EN 60076-2:2011

SLOVENSKI STANDARD
01-junij-2011
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SIST EN 60076-2:1997
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Power transformers - Part 2: Temperature rise for liquid-immersed transformers (IEC
60076-2:2011)
Leistungstransformatoren - Teil 2: Übertemperaturen für flüssigkeitsgefüllte
Transformatoren (IEC 60076-2:2011)
Transformateurs de puissance - Partie 2: Echauffement des transformateurs immergés
dans le liquide (CEI 60076-2:2011)
Ta slovenski standard je istoveten z: EN 60076-2:2011
ICS:
29.180 Transformatorji. Dušilke Transformers. Reactors
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD
EN 60076-2
NORME EUROPÉENNE
April 2011
EUROPÄISCHE NORM
ICS 29.180 Supersedes EN 60076-2:1997

English version
Power transformers -
Part 2: Temperature rise for liquid-immersed transformers
(IEC 60076-2:2011)
Transformateurs de puissance -  Leistungstransformatoren -
Partie 2: Echauffement des Teil 2: Übertemperaturen für
transformateurs immergés dans le liquide flüssigkeitsgefüllte Transformatoren
(CEI 60076-2:2011) (IEC 60076-2:2011)

This European Standard was approved by CENELEC on 2011-03-30. 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 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, 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 60076-2:2011 E
Foreword
The text of document 14/669/FDIS, future edition 3 of IEC 60076-2, prepared by IEC TC 14, Power
transformers, was submitted to the IEC-CENELEC parallel vote and was approved by CENELEC as
EN 60076-2 on 2011-03-30.
This European Standard supersedes EN 60076-2:1997.
— the standard is applicable only to liquid immersed transformers;
— the winding hot-spot temperature rise limit was introduced among the prescriptions;
— the modalities for the temperature rise test were improved in relation to the new thermal
requirements;
— five informative annexes were added in order to facilitate the standard application.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN and CENELEC shall not be held responsible for identifying any or all such patent
rights.
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) 2011-12-30
– latest date by which the national standards conflicting
with the EN have to be withdrawn (dow) 2014-03-30
Annex ZA has been added by CENELEC.
__________
Endorsement notice
The text of the International Standard IEC 60076-2:2011 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:
[2] IEC 60296:2003 NOTE  Harmonized as EN 60296:2004 (not modified).
[3] IEC 60567:2005 NOTE  Harmonized as EN 60567:2005 (not modified).
[4] IEC 60599:1999 NOTE  Harmonized as EN 60599:1999 (not modified).
[5] IEC 60836:2005 NOTE  Harmonized as EN 60836:2005 (not modified).
[6] IEC 61099:2010 NOTE  Harmonized as EN 61099:2010 (not modified).
__________
- 3 - EN 60076-2:2011
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 60076-1 (mod) - Power transformers - EN 60076-1 -
Part 1: General
IEC 60076-8 1997 Power transformers - - -
Part 8: Application guide
IEC 60085 2007 Electrical insulation - EN 60085 2008
Thermal evaluation and designation

IEC 61181 2007 Mineral oil-filled electrical equipment - EN 61181 2007
Application of dissolved gas analysis (DGA)
to factory tests on electrical equipment

IEC Guide 115 2007 Application of uncertainty of measurement - -
to conformity assessment activities in the
electrotechnical sector
IEC 60076-2 ®
Edition 3.0 2011-02
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Power transformers –
Part 2: Temperature rise for liquid-immersed transformers

Transformateurs de puissance –
Partie 2: Echauffement des transformateurs immergés dans le liquide

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
CODE PRIX X
ICS 29.180 ISBN 978-2-88912-346-9

– 2 – 60076-2  IEC:2011
CONTENTS
FOREWORD . 4
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 6
4 Cooling methods . 8
4.1 Identification symbols . 8
4.2 Transformers with alternative cooling methods . 9
5 Normal cooling conditions. 9
5.1 Air-cooled transformers . 9
5.2 Water-cooled transformers . 10
6 Temperature rise limits . 10
6.1 General . 10
6.2 Temperature rise limits at rated power . 10
6.3 Modified requirements for special cooling conditions . 12
6.3.1 General . 12
6.3.2 Air-cooled transformers . 12
6.3.3 Water-cooled transformers . 13
6.4 Temperature rise during a specified load cycle . 13
7 Temperature rise tests . 13
7.1 General . 13
7.2 Temperature of the cooling media . 13
7.2.1 Ambient temperature . 13
7.2.2 Water temperature . 14
7.3 Test methods for temperature rise determination . 14
7.3.1 General . 14
7.3.2 Test by short-circuit method for two winding transformers. 14
7.3.3 Test modification for particular transformers . 15
7.4 Determination of liquid temperatures . 16
7.4.1 Top-liquid temperature . 16
7.4.2 Bottom and average liquid temperatures . 17
7.5 Determination of top, average and bottom liquid temperature rises . 18
7.6 Determination of average winding temperature . 18
7.7 Determination of winding resistance at the instant of shutdown . 19
7.8 Determination of average winding temperature rise at the instant of
shutdown . 19
7.9 Determination of the average winding to liquid temperature gradient . 19
7.10 Determination of the hot-spot winding temperature rise . 20
7.10.1 General . 20
7.10.2 Determination by calculation . 20
7.10.3 Direct measurement during the temperature rise test . 20
7.11 Uncertainties affecting the results of the temperature rise test. 21
7.12 Dissolved gas-in-oil analysis . 21
7.13 Corrections. 21
Annex A (informative) Hot-spot winding temperature rise determination for OFAF and
OFWF cooled transformers based on the top-liquid temperature in tank . 23
Annex B (informative) Methods to estimate the hot-spot winding temperature rises. 25

60076-2  IEC:2011 – 3 –
Annex C (informative) Techniques used in temperature rise testing of liquid-immersed
transformers . 30
Annex D (informative) Dissolved gases analysis for the detection of local overheating . 39
Annex E (informative) Application of optical fibre sensors for winding hot-spot
measurements . 43
Bibliography . 47

Figure B.1 – Temperature rise distribution model for ON cooling methods . 26
Figure B.2 – Value of factor Q as a function of rated power and strand height (W) . 27
Figure B.3 – Typical liquid flow paths in a disk winding with diverting washers . 28
Figure C.1 – Recommended circuit for transformers with a low resistance winding
using two separate direct current sources, one for each winding . 32
Figure C.2 – Alternative recommended circuit using only one direct current source for
both windings. 32
Figure C.3 – Average winding temperature variation after shutdown . 33
Figure C.4 – Extrapolation of the cooling down curve, using the fitting curve
−t/T
w
θ (t ) = A − kt+ Be . 38
w 0
Figure E.1 – Optical fibre sensor application for a disk winding of core type transformer . 45
Figure E.2 – Optical fibre sensor application for a transposed cable of core type
transformer . 45
Figure E.3 – Modality of optical fibre sensor application in the winding spacer of core
type transformer . 46
Figure E.4 – Optical fibre sensor application for high voltage winding of shell type
transformer . 46

Table 1 – Temperature rise limits .
...