SIST EN 60214-1:2014

SLOVENSKI STANDARD
01-oktober-2014
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SIST EN 60214-1:2004
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Tap-changers - Part 1: Performance requirements and test methods
Stufenschalter -- Teil 1: Leistungsanforderungen und Prüfverfahren
Ta slovenski standard je istoveten z: EN 60214-1:2014
ICS:
29.180 Transformatorji. Dušilke Transformers. Reactors
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD EN 60214-1
NORME EUROPÉENNE
EUROPÄISCHE NORM
August 2014
ICS 29.180 Supersedes EN 60214-1:2003
English Version
Tap-changers - Part 1: Performance requirements and test
methods
(IEC 60214-1:2014)
Changeurs de prises - Partie 1: Prescriptions de Stufenschalter - Teil 1: Leistungsanforderungen und
performances et méthodes d'essai Prüfverfahren
(CEI 60214-1:2014) (IEC 60214-1:2014)
This European Standard was approved by CENELEC on 2014-06-26. 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.

European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2014 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.
Ref. No. EN 60214-1:2014 E
Foreword
The text of document 14/746/CDV, future edition 2 of IEC 60214-1, prepared by IEC/TC 14 "Power
transformers" was submitted to the IEC-CENELEC parallel vote and approved by CENELEC as
The following dates are fixed:
– latest date by which the document has to be implemented at (dop) 2015-03-26
national level by publication of an identical national
standard or by endorsement
– latest date by which the national standards conflicting with (dow) 2017-06-26
the document have to be withdrawn

This document supersedes EN 60214-1:2003.
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.
Endorsement notice
The text of the International Standard IEC 60214-1:2014 was approved by CENELEC as a European
Standard without any modification.
In the official version, for Bibliography, the following notes have to be added for the standards indicated:
IEC 60076-1:2011 NOTE Harmonized in EN 60076-1:2011.
IEC 60076-11 NOTE Harmonized as EN 60076-11.
IEC 60376 NOTE Harmonized as EN 60376.
IEC 60599 NOTE Harmonized as EN 60599.

- 3 - EN 60214-1:2014
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 1 When an International Publication has been modified by common modifications, indicated by (mod), the relevant
EN/HD applies.
NOTE 2 Up-to-date information on the latest versions of the European Standards listed in this annex is available here:
www.cenelec.eu.
Publication Year Title EN/HD Year
IEC 60050 series International Electrotechnical Vocabulary - - series
Electrical and electronic measurements
and measuring
IEC 60060-1 -  High-voltage test techniques -- Part 1: EN 60060-1 -
General definitions and test requirements
IEC 60076-3 2013 Power transformers -- Part 3: Insulation EN 60076-3 2013
levels, dielectric tests and external
clearances in air
IEC 60076-7 2005 Power transformers -- Part 7: Loading - -
guide for oil-immersed power transformers
IEC 60076-21 2011  - -
IEC 60137 2008 Insulated bushings for alternating voltages EN 60137 2008
above 1 000 V
IEC 60214-2 2004 Tap changers -- Part 2: Application guide - -
IEC 60270 -  High-voltage test techniques - Partial EN 60270 -
discharge measurements
IEC 60296 -  Fluids for electrotechnical applications - EN 60296 -
Unused mineral insulating oils for
transformers and switchgear
IEC 60529 -  Degrees of protection provided by - -
enclosures (IP Code)
IEC 60214-1 ®
Edition 2.0 2014-05
INTERNATIONAL
STANDARD
colour
inside
Tap-changers –
Part 1: Performance requirements and test methods

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
PRICE CODE
XC
ICS 29.180 ISBN 978-2-8322-1621-7

– 2 – IEC 60214-1:2014 © IEC:2014
CONTENTS
FOREWORD . 6
1 Scope . 8
2 Normative references . 8
3 Terms and definitions . 9
4 Service conditions . 15
4.1 Temperature of tap-changer environment . 15
4.2 Temperature of motor-drive mechanism environment . 16
4.3 Overload conditions . 16
5 Requirements for on-load tap-changers . 16
5.1 General requirements . 16
5.1.1 Rating . 16
5.1.2 Compartments for diverter and selector switches . 17
5.1.3 Liquid-level gauges and gas monitoring devices . 17
5.1.4 Safety requirements for protection against internal failure. 17
5.1.5 Limiting devices for the protection against transient overvoltages . 18
5.1.6 Change-over selector recovery voltages . 18
5.1.7 Leakage inductance in coarse fine regulation arrangements . 18
5.2 Type tests . 18
5.2.1 General . 18
5.2.2 Temperature rise of contacts . 19
5.2.3 Switching tests . 20
5.2.4 Short-circuit current test . 25
5.2.5 Transition impedance test . 26
5.2.6 Mechanical tests . 27
5.2.7 Tightness test . 29
5.2.8 Dielectric tests . 30
5.2.9 Type-test certificate . 35
5.3 Routine tests . 35
5.3.1 General . 35
5.3.2 Mechanical test . 35
5.3.3 Sequence test . 35
5.3.4 Auxiliary circuits insulation test . 35
5.3.5 Pressure and vacuum tests . 35
6 Requirements for motor-drive mechanisms for on-load tap-changers . 35
6.1 General requirements . 35
6.1.1 Compliance of component parts . 35
6.1.2 Permissible variation of auxiliary supply . 36
6.1.3 Step-by-step control . 36
6.1.4 Tap position indicator . 36
6.1.5 Tap-change in progress indication . 36
6.1.6 Limiting devices . 36
6.1.7 Parallel control devices . 36
6.1.8 Direction of rotation protection . 36
6.1.9 Overcurrent blocking device . 36
6.1.10 Restarting device . 37
6.1.11 Operation counter . 37

IEC 60214-1:2014 © IEC:2014 – 3 –
6.1.12 Manual operation of the motor-drive mechanism . 37
6.1.13 Motor-drive cubicle . 37
6.1.14 Protective device against running-through . 37
6.1.15 Protection against access to hazardous parts . 37
6.2 Type tests . 37
6.2.1 Mechanical load test . 37
6.2.2 Overrun test . 38
6.2.3 Degree of protection of motor-drive cubicle. 38
6.3 Routine tests . 38
6.3.1 Mechanical tests . 38
6.3.2 Auxiliary circuits insulation test . 38
7 Requirements for de-energized tap-changers . 38
7.1 General requirements . 38
7.1.1 Rated characteristics . 38
7.1.2 Types . 39
7.1.3 Handles and drives . 39
7.1.4 Glands . 39
7.1.5 Interlocks . 39
7.1.6 Mechanical end stops . 39
7.2 Type tests . 40
7.2.1 General . 40
7.2.2 Temperature rise of contacts . 40
7.2.3 Short-circuit current test . 41
7.2.4 Mechanical tests . 41
7.2.5 Dielectric tests . 42
7.2.6 Type test certificate . 47
7.3 Routine tests . 47
7.3.1 Mechanical tests . 47
7.3.2 Pressure and vacuum tests . 47
8 Requirements for motor-drive mechanisms for de-energized tap-changers . 47
8.1 General requirements . 47
8.1.1 General . 47
8.1.2 Compliance of component parts . 47
8.1.3 Permissible variation of auxiliary supply . 47
8.1.4 Tap position indicator . 47
8.1.5 Limiting devices . 48
8.1.6 Operation counter . 48
8.1.7 Manual operation of the motor-drive mechanism . 48
8.1.8 Motor-drive cubicle . 48
8.1.9 Protection against access to hazardous parts . 48
8.2 Type tests . 48
8.2.1 Mechanical load test . 48
8.2.2 Overrun test . 49
8.2.3 Degree of protection of motor-drive cubicle. 49
8.3 Routine tests . 49
8.3.1 Mechanical tests . 49
8.3.2 Auxiliary circuits insulation test . 49
9 Nameplate . 49
9.1 Tap-changers (on-load and de-energized) . 49

– 4 – IEC 60214-1:2014 © IEC:2014
9.2 Motor-drive mechanisms . 50
10 De-energized tap-changer warning label . 50
11 Manufacturers operating instructions . 51
Annex A (normative) Supplementary information on switching duty on main and
transition contacts relating to resistor type tap-changers . 52
Annex B (normative) Supplementary information on switching duty relating to reactor
type tap-changers . 58
B.1 Additional test parameters . 58
B.1.1 Service duty test . 58
B.1.2 Breaking capacity test . 58
B.2 Duty of switching contacts . 58
Annex C (normative) Method for determining the equivalent temperature of the
transition resistor using power pulse current . 69
Annex D (informative) Simulated a.c. circuits for service duty and breaking capacity
tests . 70
D.1 General . 70
D.2 Transformer method. 70
D.3 Resistance method . 71
Annex E (informative) Example of a synthetic test circuit for service duty test of
vacuum type tap-changers . 73
E.1 Definitions with relevance to the synthetic test circuit . 73
E.1.1 Synthetic test circuit . 73
E.1.2 Simulated a.c. test circuit. 73
E.1.3 Pre-arc . 73
E.1.4 Making voltage . 73
E.2 Example for the test setup of a synthetic test circuit . 73
E.3 Example for the breaking/making condition during a switching operation. 74
Bibliography . 76

Figure 1 – Short-circuit test current (r.m.s. value) as a multiple of the maximum rated
through-current (on-load tap-changer) . 25
Figure 2 – Time sequence for the application of test voltage (on-load tap-changer) . 34
Figure 3 – Short-circuit test current (r.m.s. value) as a multiple of the maximum rated
through-current (de-energized tap-changer) . 41
Figure 4 – Time sequence for the application of test voltage (de-energized tap-
changer) . 46
Figure 5 – Warning label (example) . 50
Figure A.1 – Examples of current and voltage vectors for resistor type tap-changers . 53
Figure B.1 – Operating sequence of reactor type tap-changers with selector switch . 59
Figure B.2 – Current and voltage vectors for reactor type tap-changers with selector
switch . 60
Figure B.3 – Operating sequence of reactor type tap-changers with selector switch
and equalizer windings . 61
Figure B.4 – Current and voltage vectors for reactor type tap-changers with selector
switch and equalizer windings . 62
Figure B.5 – Operating sequence of a reactor type tap-changer with diverter switch
and tap selector . 64
Figure B.6 – Current and voltage vectors for reactor type tap-changers with diverter
switch and tap selector . 65

IEC 60214-1:2014 © IEC:2014 – 5 –
Figure B.7 – Operating sequence of a reactor type tap-changer with vacuum
interrupter and tap selector . 67
Figure B.8 – Current and voltage vectors for reactor type tap-changers with vacuum
interrupter and tap selector . 68
Figure D.1 – Simulated test circuit – Transformer method . 70
Figure D.2 – Simulated test circuit – Resistance method . 71
Figure E.1 – Synthetic test circuit for service duty test of vacuum type tap-changers . 73
Figure E.2 – Currents of the synthetic test circuit . 74
Figure E.3 – Example of the synthetic test for a switching operation with equal voltages
for breaking and making duty . 74

Table 1 – Temperature of tap-changer environment . 16
Table 2 – Contact temperature-rise limits for on-load tap-changers . 19
Table 3 – Test voltage levels for on-load tap-changers . 30
Table 4 – Contact temperature-rise limits for de-energized tap-changers . 40
Table 5 – Test voltage levels for de-energized tap-changers . 43
Table A.1 – Duty of main and transition contacts for resistor type tap-changers (non-
vacuum type) . 54
Table A.2 – Effect of load power-factor on circuit-breaking duty for resistor type tap-
changers (non-vacuum type) . 55
Table A.3 – Duty of main and transition contacts for resistor type tap-changers
(vacuum type) (1 of 2) . 56
Table B.1 – Duty of switching contacts for reactor type tap-changers with selector
switch – Switching direction from P1 to P5 . 59
Table B.2 – Duty of switching contacts for reactor type tap-changers with selector
switch and equalizer windings – Switching direction from P1 to P5 . 61
Table B.3 – Duty of switching contacts for reactor type tap-changers with diverter
switch and tap selector – Switching direction from P1 to P7 . 63
Table B.4 – Duty of switching contacts for reactor type tap-changers with vacuum
interrupter and tap selector – Switching direction from P1 to P11 . 66

– 6 – IEC 60214-1:2014 © IEC:2014
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
TAP-CHANGERS –
Part 1: Performance requirements
and test methods
FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote
international co-operation on all questions concerning standardization in the electrical and electronic fields. To
this end and in addition to other activities, IEC publishes International Standards, Technical Specifications,
Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC
Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested
in the subject dealt with may participate in this preparatory work. International, governmental and non-
governmental organizations liaising with the IEC also participate in this preparation. IEC collaborates closely
with the International Organization for Standardization (ISO) in accordance with conditions determined by
agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
consensus of opinion on the relevant subjects since each technical committee has representation from all
interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
misinterpretation by any end user.
4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
transparently to the maximum extent possible in their national and regional publications. Any divergence
between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
the latter.
5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any
services carried out by independent certification bodies.
6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
members of its technical committees and IEC National Committees for any personal injury, property damage or
other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
Publications.
8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 60214-1 has been prepared by IEC technical committee 14: Power
transformers.
This second edition cancels and replaces the first edition published in 2003. This edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
• incorporation of requirements on vacuum type on-load tap-changers,
• incorporation of requirements on gas insulated tap-changers,
• changes in the type tests to fit with the service conditions,
• reference to the newest edition of IEC 60076-3:2013.

IEC 60214-1:2014 © IEC:2014 – 7 –
The text of this standard is based on the following documents:
CDV Report on voting
14/746/CDV 14/767A/RVC
Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
A list of all parts in the IEC 60214 series, published under the general title Tap-changers, can
be found on the IEC website.
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.
A bilingual version of this publication may be issued at a later date.

IMPORTANT – The 'colour inside' logo on the cover page of this publication indicates
that it contains colours which are considered to be useful for the correct
understanding of its contents. Users should therefore print this document using a
colour printer.
– 8 – IEC 60214-1:2014 © IEC:2014
TAP-CHANGERS –
Part 1: Performance requirements
and test methods
1 Scope
This part of IEC 60214 applies to on-load tap-changers of both resistor and reactor types, de-
energized tap-changers, and their motor-drive mechanisms.
It applies mainly to tap-changers immersed in mineral insulating oil according to IEC 60296
but may also be used for tap-changers with air or gas insulation or immersed in other
insulating liquids insofar as conditions are applicable.
It applies mainly to tap-changers with arcing contacts but may also be used for arcing-free on-
load tap-changers (such as electronic switching) insofar as conditions are applicable.
This part of IEC 60214 applies to power and distribution transformers of all types and also to
reactors.
It does not apply to transformers and reactors mounted on railway rolling stock.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and
are indispensable for its application. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any
amendments) applies.
IEC 60050 (all parts), International Electrotechnical Vocabulary (available at
http://www.electropedia.org)
IEC 60050-421, International Electrotechnical Vocabulary – Chapter 421: Power transformers
and reactors
IEC 60060-1, High voltage test techniques – Part 1: General definitions and test requirements
IEC 60076-3:2013, Power transformers – Part 3: Insulation levels, dielectric tests and external
clearances in air
IEC 60076-7:2005, Power transformers – Part 7: Loading guide for oil-immersed power
transformers
IEC 60076-21:2011, Power transformers – Part 21: Standard requirements, terminology, and
test code for step-voltage regulators
IEC 60137:2008, Insulated bushings for alternating voltages above 1 000 V
IEC 60214-2:2004, Tap-changers – Part 2: Application guide
IEC 60270, High-voltage test techniques – Partial discharge measurements

IEC 60214-1:2014 © IEC:2014 – 9 –
IEC 60296, Fluids for electrotechnical applications – Unused mineral insulating oils for
transformers and switchgear
IEC 60529, Degrees of protection provided by enclosures (IP Code)
3 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 60050-421 as well
as the following apply.
3.1
on-load tap-changer
OLTC
device for changing the tap connections of a winding, suitable for operation while the
transformer is energized or on load
Note 1 to entry: On-load tap-changers are sometimes called load tap-changers (LTC).
3.2
non-vacuum type on-load tap-changer
on-load tap-changer with contacts that break and make the load and circulating currents and
where the arcing takes place in a liquid or gas, the tap-changer itself being placed in liquid or
gas
Note 1 to entry: This definition does not apply to arcing-free on-load tap-changers.
3.3
vacuum type on-load tap-changer
on-load tap-changer where vacuum interrupters (VI) break and make the load and circulating
currents, the tap-changer itself being placed in a different medium such as liquid or gas
3.4
tap selector
device designed to carry, but not to make or break, current, used in conjunction with a
diverter switch to select tap connections
3.5
diverter switch
switching device used in conjunction with a tap selector to carry, make and break currents in
circuits which have already been selected
Note 1 to entry: Diverter switches are sometimes called arcing switches.
3.6
selector switch
switching device capable of carrying, making and breaking current, combining the duties of
a tap selector and a diverter switch
Note 1 to entry: Selector switches are sometimes called arcing tap switches.
Note 2 to entry: In non-vacuum type selector switches the selection of tap connections (tap selector duty) and the
diversion of the through-current (diverter switch duty) are carried out by the same contacts.
Note 3 to entry: In vacuum type selector switches the selection of tap connections (tap selector duty) and the
diversion of the through-current (diverter switch duty) are carried out by different contacts.

– 10 – IEC 60214-1:2014 © IEC:2014
3.7
de-energized tap-changer
DETC
device for changing the tap connections of a winding, suitable for operation only while the
transformer is de-energized (isolated from the system)
Note 1 to entry: De-energized tap-changers are sometimes called off-circuit tap-changers.
Note 2 to entry: De-energized tap-changers are sometimes abbreviated as DTC.
3.8
change-over selector
device designed to carry, but not to make or break, through-current, used in conjunction with
the tap selector or selector switch to enable its contacts and the connected taps to be used
more than once when moving from one extreme position to the other
3.9
coarse change-over selector
change-over selector connecting the tap winding to either the main winding or the coarse
winding or parts thereof
3.10
reversing change-over selector
change-over selector connecting either end of the tap winding to the main winding
3.11
transition impedance
resistor or reactor consisting of one or more units bridging the tap in use and the tap next to
be used, for the purpose of transferring load from one tap to the other without interruption or
appreciable change in the load current, at the same time limiting the circulating current for the
period that both taps are used
Note 1 to entry: For reactor type tap-changers, the transition impedance (reactor) is commonly called a preventive
auto transformer. Reactor type tap-changers normally use the bridging position as a service position (mid-point or
centre tapped reactor tap-changers) and, therefore, the reactor is designed for continuous operation.
3.12
preventive auto transformer
auto transformer (or centre tapped reactor) used in on-load tap-changing and regulating
transformers, or step voltage regulators to limit the circulating current when operating on a
position in which two adjacent taps are bridged, or during the change of tap between adjacent
positions
3.13
equalizer winding
winding on the same magnetic circuit (core) as the excitation and tap winding of a reactor
type regulating transformer with approximately half the number of turns of each tap section
3.14
drive mechanism
means by which the drive to the tap-changer is actuated
Note 1 to entry: The mechanism may include an independent means of storing energy to control the operation.
3.15
set of contacts
pair of individual fixed and moving contacts or a combination of such pairs operating
substantially simultaneously
IEC 60214-1:2014 © IEC:2014 – 11 –
3.16
diverter switch and selector switch main contacts
set of through-current carrying contacts which usually by-passes the main switching contact
and only commutates any current (sparking often occurs)
3.17
diverter switch and selector switch main switching contacts changer>
set of contacts which has no transition resistor between the transformer winding and the
contacts and makes and breaks current (arcing will occur)
Note 1 to entry: In case of vacuum type tap-changers, these contact systems are replaced by vacuum
interrupters.
3.18
diverter switch and selector switch transition contacts,
set of contacts which is connected in series with a transition resistor and makes or breaks
current (arcing will occur)
Note 1 to entry: In case of vacuum type tap-changers, these contact systems are replaced by vacuum
interrupters.
3.19
transfer contacts
set of contacts that makes or breaks current
Note 1 to entry: Where by-pass contacts are not provided, the transfer contact is a continuous current-carrying
contact.
3.20
by-pass contacts
set of through-current carrying contacts that commutates the current to the transfer contacts
without any arc (sparking may occur)
3.21
bridging position
position of a reactor type tap-changer with the selector and transfer contacts being on two
adjacent taps and with the output terminal being electrically in the middle between two
adjacent taps
3.22
non-bridging position
position of a reactor type tap-changer with the selector and transfer contacts being on the
same tap
3.23
circulating current
that part of the current that flows through the transition impedance at the time when two taps
are momentarily bridged during a tap-change operation for a resistor type tap-changer or
when bridged in an operating position for a reactor type tap-changer
Note 1 to entry: The circulating current is due to the voltage difference between the taps.
3.24
switched current
prospective current to be broken during switching operation by each set of main switching or
transition contacts (resistor type tap-changer) or transfer contacts (reactor type tap-changer)
incorporated in the diverter switch or the selector switch

– 12 – IEC 60214-1:2014 © IEC:2014
3.25
recovery voltage
power-frequency voltage which appears across each set of main switching or transition
contacts (resistor type tap-changer) or transfer contacts (reactor type tap-changer) of the
diverter switch or selector switch after these contacts have broken the switched current
3.26
tap-change operation
complete sequence of events from the initiation to the completion of a tap-change from one
service tap position to an adjacent position
3.27
cycle of operation
movement of the tap-changer from one end of its range to the other end and the return to its
original position
3.28
rated insulation level
withstand values of the impulse and applied voltages to earth, and where appropriate between
phases, and between those parts where insulation is required
3.29
rated through-current
I
r
current flowing through an on-load tap-changer towards the external circuit, which the
apparatus is capable of transferring from one tap to the other at the relevant rated step
voltage and which can be carried continuously while meeting the requirements of this
standard
3.30
maximum rated through-current
I
rm
highest rated through-current for which the tap-changer is designed for and all the current
related tests are based on
3.31
rated step voltage
U
ir
for each value of rated through-current, the highest permissible voltage between terminals
which are intended to be connected to successive taps of the transformer
3.32
relevant rated step voltage
highest step voltage permitted in connection with a given rated through-current
3.33
maximum rated step voltage
U
irm
highest value of the rated step voltage for which the tap-changer is designed
3.34
rated frequency
frequency of the alternating current for which the tap-changer is designed
3.35
number of inherent tap positions
highest number of tap positions for half a cycle of operation for which a tap-changer can be
used according to its design
IEC 60214-1:2014 © IEC:2014 – 13 –
Note 1 to entry: The term “tap positions” is generally given as the ± value of the relevant number, for example,
±11 positions. They are in principle also valid for the motor-driven mechanism. When using a “number of tap
positions” in connection with a transformer, this always refers to the number of service tap positions of the
transformer.
3.36
number of service tap positions
number of tap positions for half a cycle of operation for which a tap-changer is used in the
transformer
Note 1 to entry: The term “tap position” is generally given as the ± values of the relevant number, for example,
±11 positions. They are in principle also valid for the motor-driven mechanism. When using the term “number of tap
positions” in connection with a transformer, this always refers to the number of service tap positions of the
transformer.
3.37
type test
test made on a tap-changer which is representative of other tap-changers, to demonstrate that
these tap-changers comply with the specified requirements not covered by the routine tests: a
tap-changer is considered to be representative of others if it is built to the same drawings
using the same techniques and same materials
Note 1 to entry: In general a type test can be carried out on a tap-changer or th
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