Converter transformers - Part 1: Transformers for industrial applications

This Part of IEC 61378 deals with the specification, design and testing of power transformers and reactors which are intended for integration within semiconductor converter plants; it is not applicable to transformers designed for industrial or public distribution of a.c. power in general. The scope of this International Standard is limited to application of power converters of any power rating. Typical applications are: thyristor rectifiers for electrolysis; diode rectifiers for electrolysis; thyristor rectifiers for large drives; thyristor rectifiers for scrap melting furnaces, and diode rectifiers feeding inverters for variable speed drives. The standard also covers the regulating unit utilized in such application as step down regulating transformers or autotransformers. The valve winding highest voltage for equipment is limited to 36 kV. This standard is not applicable to transformers for HVDC power transmission. These are highvoltage transformers, and they are subjected to d.c. voltage tests. The standards for the complete converter plant (IEC 60146 series, or other publications dedicated to particular fields of application) may contain requirements of guarantees and tests (such as insulation and power loss) for the whole plant, including the converter transformer and possibly auxiliary transformers and reactor equipment. This does not relieve the application of the requirements of this standard concerning the guarantees and tests applicable to the converter transformer itself as a separate component before being assembled with the remainder of the converter plant. The guarantees, service and type tests defined in this standard apply equally to transformers supplied as part of an overall converter package, or to those transformers ordered separately but for use with converter equipment. Any supplementary guarantee or special verification has to be specifically agreed in the transformer contract. The converter transformers covered by this standard may be of the oil-immersed or dry-type design. Unless specific exceptions are stated in this standard, the transformers comply with IEC 60076 series for oil-immersed transformers, and with IEC 60076-11 for dry-type transformers.

Stromrichtertransformatoren - Teil 1: Transformatoren für industrielle Anwendungen

Transformateurs de conversion - Partie 1: Transformateurs pour applications industrielles

L'IEC 61378-1:2011 traite de la spécification, la conception et l'essai des transformateurs de puissance et des réacteurs qui sont destinés à l'intégration au sein des convertisseurs à semi-conducteurs, il n'est pas applicable aux transformateurs conçus pour la distribution industrielle ou publique de pouvoir a.c. en général. Cette édition inclut les changements techniques significatifs suivants par rapport à la précédente édition:
- Addition de couplages d'enroulements (zigzag, triangle prolongé, etc.) avec déphasage (<30°).
- Addition de transformateurs ayant plus d'une partie active dans la même cuve.
- Changement de la définition de la puissance de référence (elle est désormais basée sur la composante fondamentale du courant).
- Addition de considérations pour des lignes directrices relatives à la sélection de changeurs de prise en charge (OLTC, On-Load Tap-Changers).
- Addition du transformateur de régulation alimentant un transformateur de conversion.
- Addition de considérations relatives à la répartition des courants et aux points chauds dans les enroulements à fort courant pour diverses dispositions d'enroulements.
- Addition de transducteurs magnétiques pour la régulation de tension continue avec des redresseurs à diodes.
- Amélioration des anciennes annexes avec plusieurs exemples de calcul.
- Additions de nouvelles annexes pour les montages de mesure spéciaux.

Konvertorski transformatorji - 1. del: Transformatorji za industrijsko uporabo

Ta del IEC 61378 obravnava specifikacijo, projektiranje in preskušanje močnostnih transformatorjev in reaktorjev za vgradnjo v polprevodniško konvertorsko opremo; ne velja za transformatorje, projektirane za industrijsko ali javno distribucijo izmeničnega toka na splošno. Obseg tega mednarodnega standarda je omejen na uporabo močnostnih pretvornikov vseh nazivnih moči. Tipične uporabe so: tiristorski usmerniki za elektrolizo; diodni usmerniki za elektrolizo; tiristorski usmerniki za velike pogone; tiristorski usmerniki za peči za taljenje starega železa in diodni usmerniki, ki napajajo razsmernike za pogone s spremenljivimi hitrostmi. Standard zajema tudi regulacijsko enoto, ki se uporablja pri teh uporabah za uravnavanje transformatorjev ali avtotransformatorjev z zmanjševanjem napetosti. Najvišja napetost naprave ventilskega navitja je omejena na 36 kV. Ta standard ne velja za transformatorje za visokonapetostni enosmerni prenos toka. To so visokonapetostni transformatorji in zanje veljajo preskusi z enosmerno napetostjo. Standardi za popolno konvertorsko opremo (serija IEC 60146 ali druge objave za posamezna področja uporabe) lahko vsebujejo zahteve za jamstva in preskuse (kot so izolacija in izguba moči) za celotno opremo, vključno s konvertorskim transformatorjem in morebiti pomožnimi transformatorji in reaktorsko opremo. To ne razbremeni uporabe zahtev tega standarda v zvezi z jamstvi in preskusi, ki veljajo za sam konvertorski pretvornik kot ločeno komponento, preden se združi s preostalo konvertorsko opremo. Jamstva, preskusi delovanja in tipski preskusi v tem standardu veljajo enako za transformatorje, dobavljene kot del celotnega konvertorskega paketa, in za transformatorje, naročene ločeno, ki pa se uporabljajo s konvertorsko opremo. O dodatnih jamstvih ali posebnem preverjanju se je treba posebej dogovoriti v pogodbi o transformatorjih. Konvertorski transformatorji, ki jih zajema ta standard, so lahko oljni ali suhi. Razen če so v tem standardu navedene posebne izjeme, so transformatorji v skladu s serijo IEC 60076 za oljne transformatorje in z IEC 60076-11 za suhe transformatorje.

General Information

Status
Published
Publication Date
22-Nov-2011
Technical Committee
Current Stage
6060 - National Implementation/Publication (Adopted Project)
Start Date
16-Nov-2011
Due Date
21-Jan-2012
Completion Date
23-Nov-2011

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SLOVENSKI STANDARD
SIST EN 61378-1:2012
01-januar-2012
Konvertorski transformatorji - 1. del: Transformatorji za industrijsko uporabo
Converter transformers - Part 1: Transformers for industrial applications
Stromrichtertransformatoren - Teil 1: Transformatoren für industrielle Anwendungen
Transformateurs de conversion - Partie 1: Transformateurs pour applications
industrielles
Ta slovenski standard je istoveten z: EN 61378-1:2011
ICS:
29.180 Transformatorji. Dušilke Transformers. Reactors
SIST EN 61378-1:2012 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

---------------------- Page: 1 ----------------------

EUROPEAN STANDARD
EN 61378-1

NORME EUROPÉENNE
November 2011
EUROPÄISCHE NORM

ICS 29.180 Supersedes EN 61378-1:1998 + corr. Nov.1998


English version


Convertor transformers -
Part 1: Transformers for industrial applications
(IEC 61378-1:2011)


Transformateurs de conversion -  Stromrichtertransformatoren -
Partie 1: Transformateurs pour Teil 1: Transformatoren für industrielle
applications industrielles Anwendungen
(CEI 61378-1:2011) (IEC 61378-1:2011)





This European Standard was approved by CENELEC on 2011-08-30. CENELEC members are bound to comply
with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard
the status of a national standard without any alteration.

Up-to-date lists and bibliographical references concerning such national standards may be obtained on
application to the CEN-CENELEC Management Centre or to any CENELEC member.

This European Standard exists in three official versions (English, French, German). A version in any other
language made by translation under the responsibility of a CENELEC member into its own language and notified
to the CEN-CENELEC Management Centre has the same status as the official versions.

CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus,
the Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy,
Latvia, Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia,
Spain, Sweden, Switzerland 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


© 2011 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.
Ref. No. EN 61378-1:2011 E

---------------------- Page: 2 ----------------------

EN 61378-1:2011 - 2 -
Foreword
The text of document 14/686/FDIS, future edition 2 of IEC 61378-1, prepared by IEC/TC 14, "Power
transformers", was submitted to the IEC-CENELEC parallel vote and approved by CENELEC as
EN 61378-1:2011.

The following dates are fixed:
(dop) 2012-05-30
• latest date by which the document has
to be implemented at national level by
publication of an identical national
standard or by endorsement
(dow) 2014-08-30
• latest date by which the national
standards conflicting with the
document have to be withdrawn

This document supersedes EN 61378-1:1998 + corr. Nov.1998.

EN 61378-1:2011 includes the following significant technical changes with respect to EN 61378-1:1998 +
corr. Nov.1998:

• addition of winding connections (zig-zag, extended delta, etc.) with phase displacement (<30º);
• addition of transformers with more than one active part in the same tank;
• change of reference power definition (it is now based on fundamental component of the current);
• addition of considerations for guidelines for OLTC selection;
• addition of regulating transformer feeding converter transformer;
• addition of considerations about current sharing and hot spot temperature in high currentwindings for
various winding arrangements;
• addition of transductors used for d.c. voltage regulation together with diode rectifiers;
• improved old annexes with several calculation examples;
• addition of new annexes for special measurements setups.

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 61378-1:2011 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 60076-4:2002 NOTE  Harmonized as EN 60076-4:2002 (not modified).
IEC 60076-5:2006 NOTE  Harmonized as EN 60076-5:2006 (not modified).
IEC 60076-10:2001 NOTE  Harmonized as EN 60076-10:2001 (not modified).
IEC 60146-1-3:1991 NOTE  Harmonized as EN 60146-1-3:1993 (not modified).
IEC 61378-2:2001 NOTE  Harmonized as EN 61378-2:2001 (not modified).
__________

---------------------- Page: 3 ----------------------

- 3 - EN 61378-1:2011
Annex ZA
(normative)

Normative references to international publications
with their corresponding European publications

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.

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 60050-421 1990 International electrotechnical vocabulary - -
(IEV) -
Chapter 421: Power transformers and
reactors


IEC 60076 Series Power transformers EN 60076 Series

IEC 60076-1 2011 Power transformers - EN 60076-1 2011
Part 1: General


IEC 60076-2 2011 Power transformers - EN 60076-2 2011
Part 2: Temperature rise for liquid-immersed
transformers


IEC 60076-3 2000 Power transformers - EN 60076-3 2001
+ corr. December 2000 Part 3: Insulation levels, dielectric tests and
external clearances in air


IEC 60076-6 2007 Power transformers - EN 60076-6 2008
Part 6: Reactors


IEC 60076-8 1997 Power transformers - - -
Part 8: Application guide


IEC 60076-11 2004 Power transformers - EN 60076-11 2004
Part 11: Dry-type transformers


IEC 60146 Series Semiconductor converters - General EN 60146 Series
requirements and line commutated converters

IEC 60146-1-1 2009 Semiconductor converters - General EN 60146-1-1 2010
requirements and line commutated
converters -
Part 1-1: Specification of basic requirements


IEC/TR 60146-1-2 2011 Semiconductor converters - General - -
requirements and line commutated
converters -
Part 1-2: Application guide


IEC/TR 60616 1978 Terminal and tapping markings for power - -
transformers

---------------------- Page: 4 ----------------------

IEC 61378-1
®

Edition 2.0 2011-07
INTERNATIONAL
STANDARD

colour
inside

Converter transformers –
Part 1: Transformers for industrial applications


INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
PRICE CODE
XC
ICS 29.180 ISBN 978-2-88912-602-6

® Registered trademark of the International Electrotechnical Commission

---------------------- Page: 5 ----------------------

– 2 – 61378-1 © IEC:2011(E)
CONTENTS
FOREWORD . 6
1 Scope . 8
2 Normative references. 9
3 Terms, definitions and acronyms . 9
3.1 Terms and definitions . 9
3.2 Acronyms . 10
4 Classification . 11
4.1 General . 11
4.2 Normal service conditions . 11
4.3 Provision for unusual service conditions . 12
5 Ratings . 12
5.1 General . 12
5.2 Rated power at rated frequency and load capability . 12
5.3 Rated and service voltages . 13
5.3.1 Transformer energized from an a.c. power system . 13
5.3.2 Transformer energized from a converter/inverter with or without
variable frequency . 13
5.4 Rated current . 13
5.5 Phase displacement and terminal identification for three-phase transformer . 13
5.6 Rating plate . 14
5.7 Units with tertiary windings loaded with filter and compensation . 14
5.8 On load tap-changers . 15
6 Load loss and voltage drop in transformers and reactors . 15
6.1 General . 15
6.2 Determination of transformer load loss under distorted current loading . 15
6.3 Current sharing, losses and hot spot in high current windings . 19
6.4 Effect of geometrical winding arrangement and magnetic coupling between
windings on their eddy current losses due to harmonics in transformers with
three or more windings wound on the same core limb . 20
6.5 Losses in interphase transformers, current-balancing reactors, series-
smoothing reactors and transductors . 26
6.5.1 General . 26
6.5.2 Interphase transformers . 26
6.5.3 Current-balancing reactors . 26
6.5.4 Series-smoothing reactors . 26
6.5.5 Transductors . 26
6.6 Voltage drops in transformers and reactors . 27
6.6.1 General . 27
6.6.2 Transductors . 28
7 Tests for converter transformers . 29
7.1 General . 29
7.2 Measurement of commutating reactance and determination of the inductive
voltage drop . 30
7.2.1 Commutating reactance . 30
7.2.2 Inductive voltage regulation . 30
7.3 Measurement of voltage ratio and phase displacement . 31
7.4 Dielectric tests . 31

---------------------- Page: 6 ----------------------

61378-1 © IEC:2011(E) – 3 –
7.4.1 General . 31
7.4.2 Dielectric test between interleaved valve windings . 31
7.5 Load loss test . 32
7.5.1 General . 32
7.5.2 Load loss measurement in rectifier transformers with transductors in
the same tank . 32
7.5.3 Test bus bars configuration for short circuit of high current valve
windings . 32
7.6 Temperature rise tests . 32
7.6.1 General . 32
7.6.2 Total loss injection . 33
7.6.3 Rated load loss injection . 33
7.6.4 Test of temperature rise on dry-type transformers . 35
8 On load noise level with transductors and/or IPT . 35
Annex A (informative) Determination of transformer service load loss at rated non-
sinusoidal converter current from measurements with rated transformer current
of fundamental frequency . 38
Annex B (informative) Short-circuit test currents and load losses in transformers for
single-way converters (total loss injection) . 56
Annex C (informative) Current sharing measurement in high current valve windings . 57
Annex D (informative) Examples of duty cycles . 66
Annex E (informative) Guidelines for design review . 67
Annex F (informative) Determination of loss in transformer tank due to magnetic field.
3D simulation and guidelines for tank losses evaluation and tank hotspot
calculation . 70
Annex G (informative) Short-circuit measurements of rectifier transformers equipped
with built in transductors . 71
Annex H (informative) Determination of the transformer voltage ratio and phase
displacement by the turn ratio measurements . 73
Annex I (informative) Phase displacement connections and terminal indications of
converter transformers . 78
Annex J (normative) Correlation between IEC 61378-1 and IEC 60146-1-1 ratings . 83
Bibliography . 90

Figure 1 – B6U or DB 6 pulse double bridge connection . 10
Figure 2 – DSS 6 pulse connection . 11
Figure 3 – Leakage fields for a three-winding transformer with closely coupled valve
windings. 22
Figure 4 – Leakage fields for a three-winding transformer with decoupled valve
windings. 23
Figure 5 – Leakage fields for a three winding transformer with loosely coupled double
concentric valve windings . 24
Figure 6 – Leakage fields for a three winding transformer with loosely coupled double-
tier valve windings . 25
Figure 7 – Typical transductor regulating curve (with max voltage drop at zero control
current) and tolerance band . 28
Figure A.1 – Cross-section of a winding strand . 40
Figure A.2 – Terminal identification for winding connection Y y0y6 . 43
Figure A.3 – Terminal identification for winding connection D d0y1 . 46

---------------------- Page: 7 ----------------------

– 4 – 61378-1 © IEC:2011(E)
Figure A.4 – Valve current DB connection rectangular shape positive shape . 47
Figure A.5 – Valve current DB connection rectangular shape positive and negative
shape. 48
Figure A.6 – Valve current DSS connection rectangular shape . 52
Figure C.1 – Example of valve high current winding and measurement equipment
disposition . 58
Figure C.2 – Transformer windings arrangement . 59
Figure C.3 – Measurement circuit for the in-phase measurement . 60
Figure C.4 – Measurement circuit for the in-opposition measurement. 61
Figure C.5 – Measurements and comparison with the simulations made by finite
element method software for the in-phase current distribution . 63
Figure C.6 – Measurements and comparison with the simulations made by finite
element method software for the in-opposition current distribution . 65
Figure H.1 – Yd1 connection . 74
Figure H.2 – Yd11 connection . 74
Figure H.3 – Pd0+7,5 connection . 75
Figure H.4 – Oscilloscope connection . 76
Figure H.5 – Oscilloscope with phase B + 7,5° lag referring to phase A . 76
Figure H.6 – Oscilloscope with phase B – 7,5° lead referring to phase A . 77
Figure I.1 – Counterclockwise phase displacement . 78
Figure I.2 – Yd11 connection . 78
Figure I.3 – Yd1 connection . 78
Figure I.4 – Example I.1 phase displacement . 79
Figure I.5 – Example I.2 phase displacement . 79
Figure J.1 – DB connection ideal rectangular current blocks . 83
Figure J.2 – DSS Connection rectangular current blocks . 84


Table 1 – Connections and calculation factors . 36
Table A.1 – Specified harmonic currents and phase displacement in the valve windings . 41
Table A.2 – Resistance measurements at 20 °C winding temperature . 42
Table A.3 – Specified harmonic currents and phase displacement in the line and valve
windings. 45
Table A.4 – Measurements from test report . 46
Table A.5 – Resulting current harmonics . 48
Table A.6 – Resulting current harmonics . 49
Table A.7 – Resulting current harmonics . 50
Table A.8 – Detailed transformer load losses at rated tap position, with tertiary unloaded . 51
Table A.9 – Resulting current harmonics . 52
Table A.10 – Specified harmonic currents and phase displacement in the line and valve
windings. 53
Table A.11 – Resulting current harmonics . 54
Table A.12 – Detailed transformer load losses at rated tap position, with tertiary
unloaded . 55
Table C.1 – Measurements and comparison with the simulations made by finite element
method software for the in-phase current distribution . 62

---------------------- Page: 8 ----------------------

61378-1 © IEC:2011(E) – 5 –
Table C.2 – Measurements and comparison with the simulations made by finite element
method software for the in-opposition current distribution . 64
Table D.1 – Examples of duty cycles for different applications . 66
Table H.1 – Single phase ratio measurements . 73
th
Table J.1 – Harmonics content up to 25 in DB 6 pulse connection (ideal rectangular
current waveshape) . 84
th
Table J.2 – Harmonics content up to 25 in DSS 6 pulse connection (ideal rectangular
current waveshape) . 85
Table J.3 – Calculation factor comparison example . 86
Table J.4 – Calculation factor comparison general factors . 87

---------------------- Page: 9 ----------------------

– 6 – 61378-1 © IEC:2011(E)
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________

CONVERTER TRANSFORMERS –

Part 1: Transformers for industrial applications


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 61378-1 has been prepared by IEC technical committee 14: Power
transformers.
This second edition cancels and replaces the first edition published in 1997. It constitutes a
technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
• addition of winding connections (zig-zag, extended delta, etc.) with phase displacement
(<30º);
• addition of transformers with more than one active part in the same tank;
• change of reference power definition (it is now based on fundamental component of the
current);
• addition of considerations for guidelines for OLTC selection;
• addition of regulating transformer feeding converter transformer;

---------------------- Page: 10 ----------------------

61378-1 © IEC:2011(E) – 7 –
• addition of considerations about current sharing and hot spot temperature in high current
windings for various winding arrangements;
• addition of transductors used for d.c. voltage regulation together with diode rectifiers;
• improved old annexes with several calculation examples;
• addition of new annexes for special measurements setups.
The text of this standard is based on the following documents:
FDIS Report on voting
14/686/FDIS 14/695/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.
A list of all parts of the IEC 61378 series can be found, under the general title Converter
transformers, 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 bilin
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