EN 60214-1:2003

SLOVENSKI SIST EN 60214-1:2004

STANDARD
februar 2004
Tap-changers - Part 1: Performance requirements and test methods (IEC 60214-
1:2003)
ICS 29.180 Referenčna številka
©  Standard je založil in izdal Slovenski inštitut za standardizacijo. Razmnoževanje ali kopiranje celote ali delov tega dokumenta ni dovoljeno

EUROPEAN STANDARD EN 60214-1
NORME EUROPÉENNE
EUROPÄISCHE NORM April 2003
ICS 29.180 Supersedes EN 60214:1997

English version
Tap-changers
Part 1: Performance requirements and test methods
(IEC 60214-1:2003)
Changeurs de prises Stufenschalter
Partie 1: Prescriptions de performances Teil 1: Leistungsanforderungen
et méthodes d'essai und Prüfverfahren
(CEI 60214-1:2003) (IEC 60214-1:2003)

This European Standard was approved by CENELEC on 2003-03-01. 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 Central Secretariat 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 Central Secretariat has the same status as the official versions.

CENELEC members are the national electrotechnical committees of Austria, Belgium, Czech Republic,
Denmark, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Luxembourg, Malta,
Netherlands, Norway, Portugal, Slovakia, Spain, Sweden, Switzerland and United Kingdom.

CENELEC
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung

Central Secretariat: rue de Stassart 35, B - 1050 Brussels

© 2003 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.

Ref. No. EN 60214-1:2003 E
Foreword
The text of document 14/457/FDIS, future edition 1 of IEC 60214-1, prepared by IEC TC 14, Power
transformers, was submitted to the IEC-CENELEC parallel vote and was approved by CENELEC as
EN 60214-1 on 2003-03-01.
This European Standard supersedes EN 60214:1997.

The following dates were fixed:

– latest date by which the EN has to be implemented
at national level by publication of an identical
national standard or by endorsement (dop) 2003-12-01

– latest date by which the national standards conflicting
with the EN have to be withdrawn (dow) 2006-03-01

Annexes designated "normative" are part of the body of the standard.
Annexes designated "informative" are given for information only.
In this standard, annexes A, B, C and ZA are normative and annex D is informative.
Annex ZA has been added by CENELEC.
__________
Endorsement notice
The text of the International Standard IEC 60214-1:2003 was approved by CENELEC as a European
Standard without any modification.
__________
- 3 - EN 60214-1:2003
Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications
This European Standard incorporates by dated or undated reference, provisions from other
publications. These normative references are cited at the appropriate places in the text and the
publications are listed hereafter. For dated references, subsequent amendments to or revisions of any
of these publications apply to this European Standard only when incorporated in it by amendment or
revision. For undated references the latest edition of the publication referred to applies (including
amendments).
NOTE When an international publication has been modified by common modifications, indicated by (mod), the relevant
EN/HD applies.
Publication Year Title EN/HD Year
IEC 60060 Series High-voltage test techniques EN 60060 Series

IEC 60076-1 1993 Power transformers EN 60076-1 1997
(mod) Part 1: General A11 1997
A1 1999 A1 2000
A12 2002
IEC 60076-3 2000 Part 3: Insulation levels, dielectric tests EN 60076-3 2001
+ corr. December 2000 and external clearances in air

1)
IEC 60137 - Insulated bushings for alternating - -
voltages above 1 000 V
1)
IEC 60214-2 - Tap changers - -
Part 2: Application guide
2) 3)
IEC 60270 - High-voltage test techniques - Partial EN 60270 2001
discharge measurements
2)
IEC 60296 - Specification for unused mineral - -
insulating oils for transformers and
switchgear
2)
IEC 60354 - Loading guide for oil-immersed power - -
transformers
2) 3)
IEC 60529 - Degrees of protection provided by EN 60529 1991
enclosures (IP Code) + corr. May 1993

1)
At draft stage.
2)
Undated reference.
3)
Valid edition at date of issue.

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60214-1 © IEC:2003 – 3 –
CONTENTS
FOREWORD .11
1 Scope .15
2 Normative references.15
3 Terms and definitions .17
4 Service conditions .29
4.1 Temperature of tap-changer environment .29
4.2 Temperature of motor-drive mechanism environment.29
4.3 Overload conditions .29
5 Requirements for on-load tap-changers .29
5.1 General requirements .29
5.1.1 Rating.29
5.1.2 Liquid filled compartments for diverter and selector switches .31
5.1.3 Liquid-level gauges.31
5.1.4 Safety requirements for protection against increase in pressure.31
5.1.5 Limiting devices for the protection against transient overvoltages .33
5.1.6 Change-over selector recovery voltages .33
5.1.7 Coarse fine regulation leakage inductance switching .33
5.2 Type tests.33
5.2.1 Temperature rise of contacts .35
5.2.2 Switching tests.35
5.2.3 Short-circuit current test.41
5.2.4 Transition impedance test .43
5.2.5 Mechanical tests .45
5.2.6 Dielectric tests .49
5.2.7 Type-test certificate .59
5.3 Routine tests .59
5.3.1 Mechanical tests .59
5.3.2 Sequence tests .59
5.3.3 Auxiliary circuits insulation test .59
5.3.4 Pressure and vacuum tests.61
5.4 Special tests.61
5.4.1 General.61
5.4.2 Dielectric discharge tests .61
6 Requirements for motor drive mechanisms for on-load tap-changers .61
6.1 General requirements .61
6.1.1 Compliance of component parts .61
6.1.2 Permissible variation of auxiliary supply.61
6.1.3 Step-by-step control.61
6.1.4 Tap position indicator.61
6.1.5 Tap-change in progress indication .61
6.1.6 Limiting devices .63
6.1.7 Parallel control devices.63
6.1.8 Direction of rotation protection .63

60214-1 © IEC:2003 – 5 –
6.1.9 Overcurrent blocking device.63
6.1.10 Restarting device.63
6.1.11 Operation counter .63
6.1.12 Manual operation of the motor-drive mechanism .63
6.1.13 Motor-drive cubicle .63
6.1.14 Protective device against running-through .63
6.1.15 Protection against access to hazardous parts .65
6.2 Type tests.65
6.2.1 Mechanical load test .65
6.2.2 Overrun test.65
6.2.3 Degree of protection of motor-drive cubicle.65
6.3 Routine tests .65
6.3.1 Mechanical tests .65
6.3.2 Auxiliary circuits insulation test .67
7 Requirements for off-circuit tap-changers .67
7.1 General requirements .67
7.1.1 Rated characteristics .67
7.1.2 Types .67
7.1.3 Handles and drives .67
7.1.4 Glands .67
7.1.5 Interlocks.67
7.1.6 Mechanical end stops .69
7.2 Type tests.69
7.2.1 General.69
7.2.2 Temperature rise of contacts .69
7.2.3 Short-circuit current test.71
7.2.4 Mechanical tests .73
7.2.5 Dielectric tests .73
7.2.6 Type test certificate .77
7.3 Routine tests .77
7.3.1 Mechanical tests .77
7.3.2 Pressure and vacuum tests.77
8 Requirements for motor drive mechanisms for off-circuit tap-changers.79
8.1 General requirements .79
8.1.1 Compliance of component parts .79
8.1.2 Permissible variation of auxiliary supply.79
8.1.3 Tap position indicator.79
8.1.4 Limiting devices .79
8.1.5 Operation counter .79
8.1.6 Manual operation of the motor-drive mechanism .79
8.1.7 Motor-drive cubicle .81
8.1.8 Protection against access to hazardous parts .81
8.2 Type tests.81
8.2.1 Mechanical load test .81
8.2.2 Overrun test.81
8.2.3 Degree of protection of motor-drive cubicle.81

60214-1 © IEC:2003 – 7 –
8.3 Routine tests .83
8.3.1 Mechanical tests .83
8.3.2 Auxiliary circuits insulation test .83
9 Nameplate .83
9.1 Tap-changers (on-load and off-circuit) .83
9.2 Motor-drive mechanisms.83
10 Off-circuit tap-changer warning label.85
11 Manufacturers operating instructions .85
Annex A (normative) Supplementary information on switching duty relating to
resistor type tap-changers.87
Annex B (normative) Supplementary information on switching duty relating
to reactor type tap-changers .93
Annex C (normative) Method for determining the equivalent temperature of the
transition resistor using power pulse current .115
Annex D (informative) Simulated circuits for service duty and breaking capacity tests.117
Figure 1 – Short-circuit test current as a multiple of the maximum rated through-current.43
Figure 2 – Time sequence for the application of test voltage .57
Figure 3 – Short-circuit test current as a multiple of the maximum rated through-current.71
Figure 4 – Warning label .85
Figure A.1 – Current and voltage vectors for resistor type tap-changers.87
Figure B.1 – Operating sequence of reactor type tap-changers with selector switch .95
Figure B.2 – Current and voltage vectors for reactor type tap-changers with
selector switch .97
Figure B.3 – Operating sequence of reactor type tap-changers with selector switch
and equalizer windings.99
Figure B.4 – Current and voltage vectors for reactor type tap-changers with
selector switch and equalizer windings.101
Figure B.5 – Operating sequence of a reactor type tap-changer with diverter switch
and tap selector .105
Figure B.6 – Current and voltage vectors for reactor type tap-changers with diverter
switch and tap selector.107
Figure B.7 – Operating sequence of a reactor type tap-changer with vacuum interrupter
and tap selector .111
Figure B.8 – Current and voltage vectors for reactor type tap-changers with vacuum
interrupter and tap selector .113
Figure D.1 – Simulated test circuit – transformer method .117
Figure D.2 – Simulated test circuit – resistance method .119
Table 1 – Temperature of tap-changer environment .29
Table 2 – Contact temperature-rise limits .35
Table 3 – Classes of on-load tap-changer .49

60214-1 © IEC:2003 – 9 –
Table 4 – Rated withstand voltages – Series I based on European practice .51
Table 5 – Rated withstand voltages – Series II based on North American Practice.53
Table 6 – Contact temperature-rise limits for off-circuit tap-changers .69
Table 7 – Classes of off-circuit tap-changer .75
Table A.1 – Duty on main and transition contacts for resistor type tap-changers .89
Table A.2 – Effect of load power-factor on circuit-breaking duty
for resistor type tap-changers.91
Table B.1 – Duty on switching contacts for reactor type tap-changers with
selector switch – switching direction from P1 to P5 .95
Table B.2 – Duty on switching contacts for reactor type tap-changers with selector
switch and equalizer windings – switching direction from P1 to P5 .99
Table B.3 – Duty on switching contacts for reactor type tap-changers with
diverter switch and tap selector – switching direction from P1 to P7 .103
Table B.4 – Duty on switching contacts for reactor type tap-changers with vacuum
interrupter and tap selector – switching direction from P1 to P11 .109

60214-1 © IEC:2003 – 11 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
___________
TAP-CHANGERS –
Part 1: Performance requirements
and test methods
FOREWORD
1) The IEC (International Electrotechnical Commission) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of the 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, the IEC publishes International Standards. 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. The 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 the 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 National Committees.
3) The documents produced have the form of recommendations for international use and are published in the form
of standards, technical specifications, technical reports or guides and they are accepted by the National
Committees in that sense.
4) In order to promote international unification, IEC National Committees undertake to apply IEC International
Standards transparently to the maximum extent possible in their national and regional standards. Any
divergence between the IEC Standard and the corresponding national or regional standard shall be clearly
indicated in the latter.
5) The IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for any
equipment declared to be in conformity with one of its standards.
6) Attention is drawn to the possibility that some of the elements of this International Standard may be the subject
of patent rights. The 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 first edition of IEC 60214-1 cancels and replaces IEC 60214 published in 1989. This first
edition constitutes a technical revision.
The text of this standard is based on the following documents:
FDIS Report on voting
14/457/FDIS 14/462/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.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
IEC 60214 consists of the following parts, under the general title Tap-changers:
Part 1: Performance requirements and test methods
Part 2: Application guide (under consideration)

60214-1 © IEC:2003 – 13 –
The committee has decided that the contents of this publication will remain unchanged
until 2007. At this date, the publication will be
 reconfirmed;
 withdrawn;
 replaced by a revised edition, or
 amended.
60214-1 © IEC:2003 – 15 –
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, off-
circuit tap-changers, and their motor drive mechanisms. It applies mainly to tap-changers
immersed in transformer oil according to IEC 60296 but may also be used for tap-changers with
gas insulation or immersed in other insulating liquids insofar as conditions are applicable.
It 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 referenced documents are indispensable for the application of this document.
For dated references, only the edition cited applies. For undated references, the latest edition
of the referenced document (including any amendments) applies.
IEC 60060, High voltage test techniques
IEC 60076-1:2000, Power transformers – Part 1: General
IEC 60076-3:2000, Power transformers – Part 3: Insulation levels, dielectric tests and external
clearances in air
IEC 60137, Insulated Bushings for alternating voltages above 1 000 volts
IEC 60214-2, Tap-changers – Part 2: Application guide
IEC 60270, High voltage test techniques – Partial discharge measurements
IEC 60296, Specification for unused mineral insulating oils for transformers and switchgear
IEC 60354, Loading guide for oil-immersed transformers
IEC 60529, Degrees of protection provided by enclosures (IP Code)
___________
To be published.
At present under revision, document currently IEC 60542.

60214-1 © IEC:2003 – 17 –
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
on-load tap-changer
device for changing the tap of a winding, suitable for operation whilst the transformer is
energized or on load
3.2
tap selector
device designed to carry, but not to make or break, current, used in conjunction with a
diverter switch to select tap connections
3.3
diverter switch
switching device used in conjunction with a tap selector to carry, make or break currents in
circuits which have already been selected
NOTE Diverter switches are sometimes called arcing switches.
3.4
selector switch
switching device capable of making, carrying and breaking current, combining the duties of
a tap selector and a diverter switch
NOTE Selector switches are sometimes called arcing tap switches.
3.5
off-circuit tap-changer
device for changing the tap of a winding, suitable for operation only when the transformer is
de-energized
3.6
change-over selector
device designed to carry, but not to make or break, current, used in conjunction with the tap
selector or selector switch to enable its contacts and the connection taps to be used more
than once when moving from one extreme position to the other
3.7
coarse change-over selector
change-over selector connecting the tapped winding to either the coarse winding or the main
winding or parts thereof
3.8
reversing change-over selector
change-over selector connecting either end of the tapped winding to the main winding
3.9
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 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.

60214-1 © IEC:2003 – 19 –
3.10
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
3.11
equalizer winding
winding on the same magnetic circuit (core) as the excitation and tapped winding of a reactor
type regulating transformer with approximately half the number of turns of each tap section
3.12
drive mechanism
means by which the drive to the tap-changer is actuated
NOTE The mechanism may include an independent means of storing energy to control the operation.
3.13
set of contacts
pair of individual fixed and moving contacts or a combination of such pairs operating
substantially simultaneously
3.14
diverter switch and selector switch main contacts (resistor type tap-changer)
set of through-current-carrying contacts which has no transition impedance between the
transformer winding and the contacts and does not switch any current
3.15
diverter switch and selector switch main switching contacts (resistor type tap-changer)
set of contacts which has no transition impedance between the transformer winding and the
contacts and makes and breaks current
3.16
diverter switch and selector switch transition contacts (resistor type tap-changer)
set of contacts which is connected in series with a transition impedance and makes or breaks
current
3.17
transfer contacts (reactor type tap-changer)
set of contacts that makes or breaks current
NOTE Where by-pass contacts are not provided, the transfer contact is a continuous current-carrying contact.
3.18
by-pass contacts (reactor type tap-changer)
set of through-current-carrying contacts that commutates the current to the transfer contacts
without any arc
3.19
bridging contacts
moveable current-carrying contacts that bridge between two fixed contacts when on-position

60214-1 © IEC:2003 – 21 –
3.20
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. The circulating current
is due to the voltage difference between the taps.
3.21
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
3.22
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
3.23
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
3.24
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
3.25
rated insulation level
withstand values of the impulse and separate source AC withstand voltages to earth, and
where appropriate between phases, and between those parts where insulation is required
3.26
rated through-current (I )
u
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
3.27
maximum rated through-current (I )
um
highest rated through-current for which the tap-changer is designed for and which forms the
basis for all current related tests
3.28
rated step voltage (U )
i
for each value of rated through-current, highest permissible voltage between terminals which
are intended to be connected to successive taps of the transformer
3.29
relevant rated step voltage
highest step voltage allowable in connection with a given rated through-current

60214-1 © IEC:2003 – 23 –
3.30
maximum rated step voltage (U )
im
highest value of the rated step voltage for which the tap-changer is designed
3.31
rated frequency
frequency of the alternating current for which the tap-changer is designed
3.32
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
NOTE 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.
3.33
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 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.
3.34
type test
test made on a tap-changer or the components of a tap-changer or a range of tap-changers or
components all based on the same design, to prove compliance with this standard
NOTE A range of tap-changers is a number of tap-changers based on the same design and having the same
characteristics, with the exception of the insulation levels to earth and possibly between phases, the number of
steps and the value of the transition impedance.
3.35
routine test
test made on each completed tap-changer, the design of which has been verified by type test,
to establish that the tap-changer is without manufacturing defects
3.36
motor drive mechanism
driving mechanism which incorporates an electric motor and a control circuit
3.37
step-by-step control of a motor-drive mechanism
device for stopping the motor-drive mechanism after completion of a tap-change,
independently of the operating sequence of the control switch
3.38
tap position indicator
device for indicating the tap position of the tap-changer
3.39
tap-change in progress indicator
device for indicating that the motor-drive mechanism is running

60214-1 © IEC:2003 – 25 –
3.40
limit switches
devices for preventing operation of the tap-changer beyond either end position, but allowing
operation in the opposite direction
3.41
mechanical end stop
device which physically prevents operation of the tap-changer beyond either end position, but
allows operation in the opposite direction
3.42
parallel control devices
control devices to move, in the case of parallel operation of several transformers with taps, all
tap-changers to the required position and to avoid divergence of the respective motor-drive
mechanisms
NOTE Such devices would be necessary also in the case of single-phase transformers forming a three-phase
bank when each single-phase tap-changer is fitted with its own motor-drive mechanisms.
3.43
emergency tripping device
device for stopping the motor-drive mechanism at any time in such a way that a special action
has to be performed before the next tap-change operation can be started
3.44
overcurrent blocking device
device for preventing or interrupting operation of the motor-drive mechanism for the period in
which an overcurrent exceeding a pre-set value is flowing in the transformer winding
NOTE Where diverter switches are actuated by spring energy systems, interruption of the operation of the motor-
drive mechanism will not prevent operation of the diverter switch if the spring release has been actuated.
3.45
restarting device
device designed to restart the motor-drive mechanism after an interruption of the supply
voltage to complete a tap-change operation already initiated
3.46
operation counter
device for indicating the number of tap-changes accomplished
3.47
manual operation of a motor-drive mechanism
operation of the tap-changer manually by a mechanical device, blocking at the same time
operation by the electric motor
3.48
motor-drive cubicle
cubicle that houses the motor-drive mechanism
3.49
protective device against running-through
device that stops the motor-drive mechanism in case of a failure of the step-by-step control
circuit which would cause the motor drive mechanism to run through several tap positions

60214-1 © IEC:2003 – 27 –
3.50
flag cycle
method of performing a tap-change operation in which the through-current is diverted from the
main switching contacts before the circulating current starts to flow
NOTE This cycle requires that the through-current connection is at the midpoint of the transition impedance when
this is carrying the circulating current.
3.51
symmetrical pennant cycle
method of performing a tap-change operation in which the circulating current starts to flow
before the through-current is diverted from the main switching contacts
NOTE This cycle requires that the through-current connection is at the midpoint of the transition impedance when
this is carrying the circulating current.
3.52
asymmetrical pennant cycle
method of performing a tap-change operation in which, in one direction of movement of
the switch, the circulating current starts to flow before the through-current is diverted from the
main switching contacts, while in the other direction of movement the through-current is
diverted before the circulating current starts to flow
NOTE 1 This cycle requires that the through-current connection is at one end of the transition impedance when
this is carrying circulating current.
NOTE 2 Tap-changers employing the asymmetrical pennant cycle are normally used with load flow in one
direction only.
3.53
class I tap-changer
tap-changer only suitable for use at the neutral point of windings
3.54
class II tap-changer
a tap-changer suitable for use at a position other than the neutral point of windings
NOTE Classes I and II tap-changers have no relation with classes I and II transformers described in IEC 60076-3.
3.55
liquid environment tap-changer
tap-changer mounted inside the main transformer tank and immersed in the insulating liquid of
the transformer
3.56
air environment tap-changer
tap-changer mounted in a container outside the main transformer tank and immersed in its
own insulating liquid
3.57
highest voltage for equipment, U
m
highest r.m.s. phase-to-phase voltage in a three-phase system for which a tap-changer is
designed with respect to its insulation
___________
The derivation of the designations ‘flag cycle’ and ‘pennant cycle’ arises from the appearance of the vector
diagrams showing the change in output voltage of the transformer in moving from one tapping to the adjacent
one. In the ‘flag cycle’ the change of voltage comprises four steps, while in the ‘pennant cycle’ only two steps
occur, see Figure A.1.
60214-1 © IEC:2003 – 29 –
4 Service conditions
4.1 Temperature of tap-changer environment
Unless more onerous conditions are specified by the purchaser, tap-changers shall be
regarded as suitable for operation over the ranges of temperature given in Table 1.
Table 1 – Temperature of tap-changer environment
Temperature
Tap-changer environment
Minimum Maximum
Air –25 °C 40 °C
Liquid –25 °C 100 °C
NOTE 1 For the definitions of the tap-changer environments, see 3.55 and 3.56.
NOTE 2 The value of 100 °C quoted above is based on normal rated load and a maximum
ambient temperature of 40 °C as specified in IEC 60076-1.
4.2 Temperature of motor-drive mechanism environment
Unless more onerous conditions are specified by the purchaser, motor drive mechanisms
shall be regarded as suitable for operation in any ambient temperature between –25 °C and
40 °C.
NOTE For more onerous conditions for tap-changer or motor-drive mechanism environments, reference should be
made to IEC 60214-2.
4.3 Overload conditions
Tap-changers which comply with this standard and are selected and installed in accordance
with IEC 60214-2 shall not restrict emergency loading of the transformer according to
IEC 60354, which could result in top oil temperatures as high as 115 °C.
5 Requirements for on-load tap-changers
5.1 General requirements
5.1.1 Rating
5.1.1.1 Rated characteristics
The rated characteristics of an on-load tap-changer are:
– rated through-current;
– maximum rated through current;
– rated step voltage;
– maximum rated step voltage;
– rated frequency;
– rated insulation level.
60214-1 © IEC:2003 – 31 –
5.1.1.2 Interrelation between rated through-current and rated step voltage
Up to the maximum rated through-current of the on-load tap-changer there may be different
assigned combinations of values of rated through-current and corresponding rated step
voltage. When a value of rated step voltage is referred to a specific value of rated through-
current it is called the ‘relevant rated step voltage’.
5.1.2 Liquid filled compartments for diverter and selector switches
The liquid filled compartments for diverter and selector switches shall be liquid-tight. Where
appropriate, pressure and vacuum withstand values shall be declared by the manufacturer.
NOTE If the transformer oil is to be supervised by gas-in-oil analysis, the liquid filled compartment of the diverter
or selector switch should be provided with a liquid conservator which has no connection to the conservator of the
transformer .
5.1.3 Liquid-level gauges
Liquid compartments for diverter or selector switches with integral expansion volume or
separate conservators for these compartments, when fitted, shall be provided with liquid-level
gauges.
5.1.4 Safety requirements for protection against increase in pressure
In order to minimize the risk of fire or explosion resulting from an internal failure within the
diverter or selector switch compartment, one or more of the following protective devices shall
be fitted.
NOTE 1 The tap selector compartments of air environment on-load tap-changers are usually piped to the main
transformer buchholz relay. Consideration should also be given to fitting a separate buchholz relay between the
tap-selector compartment and the conservator.
NOTE 2 For those types of on-load tap-changers that do not create an arc and are installed in sealed
compartments, other protective devices may
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