EN IEC 61558-2-2:2025
(Main)Safety of transformers, reactors, power supply units and combinations thereof - Part 2-2: Particular requirements and tests for control transformers and power supply units incorporating control transformers
Safety of transformers, reactors, power supply units and combinations thereof - Part 2-2: Particular requirements and tests for control transformers and power supply units incorporating control transformers
This part of IEC 61558 deals with the safety of control transformers and power supply units incorporating control transformers. Transformers incorporating electronic circuits are also covered by this document. NOTE 1 Safety includes electrical, thermal and mechanical aspects. Unless otherwise specified, from here onward, the term transformer covers control transformers and power supply units incorporating control transformers. For power supply units (linear) this document is applicable. For switch mode power supply units IEC 61558-2-16 is applicable together with this document. Where two requirements are in conflict, the most severe take precedence. This document does not apply to transformers covered by IEC 60076-11. This document is applicable to stationary or portable, single-phase or polyphase, air-cooled (natural or forced) independent or associated dry- type transformers. The windings can be encapsulated or non-encapsulated. The rated supply voltage does not exceed 1 000 V AC and the rated supply frequency and the internal operating frequencies do not exceed 500 Hz. The rated thermal output does not exceed: - 25 kVA for single-phase transformers, - 40 kVA for polyphase transformers; This document is applicable to transformers without limitation of the rated thermal output, subject to an agreement between the purchaser and the manufacturer. NOTE 2 Transformers intended to supply distribution networks are not included in the scope. The no-load output voltage or the rated output voltage does not exceed 1 000 V AC or 1 415 V ripple-free DC. For independent transformers the no-load output voltage and / or the rated output voltage is not less than 50 V AC or 120 V ripple-free DC. This document is not applicable to external circuits and their components intended to be connected to the input terminals and output terminals of the transformers. NOTE 3 Transformers covered by this document are only used in applications where double or reinforced insulation between circuits is not required by the installation rules or by the end product standard. NOTE 4 Normally the control transformers are intended to be used with equipment to provide voltages different from the supply voltage for the functional requirements of the equipment. The protection against electric shock may be provided or completed by other features of the equipment, such as the body. Parts of output circuits may be connected to the input circuits or to protective earthing. Attention is drawn to the following: - for transformers intended to be used in vehicles, on board ships, and aircraft, additional requirements (from other applicable standards, national rules, etc.); - measures to protect the enclosure and the components inside the enclosure against external influences such as fungus, vermin, termites, solar-radiation, and icing; - the different conditions for transportation, storage, and operation of the transformers; - additional requirements in accordance with other appropriate standards and national rules may be applicable to transformers intended for use in special environments. Future technological development of transformers may necessitate a need to increase the upper limit of the frequencies. Until then this document may be used as a guidance document. This GROUP SAFETY PUBLICATION focusing on SAFETY guidance is primarily intended to be used as a PRODUCT SAFETY STANDARD for the products mentioned in the scope, but is also intended to be used by TCs in the preparation of publications for products similar to those mentioned in the scope of this GROUP SAFETY PUBLICATION, in accordance with the principles laid down in IEC Guide 104 and lSO/lEC Guide 51. One of the RESPONSIBILITIES of a TC is, wherever applicable, to make use of BSPs and/or GSPs in the preparation of its publications.
Sicherheit von Transformatoren, Drosseln, Netzgeräten und entsprechenden Kombinationen -Teil 2-2: Besondere Anforderungen und Prüfungen für Steuertransformatoren und Netzgeräte, die Steuertransformatoren enthalten
Sécurité des transformateurs, bobines d'inductance, blocs d'alimentation et combinaisons de ces éléments - Partie 2-2: Exigences particulières et essais pour les transformateurs de commande et les blocs d'alimentation qui incorporent des transformateurs de commande
IEC 61558-2-2:2022 est disponible sous forme de IEC 61558-2-2:2022 RLV qui contient la Norme internationale et sa version Redline, illustrant les modifications du contenu technique depuis l'édition précédente. L'IEC 61558-2-2:2022 traite de la sécurité des transformateurs de commande et des blocs d'alimentation qui incorporent des transformateurs de commande. Les transformateurs qui incorporent des circuits électroniques sont également couverts par le présent document. Cette troisième édition annule et remplace la deuxième édition parue en 2007. Cette édition constitue une révision technique. Cette édition inclut les modifications techniques majeures suivantes par rapport à l'édition précédente: - la structure et les références ont été alignées sur l'IEC 61558-1:2017; - un nouveau symbole général a été ajouté pour les transformateurs de commande; - un nouveau symbole a été ajouté pour les blocs d'alimentation dont la régulation de la tension secondaire est linéaire. Il a le statut de publication groupée de sécurité conformément au Guide 104 de l'IEC.
Varnost transformatorjev, dušilk, napajalnikov in kombinacij teh elementov - 2-2. del: Posebne zahteve in preskusi za kontrolne transformatorje in napajalnike s kontrolnimi transformatorji
Ta del standarda IEC 61558 obravnava varnost kontrolnih transformatorjev in napajalnikov s kontrolnimi transformatorji. 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« zajema kontrolne transformatorje in napajalnike s kontrolnimi transformatorji. Za linearne napajalnike se uporablja ta dokument. Za stikalne napajalnike se uporablja standard IEC 61558-2-16 v kombinaciji s tem dokumentom. Če sta zahtevi v nasprotju ena z drugo, ima prednost strožja. Ta dokument se ne uporablja za transformatorje, zajete v standardu IEC 60076-11. 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 toplotna izhodna moč ne presega: – 25 kVA za enofazne transformatorje; – 40 kVA za večfazne transformatorje. Ta dokument se uporablja za transformatorje brez omejitev nazivne toplotne 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 1000 V izmenične napetosti oziroma 1415 V enosmerne napetosti brez valovitosti. Za samostojne transformatorje izhodna napetost brez obremenitve in/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 samo, kadar v skladu s pravili namestitve ali standardom končnega izdelka ni potrebna dvojna ali okrepljena izolacija med vezji. OPOMBA 4: Kontrolni transformatorji se običajno uporabljajo v opremi za zagotovitev napetosti, ki se razlikuje od napajalne napetosti, in sicer zaradi funkcionalnih zahtev opreme. Zaščita pred električnim udarom se lahko zagotovi ali dopolni z drugimi elementi opreme, npr. z ohišjem. Deli izhodnih vezij se lahko povežejo z vhodnimi vezji ali zaščitno ozemljitvijo. 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 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
- 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
- Due Date
- 02-May-2022
- Completion Date
- 14-Mar-2025
Relations
- Effective Date
- 24-Jan-2023
Overview
EN IEC 61558-2-2:2025 is the European adoption of IEC 61558-2-2 and specifies particular safety requirements and tests for control transformers and power supply units incorporating control transformers. It supplements the general rules in EN IEC 61558-1 and covers electrical, thermal and mechanical safety for stationary or portable, single- or polyphase, air‑cooled dry‑type transformers (encapsulated or not). The standard applies mainly to linear power supplies and control transformers used in industrial and equipment control applications; switch‑mode power supplies are covered together with EN IEC 61558-2-16 where applicable.
Key topics and requirements
- Scope and limits: rated supply voltage ≤ 1 000 V AC; rated and internal operating frequencies ≤ 500 Hz. No‑load or rated output voltage ≤ 1 000 V AC or 1 415 V ripple‑free DC. Typical thermal output guidance: ≤ 25 kVA (single‑phase) and ≤ 40 kVA (polyphase), though higher ratings can be agreed between purchaser and manufacturer.
- Safety aspects covered: protection against electric shock, heating, short‑circuit and overload protection, mechanical strength, ingress protection, insulation resistance, dielectric strength and leakage current.
- Construction and components: requirements for internal wiring, terminals, earthing provisions, screws/connections, and resistance to heat, fire and tracking.
- Testing and marking: prescribed tests for no‑load and load voltages, short‑circuit characteristics, heating tests, mechanical and environmental robustness, plus mandatory marking and information.
- Application notes and exclusions: not intended for transformers for distribution networks or for external circuits connected to input/output terminals. Double or reinforced insulation scenarios are outside scope; additional rules apply for transport, storage and special environments (vehicles, ships, aircraft).
- Conflict rule: if requirements conflict between this part and other parts, the most severe requirement takes precedence.
Practical applications
- Design and safety verification of control transformers used in:
- Industrial control panels and motor starters
- Machine tools and automation equipment
- Building management systems and instrumentation
- Linear power supply modules incorporating control transformers
- Basis for type‑testing, production testing and conformity assessment prior to CE marking and market entry in Europe.
Who should use this standard
- Transformer and power supply manufacturers
- Design and electrical safety engineers
- Test laboratories and certification bodies
- Compliance officers, procurement specialists and technical committees preparing related product standards
Related standards
- EN IEC 61558-1 (General requirements and tests)
- EN IEC 61558-2-16 (Switch mode power supply units)
- IEC 60076-11 (power transformers - excluded when applicable)
- IEC 60204-1 and other product/installation standards referenced in annexes
Keywords: EN IEC 61558-2-2:2025, control transformers, power supply units, transformer safety, tests, electrical protection, IEC 61558.
Frequently Asked Questions
EN IEC 61558-2-2:2025 is a standard published by CLC. Its full title is "Safety of transformers, reactors, power supply units and combinations thereof - Part 2-2: Particular requirements and tests for control transformers and power supply units incorporating control transformers". This standard covers: This part of IEC 61558 deals with the safety of control transformers and power supply units incorporating control transformers. Transformers incorporating electronic circuits are also covered by this document. NOTE 1 Safety includes electrical, thermal and mechanical aspects. Unless otherwise specified, from here onward, the term transformer covers control transformers and power supply units incorporating control transformers. For power supply units (linear) this document is applicable. For switch mode power supply units IEC 61558-2-16 is applicable together with this document. Where two requirements are in conflict, the most severe take precedence. This document does not apply to transformers covered by IEC 60076-11. This document is applicable to stationary or portable, single-phase or polyphase, air-cooled (natural or forced) independent or associated dry- type transformers. The windings can be encapsulated or non-encapsulated. The rated supply voltage does not exceed 1 000 V AC and the rated supply frequency and the internal operating frequencies do not exceed 500 Hz. The rated thermal output does not exceed: - 25 kVA for single-phase transformers, - 40 kVA for polyphase transformers; This document is applicable to transformers without limitation of the rated thermal output, subject to an agreement between the purchaser and the manufacturer. NOTE 2 Transformers intended to supply distribution networks are not included in the scope. The no-load output voltage or the rated output voltage does not exceed 1 000 V AC or 1 415 V ripple-free DC. For independent transformers the no-load output voltage and / or the rated output voltage is not less than 50 V AC or 120 V ripple-free DC. This document is not applicable to external circuits and their components intended to be connected to the input terminals and output terminals of the transformers. NOTE 3 Transformers covered by this document are only used in applications where double or reinforced insulation between circuits is not required by the installation rules or by the end product standard. NOTE 4 Normally the control transformers are intended to be used with equipment to provide voltages different from the supply voltage for the functional requirements of the equipment. The protection against electric shock may be provided or completed by other features of the equipment, such as the body. Parts of output circuits may be connected to the input circuits or to protective earthing. Attention is drawn to the following: - for transformers intended to be used in vehicles, on board ships, and aircraft, additional requirements (from other applicable standards, national rules, etc.); - measures to protect the enclosure and the components inside the enclosure against external influences such as fungus, vermin, termites, solar-radiation, and icing; - the different conditions for transportation, storage, and operation of the transformers; - additional requirements in accordance with other appropriate standards and national rules may be applicable to transformers intended for use in special environments. Future technological development of transformers may necessitate a need to increase the upper limit of the frequencies. Until then this document may be used as a guidance document. This GROUP SAFETY PUBLICATION focusing on SAFETY guidance is primarily intended to be used as a PRODUCT SAFETY STANDARD for the products mentioned in the scope, but is also intended to be used by TCs in the preparation of publications for products similar to those mentioned in the scope of this GROUP SAFETY PUBLICATION, in accordance with the principles laid down in IEC Guide 104 and lSO/lEC Guide 51. One of the RESPONSIBILITIES of a TC is, wherever applicable, to make use of BSPs and/or GSPs in the preparation of its publications.
This part of IEC 61558 deals with the safety of control transformers and power supply units incorporating control transformers. Transformers incorporating electronic circuits are also covered by this document. NOTE 1 Safety includes electrical, thermal and mechanical aspects. Unless otherwise specified, from here onward, the term transformer covers control transformers and power supply units incorporating control transformers. For power supply units (linear) this document is applicable. For switch mode power supply units IEC 61558-2-16 is applicable together with this document. Where two requirements are in conflict, the most severe take precedence. This document does not apply to transformers covered by IEC 60076-11. This document is applicable to stationary or portable, single-phase or polyphase, air-cooled (natural or forced) independent or associated dry- type transformers. The windings can be encapsulated or non-encapsulated. The rated supply voltage does not exceed 1 000 V AC and the rated supply frequency and the internal operating frequencies do not exceed 500 Hz. The rated thermal output does not exceed: - 25 kVA for single-phase transformers, - 40 kVA for polyphase transformers; This document is applicable to transformers without limitation of the rated thermal output, subject to an agreement between the purchaser and the manufacturer. NOTE 2 Transformers intended to supply distribution networks are not included in the scope. The no-load output voltage or the rated output voltage does not exceed 1 000 V AC or 1 415 V ripple-free DC. For independent transformers the no-load output voltage and / or the rated output voltage is not less than 50 V AC or 120 V ripple-free DC. This document is not applicable to external circuits and their components intended to be connected to the input terminals and output terminals of the transformers. NOTE 3 Transformers covered by this document are only used in applications where double or reinforced insulation between circuits is not required by the installation rules or by the end product standard. NOTE 4 Normally the control transformers are intended to be used with equipment to provide voltages different from the supply voltage for the functional requirements of the equipment. The protection against electric shock may be provided or completed by other features of the equipment, such as the body. Parts of output circuits may be connected to the input circuits or to protective earthing. Attention is drawn to the following: - for transformers intended to be used in vehicles, on board ships, and aircraft, additional requirements (from other applicable standards, national rules, etc.); - measures to protect the enclosure and the components inside the enclosure against external influences such as fungus, vermin, termites, solar-radiation, and icing; - the different conditions for transportation, storage, and operation of the transformers; - additional requirements in accordance with other appropriate standards and national rules may be applicable to transformers intended for use in special environments. Future technological development of transformers may necessitate a need to increase the upper limit of the frequencies. Until then this document may be used as a guidance document. This GROUP SAFETY PUBLICATION focusing on SAFETY guidance is primarily intended to be used as a PRODUCT SAFETY STANDARD for the products mentioned in the scope, but is also intended to be used by TCs in the preparation of publications for products similar to those mentioned in the scope of this GROUP SAFETY PUBLICATION, in accordance with the principles laid down in IEC Guide 104 and lSO/lEC Guide 51. One of the RESPONSIBILITIES of a TC is, wherever applicable, to make use of BSPs and/or GSPs in the preparation of its publications.
EN IEC 61558-2-2:2025 is classified under the following ICS (International Classification for Standards) categories: 29.180 - Transformers. Reactors. The ICS classification helps identify the subject area and facilitates finding related standards.
EN IEC 61558-2-2:2025 has the following relationships with other standards: It is inter standard links to EN 61558-2-2:2007. Understanding these relationships helps ensure you are using the most current and applicable version of the standard.
EN IEC 61558-2-2:2025 is associated with the following European legislation: EU Directives/Regulations: 2014/35/EU; Standardization Mandates: M/511. When a standard is cited in the Official Journal of the European Union, products manufactured in conformity with it benefit from a presumption of conformity with the essential requirements of the corresponding EU directive or regulation.
You can purchase EN IEC 61558-2-2:2025 directly from iTeh Standards. The document is available in PDF format and is delivered instantly after payment. Add the standard to your cart and complete the secure checkout process. iTeh Standards is an authorized distributor of CLC standards.
Standards Content (Sample)
SLOVENSKI STANDARD
01-maj-2025
Varnost transformatorjev, dušilk, napajalnikov in kombinacij teh elementov - 2-2.
del: Posebne zahteve in preskusi za kontrolne transformatorje in napajalnike s
kontrolnimi transformatorji
Safety of transformers, reactors, power supply units and combinations thereof - Part 2-2:
Particular requirements and tests for control transformers and power supply units
incorporating control transformers
Sicherheit von Transformatoren, Drosseln, Netzgeräten und entsprechenden
Kombinationen – Teil 2-2: Besondere Anforderungen und Prüfungen für
Steuertransformatoren und Netzgeräten, die Steuertransformatoren enthalten
Sécurité des transformateurs, alimentations, bobines d'inductance et produits analogues
- Partie 2-2: Règles particulières et essais pour les transformateurs de commande et les
alimentations incorporant les transformateurs de commande
Ta slovenski standard je istoveten z: EN IEC 61558-2-2:2025
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 61558-2-2
NORME EUROPÉENNE
EUROPÄISCHE NORM March 2025
ICS 29.180 Supersedes EN 61558-2-2:2007
English Version
Safety of transformers, reactors, power supply units and
combinations thereof - Part 2-2: Particular requirements and
tests for control transformers and power supply units
incorporating control transformers
(IEC 61558-2-2:2022)
Sécurité des transformateurs, bobines d'inductance, blocs Sicherheit von Transformatoren, Drosseln, Netzgeräten und
d'alimentation et combinaisons de ces éléments - Partie 2- entsprechenden Kombinationen - Teil 2-2: Besondere
2: Exigences particulières et essais pour les Anforderungen und Prüfungen für Steuertransformatoren
transformateurs de commande et les blocs d'alimentation und Netzgeräten, die Steuertransformatoren enthalten
qui incorporent des transformateurs de commande (IEC 61558-2-2:2022)
(IEC 61558-2-2:2022)
This European Standard was approved by CENELEC on 2024-10-16. 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 61558-2-2:2025 E
European foreword
The text of document 96/548/FDIS, future edition 3 of IEC 61558-2-2, 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 61558-2-2:2025.
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 61558-2-2:2007 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 61558-2-2:2022 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 60076-11:2018 NOTE Approved as EN IEC 60076-11:2018 (not modified)
IEC 60204-1:2016 NOTE Approved as EN 60204-1:2018
IEC 61558 series NOTE Approved as EN 61558 series
IEC 61558-2-13:2022 NOTE Approved as EN IEC 61558-2-13:2025 (not modified)
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 61558-2-16 2021 Safety of transformers, reactors, power EN IEC 61558-2-16 2025
supply units and combinations thereof -
Part 2-16: Particular requirements and
tests for switch mode power supply units
and transformers for switch mode power
supply units for general applications
IEC 61558-2-2 ®
Edition 3.0 2022-10
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
GROUP SAFETY PUBLICATION
PUBLICATION GROUPÉE DE SÉCURITÉ
Safety of transformers, reactors, power supply units and combinations thereof –
Part 2-2: Particular requirements and tests for control transformers and power
supply units incorporating control transformers
Sécurité des transformateurs, bobines d'inductance, blocs d'alimentation et
combinaisons de ces éléments –
Partie 2-2: Exigences particulières et essais pour les transformateurs de
commande et les blocs d'alimentation qui incorporent des transformateurs de
commande
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 29.180 ISBN 978-2-8322-5809-5
– 2 – IEC 61558-2-2:2022 IEC 2022
CONTENTS
FOREWORD . 3
INTRODUCTION . 5
1 Scope . 6
2 Normative references . 7
3 Terms and definitions . 7
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 . 11
12 No-load output voltage . 11
13 Short-circuit voltage . 12
14 Heating . 12
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 . 13
20 Components . 14
21 Internal wiring . 14
22 Supply connection and other external flexible cables or cords . 14
23 Terminals for external conductors . 14
24 Provisions for protective earthing. 14
25 Screws and connections . 14
26 Creepage distances, clearances and distances through insulation . 14
27 Resistance to heat, fire and tracking . 14
28 Resistance to rusting . 14
Annexes . 15
Bibliography . 16
Table 101 – Symbols indicating the kind of transformer . 10
IEC 61558-2-2:2022 IEC 2022 – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
SAFETY OF TRANSFORMERS, REACTORS,
POWER SUPPLY UNITS AND COMBINATIONS THEREOF –
Part 2-2: Particular requirements and tests for control transformers
and power supply units incorporating control transformers
FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote international
co-operation on all questions concerning standardization in the electrical and electronic fields. To this end and
in addition to other activities, IEC publishes International Standards, Technical Specifications, Technical Reports,
Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC Publication(s)”). Their
preparation is entrusted to technical committees; any IEC National Committee interested in the subject dealt with
may participate in this preparatory work. International, governmental and non-governmental organizations liaising
with the IEC also participate in this preparation. IEC collaborates closely with the International Organization for
Standardization (ISO) in accordance with conditions determined by agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
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International standard IEC 61558-2-2 has been prepared by IEC technical committee 96:
Transformers, reactors, power supply units and combinations thereof.
This third edition cancels and replaces the second edition published in 2007. This edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) adjustment of structure and references in accordance with IEC 61558-1:2017;
b) new general symbol for control transformers;
c) new symbol for power supply unit with linearly regulated output voltage.
– 4 – IEC 61558-2-2:2022 IEC 2022
The text of this document is based on the following documents:
Draft Report on voting
96/548/FDIS 96/554/RVD
Full information on the voting for its approval can be found in the report on voting indicated in
the above table.
The language used for the development of this document is English.
This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in
accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement, available
at www.iec.ch/members_experts/refdocs. The main document types developed by IEC are
described in greater detail at www.iec.ch/standardsdev/publications.
It has the status of a group safety publication in accordance with IEC Guide 104.
This document is to be used in conjunction with IEC 61558-1:2017.
This document supplements or modifies the corresponding clauses in IEC 61558-1:2017, so as
to convert that publication into the IEC standard: Particular requirements and tests for control
transformers and power supply units incorporating control transformers.
A list of all parts in the IEC 61558 series published under the general title Safety of
transformers, reactors, power supply units and combinations thereof, can be found on the IEC
website.
Future standards in this series will carry the new general title as cited above. Titles of existing
standards in this series will be updated at the time of the next edition.
Where this document states "addition", "modification" or "replacement", the relevant text of
IEC 61558-1:2017 is to be adopted accordingly.
In this document, the following print types are used:
• requirements proper: in roman type;
• test specifications: in italic type;
• explanatory matter: in smaller roman type.
In the text of this document, the words in bold are defined in Clause 3.
Subclauses, notes, figures and tables additional to those in IEC 61558-1:2017 are numbered
starting from 101; supplementary annexes are entitled AA, BB, etc.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under www.webstore.iec.ch in the data related to the
specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
IEC 61558-2-2:2022 IEC 2022 – 5 –
INTRODUCTION
IEC TC 96 has a group safety function in accordance with IEC Guide 104 for transformers other
than those intended to supply distribution networks, in particular transformers and power supply
units intended to allow the application of protective measures against electric shock as defined
by TC 64, but in certain cases including the limitation of voltage and horizontal safety function
for SELV, in accordance with IEC 60364-4-41.
The group safety function (GSF) is used because of responsibility for example for safety extra-
low voltage (SELV) in accordance with IEC 61140:2016, 5.2.6 and IEC 60364-4-41:2005,
414.3.1 or control circuits in accordance with IEC 6020
...
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