EN 50708-2-3:2022

Power transformers - Additional European requirements - Part 2-3: Medium power transformer - Accessories

This document describes the list of typical accessories used for liquid and dry type Medium Power Transformers (≤ 3 150 kVA).

Leistungstransformatoren - Zusätzliche europäische Anforderungen - Teil 2-3: Mittelleistungstransformatoren - Zubehör

Transformateurs de puissance - Exigences européennes supplémentaires - Partie 2-3 : Transformateurs de moyenne puissance - Accessoires

Le présent document décrit la liste des accessoires types utilisés pour les transformateurs de moyenne puissance (≤ 3 150 kVA) à diélectrique liquide et de type sec.

Močnostni transformatorji - Dodatne evropske zahteve - 2-3. del: Srednji močnostni transformatorji - Pribor

Ta dokument opisuje sezname tipičnega pribora, ki se uporablja za srednje močnostne transformatorje (≤ 3150 kVA) vlažnega in suhega tipa. Določa vmesnik med terminali transformatorja, vključno s kabelskimi omaricami in električnim omrežjem.

General Information

• Status: Published
• Publication Date: 22-Sep-2022
• ICS: 29.180 - Transformers. Reactors
• Technical Committee: CLC/TC 14 - Power transformers
• Drafting Committee: CLC/TC 14/WG 21 - Revision of HD 428 and HD 538
• Current Stage: 6060 - Document made available - Publishing
• Start Date: 23-Sep-2022
• Due Date: 29-Jul-2022
• Completion Date: 23-Sep-2022
• Ref Project: SIST EN 50708-2-3:2022 - Power transformers - Additional European requirements - Part 2-3: Medium power transformer - Accessories

Relations

• Refers: EN 50180-3:2015 - Bushings above 1 kV up to 52 kV and from 250 A to 3,15 kA for liquid filled transformers - Part 3: Requirements for bushing fixations
• Effective Date: 03-Feb-2026
• Refers: EN 50336:2021 - Bushings for transformers and reactor cable boxes not exceeding 36 kV
• Effective Date: 03-Feb-2026
• Refers: EN IEC 60076-11:2018 - Power transformers - Part 11: Dry-type transformers
• Effective Date: 03-Feb-2026
• Refers: EN 50708-1-2:2021 - Power transformers - Additional European requirements: Part 1-2 Common part - Assessment of energy performance
• Effective Date: 03-Feb-2026
• Refers: EN 50708-2-1:2020 - Power transformers - Additional European requirements: Part 2-1 Medium power transformer - General requirements
• Effective Date: 03-Feb-2026
• Refers: EN 50387:2002 - Busbar bushings up to 1 kV and from 1,25 kA to 5 kA, for liquid filled transformers
• Effective Date: 03-Feb-2026
• Refers: EN 50180-3:2015/A1:2017 - Bushings above 1 kV up to 52 kV and from 250 A to 3,15 kA for liquid filled transformers - Part 3: Requirements for bushing fixations
• Effective Date: 03-Feb-2026
• Refers: EN 50708-1-1:2020 - Power transformers - Additional European requirements: Part 1-1: Common part - General requirements
• Effective Date: 03-Feb-2026
• Refers: EN 50180-1:2015 - Bushings above 1 kV up to 52 kV and from 250 A to 3,15 kA for liquid filled transformers - Part 1: General requirements for bushings
• Effective Date: 03-Feb-2026
• Refers: EN 50386:2010 - Bushings up to 1 kV and from 250 A to 5 kA, for liquid filled transformers
• Effective Date: 03-Feb-2026
• Refers: EN 50180-2:2015 - Bushings above 1 kV up to 52 kV and from 250 A to 3,15 kA for liquid filled transformers - Part 2: Requirement for bushing components
• Effective Date: 03-Feb-2026
• Refers: EN IEC 60076-22-7:2020 - Power transformers - Part 22-7: Power transformer and reactor fittings - Accessories and fittings
• Effective Date: 03-Feb-2026

Overview

EN 50708-2-3:2022 is a European standard developed by the European Committee for Electrotechnical Standardization (CENELEC/CLC), focusing on medium power transformers with a rated power not exceeding 3,150 kVA. This part of the EN 50708 series defines the requirements for typical accessories used with both liquid-immersed and dry-type medium power transformers. The standard ensures that these accessories meet additional European requirements beyond general transformer standards, supporting safety, performance, and interoperability across diverse applications.

Key Topics

• Scope of Accessories: EN 50708-2-3:2022 presents a comprehensive list of standard accessories for medium power transformers, tailored to both liquid-immersed and dry-type designs.
• Types of Accessories: The main accessories include tap changers, rating plates, lifting devices, filling holes and plugs, wheels or skid chassis, various bushings, oil level indicators, and earthing terminals. For liquid-immersed transformers, components like oil level indicators and breathing devices are emphasized, while dry-type transformers focus on clear terminal markings and enclosures.
• Design and Installation Requirements: The standard details installation practices and physical characteristics, such as terminal markings (in line with IEC/TR 60616), wheel specifications (from EN IEC 60076-22-7), and distances between bushings (referencing EN 50336). This ensures compatibility and ease of maintenance.
• Compliance with General Standards: EN 50708-2-3:2022 is intended to be used alongside general transformer standards such as EN 50708-1-1 and EN IEC 60076 series, ensuring a harmonized technical framework.
• Normative References: The standard references a set of related European and international standards for bushings, fittings, cable boxes, and enclosures, promoting adherence to proven engineering practices.

Applications

EN 50708-2-3:2022 has practical value for various stakeholders in the electrical power industry, including:

• Transformer Manufacturers: Ensures that manufacturers equip medium power transformers with the required and compatible accessories as per European regulations. This reduces procurement and installation complexity for end-users.
• Utilities and Network Operators: Supports safe and standardized installation, operation, and maintenance of transformers, enhancing reliability and reducing downtime in power distribution networks.
• Design and Engineering Consultancies: Facilitates specification and tendering processes for public and private infrastructure projects by defining clear, standardized accessory requirements.
• Maintenance Teams: Makes maintenance easier by standardizing the layout and functionality of accessories such as lifting devices, wheels, and terminal markings, which helps in routine inspections and interventions.
• Export/Import Compliance: Aligns transformer accessory requirements across European markets, fostering easier trade and regulatory acceptance within the EU and associated countries.

Related Standards

The following standards are referenced in EN 50708-2-3:2022 and provide additional guidelines or complementary requirements:

• EN 50708-1-1:2020 – Power transformers - General requirements; forms the foundation for the current document.
• EN IEC 60076 (all parts) – Addresses general transformer design, testing, insulation, and other technical criteria.
• EN 50180 / EN 50386 / EN 50387 / EN 50336 – Define requirements for bushings at various voltages and currents.
• EN IEC 60076-11 – Applies specifically to dry-type transformers.
• EN IEC 60076-22-7:2020 – Outlines fittings and accessories for power transformers and reactors.
• IEC/TR 60616 – Specifies terminal and tapping markings for transformers.
• EN 60529 – Specifies degrees of protection provided by enclosures (IP Code).

Conclusion

EN 50708-2-3:2022 provides a unified approach for specifying, installing, and maintaining accessories for medium power transformers across Europe. By adhering to this standard, organizations can ensure safety, ease of maintenance, and regulatory compliance, supporting reliable and efficient power distribution networks. For those involved in transformer procurement, engineering, or maintenance, understanding and applying the accessory requirements of EN 50708-2-3 is essential for achieving operational excellence and compatibility in European markets.

Standards Content (Sample)

SLOVENSKI STANDARD
01-november-2022
Močnostni transformatorji - Dodatne evropske zahteve - 2-3. del: Srednji
močnostni transformatorji - Pribor
Power transformers - Additional European requirements - Part 2-3: Medium power
transformer - Accessories
Transformateurs de puissance - Exigences européennes supplémentaires - Partie 2-3 :
Transformateurs de moyenne puissance - Accessoires
Ta slovenski standard je istoveten z: EN 50708-2-3:2022
ICS:
29.180 Transformatorji. Dušilke Transformers. Reactors
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD EN 50708-2-3

NORME EUROPÉENNE
EUROPÄISCHE NORM September 2022
ICS 29.180
English Version
Power transformers - Additional European requirements -
Part 2-3: Medium power transformer - Accessories
Transformateurs de puissance - Exigences européennes Leistungstransformatoren - Zusätzliche europäische
supplémentaires - Partie 2-3 : Transformateurs de moyenne Anforderungen - Teil 2-3: Mittelleistungstransformatoren -
puissance - Accessoires Zubehör
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 50708-2-3:2022 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 Electrical characteristics . 5
6 Design requirements . 5
6.1 Liquid immersed transformers . 5
6.1.1 Type of liquid preservation system . 5
6.1.2 Terminals . 6
6.1.3 Terminal markings . 6
6.1.4 Distance between bushings . 6
6.1.5 Wheels . 6
6.1.6 Filling hole . 7
6.2 Dry-type transformers . 7
6.2.1 Terminals . 7
6.2.2 Terminal markings . 7
6.2.3 Wheels . 7
6.2.4 Enclosure. 7
7 Accessories . 7
7.1 Liquid immersed transformers . 7
7.2 Dry-type transformers . 9
Bibliography . 10
European foreword
This document (EN 50708-2-3:2022) 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 the accessories.
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 EN 50708
...