EN IEC 61558-2-6:2025

Safety of transformers, reactors, power supply units and combinations thereof - Part 2-6: Particular requirements and tests for safety isolating transformers and power supply units incorporating safety isolating transformers for general applications

IEC 61558-2-6:2021 is available as IEC 61558-2-6:2021 RLV which contains the International Standard and its Redline version, showing all changes of the technical content compared to the previous edition.IEC 61558-2-6:2021 deals with the safety of safety isolating transformers for general applications and power supply units incorporating safety isolating transformers for general applications. Transformers incorporating electronic circuits are also covered by this document. This third edition cancels and replaces the second edition published in 2009. This edition constitutes a technical revision. - adjustment of structure and references in accordance with IEC 61558-1:2017; - description of constructions moved in IEC 61558-1:2017; - new symbol for power supply unit with linearly regulated output voltage. It has the status of a group safety publication in accordance with IEC Guide 104. This International Standard is to be used in conjunction with IEC 61558-1:2017.

Sicherheit von Transformatoren, Drosseln, Netzgeräten und deren Kombinationen - Teil 2-6: Besondere Anforderungen und Prüfungen für Sicherheitstransformatoren und Netzgeräten, die Sicherheitstransformatoren enthalten für allgemeine Anwendungen

Sécurité des transformateurs, bobines d'inductance, blocs d'alimentation et produits analogues pour des tensions d'alimentation jusqu'à 1 100 V - Partie 2-6: Règles particulières et essais pour les transformateurs de sécurité et les blocs d'alimentation incorporant des transformateurs de sécurité

IEC 61558-2-6:2021 est disponible sous forme de IEC 61558-2-6:2021 RLV qui contient la Norme internationale et sa version Redline, illustrant les modifications du contenu technique depuis l'édition précédente.

Varnost transformatorjev, dušilk, napajalnikov in kombinacije teh - 2-6. del: Posebne zahteve in preskusi za varnostne ločilne transformatorje in napajalnike z varnostnimi ločilnimi transformatorji za splošno rabo

Ta del standarda IEC 61558 obravnava varnost varnostnih ločilnih transformatorjev za splošno rabo in napajalnikov z varnostnimi ločilnimi transformatorji za splošno rabo. V tem dokumentu so zajeti tudi transformatorji z vgrajenimi elektronskimi vezji.
OPOMBA 1: Varnost vključuje električne, toplotne in mehanske vidike.
Če ni navedeno drugače, od tu dalje izraz »transformator« varnost zajema varnostne ločilne transformatorje za splošno rabo in napajalnike z varnostnimi ločilnimi transformatorji za splošno rabo.
Za linearne napajalnike se uporablja ta dokument. Za stikalne napajalnike se uporablja standard IEC 61558-2-16.
Ta dokument se uporablja za stacionarne ali prenosne, eno- ali večfazne, zračno hlajene (naravno ali umetno) samostojne ali povezane suhe transformatorje. Navitja so lahko enkapsulirana ali neenkapsulirana.
Nazivna napajalna napetost ne presega 1000 V izmenične napetosti, nazivna napajalna frekvenca in notranja obratovalna frekvenca pa ne presegata 500 Hz.
Nazivna izhodna moč ne presega:
• 10 kVA za enofazne transformatorje; • 16 kVA za večfazne transformatorje.
Ta dokument se uporablja za transformatorje brez omejitev nazivne izhodne moči, o čemer se dogovorita kupec in proizvajalec.
OPOMBA 2: V to področje uporabe niso vključeni transformatorji, namenjeni napajanju razdelilnih omrežij.
Izhodna napetost brez obremenitve ali nazivna izhodna napetost ne presega 50 V izmenične napetosti oziroma 120 V enosmerne napetosti brez valovitosti.
Ta dokument se ne uporablja za zunanja vezja in njihove sestavne dele, ki so namenjeni za povezavo z vhodnimi in izhodnimi priključki transformatorjev.
OPOMBA 3: Transformatorji, obravnavani v tem dokumentu, se uporabljajo, kadar je v skladu s pravili namestitve ali standardom končnega izdelka potrebna dvojna ali okrepljena izolacija med vezji.
Upošteva se naslednje:
• dodatne zahteve (iz drugih veljavnih standardov, nacionalnih pravil itd.) za transformatorje, ki so namenjeni za uporabo v vozilih, na ladjah in letalih; • ukrepi za zaščito ohišja in sestavnih delov v ohišju pred zunanjimi vplivi, kot so glive, mrčes, termiti, sončno sevanje in zmrzovanje; • različni pogoji za transport, shranjevanje in delovanje transformatorjev; • dodatne zahteve v skladu z drugimi ustreznimi standardi in nacionalnimi pravili, ki lahko veljajo za transformatorje, namenjene za uporabo v posebnih okoljih.
Za prihodnji tehnološki razvoj transformatorjev bo morda treba zvišati zgornjo mejo frekvenc, dotlej pa se ta dokument lahko uporablja kot vodilo.
Ta publikacija skupinske varnosti, ki se osredotoča na varnostne smernice, se uporablja predvsem kot standard o varnosti izdelka za izdelke, ki so omenjeni v okviru publikacije, vendar je namenjena tudi tehničnim odborom pri pripravi publikacij za izdelke, ki so podobni izdelkom, omenjenim v okviru te publikacije skupinske varnosti, skladno z načeli vodil IEC 104 in ISO/IEC 51.
Ena od dolžnosti tehničnega odbora je, da med pripravo publikacij uporablja osnovne varnostne publikacije (BSP) in/ali publikacije skupinske varnosti (GSP), kadar je to primerno.

General Information

• Status: Published
• Publication Date: 13-Mar-2025
• Withdrawal Date: 22-Feb-2022
• ICS: 29.180 - Transformers. Reactors
• Technical Committee: CLC/SR 96 - Small power transformers, reactors, power supply units and similar products
• Drafting Committee: IEC/TC 96 - IEC_TC_96
• Current Stage: 6060 - Document made available - Publishing
• Start Date: 14-Mar-2025
• Completion Date: 14-Mar-2025
• Directive: 2014/35/EU - Directive 2014/35/EU of the European Parliament and of the Council of 26 February 2014 on the harmonisation of the laws of the Member States relating to the making available on the market of electrical equipment designed for use within certain voltage limits
• Mandate: M/511 - Mandate to CEN, CENELEC and ETSI relating to harmonised standards in the field of the Low Voltage Directive
• Ref Project: SIST EN IEC 61558-2-6:2025 - Safety of transformers, reactors, power supply units and combinations thereof - Part 2-6: Particular requirements and tests for safety isolating transformers and power supply units incorporating safety isolating transformers for general applications

Relations

• Replaces: EN 61558-2-6:2009 - Safety of transformers, reactors, power supply units and similar products for supply voltages up to 1 100 V - Part 2-6: Particular requirements and tests for safety isolating transformers and power supply units incorporating safety isolating transformers
• Effective Date: 16-Jul-2019

Overview - EN IEC 61558-2-6:2025 (Safety isolating transformers & PSUs)

EN IEC 61558-2-6:2025 (CLC) is the European adoption of IEC 61558-2-6:2021 and is the third edition replacing EN 61558-2-6:2009. It specifies particular safety requirements and tests for safety isolating transformers and for power supply units (PSUs) incorporating safety isolating transformers intended for general applications. The document covers transformers that include electronic circuits and introduces editorial and technical updates aligned with IEC 61558-1:2017, including a new symbol for power supplies with linearly regulated outputs. This part is to be used together with IEC/EN 61558-1 (general requirements and tests).

Key topics and technical requirements

The standard supplements IEC 61558-1 and focuses on practical test and construction criteria for safety isolating transformers and related PSUs. Major topics include:

• Protection against electric shock and requirements for achieving SELV or equivalent protective measures.
• Insulation and dielectric tests: insulation resistance, dielectric strength and leakage current checks.
• Thermal requirements: heating tests and temperature limits under rated conditions.
• Short-circuit and overload protection requirements and related tests.
• Output characteristics: output voltage and current under load, no-load voltage and short-circuit voltage considerations.
• Mechanical and environmental requirements: mechanical strength, ingress protection (dust/moisture), resistance to heat, fire and tracking, and resistance to rusting.
• Construction and components: internal wiring, terminals, screws, protective earthing provisions, creepage and clearance distances.
• Marking, classification and documentation: symbols, ratings, and required information for safe operation and conformity.

Practical applications and who uses it

EN IEC 61558-2-6 is used by:

• Manufacturers and designers of safety isolating transformers and power supply units for industrial, laboratory, control and consumer equipment.
• Test laboratories and conformity assessment bodies performing type and routine testing.
• Electrical safety engineers and compliance managers preparing technical files for CE marking and national approvals.
• Procurement teams, spec writers and OEMs who need to specify transformer/PSU safety and performance for product integration.

Typical applications include control circuits, SELV supplies, instrumentation, medical-adjacent equipment (where appropriate standards apply), and general-purpose isolated power supplies.

Related standards

• EN/IEC 61558-1 (general requirements and tests) - mandatory companion document.
• IEC 61140 (protective measures), IEC 60364-4-41 (SELV guidance), IEC 60204-1 (control circuit considerations) - referenced for group safety context.
• Other parts of the IEC 61558 series for specific transformer types and applications.

Keywords: EN IEC 61558-2-6:2025, safety isolating transformers, power supply units, transformer safety standard, transformer tests, insulation testing, SELV, IEC 61558.

Standards Content (Sample)

SLOVENSKI STANDARD
01-maj-2025
Nadomešča:
SIST EN 61558-2-6:2010
Varnost transformatorjev, dušilk, napajalnikov in kombinacije teh - 2-6. del:
Posebne zahteve in preskusi za varnostne ločilne transformatorje in napajalnike z
varnostnimi ločilnimi transformatorji za splošno rabo
Safety of transformers, reactors, power supply units and combinations thereof - Part 2-6:
Particular requirements and tests for safety isolating transformers and power supply
units incorporating safety isolating transformers for general applications
Sicherheit von Transformatoren, Drosseln, Netzgeräten und entsprechenden
Kombinationen - Teil 2-6: Besondere Anforderungen und Prüfungen an
Sicherheitstransformatoren und Netzgeräte, die Sicherheitstransformatoren enthalten,
für allgemeine Anforderungen
Sécurité des transformateurs, bobines d'inductance, blocs d'alimentation et produits
analogues pour des tensions d'alimentation jusqu'à 1 100 V - Partie 2-6: Règles
particulières et essais pour les transformateurs de sécurité et les blocs d'alimentation
incorporant des transformateurs de sécurité
Ta slovenski standard je istoveten z: EN IEC 61558-2-6:2025
ICS:
29.180 Transformatorji. Dušilke Transformers. Reactors
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD EN IEC 61558-2-6

NORME EUROPÉENNE
EUROPÄISCHE NORM March 2025
ICS 29.180 Supersedes EN 61558-2-6:2009
English Version
Safety of transformers, reactors, power supply units and
combinations thereof - Part 2-6: Particular requirements and
tests for safety isolating transformers and power supply units
incorporating safety isolating transformers for general
applications
(IEC 61558-2-6:2021)
Sécurité des transformateurs, bobines d'inductance, blocs Sicherheit von Transformatoren, Drosseln, Netzgeräten und
d'alimentation et produits analogues pour des tensions entsprechenden Kombinationen - Teil 2-6: Besondere
d'alimentation jusqu'à 1 100 V - Partie 2-6: Règles Anforderungen und Prüfungen für
particulières et essais pour les transformateurs de sécurité Sicherheitstransformatoren und Netzgeräte, die
et les blocs d'alimentation incorporant des transformateurs Sicherheitstransformatoren enthalten, für allgemeine
de sécurité Anforderungen
(IEC 61558-2-6:2021) (IEC 61558-2-6:2021)
This European Standard was approved by CENELEC on 2021-06-22. 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
© 2025 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.
Ref. No. EN IEC 61558-2-6:2025 E

European foreword
The text of document 96/506/FDIS, future edition 3 of IEC 61558-2-6, prepared by TC 96
"Transformers, reactors, power supply units, and combinations thereof" was submitted to the IEC-
CENELEC parallel vote and approved by CENELEC as EN IEC 61558-2-6:2025.
The following dates are fixed:
• latest date by which the document has to be implemented at national (dop) 2026-03-31
level by publication of an identical national standard or by endorsement
• latest date by which the national standards conflicting with the (dow) 2028-03-31
document have to be withdrawn
This document supersedes EN 61558-2-6:2009 and all of its amendments and corrigenda (if any).
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.
This document is read in conjunction with EN IEC 61558-1:2019.
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.
Endorsement notice
The text of the International Standard IEC 61558-2-6:2021 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 standard indicated:
IEC 61558 series NOTE Approved as EN 61558 series
IEC 60204-1:2016 NOTE Approved as EN 60204-1:2018
Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications
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.
NOTE 1  Where an International Publication has been modified by common modifications, indicated by (mod),
the relevant EN/HD applies.
NOTE 2  Up-to-date information on the latest versions of the European Standards listed in this annex is available
here: www.cencenelec.eu.
Annex ZA of EN IEC 61558-1 is applicable, except as follows:
Add:
Publication Year Title EN/HD Year
IEC 61558-1 2017 Safety of transformers, reactors, power EN IEC 61558-1 2019
supply units and combinations thereof -
Part 1: General requirements and tests

IEC 61558-2-6 ®
Edition 3.0 2021-05
INTERNATIONAL
STANDARD
GROUP SAFETY PUBLICATION
Safety of transformers, reactors, power supply units and combinations thereof –

Part 2-6: Particular requirements and tests for safety isolating transformers and

power supply units incorporating safety isolating transformers for general

applications
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 29.180 ISBN 978-2-8322-9791-9

– 2 – IEC 61558-2-6:2021 © IEC 2021
CONTENTS
FOREWORD . 3
INTRODUCTION . 6
1 Scope . 7
2 Normative references . 8
3 Terms and definitions . 8
4 General requirements . 8
5 General notes on tests . 8
6 Ratings . 8
7 Classification . 9
8 Marking and other information . 9
9 Protection against electric shock . 10
10 Change of input voltage setting . 10
11 Output voltage and output current under load . 10
12 No-load output voltage . 10
13 Short-circuit voltage . 11
14 Heating . 11
15 Short-circuit and overload protection . 12
16 Mechanical strength . 12
17 Protection against harmful ingress of dust, solid objects and moisture . 12
18 Insulation resistance, dielectric strength and leakage current . 12
19 Construction . 12
20 Components . 12
21 Internal wiring . 12
22 Supply connection and other external flexible cable or cords . 12
23 Terminals for external conductors . 12
24 Provisions for protective earthing. 12
25 Screws and connections . 12
26 Creepage distances, clearances and distances through insulation . 12
27 Resistance to heat, fire and tracking . 13
28 Resistance to rusting . 13
Annexes . 14
Bibliography . 15

Table 101 – Symbols indicating the kind of transformer . 10
Table 102 – Output voltage ratio . 11

IEC 61558-2-6:2021 © IEC 2021 – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
SAFETY OF TRANSFORMERS, REACTORS, POWER SUPPLY
UNITS AND COMBINATIONS THEREOF –

Part 2-6: Particular requirements and tests for safety isolating
transformers and power supply units incorporating safety
isolating transformers for general applications

FOREWORD
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