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

IEC 61558-2-14:2022 is available as IEC 61558-2-14:2022 RLV which contains the International Standard and its Redline version, showing all changes of the technical content compared to the previous edition.IEC 61558-2-14:2022 deals with the 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 document. This second edition cancels and replaces the first edition published in 2012. This edition constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition:
- adjustment of structure and references in accordance with IEC 61558-1:2017;
- description of constructions moved to IEC 61558-1:2017;
- new symbols for power supply units with linearly regulated output voltages and required current collector position changes.
It has the status of a group safety publication in accordance with IEC Guide 104.

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 pour applications générales

IEC 61558-2-14:2022 est disponible sous forme de IEC 61558-2-14:2022 RLV qui contient la Norme internationale et sa version Redline, illustrant les modifications du contenu technique depuis l'édition précédente.L'IEC 61558-2-14:2022 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 le présent document. Cette deuxième édition annule et remplace la première édition parue en 2012. Cette édition constitue une révision technique. Cette édition inclut les modifications techniques majeures suivantes par rapport à l'édition précédente:
- ajustement de la structure et des références conformément à l'IEC 61558-1:2017;
- description des constructions déplacées vers l'IEC 61558-1:2017;
- nouveaux symboles pour les blocs d'alimentation avec des tensions secondaires régulées linéairement et modifications de position du collecteur de courant exigées.
Il a le statut de publication groupée de sécurité conformément au Guide IEC 104.

General Information

Status
Published
Publication Date
01-May-2022
Current Stage
PPUB - Publication issued
Completion Date
02-May-2022
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IEC 61558-2-14:2022 - 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
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IEC 61558-2-14
Edition 2.0 2022-05
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
GROUP SAFETY PUBLICATION
PUBLICATION GROUPÉE DE SÉCURITÉ
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
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 pour
applications générales
IEC 61558-2-14:2022-05(en-fr)
---------------------- Page: 1 ----------------------
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---------------------- Page: 2 ----------------------
IEC 61558-2-14
Edition 2.0 2022-05
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
GROUP SAFETY PUBLICATION
PUBLICATION GROUPÉE DE SÉCURITÉ
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
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 pour
applications générales
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 29.180 ISBN 978-2-8322-1104-3

Warning! Make sure that you obtained this publication from an authorized distributor.

Attention! Veuillez vous assurer que vous avez obtenu cette publication via un distributeur agréé.

® Registered trademark of the International Electrotechnical Commission
Marque déposée de la Commission Electrotechnique Internationale
---------------------- Page: 3 ----------------------
– 2 – IEC 61558-2-14:2022  IEC 2022
CONTENTS

FOREWORD ........................................................................................................................... 3

INTRODUCTION ..................................................................................................................... 5

1 Scope .............................................................................................................................. 6

2 Normative references ...................................................................................................... 8

3 Terms and definitions ...................................................................................................... 8

4 General requirements ...................................................................................................... 9

5 General notes on tests .................................................................................................... 9

6 Ratings ............................................................................................................................ 9

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 .................................................................................................................. 16

21 Internal wiring ................................................................................................................ 16

22 Supply connection and other external flexible cables or cords ....................................... 16

23 Terminals for external conductors .................................................................................. 17

24 Provisions for protective earthing................................................................................... 17

25 Screws and connections ................................................................................................ 17

26 Creepage distances, clearances and distances through insulation ................................. 17

27 Resistance to heat, fire and tracking .............................................................................. 17

28 Resistance to rusting ..................................................................................................... 17

Annexes ............................................................................................................................... 18

Bibliography .......................................................................................................................... 19

Table 101 – Symbols indicating the kind of transformer ........................................................ 11

Table 102 – Output voltage ratio for auto-transformers, separating transformers and

safety isolating transformers ................................................................................................. 14

Table 103 – Output voltage ratio for isolating transformers ................................................... 14

Table 104 – Maximum permitted temperatures of the winding ............................................... 15

---------------------- Page: 4 ----------------------
IEC 61558-2-14:2022  IEC 2022 – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
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
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

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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

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Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any

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services carried out by independent certification bodies.

6) All users should ensure that they have the latest edition of this publication.

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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.

IEC 61558-2-14 has been prepared by IEC technical committee 96: Transformers, reactors,

power supply units and combinations thereof. It is an International standard.

This second edition cancels and replaces the first edition published in 2012. 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) description of constructions moved to IEC 61558-1:2017;

c) new symbols for power supply units with linearly regulated output voltages and required

current collector position changes.
---------------------- Page: 5 ----------------------
– 4 – IEC 61558-2-14:2022  IEC 2022
The text of this International standard is based on the following documents:
Draft Report on voting
96/507/CDV 96/528/RVC

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 International Standard 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/publications.

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.
NOTE When "Part 1" is mentioned in this standard, it refers to 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 variable

transformers and power supply units incorporating variable transformers for general

applications.

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 adapted 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 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.
---------------------- Page: 6 ----------------------
IEC 61558-2-14:2022  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 limitation of voltage and horizontal safety

function for SELV in accordance with IEC 60364-4-41.

The group safety function (GSF) is necessary because of responsibility e.g. 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 60204-1:2016, 7.2.4.

The group safety function is needed for each part of IEC 61558-2 because different standards

of the IEC 61558 series can be combined in one construction but in certain cases with no

limitation of rated output power.

For example an auto-transformer in accordance with IEC 61558-2-13 can be designed with a

separate SELV-circuit in accordance with the particular requirements for IEC 61558-2-6 relating

to the general requirements of IEC 61558-1.
---------------------- Page: 7 ----------------------
– 6 – IEC 61558-2-14:2022  IEC 2022
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
1 Scope
Replacement

This part of IEC 61558 deals with the 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 document.

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.

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 variable dry-type transformers:
– variable auto-transformers;
– variable separating transformers;
– variable isolating transformers;
– variable safety isolating 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 operational frequencies do not exceed 500 Hz.
The rated output does not exceed:
– 40 kVA for single-phase variable auto-transformers;
– 200 kVA for polyphase variable auto-transformers;
– 1 kVA for single-phase variable separating transformers;
– 5 kVA for polyphase variable separating transformers;
– 25 kVA for single-phase variable isolating transformers;
– 40 kVA for polyphase variable isolating transformers;
– 10 kVA for single-phase variable safety isolating transformers;
– 16 kVA for polyphase variable safety isolating transformers.

This document is applicable to variable 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.

---------------------- Page: 8 ----------------------
IEC 61558-2-14:2022  IEC 2022 – 7 –
For variable auto-transformers:

– 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 variable auto-transformers the rated output voltage does exceed

50 V AC or 120 V ripple-free DC but does not exceed 250 V AC.

NOTE 3 Normally, variable auto-transformers are intended to be associated with equipment to provide voltages

different from the supply voltage for the functional requirements of the equipment. The protection against electric

shock can be provided or completed by other features of the equipment, such as the body.

NOTE 4 Variable auto-transformers intended to be used by technically skilled or trained personnel are considered

as associated variable transformers and can have a rated output voltage less than 50 V AC.

For variable separating transformers:

– 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 portable variable separating transformers the rated output voltage does exceed

50 V AC or 120 V ripple-free DC;

– are only used where double or reinforced insulation between circuits is not required by

the installation rules or by the end product standard.

NOTE 5 Normally, variable separating transformers are intended to be associated with equipment to provide

voltages different from the supply voltage for the functional requirements of the equipment. 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 earthing.

NOTE 6 Variable separating transformers intended to be used by technically skilled or trained personnel are

considered as associated variable transformers and can have a rated output voltage less than 50 V AC or 120 V

ripple-free DC.
For variable isolating transformers:

– the no-load output voltage or the rated output voltage does not exceed 500 V AC or

708 V ripple-free DC. The no-load output voltage and the rated output voltage can be up

to 1 000 V AC or 1 415 V ripple-free DC for special applications or in accordance with the

installation rules;

– for independent variable isolating transformers the rated output voltage does not

exceed 250 V AC;

– 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:

– the no-load output voltage or the rated output voltage does not exceed 50 V AC or

120 V ripple-free DC;

– are used where double or reinforced insulation between circuits is required by the

installation rules or by the end product standard.

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.
Attention is drawn to the following, if necessary:

– additional requirements for transformers intended to be used in vehicles, on board ships,

and aircraft, (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

can be applicable to transformers intended for use in special environments.
---------------------- Page: 9 ----------------------
– 8 – IEC 61558-2-14:2022  IEC 2022

Future technological development of transformers can necessitate a need to increase the

upper limit of the frequencies. Until then this document can 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.
2 Normative references
This clause of Part 1 is applicable except as follows:
Addition

IEC 61558-1:2017, Safety of transformers, reactors, power supply units and combinations

thereof – Part 1: General requirements and tests
3 Terms and definitions

For the purposes of this document, the terms and definitions given in Part 1 apply except as

follows:

ISO and IEC maintain terminology databases for use in standardization at the following

addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
3.1 Transformers
Addition
3.1.101
variable transformer

transformer having unlimited numbers of transformation ratios and adjustable by means of a

movable current collector positioned along a continuous path of locally exposed winding turns

3.1.102
variable auto-transformer

variable transformer in which input and output voltages are derived from a common winding

3.2 General terms
Addition
3.2.101
current collector

assembly of moving contact parts which serve to transmit current from a point on the contact

path to the tapping point at the bushings or terminals
3.2.102
drive
mechanical assembly used for moving the current collector
3.2.103
fixed winding

winding or part of the winding with no means for varying the transformation ratio

---------------------- Page: 10 ----------------------
IEC 61558-2-14:2022  IEC 2022 – 9 –
3.2.104
variable winding

winding or part of the winding with a contact path used for varying the transformation ratio

3.5 Ratings
Modification
3.5.5 is not applicable.
Addition
3.5.101
rated output voltage range

output voltage range (for polyphase transformer and power supply units, the phase-to-phase

voltage) at rated supply voltage, rated supply frequency, rated output current, and rated

power factor assigned to the transformer or power supply unit by the manufacturer

4 General requirements
This clause of Part 1 is applicable except as follows:
Addition

If the current collector cannot stay permanently in the same position it shall be marked on the

variable transformer with the symbol IEC 60417-6263:2014-03 (see 8.11) placed adjacent to

the supply information (e.g. on the rating plate).
5 General notes on tests
This clause of Part 1 is applicable except as follows:
5.3
Addition
The test of 16.101 shall be conducted before all other tests.
6 Ratings
This clause of Part 1 is applicable except as follows:
Addition
6.101 The rated output voltage shall not exceed:

– 1 000 V AC or 1 415 V ripple-free DC for variable auto-transformers and variable

separating transformers;

– 500 V AC or 708 V ripple-free DC for variable isolating transformers; the rated output

voltage can exceed these limits in order to be in accordance with the installation rules,

however, it shall not exceed 1 000 V AC or 1 415 V ripple-free DC;
– 250 V AC for portable variable auto-transformers, portable variable separating
transformers and independent variable isolating transformers;
– 50 V AC or 120 V ripple-free DC for variable safety isolating transformers.

This document is also applicable to variable transformers of a rated output voltage of more

than 1 000 V AC or 1 415 V ripple-free DC. Such transformers, however, are classified as

special transformers and are subject to agreement between purchaser and manufacturer.

The
...

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