SIST EN 61558-2-14:2013

Safety of transformers, reactors, power supply units and combinations thereof - Part 2-14: Particular requirements and test for variable transformers and power supply units incorporating variable transformers

IEC 61558-2-14:2012 deals with safety of variable transformers for general applications and power supply units incorporating variable transformers for general applications. Transformers incorporating electronic circuits are also covered by this standard. This first edition cancels and replaces the chapter IV of the IEC 60989 published in 1991. It is a technical revision. This edition includes the following significant technical changes with respect to the previous edition:   a) update of the existing text;  b) complete editorial review.  This part has the status of a group safety publication in accordance with IEC Guide 104:2010. The preparation of safety publications and the use of basic safety publications and group safety publications. The attention of National Committees is drawn to the fact that equipment manufacturers and testing organizations may need a transitional period following publication of a new, amended or revised IEC publication in which to make products in accordance with the new requirements and to equip themselves for conducting new or revised tests. It is the recommendation of the committee that the content of this publication be adopted for implementation nationally not earlier than 12 months from the date of publication.

Sicherheit von Transformatoren, Drosseln, Netzgeräten und deren Kombinationen - Teil 2-14: Besondere Anforderungen und Prüfungen für Stelltransformatoren und Netzgeräte, die Stelltransformatoren enthalten

Sécurité des transformateurs, bobines d’inductance, blocs d’alimentation et des combinaisons de ces éléments - Partie 2-14 : Exigences particulières et essais pour les transformateurs variables et les blocs d’alimentation incorporant des transformateurs variables

La CEI 61558-2-14:2012 traite de la sécurité des transformateurs variables pour applications générales et des blocs d'alimentation incorporant des transformateurs variables pour applications générales. Les transformateurs incorporant des circuits électroniques sont également couverts par la présente norme. Cette première édition annule et remplace le chapitre IV de la CEI 60989 parue en 1991. Elle constitue une révision technique. Cette édition inclut les modifications techniques majeures suivantes par rapport à l'édition précédente:  a) mise à jour du texte existant;  b) revue éditoriale complète.  La présente partie a le statut de publication groupée de sécurité conformément au guide CEI 104:2010. The preparation of safety publications and the use of basic safety publications and group safety publications (disponible en anglais seulement). L'attention des Comités Nationaux est attirée sur le fait que les fabricants d'appareils et les organismes d'essai peuvent avoir besoin d'une période transitoire après la publication d'une nouvelle publication CEI, ou d'une publication amendée ou révisée, pour fabriquer des produits conformes aux nouvelles exigences et pour adapter leurs équipements aux nouveaux essais ou aux essais révisés. Le comité recommande que le contenu de cette publication soit entériné au niveau national au plus tôt 12 mois après la date de publication.

Varnost transformatorjev, dušilk, napajalnikov in kombinacij teh elementov - 2-14. del: Posebne zahteve in preskus za spremenljive transformatorje in napajalnike z vgrajenimi spremenljivimi transformatorji

Ta del standarda IEC 61558 obravnava varnost spremenljivih transformatorjev za splošno uporabo in napajalnikov z vgrajenimi spremenljivimi transformatorji za splošno uporabo. V tem standardu so obravnavani transformatorji z vgrajenimi elektronskimi vezji. OPOMBA 1: Varnost vključuje električne, toplotne, mehanske in kemijske vidike. Če ni navedeno drugače, od tu dalje velja, da izraz transformator zajema spremenljive transformatorje za splošno uporabo in napajalnike z vgrajenimi spremenljivimi transformatorji za splošno uporabo. Nazivna napajalna napetost ne presega 1000 V izmeničnega napajanja, nazivna napajalna frekvenca pa ne presega 500 Hz. Ta standard velja za transformatorje in napajalnike (linearne) z notranjimi operativnimi frekvencami do 500 Hz. Ta standard, uporabljen skupaj z 2. do 16. delom za stikalne napajalnike (SMPS), prav tako velja za napajalnike z notranjimi operativnimi frekvencami, ki presegajo 500 Hz. Če sta zahtevi v nasprotju ena z drugo, prevlada natančnejša. Ta del ne velja za transformatorje, obravnavane v standardu IEC 60076-11. Ta del velja za stacionarne ali prenosne, eno- ali večfazne, zračno hlajene (naravno ali umetno) neodvisne ali povezane suhe transformatorje.
– spremenljivi avtotransformatorji in napajalniki z vgrajenimi spremenljivimi avtotransformatorji;
– spremenljivi ločilni transformatorji in napajalniki z vgrajenimi spremenljivimi ločilnimi transformatorji;
– spremenljivi izolirni transformatorji in napajalniki z vgrajenimi spremenljivimi izolirnimi transformatorji;
– spremenljivi varnostni izolirni transformatorji in napajalniki z vgrajenimi spremenljivimi varnostnimi izolirnimi transformatorji. Navitja so lahko enkapsulirana ali neenkapsulirana. Nazivna izhodna moč ne preseže:
– 40 kVA pri enofaznih spremenljivih avtotransformatorjih in napajalnikih
z enofaznimi spremenljivimi avtotransformatorji;
– 200 kVA pri večfaznih spremenljivih avtotransformatorjih in napajalnikih
z večfaznimi spremenljivimi avtotransformatorji;
– 1 kVA pri enofaznih spremenljivih ločilnih transformatorjih in napajalnikih z vgrajenimi enofaznimi spremenljivimi ločilnimi transformatorji;
– 5 kVA pri večfaznih spremenljivih ločilnih transformatorjih in napajalnikih z vgrajenimi večfaznimi spremenljivimi ločilnimi transformatorji;
– 25 kVA pri enofaznih spremenljivih izolirnih transformatorjih in napajalnikih z vgrajenimi enofaznimi spremenljivimi izolirnimi transformatorji;
– 40 kVA pri večfaznih spremenljivih izolirnih transformatorjih in napajalnikih z vgrajenimi večfaznimi spremenljivimi izolirnimi transformatorji;
– 10 kVA pri enofaznih spremenljivih varnostnih izolirnih transformatorjih in napajalnikih z vgrajenimi enofaznimi spremenljivimi varnostnimi izolirnimi transformatorji;
– 16 kVA pri večfaznih spremenljivih varnostnih izolirnih transformatorjih in napajalnikih z vgrajenimi večfaznimi spremenljivimi varnostnimi izolirnimi transformatorji. Ta del velja 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. Za spremenljive avtotransformatorje in napajalnike z vgrajenimi spremenljivimi avtotransformatorji velja naslednje:
– izhodna napetost brez obremenitve ali nazivna izhodna napetost ne preseže 1000 V izmeničnega toka oziroma 1415 V enosmernega toka brez valovitosti;
– nazivna izhodna napetost pri neodvisnih avtotransformatorjih ne preseže 50 V izmeničnega toka ali 120 V enosmernega toka brez valovitosti, ne preseže pa 250 V izmeničnega toka.

General Information

• Status: Published
• Publication Date: 09-May-2013
• ICS: 29.180 - Transformers. Reactors
• Technical Committee: I96 - Imaginarni 96
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 09-May-2013
• Due Date: 14-Jul-2013
• Completion Date: 10-May-2013
• Directive: 2006/95/EC - Directive 2006/95/EC of the European Parliament and of the Council of 12 December 2006 on the harmonisation of the laws of Member States relating to electrical equipment designed for use within certain voltage limits (codified version)
• 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
• Ref Project: EN 61558-2-14:2013 - Safety of transformers, reactors, power supply units and combination thereof - Part 2-14: Particular requirements and tests for variable transformers and power supply units incorporating variable transformers

Relations

• Replaced By: SIST EN IEC 61558-2-14:2025 - Safety of transformers, reactors, power supply units and combinations thereof - Part 2-14: Particular requirements and tests for variable transformers and power supply units incorporating variable transformers for general applications
• Effective Date: 01-May-2025

Overview

EN 61558-2-14:2013 (IEC 61558-2-14:2012) specifies particular safety requirements and test procedures for variable transformers and power supply units incorporating variable transformers for general applications. This part supplements EN/IEC 61558-1 and covers devices that may incorporate electronic circuits. It is a group safety publication intended to harmonize manufacturer, testing and certification practices across CENELEC/IEC members and replaces the earlier chapter IV of IEC 60989 (1991).

Key topics and requirements

The standard focuses on practical electrical safety and testing aspects, including:

• Scope and ratings - intended uses, rated voltages/currents and classification of variable transformers and associated power supplies.
• Marking and documentation - required manufacturer's information, identification and safety labels.
• Protection against electric shock - insulation, earthing and construction measures to reduce shock risk.
• Voltage and current behaviour - tests and limits for output voltage under load, no-load output, short-circuit voltage and change of input-voltage settings.
• Thermal performance and heating - temperature limits, heating tests and allowable operating temperatures for windings and components.
• Short-circuit and overload protection - requirements for protective devices and failure modes.
• Mechanical and environmental robustness - mechanical strength, protection against ingress of dust/moisture (IP considerations) and resistance to corrosion.
• Insulation and leakage - dielectric strength, insulation resistance and leakage current tests.
• Construction and components - wiring, terminal design, creepage/clearance distances, materials and component selection.
• Fire/heat resistance and tracking - requirements to mitigate fire and tracking risks.
• Test specifications, tables and annexes supplement Part 1 where clauses are not modified.

Applications and who uses it

EN 61558-2-14 is essential for:

• Manufacturers and designers of variable transformers, auto-transformers and power supplies with adjustable outputs - to design compliant, safe products.
• Testing laboratories and certification bodies - to perform standardized safety tests and issue conformity reports.
• Quality and compliance teams - for CE marking and to demonstrate alignment with the Low Voltage Directive (LVD) safety objectives.
• Product engineers and procurement - to verify supplier compliance and select appropriate components for systems requiring adjustable voltage control.

Related standards

• EN/IEC 61558-1 (General requirements and tests) - this part must be used together with Part 1.
• The standard aligns with CENELEC/IEC safety frameworks and is a group safety publication; users should follow national implementation timelines and transitional guidance published by CENELEC.

Keywords: EN 61558-2-14:2013, IEC 61558-2-14, variable transformers, safety standard, power supply units, electrical safety, testing requirements, transformer certification.

Standards Content (Sample)

SLOVENSKI STANDARD
01-junij-2013
Varnost transformatorjev, dušilk, napajalnikov in kombinacij teh elementov - 2-14.
del: Posebne zahteve in preskus za spremenljive transformatorje in napajalnike z
vgrajenimi spremenljivimi transformatorji
Safety of transformers, reactors, power supply units and combinations thereof - Part 2-
14: Particular requirements and test for variable transformers and power supply units
incorporating variable transformers
Sécurité des transformateurs, bobines d’inductance, blocs d’alimentation et des
combinaisons de ces éléments - Partie 2-14 : Exigences particulières et essais pour les
transformateurs variables et les blocs d’alimentation incorporant des transformateurs
variables
Ta slovenski standard je istoveten z: EN 61558-2-14:2013
ICS:
29.180 Transformatorji. Dušilke Transformers. Reactors
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD
EN 61558-2-14
NORME EUROPÉENNE
March 2013
EUROPÄISCHE NORM
ICS 29.180
English version
Safety of transformers, reactors, power supply units
and combination thereof -
Part 2-14: Particular requirements and tests for variable transformers
and power supply units incorporating variable transformers
(IEC 61558-2-14:2012)
Sécurité des transformateurs, bobines Sicherheit von Transformatoren, Drosseln,
d’inductance, blocs d’alimentation Netzgeräten und deren Kombinationen -
et des combinaisons de ces éléments - Teil 2-14: Besondere Anforderungen und
Partie 2-14 : Exigences particulières et Prüfungen für Stelltransformatoren
essais pour les transformateurs variables und Netzgeräte, die Stelltransformatoren
et les blocs d’alimentation incorporant des enthalten
transformateurs variables (IEC 61558-2-14:2012)
(CEI 61558-2-14:2012)
This European Standard was approved by CENELEC on 2012-12-27. 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, Former Yugoslav Republic of Macedonia, France, Germany,
Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland,
Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom.

CENELEC
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung

Management Centre: Avenue Marnix 17, B - 1000 Brussels

© 2013 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.
Ref. No. EN 61558-2-14:2013 E
Foreword
The text of document 96/395/FDIS, future edition 1 of IEC 61558-2-14, prepared by IEC/TC 96
"Transformers, reactors, power supply units and combination thereof" was submitted to the
IEC-CENELEC parallel vote and approved by CENELEC as EN 61558-2-14:2013.
The following dates are fixed:
(dop) 2013-09-27
• latest date by which the document has
to be implemented at national level by
publication of an identical national
standard or by endorsement
• latest date by which the national (dow) 2015-12-27
standards conflicting with the
document have to be withdrawn
This standard is to be used in conjunction with EN 61558-1:2005 + A1:2009.

This part supplements or modifies the corresponding clauses in EN 61558-1, so as to convert that
publication into the EN standard: Particular requirements and tests for variable transformers and
power supply units incorporating variable transformers.

A list of all parts of the EN 61558 series, under the general title: Safety of transformers, reactors,
power supply units and combination thereof, can be found on the CENELEC 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 a particular subclause of Part 1 is not mentioned in this part, that subclause applies as far as is
reasonable. Where this part states "addition", "modification" or "replacement", the relevant text of
Part 1 is to be adapted accordingly.

In this part, 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 part, the words in bold are defined in Clause 3.

Subclauses, notes, figures and tables additional to those in Part 1 are numbered starting from 101;
supplementary annexes are entitled AA, BB, etc.

Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CENELEC [and/or CEN] shall not be held responsible for identifying any or all such
patent rights.
This standard covers the Principle Elements of the Safety Objectives for Electrical Equipment
Designed for Use within Certain Voltage Limits (LVD - 2006/95/EC).
Endorsement notice
The text of the International Standard IEC 61558-2-14:2012 was approved by CENELEC as a
European Standard without any modification.
In the Bibliography of EN 61558-1:2005, the following notes have to be added for the standards
indicated:
IEC 60076-11 NOTE Harmonised as EN 60076-11.
IEC 61558-2-16 NOTE Harmonised as EN 61558-2-16.

- 3 - EN 61558-2-14:2013
Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications

The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including any amendments) applies.

NOTE  When an international publication has been modified by common modifications, indicated by (mod), the relevant EN/HD
applies.
Annex ZA of EN 61558-1:2005 is applicable except as follows:

Publication Year Title EN/HD Year
In Annex ZA of EN 61558-1:2005 add:
IEC 61558-1 2005 Safety of power transformers, power EN 61558-1 2005
+ corr. March 2010 supplies, reactors and similar products - + corr. August 2006
+ corr. March 2008 Part 1: General requirements and tests + A1 2009
+ corr. April 2011
+ A1 2009
IEC 61558-2-14 ®
Edition 1.0 2012-11
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
GROUP SAFETY PUBLICATION
PUBLICATION GROUPÉE DE SÉCURITÉ

Safety of transformers, reactors, power supply units and combination thereof –

Part 2-14: Particular requirements and tests for variable transformers and power

supply units incorporating variable transformers

Sécurité des transformateurs, bobines d’inductance, blocs d’alimentation et des

combinaisons de ces éléments –

Partie 2-14: Exigences particulières et essais pour les transformateurs variables

et les blocs d’alimentation incorporant des transformateurs variables

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
CODE PRIX T
ICS 29.180 ISBN 978-2-83220-499-3

– 2 – 61558-2-14 © IEC:2012
CONTENTS
FOREWORD . 3
1 Scope . 6
2 Normative references . 8
3 Terms and definitions . 8
4 General requirements . 9
5 General notes on tests . 9
6 Ratings . 10
7 Classification . 10
8 Marking and other information . 10
9 Protection against electric shock . 12
10 Change of input voltage setting . 12
11 Output voltage and output current under load . 12
12 No-load output voltage . 12
13 Short-circuit voltage . 14
14 Heating . 15
15 Short circuit and overload protection . 15
16 Mechanical strength . 15
17 Protection against harmful ingress of dust, solid objects and moisture . 16
18 Insulation resistance, dielectric strength and leakage current . 16
19 Construction . 16
20 Components . 20
21 Internal wirings . 20
22 Supply connection and other external flexible cables or cords . 20
23 Terminals for external conductors . 20
24 Provision for protective earthing . 20
25 Screws and connections . 21
26 Creepage distances, clearances and distances through insulation . 21
27 Resistance to heat, fire and tracking . 21
28 Resistance to rusting . 21
Annexes . 22
Bibliography . 23

Table 101 – Output voltages difference for auto transformers, separating and safety
isolating transformers . 14
Table 102 – Output voltages difference for isolating transformers . 14
Table 103 – Maximum permitted temperatures of the winding . 15

61558-2-14 © IEC:2012 – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
SAFETY OF TRANSFORMERS, REACTORS,
POWER SUPPLY UNITS AND COMBINATION THEREOF –

Part 2-14: Particular requirements and tests for variable transformers
and power supply units incorporating variable 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
consensus of opinion on the relevant subjects since each technical committee has representation from all
interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
misinterpretation by any end user.
4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
transparently to the maximum extent possible in their national and regional publications. Any divergence
between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
the latter.
5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any
services carried out by independent certification bodies.
6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
members of its technical committees and IEC National Committees for any personal injury, property damage or
other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
Publications.
8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
International standard IEC 61558-2-14 has been prepared by technical committee 96:
Transformers, reactors, power supply units and combination thereof.
This first edition cancels and replaces the chapter IV of the IEC 60989 published in 1991. It is a
technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) update of the existing text;
b) complete editorial review.
– 4 – 61558-2-14 © IEC:2012
The text of this standard is based on the following documents:
FDIS Report on voting
96/395/FDIS 96/398/RVD
Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
This part has the status of a group safety publication in accordance with IEC Guide 104:2010,
The preparation of safety publications and the use of basic safety publications and group
safety publications.
This part is intended to be used in conjunction with the latest edition of IEC 61558-1 and its
amendments. It is based on the second edition (2005) of that standard and its Amendment 1
(2009).
This part supplements or modifies the corresponding clauses in IEC 61558-1, so as to convert
that publication into the IEC standard: Particular requirements and tests for variable
transformers and power supply units incorporating variable transformers.
A list of all parts of the IEC 61558 series, under the general title: Safety of transformers,
reactors, power supply units and combination 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 a particular subclause of Part 1 is not mentioned in this part, that subclause applies as
far as is reasonable. Where this part states "addition", "modification" or "replacement", the
relevant text of Part 1 is to be adapted accordingly.
In this part, 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 part, the words in bold are defined in Clause 3.
Subclauses, notes, figures and tables additional to those in Part 1 are numbered starting from
101; supplementary annexes are entitled AA, BB, etc.
The committee has decided that the contents of this publication will remain unchanged until the
stability date indicated on the IEC web site under "http://webstore.iec.ch" in the data related to
the specific publication. At this date, the publication will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
NOTE The attention of National Committees is drawn to the fact that equipment manufacturers and testing
organizations may need a transitional period following publication of a new, amended or revised IEC publication in
which to make products in accordance with the new requirements and to equip themselves for conducting new or
revised tests.
61558-2-14 © IEC:2012 – 5 –
It is the recommendation of the committee that the content of this publication be adopted for implementation
nationally not earlier than 12 months from the date of publication.

– 6 – 61558-2-14 © IEC:2012
SAFETY OF TRANSFORMERS, REACTORS,
POWER SUPPLY UNITS AND COMBINATION THEREOF –

Part 2-14: Particular requirements and tests for variable transformers
and power supply units incorporating variable transformers

1 Scope
Replacement:
This part of IEC 61558 deals with safety of variable transformers for general applications and
power supply units incorporating variable transformers for general applications.
Transformers incorporating electronic circuits are also covered by this standard.
NOTE 1 Safety includes electrical, thermal, mechanical and chemical aspects.
Unless otherwise specified, from here onward, the term transformer covers variable
transformers for general applications and power supply units incorporating variable
transformers for general applications.
The rated supply voltage does not exceed 1 000 V a.c., and the rated supply frequency
does not exceed 500 Hz.
This standard is applicable to transformers and power supply units (linear) with internal
operational frequencies not exceeding 500 Hz.
This standard used in combination with Part 2-16 for switch mode power supply units
(SMPS) is also applicable to power supplies with internal operational frequencies higher than
500 Hz. Where the two requirements are in conflict the most severe take precedence
This part does not apply to transformers covered by IEC 60076-11.
This part is applicable to stationary or portable, single-phase or polyphase, air-cooled (natural
or forced) independent or associated dry-type transformers.
– variable auto-transformers and power supply units incorporating variable auto-
transformers;
– variable separating transformers and power supply units incorporating variable
separating transformers;
– variable isolating transformers and power supply units incorporating variable isolating
transformers;
– variable safety isolating transformers and power supply units incorporating variable
safety isolating transformers.
The windings may be encapsulated or non-encapsulated.
The rated output does not exceed:
– 40 kVA for single-phase variable auto-transformers and power supply units
incorporating single-phase variable auto-transformers;

61558-2-14 © IEC:2012 – 7 –
– 200 kVA for poly-phase variable auto-transformers and power supply units
incorporating poly-phase variable auto-transformers;
– 1 kVA for single-phase variable separating transformers and power supply units
incorporating single-phase variable separating transformers;
– 5 kVA for poly-phase variable separating transformers and power supply units
incorporating poly-phase variable separating transformers;
– 25 kVA for single-phase variable isolating transformers and power supply units
incorporating single-phase variable isolating transformers;
– 40 kVA for poly-phase variable isolating transformers and power supply units
incorporating poly-phase variable isolating transformers;
– 10 kVA for single-phase variable safety isolating transformers and power supply units
incorporating single-phase variable safety isolating transformers;
– 16 kVA for poly-phase variable safety isolating transformers and power supply units
incorporating poly-phase variable safety isolating transformers.
This part is applicable to transformers without limitation of the rated 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.
For variable auto-transformers and power supply units incorporating variable auto-
transformers:
– the no-load output voltage or the rated output voltage does not exceed 1 000 V a.c. or
1 415 V ripple free d.c.;
– for independent auto-transformers the rated output voltage does exceed 50 V a.c or
120 V ripple-free d.c. but not exceed 250 V a.c. .
NOTE 3 Normally, the variable auto-transformers and power supply units are intended to be associated
with the equipment to provide voltages different from the supply voltage for the functional reasons. The
protection against electric shock can be provided by other features of the equipment, such as the body.
Variable auto-transformers and power supply units incorporating variable auto-
transformers intended to be used by technically skilled or trained personnel are considered as
associated transformers and associated power supply units and may have a rated output
voltage less than 50 V a.c.
For variable separating transformers and power supply units incorporating variable
separating transformers:
– the no-load output voltage or the rated output voltage does not exceed 1 000 V a.c. or
1 415 V ripple free d.c.;
– for portable separating transormers the rated output voltage does exceed 50 V a.c or
120 V ripple-free d.c.;
– covered by this part may only be used where double or reinforced insulation between
circuits is not required by the installation rules or by the end product standard.
NOTE 4 Normally, variable separating transformers and power supply units are intended to be associated with
equipment to provide voltages different from the supply voltage for the functional reasons. The protection against
electric shock can be provided (or completed) by other features of the equipment, such as the body. Parts of
output circuits can be connected to the protective earth.
NOTE 5 Variable separating transformers and power supply units incorporating variable separating
transformers intended to be used by technically skilled or trained personal are considered as associated
transformers and associated power supply units and can have a rated output voltage less than 50 V a.c. or 120
V ripple-free d.c.
For variable isolating transformers and power supply units incorporating variable
isolating transformers:
– 8 – 61558-2-14 © IEC:2012
– the no-load output voltage or the rated output voltage does not exceed 500 V a.c. or
708 V ripple free d.c. The no-load output voltage and the rated output voltage may be
up to 1 000 V a.c. or 1 415 V ripple free d.c. for special applications or in accordance with
national wiring rules;
– for independent isolating transformers the rated output voltage does not exceed
250 V a.c.; .
– are used where double or reinforced insulation between circuits is required by the
installation rules or by the end product standard.
For variable safety isolating transformers and power supply units incorporating safety
isolating transformers:
– the no-load output voltage or the rated output voltage does not exceed 50 V a.c. or
120 V ripple-free d.c.;
– are used where double or reinforced insulation between circuits is required by the
installation rules or by the end product standard.
This part is not applicable to external circuits and their components intended to be connected
to the input terminals and output terminals of the transformers.
NOTE 6 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.) can be necessary;
– measures to protect the enclosure and the components inside the enclosure against external influences such
as fungus, vermin, termites, solar-radiation, and icing are also considered;
– the different conditions for transportation, storage, and operation of the transformers are also be considered;
– additional requirements in accordance with other appropriate standards and national rules can be applicable to
transformers intended for use in special environments, such as tropical environment.
Future technological development of transformers can necessitate a need to increase the
upper limit of the frequencies, until then this part may be used as a guidance document.
2 Normative references
This clause of Part 1 is applicable except as follows.
Addition:
IEC 61558-1:2005, Safety of power transformers, power supplies, reactors and similar products
– Part 1: General requirements and tests
Amendment 1 (2009)
...