EN 50708-2-4:2022

SLOVENSKI STANDARD
01-november-2022
Močnostni transformatorji - Dodatne evropske zahteve - 2-4. del: Srednji
močnostni transformatorji - Posebni preskusi
Power transformers - Additional European requirements - Part 2-4: Medium power
transformer - Special tests
Transformateurs de puissance - Exigences européennes supplémentaires - Partie 2-4 :
Transformateurs de moyenne puissance - Essais spéciaux
Ta slovenski standard je istoveten z: EN 50708-2-4:2022
ICS:
29.180 Transformatorji. Dušilke Transformers. Reactors
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD EN 50708-2-4

NORME EUROPÉENNE
EUROPÄISCHE NORM September 2022
ICS 29.180
English Version
Power transformers - Additional European requirements - Part 2-
4: Medium power transformer - Special tests
Transformateurs de puissance - Exigences européennes Leistungstransformatoren - Zusätzliche europäische
supplémentaires - Partie 2-4 : Transformateurs de moyenne Anforderungen - Teil 2-4: Mittelleistungstransformatoren -
puissance - Essais spéciaux Sonderprüfungen
This European Standard was approved by CENELEC on 2022-07-25. 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,
Turkey 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 50708-2-4:2022 E
Contents Page
Contents . 3
European foreword . 4
Introduction . 5
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 6
4 Service conditions . 6
5 Special test for corrugated tank . 6
5.1 General information . 6
5.2 Temperature variation . 6
5.3 Sealing temperature . 7
5.4 Calculation of the liquid volume variation . 7
5.5 Test procedure . 7
5.5.1 General . 7
5.5.2 Measurement of pressure range . 7
5.5.3 Endurance test . 8
5.5.4 Leakage test . 8
5.5.5 Evaluation of the tests . 8
6 Method of measurement of losses on double LV windings . 8
6.1 Introduction . 8
6.2 Limits of this method . 8
6.3 Resistance measurement . 8
6.4 Measurement of load losses and short circuit impedance . 9
Bibliography . 10

European foreword
This document (EN 50708-2-4:2022) has been prepared by CLC/TC 14 “Power transformers”.
The following dates are fixed:
• latest date by which this document has to be (dop) 2023-07-25
implemented at national level by publication of
an identical national standard or by
endorsement
• latest date by which the national standards (dow) 2025-07-25
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 document defines the rules for the assessment of energy performance to ensure the product
conformity to the EU Regulation 548/2014 and amendment of 2019.
Regulation leads to have a minimum level of energy performances of power transformers.
NOTE In the document the term Regulation refers to the EU Regulation 548/2014 and amendment of 2019.
For the purpose of this document, the requirements of EN 50708-1-1 apply.
This document contains particular requirements for specific transformers or transformer applications,
which are based on the requirements of EN 50708-1-1.
This document should be considered in conjunction with the requirements of the general parts.
The particular requirements of the different sub parts of EN 50708 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. 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, as indicated in the normative references of this document (dated
reference).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 the special tests for Medium Power Transformers ≤ 3150 kVA compliant
with the EN 50708-2 series:
— for corrugated tank for liquid immersed transformers,
— for the method of measurement of losses for one winding in Highest Voltage (HV) and windings
in Lowest Voltage (LV) for liquid immersed and dry type transformers.
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 (series), Power transformers — Additional European
...