EN 50708-3-4:2022

SLOVENSKI STANDARD
01-november-2022
Močnostni transformatorji - Dodatne evropske zahteve - 3-4. del: Veliki močnostni
transformatorji - Posebni preskusi za rezervoarje in hladilnike iz valovite pločevine
Power transformers - Additional European requirements - Part 3-4: Large power
transformer - Special tests for corrugated tank and radiators
Transformateurs de puissance - Exigences européennes supplémentaires: Partie 3-4:
Transformateurs de grande puissance - Essais spéciaux pour cuve ondulée et radiateurs
extensibles
Ta slovenski standard je istoveten z: EN 50708-3-4:2022
ICS:
29.180 Transformatorji. Dušilke Transformers. Reactors
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD EN 50708-3-4

NORME EUROPÉENNE
EUROPÄISCHE NORM September 2022
ICS 29.180
English Version
Power transformers - Additional European requirements -
Part 3-4: Large power transformer - Special tests for corrugated
tank and radiators
Transformateurs de puissance - Exigences européennes Leistungstransformatoren - Zusätzliche europäische
supplémentaires: Partie 3-4: Transformateurs de grande Anforderungen - Teil 3-4: Großleistungstransformatoren -
puissance - Essais spéciaux pour cuve ondulée et Sonderprüfungen für Wellwandkessel und Radiatoren
radiateurs extensibles
This European Standard was approved by CENELEC on 2022-08-15. 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, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Türkiye and the United Kingdom.

European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2022 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.
Ref. No. EN 50708-3-4:2022 E
Contents Page
European foreword . 3
Introduction . 4
1 Scope . 5
2 Normative references . 5
3 Terms and definitions . 5
4 Service conditions . 5
5 Special test for corrugated tank and tank with expandable radiators . 5
5.1 General information . 5
5.2 Temperature variation . 6
5.3 Sealing temperature . 6
5.4 Calculation of the volume variation . 6
5.5 Test procedure . 7
5.5.1 General . 7
5.5.2 Measurement of pressure range . 7
5.5.3 Endurance test . 7
5.5.4 Leakage test . 8
5.5.5 Acceptance criteria . 8
6 Optional additional test . 8
Bibliography . 9
European foreword
This document (EN 50708-3-4:2022) has been prepared by CLC/TC 14 “Power transformers”.
The following dates are fixed:
• latest date by which this document has to be (dop) 2023-08-15
implemented at national level by publication of
an identical national standard or by
endorsement
• latest date by which the national standards (dow) 2025-08-15
conflicting with this document have to be
withdrawn
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. CENELEC shall not be held responsible for identifying any or all such patent rights.
Any feedback and questions on this document should be directed to the users’ national committee. A complete
listing of these bodies can be found on the CENELEC website
Introduction
This part of the EN 50708 series deals with a special test for hermetically sealed transformers.
For the purpose of this document, the requirements of the general EN 50708-1-1:2020 apply.
This document contains particular requirements for specific transformers or transformer applications, which are
based on the requirements of the general EN 50708-1-1:2020.
This document should be considered in conjunction with the requirements of the general parts.
The particular requirements of the different sub parts of the EN 50708 series supplement, modify or replace
certain requirements of the general parts of EN 50708-1 and/or EN 50708-1-X being valid at the time of
publication of this document. The absence of references to the exclusion of a part or a clause of a general part
means that the corresponding clauses of the general part are applicable (undated reference).
Requirements of other -X parts with X greater than 1 being eventually relevant for cases covered by this
document also apply. This document could therefore also supplement, modify or replace certain of these
requirements valid at the time of publication of this document.
The main clause numbering of each part follows the pattern and corresponding references of
EN 50708-1-1:2020. The numbers following the particular number of this document are those of the
corresponding parts, or clauses of the other parts of the EN 50708 series, valid at the time of publication of this
document.
In the case where new or amended general parts with modified numbering were published after the sub part
was issued, the clause numbers referring to a general part in sub parts might no longer align with the latest
edition of the general part. Dated references should be observed.
1 Scope
This document describes a special test for tanks of liquid-immersed transformers which during service are
hermetically sealed and fully filled with liquid and volume change of the liquid due to temperature change
compensated by elastic deformation of the cooling element for Large Power Transformers having a rated power
greater than 3150 kVA.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes
requirements 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.
EN 50708 (all parts), Power transformers — Additional European requirements
EN IEC 60296, Fluids for electrotechnical applications - Mineral insulating oils for electrical equipment
(IEC 60296)
EN 60836, Specifications for unused silicone insulating liquids for electrotechnical purposes
EN 62770, Fluids for electrotechnical applications - Unused natural esters for transformers and similar electrical
equipment (IEC 62770)
EN IEC 63012, Insulating liquids - Unused modified or blended esters for electrotechnical applications (IEC
63012)
IEC 60076-2, Power transformers — Part 2: Temperature rise for liquid-immersed transformers
IEC 60076-7, Power transformers — Part 7: Loading guide for mineral-oil-immersed power transformers
3 Terms and definitions
For the purposes of this document, the terms and definitions given in the EN 50708 (all parts) apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https://www.iso.org/obp
— IEC Electropedia: available at https://www.electropedia.org/
4 Service conditions
Refer to EN 60076-1.
5 Special test for corrugated tank and tank with expandable radiators
5.1 General information
For liquid immersed transformers with corrugated tank or tank with expandable radiators, a special test to ch
...