument security factor
FS
ratio of rated instrument limit primary current to the rated primary current
Note 1 to entry: Attention should be paid to the fact that the actual instrument security factor is affected by the
burden. When the burden value is significantly lower than rated one, larger current values will be produced on the
secondary side in the case of short-circuit current.
Note 2 to entry: In the event of system fault currents flowing through the primary winding of a current transformer,
the safety of the apparatus supplied by the transformer is at its highest when the value of the rated instrument
security factor (FS) is at its lowest.
[SOURCE: IEC 60050-321:1986, 321-02-28, modified notes to entry]
3.4.206
secondary limiting e.m.f. for measuring current transformers
E
FS
product of the instrument security factor FS, the rated secondary current and the vectorial sum
of the rated burden and the impedance of the secondary winding
Note 1 to entry: The secondary limiting e.m.f. for measuring current transformers E is calculated as
FS
2 2
E = FS × I × (R + R ) + X
FS sr ct b b
where: R is the resistive part of the rated burden;
b
X is the inductive part of the rated burden.
b
This method will give a higher value than the actual one. It was chosen in order to apply the same test method as
used for protective current transformers. Refer to 7.2.6.202 and 7.2.6.203.
[SOURCE: IEC 60050-321:1986, 321-02-31, modified title, synonym and note to entry]
3.4.207
rated accuracy limit primary current
value of primary current up to which the current transformer will comply with the requirements
for composite error
[SOURCE: IEC 60050-321:1986, 321-02-29]
3.4.208
accuracy limit factor
ALF
ratio of the rated accuracy limit primary current to the rated primary current
[SOURCE: IEC 60050-321:1986, 321-02-30]
3.4.209
secondary limiting e.m.f. for protective current transformers
E
ALF
product of the accuracy limit factor, the rated secondary current and the vectorial sum of the
rated burden and the impedance of the secondary winding
Note 1 to entry: The secondary limiting e.m.f for class P and PR protective current transformers E is calculated
ALF
as
2 2
E = ALF × I × (R + R ) + X
ALF sr ct b b
where: R is the resistive part of the rated burden;
b
X is the inductive part of the rated burden.
b
61869-2 © IEC:2012 – 13 –
3.4.210
saturation flux
Ψ
sat
maximum value of secondary linked flux in a current transformer, which corresponds to the
magnetic saturation of the core material
Note 1 to entry: The most suitable procedure for the determination of the saturation flux Ψ is given with the d.c.
sat
saturation method described in 2B.2.3.
Note 2 to entry: In the former standard IEC 60044-6, Ψ was defined as a knee point value, which characterized the
s
transition from the non-saturated to the fully saturated state of a core. This definition could not gain acceptance
because the saturation value was too low, and led to misunderstandings and contradictions. Therefore, it was
replaced by Ψ , which defines the condition of complete saturation.
sat
3.4.211
remanent flux
Ψ
r
value of secondary linked flux which would remain in the core 3 min after the interruption of a
magnetizing current of sufficient magnitude to induce saturation flux (Ψ )
sat
3.4.212
remanence factor
K
R
ratio of the remanent flux to the saturation flux, expressed as a percentage
3.4.213
secondary loop time constant
T
s
value of the time constant of the secondary loop of the current transformer obtained from the
sum of the magnetizing and the leakage inductances (L ) and the secondary loop resistance
s
)
(R
s
T = L / R
s s s
3.4.214
excitation characteristic
graphical or tabular presentation of the relationship between the r.m.s. value of the exciting
current and a sinusoidal voltage applied to the secondary terminals of a current transformer,
the primary and other windings being open-circuited, over a range of values sufficient to
define the characteristics from low levels of excitation up to 1.1 times the knee point e.m.f.
3.4.215
knee point voltage
r.m.s. value of the sinusoidal voltage at rated frequency applied to the secondary terminals of
the transformer, all other terminals being open-circuited, which, when increased by 10 %,
causes the r.m.s. value of the exciting current to increase by 50 %
[SOURCE: IEC 60050-321:1986, 321-02-34]
3.4.216
knee point e.m.f.
e.m.f. of a current transformer at rated frequency, which, when increased by 10 %, causes the
r.m.s. value of the exciting current to increase by 50 %
Note 1 to entry: While the knee point voltage can be applied to the secondary terminals of a current transformer,
the knee point e.m.f. is not directly accessible. The values of the knee point voltage and of the knee point e.m.f.
are deemed as equal, due to the minor influence of the voltage drop across the secondary winding resistance.
– 14 – 61869-2 © IEC:2012
3.4.217
rated knee point e.m.f.
E
k
lower limit of the knee point e.m.f.
Note 1 to entry: The rated knee point e.m.f. appears in the specifications of class PX and PXR protective current
transformers. It may be calculated as
E = K × (R + R )× I
k x ct b sr
3.4.218
rated turns ratio
specified ratio of the number of primary turns to the number of secondary turns
EXAMPLE 1 1/600 (meaning 1 primary turn to 600 secondary turns)
EXAMPLE 2 2/1200 (meaning 2 primary turns to 1200 secondary turns)
Note 1 to entry: The rated turns ratio appears in the specifications of class PX and PXR protective current
transformers.
Note 2 to entry: Rated turns ratio and rated transformation ratio are both defined as primary to secondary entities.
If they shall be compared, the value of the rated turns ratio has to be inverted.
3.4.219
turns ratio error
difference between the actual turns ratio and the rated turns ratio, expressed as a percentage
of the rated turns ratio
3.4.220
dimensioning factor
K
x
factor to indicate the multiple of rated secondary current (I ) occurring under power system
sr
fault conditions, inclusive of safety margins, up to which the transformer is required to meet
performance requirements
Note 1 to entry: See formula under 3.4.217.
3.4.221
instantaneous error current
i
ε
difference between the instantaneous values of the secondary current (i ) multiplied by the
s
rated transformation ratio (k ) and the primary current (i ):
r p
i = k × i - i
ε r s p
Note 1 to entry: When both alternating current components (i , i ) and direct current components (i , i )
sac pac sdc pdc
are present, the constituent components (i , i ) are separately identified as follows:
εac εdc
i = i + i = (k × i - i ) + (k × i - i )
ε εac εdc r sac pac r sdc pdc
3.4.222
peak instantaneous error
ˆ
ε
peak value (î ) of instantaneous error current (see 3.4.221) for the specified duty cycle,
ε
expressed as a percentage of the peak value of the rated primary short-circuit current:
ˆ
i
ε
ˆ
ε = ×100%
2 × I
psc
61869-2 © IEC:2012 – 15 –
3.4.223
peak alternating error component
ˆ
ε
ac
ˆ
peak value i of the alternating component of the instantaneous error current, expressed as
εac
a percentage of the peak value of the rated primary short-circuit current:
ˆ
i
εac
ˆ
ε = ×100 %
ac
2 × I
psc
3.4.224
specified duty cycle (C-O and / or C-O-C-O)
duty cycle in which, during each specified energizat
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