SIST EN 50336:2022

Bushings for transformers and reactor cable boxes not exceeding 36 kV

This document is applicable to insulated bushings, excluding those plug-in bushings specified by EN 50180 series, for use in air insulated, shroud insulated and fully insulated cable boxes for liquid filled transformers and reactors for rated voltages up to 36 kV, and rated currents up to 4 000 A at frequencies from 15 Hz to 60 Hz.

Durchführungen für Kabelanschlusskästen von Transformatoren und Drosselspulen bis 36 kV

Traversées pour boîtes à câbles de transformateurs et bobines d'inductance ne dépassant pas 36 kV

Le présent document s'applique aux traversées isolées à l'exception des traversées de type embrochable spécifiées dans la série EN 50180, destinées à être utilisées dans les boîtes à câbles à isolement dans l'air, à isolement renforcé et totalement isolées des transformateurs remplis de liquide et des bobines d'inductance de tension assignée jusqu'à 36 kV et d'intensité assignée jusqu'à 4 000 A à des fréquences comprises entre 15 Hz et 60 Hz.

Skoznjiki za transformatorje in reaktorska kabelska ohišja do vključno 36 kV

Ta dokument se uporablja za izolirane skoznjike (razen vtičnih skoznjikov, opredeljenih v skupini standardov EN 50180), ki se uporabljajo v zračno izoliranih kabelskih omaricah, kabelskih omaricah, izoliranih z oplaščenjem, in popolnoma izoliranih kabelskih omaricah za tekočinske transformatorje in reaktorje z nazivno napetostjo do 36 kV ter nazivnim tokom do 4000 A pri frekvencah od 15 Hz do 60 Hz.

General Information

• Status: Published
• Public Enquiry End Date: 24-Jan-2021
• Publication Date: 20-Feb-2022
• ICS: 29.080.20 - Bushings
• ICS: 29.180 - Transformers. Reactors
• Technical Committee: IZL - Insulators
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 28-Apr-2021
• Due Date: 03-Jul-2021
• Completion Date: 21-Feb-2022
• Ref Project: EN 50336:2021 - Bushings for transformers and reactor cable boxes not exceeding 36 kV

Relations

• Replaces: SIST EN 50336:2004 - Bushings for transformers and reactor cable boxes not exceeding 36 kV
• Effective Date: 27-Apr-2021

Overview

EN 50336:2021 (CLC/CENELEC) specifies requirements for insulated bushings for transformers and reactor cable boxes with rated voltages up to 36 kV, rated currents up to 4 000 A, and frequencies from 15 Hz to 60 Hz. The standard applies to ceramic and resin (cast/moulded) bushings used in air‑insulated, shroud‑insulated and fully insulated cable boxes for liquid‑filled transformers and reactors. It supersedes earlier editions and aligns with related electrotechnical standards.

Key topics and technical requirements

• Scope & ratings
  • Voltage classes for ceramic insulators: 12 kV, 24 kV, 36 kV (standard selection rules apply).
  • Resin bushings: 12 kV in oil (also usable at 1.1 kV in air).
  • Standard rated currents include values up to 4 000 A (examples: 250, 400, 630, 800, 1 250 … 3 150 A).
• Installation rules
  • Transformer side of the bushing must be fully immersed in insulating liquid; cable box end may be immersed, shrouded, or in air if not exposed to atmosphere.
  • All current‑carrying parts are tin plated per customer requirements.
• Materials, dimensions and marking
  • Tabled conductor diameters, materials (copper/brass) and nut/thread dimensions to match rated currents.
  • Ceramic insulators comply with EN 62155 (glaze brown, glaze not relied on for insulation); permanent manufacturer markings required.
• Tests and type/routine requirements
  • Ceramic and resin bushings follow type and routine tests per EN 60137 plus EN 50336 additions.
  • Resin bushings: temperature‑cycle type test (10 cycles through 10 °C → 105 °C → ambient; 20–30 min per stage).
  • Routine tests include liquid leakage, air leakage, power‑frequency withstand (example: 28 kV for 1 min on resin bushings), and partial discharge per EN 60137.
• Mechanical fittings
  • Specified clamping arrangements and terminal layouts for both transformer and cable box sides (figures and tables define dimensions).

Applications and who uses EN 50336

• Transformer and reactor manufacturers specifying or selecting insulated bushings
• Utility and substation engineers responsible for transformer terminations and cable boxes
• Bushing designers and component suppliers ensuring compliance with voltage/current classes and mechanical interfaces
• Test laboratories performing type and routine testing and quality control
• Procurement/specification writers and maintenance teams evaluating replacement bushings

Related standards

• EN 60137 (Insulated bushings above 1 000 V / IEC 60137)
• EN 62155 (Hollow pressurized/unpressurised ceramic & glass insulators)
• IEC 60296 (Mineral insulating oils)
• EN 50180 series (plug‑in bushings - excluded from this document)

Keywords: bushings for transformers, reactor cable boxes, 36 kV bushings, insulated bushings, EN 50336, bushing tests, transformer terminations, resin bushings, ceramic bushings.

Standards Content (Sample)

SLOVENSKI STANDARD
01-marec-2022
Nadomešča:
SIST EN 50336:2004
Skoznjiki za transformatorje in reaktorska kabelska ohišja do vključno 36 kV
Bushings for transformers and reactor cable boxes not exceeding 36 kV
Durchführungen für Kabelanschlusskästen von Transformatoren und Drosselspulen bis
36 kV
Traversées pour boîtes à câbles de transformateurs et bobines d'inductance ne
dépassant pas 36 kV
Ta slovenski standard je istoveten z: EN 50336:2021
ICS:
29.080.20 Skoznjiki Bushings
29.180 Transformatorji. Dušilke Transformers. Reactors
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD EN 50336
NORME EUROPÉENNE
EUROPÄISCHE NORM
April 2021
ICS 29.080.20; 29.180 Supersedes EN 50336:2002 and all of its amendments
and corrigenda (if any)
English Version
Bushings for transformers and reactor cable boxes not
exceeding 36 kV
Traversées pour boîtes à câbles de transformateurs et Durchführungen für Kabelanschlusskästen von
bobines d'inductance ne dépassant pas 36 kV Transformatoren und Drosselspulen bis 36 kV
This European Standard was approved by CENELEC on 2021-03-30. 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 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
© 2021 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.
Ref. No. EN 50336:2021 E
Contents Page
European foreword . 3
1 Scope . 4
2 Normative references . 4
3 Terms and definitions . 4
4 Requirements . 5
4.1 General requirements . 5
4.2 Ratings . 5
4.2.1 Standard values of rated voltage for ceramic insulators (U ) . 5
r
4.2.2 Standard values of rated voltage for resin-insulated bushings (U ) . 5
r
4.2.3 Standard values of rated current (I ) . 5
r
4.3 Ceramic bushings . 5
4.3.1 General requirements . 5
4.3.2 Clamping arrangements . 6
4.3.3 Terminals . 6
4.4 Resin-insulated bushings . 7
4.4.1 General requirements . 7
4.4.2 Type test (temperature cycle) . 7
4.4.3 Routine tests . 7
5 Ceramic busing dimensions . 8
5.1 Ceramic insulator . 8
5.2 Clamping arrangement for ceramic insulators . 10
5.3 Bushing end terminal arrangement . 11
6 Resin bushing dimensions . 15
Bibliography . 17
European foreword
This document (EN 50336:2021) has been prepared by CLC/TC 36A “Insulated bushings”.
The following dates are fixed:
• latest date by which this document has to be (dop) 2022-03-30
implemented at national level by publication of
an identical national standard or by
endorsement
• latest date by which the national standards (dow) 2024-03-30
conflicting with this document have to be
withdrawn
This document supersedes EN 50336:2002 and all of its amendments and corrigenda (if any).
— 3.1 – Minimum IP rating removed from air filled cable boxes.
— 3.4 and 3.5 – EN 60137 added as a reference specification.
— 4.1 – Clarification that transformer side bushing connection is to be fully immersed in insulating liquid.
— 4.3.1 – EN 62155 referenced as standard rather than HD.
— Table 1 – Material corrected on the 400 and 630A rated items from brass to copper.
— 4.4.2 – Time frame for temperature cycle testing added.
— 4.4.3.3 – Test criteria clarified for applications over 1.1kV.
— Table 2 – Corrected L3 dimension on 36kV bushings from 250 mm - 350 mm.
— Figure 9 / Table 9 – D2 dimension added to show required plain connection size for the range of
terminals.
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.
1 Scope
This document is applicable to insulated bushings, excluding those plug-in bushings specified by
EN 50180 series, for use in air insulated, shroud insulated and fully insulated cable boxes for liquid filled
transformers and reactors for rated voltages up to 36 kV, and rated currents up to 4 000 A at frequencies from
15 Hz to 60 Hz.
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 60137, Insulated bushings for alternating voltages above 1 000 V (IEC 60137)
EN 62155, Hollow pressurized and unpressurized ceramic and glass insulators for use in electrical equipment
with rated voltages greater than 1 000 V (IEC 62155)
IEC 60296, Fluids for electrotechnical applications - Mineral insulating oils for electrical equipment
3 Terms and definitions
For the purposes of this document, the following terms and definitions 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 http://www.electropedia.org/
3.1
air insulated cable box
metallic weatherproof enclosure designed to protect the ends of cables and their associated bushings using
air as the primary source of insulation
3.2
cast or moulded resin-insulated bushing
bushing in which the major insulation consists of a cast or moulded organic material with or without an
inorganic filler
[SOURCE: EN 60137:2017, 3.13]
3.3
ceramic, glass or analogous inorganic material bushing
bushing in which the major insulation consists of a ceramic, glass or analogous inorganic material
[SOURCE: EN 60137:2017, 3.12]
3.4
fully insulated cable box
metallic weatherproof enclosure as in 3.1 where those parts of the termination and bushing within the
enclosure including live metal parts and cable cores are insulated by a liquid or compound suitable for the
appropriate system voltage
Note 1 to entry: The box shall be suitably sealed to contain the liquid or compound and allow for their expansion due to
temperature changes.
3.5
shroud insulated cable box
metallic weatherproof enclosure as in 3.1 but within which the cable cores are terminated with local insulation
enhancement, e.g. phase barrier, bushing protection or taping
4 Requirements
4.1 General requirements
Bushings specified by this document shall be installed with the transformer side of the bushing fully immersed
in insulating liquid and the other end either;
— fully immersed in an insulating liquid;
— or with shrouded insulation in air;
— or in air but not exposed to external atmospheric conditions.
All current-carrying parts shall be tin plated in accordance with customer requirements.
NOTE IEC Guide 109 and EN 62542 provide guidance which could be used to minimize the impact of bushings on
the environment during all phases of their life (including manufacturing, operation during service life, dismantling after their
end life and disposal or recycling).
4.2 Ratings
4.2.1 Standard values of rated voltage for ceramic insulators (U )
r
The value of U of a bushing shall be chosen from the standard values of the highest voltage for transformers
r
and reactors U given below in kilovolts:
m
12 - 24 - 36
— For values of U less than 12kV bushings with U = 12kV shall be chosen
m r
— For values of U greater than 12kV and less than or equal to 24kV bushings with U = 24kV shall be
...