IEC 61558-2-12:2011

Safety of transformers, reactors, power supply units and combination thereof - Part 2-12: Particular requirements and tests for constant voltage transformers and power supply units for constant voltage

IEC 61558-2-12:2011 deals with the safety of constant voltage transformers for general applications and power supply units for constant voltage for general applications. Constant voltage transformers incorporating electronic circuits are also covered by this standard. This second edition cancels and replaces the first edition published in 2001. It constitutes a technical revision. The main changes consist of updating this part in accordance with IEC 61558-1:2009. This part has the status of a group safety publication in accordance with IEC Guide 104: 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. In the meantime, the previous edition can still be ordered by contacting your local IEC member National Committee or the IEC Central Office.
This publication is to be read in conjunction with IEC 61558-1:2005.

Sécurité des transformateurs, bobines d'inductance, blocs d'alimentation et des combinaisons de ces éléments - Partie 2-12: Exigences particulières et essais pour les transformateurs à tension constante et les blocs d'alimentation pour tension constante

La CEI 61558-2-12:2011 traite de la sécurité des transformateurs à tension constante pour applications d'ordre général et des blocs d'alimentation pour tension constante pour applications d'ordre général. Les transformateurs à tension constante incorporant des circuits électroniques sont également couverts par la présente norme. Cette deuxième édition annule et remplace la première édition parue en 2001, dont elle constitue une révision technique. Les principales modifications consistent en la mise à jour de la présente partie, conformément à la CEI 61558-1:2009. La présente partie a le statut de publication groupée de sécurité, conformément au Guide CEI 104: Élaboration des publications de sécurité et utilisation des publications fondamentales de sécurité et publications groupées de sécurité. L'attention des Comités nationaux est attirée sur le fait que les constructeurs des appareils et les organismes d'essai peuvent avoir besoin d'une période transitoire, à la parution d'une publication CEI qu'elle soit nouvelle, modifiée ou révisée, pour mettre les produits en conformité avec les nouvelles exigences et pour s'équiper eux-mêmes afin de réaliser de nouveaux essais ou des essais révisés. Le comité recommande que le contenu de la présente publication soit adopté pour mise en uvre au niveau national au plus tôt 12 mois après la date de publication. Pendant ce temps, l'édition précédente peut toujours être commandée auprès du Comité National CEI de votre pays ou auprès du bureau Central de la CEI.
Cette publication doit être lue conjointement avec la CEI 61558-1:2005.

General Information

• Status: Published
• Publication Date: 26-Jan-2011
• ICS: 01 - GENERALITIES. TERMINOLOGY. STANDARDIZATION. DOCUMENTATION
• ICS: 29.180 - Transformers. Reactors
• ICS: 31.080.01 - Semiconductor devices in general
• Technical Committee: TC 96 - Transformers, reactors, power supply units, and combinations thereof
• Drafting Committee: MT 1 - TC 96/MT 1
• Current Stage: PPUB - Publication issued
• Start Date: 28-Feb-2011
• Completion Date: 27-Jan-2011

Standards Content (Sample)

IEC 61558-2-12
®

Edition 2.0 2011-01
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
GROUP SAFETY PUBLICATION
PUBLICATION GROUPÉE DE SÉCURITÉ

Safety of transformers, reactors, power supply units and combination thereof –
Part 2-12: Particular requirements and tests for constant voltage transformers
and power supply units for constant voltage

Sécurité des transformateurs, bobines d’inductance, blocs d’alimentation et des
combinaisons de ces éléments –
Partie 2-12: Exigences particulières et essais pour les transformateurs à tension
constante et les blocs d'alimentation pour tension constante

IEC 61558-2-12:2011

---------------------- Page: 1 ----------------------
THIS PUBLICATION IS COPYRIGHT PROTECTED
Copyright © 2011 IEC, Geneva, Switzerland

All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by
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---------------------- Page: 2 ----------------------
IEC 61558-2-12
®

Edition 2.0 2011-01

INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
GROUP SAFETY PUBLICATION
PUBLICATION GROUPÉE DE SÉCURITÉ

Safety of transformers, reactors, power supply units and combination thereof –
Part 2-12: Particular requirements and tests for constant voltage transformers
and power supply units for constant voltage

Sécurité des transformateurs, bobines d’inductance, blocs d’alimentation et des
combinaisons de ces éléments –
Partie 2-12: Exigences particulières et essais pour les transformateurs à tension
constante et les blocs d'alimentation pour tension constante
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
CODE PRIX S
ICS 29.180 ISBN 978-2-88912-341-4

® Registered trademark of the International Electrotechnical Commission
Marque déposée de la Commission Electrotechnique Internationale

---------------------- Page: 3 ----------------------
– 2 – 61558-2-12  IEC:2011
CONTENTS
FOREWORD . 3
1 Scope . 5
2 Normative references . 7
3 Terms and definitions . 7
4 General requirements . 7
5 General notes on tests . 7
6 Ratings . 7
7 Classification . 8
8 Marking and other information . 8
9 Protection against electric shock . 9
10 Change of input voltage setting . 9
11 Output voltage and output current under load . 9
12 No-load output voltage . 10
13 Short-circuit voltage . 11
14 Heating . 11
15 Short-circuit and overload protection . 11
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 . 17
21 Internal wiring . 17
22 Supply connection and other external flexible cables or cords . 17
23 Terminals for external conductors . 17
24 Provision 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 . 18
28 Resistance to rusting . 18
Annexes . 19
Annex C (normative) . 19
Annex D (normative) . 19
Annex L (normative) . 19
Annex R (normative) . 19
Bibliography . 20

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61558-2-12  IEC:2011 – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________

SAFETY OF TRANSFORMERS, REACTORS,
POWER SUPPLY UNITS AND COMBINATION THEREOF –

Part 2-12: Particular requirements and tests
for constant voltage transformers
and power supply units for constant voltage

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
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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.
International Standard IEC 61558-2-12 has been prepared by IEC technical committee 96:
Transformers, reactors, power supply units, and combination thereof.
This second edition cancels and replaces the first edition published in 2001. It constitutes a
technical revision. The main changes consist of updating this part in accordance with
IEC 61558-1:2009.
This part has the status of a group safety publication in accordance with IEC Guide 104: The
preparation of safety publications and the use of basic safety publications and group safety
publications.

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– 4 – 61558-2-12  IEC:2011
The text of this standard is based upon the following documents:
FDIS Report on voting
96/253/FDIS 96/266/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 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.
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 constant voltage
transformers and power supply units for constant voltage.
A list of all parts of the IEC 61558 series, 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 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 has to be adopted 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 are 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.
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.

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61558-2-12  IEC:2011 – 5 –
SAFETY OF TRANSFORMERS, REACTORS,
POWER SUPPLY UNITS AND COMBINATION THEREOF –

Part 2-12: Particular requirements and tests
for constant voltage transformers
and power supply units for constant voltage



1 Scope
Replacement:
This part of IEC 61558 deals with the safety of constant voltage transformers for general
applications and power supply units for constant voltage for general applications.
Constant voltage transformers incorporating electronic circuits are also covered by this
standard.
NOTE 1 Safety includes electrical, thermal and mechanical aspects.
Unless otherwise specified, from here onward, the term transformer covers constant
voltage transformers for general applications and power supply units for constant voltage
for general applications.
This part is applicable to stationary or portable, single-phase or polyphase, air-cooled
(natural or forced), independent or associated dry-type:
– constant voltage auto-transformers;
– constant voltage separating transformers;
– constant voltage isolating transformers;
– constant voltage safety isolating transformers.
The windings may be encapsulated or non-encapsulated.
This standard is applicable to transformers and power supply (linear) with internal operating
frequencies not exceeding 500 Hz.
This standard used in combination with Part 2-16 for switch mode power supply (SMPS)
units is also applicable to power supplies with internal operating frequencies higher than
500 Hz. Where the two requirements are in conflict, the most severe take precedence.
The rated supply voltage does not exceed 1 000 V a.c., the rated supply frequency does
not exceed 500 Hz, the internal operating resonant frequency does not exceed 30 kHz and
the internal operating frequency does not exceed 100 MHz.
The rated output does not exceed:
– 40 kVA for single-phase constant voltage auto-transformers;
– 200 kVA for poly-phase constant voltage auto-transformers;
– 25 kVA for single-phase constant voltage separating transformers and constant
voltage isolating transformers;
– 40 kVA for poly-phase constant voltage separating transformers and constant
voltage isolating transformers;
– 10 kVA for single-phase constant voltage safety isolating transformers;

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– 6 – 61558-2-12  IEC:2011
– 16 kVA for poly-phase constant voltage 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.
Where applicable to constant voltage 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., and for independent constant voltage auto-transformers, the
no-load output voltage and the rated output voltage exceed 50 V a.c. or 120 V ripple-
free d.c.;
– constant voltage auto-transformers covered by this part are used only in applications
where no insulation between circuits is required by the installation rules or by the end
product standard.
Where applicable to constant voltage 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., and for independent constant voltage separating
transformers, the no-load output voltage and the rated output voltage exceed 50 V
a.c. or 120 V ripple-free d.c.;
– constant voltage separating transformers covered by this part are used only in
applications where double or reinforced insulation between circuits is not required by
the installation rules or by the end product standard.
Where applicable to constant voltage isolating transformers
– the no-load output voltage or the rated output voltage does exceed 50 V a.c. or 120 V
ripple-free d.c. and where applicable, 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;
– constant voltage isolating transformers covered by this part are used only in
applications where double or reinforced insulation between circuits is required by the
installation rules or by the end product standard.
Where applicable to constant voltage 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.;
– constant voltage safety isolating transformers covered by this part are used only in
applications 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 3 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.) may 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 should also be considered;
– the different conditions for transportation, storage, and operation of the transformers should also be
considered;
– additional requirements in accordance with other appropriate standards and national rules may be applicable
to transformers intended for use in special environments.
NOTE 4 Future technological development of transformers may necessitate a need to increase the upper limit
of the frequencies, until then this part may be used as a guidance document.

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61558-2-12  IEC:2011 – 7 –
2 Normative references
This clause of Part 1 is applicable.
3 Terms and definitions
This clause of Part 1 is applicable except as follows:
Addition:
3.101
constant voltage transformer
transformer intended to limit the influence of the input voltage variations
NOTE This type of transformer may also limit the influence of transients.
3.102
regulation tolerance
deviation in per cent of the rated output voltage when the constant voltage transformer is
supplied within the rated supply voltage variation
3.103
internal operating resonant frequency
frequency produced within a constant voltage transformer
4 General requirements
This clause of Part 1 is applicable.
5 General notes on tests
This clause of Part 1 is applicable.
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 a.c. or 1 415 V ripple-free d.c. for constant voltage auto-transformers and
constant voltage separating transformers;
– 250 V a.c. for single-phase portable constant voltage isolating transformers;
– 400 V a.c. for polyphase portable constant voltage isolating transformers, and
– 500 V a.c. or 708 V ripple-free d.c. for constant voltage isolating transformers. For
constant voltage isolating transformers, the rated output voltage may be up to 1 000
V a.c. or 1 415 V ripple-free d.c. to be in accordance with the national wiring rules or for a
special purpose;
– 50 V a.c. or 120 V ripple-free d.c. for constant voltage safety isolating transformers.

---------------------- Page: 9 ----------------------
– 8 – 61558-2-12  IEC:2011
The rated output voltage shall exceed:
– 50 V a.c. or 120 V ripple-free d.c. for independent constant voltage auto-transformers,
constant voltage separating transformers and constant voltage isolating
transformers.
6.102 The rated output shall not exceed:
– 40 kVA for single-phase constant voltage auto-transformers,
– 200 kVA for polyphase constant voltage auto-transformers,
– 25 kVA for single-phase constant voltage separating and isolating transformers,
– 40 kVA for polyphase constant voltage separating and isolating transformers,
– 10 kVA for single-phase constant voltage safety isolating transformers,
– 16 kVA for polyphase constant voltage safety isolating transformers,
except for constant voltage transformers subject to an agreement between the purchaser
and the manufacturer.
6.103 The rated supply frequency shall not exceed 500 Hz.
6.104 The rated value of the output regulation tolerance shall be given at the rated supply
voltage range, the rated output, and the power factor = 1.
6.105 For constant voltage independent transformers, the input voltage variation shall
not be less than 10 %.
6.106 The internal operating resonant frequency shall not exceed 30 kHz.
6.107 The internal operating frequency shall not exceed 100 MHz.
Compliance with 6.101 to 6.107 is checked by inspection of the marking.
7 Classification
This clause of Part 1 is applicable.
8 Marking and other information
This clause of Part 1 is applicable except as follows:
8.1 a) Replacement of the first sentence by the following:
rated supply voltage(s) and the input voltage variation in %;
8.1 b) Replacement of the first sentence by the following:
Replace the first sentence by the following:
rated output voltage(s) and the regulation tolerance of this voltage(s) in %;
8.1 h) Replacement of the first sentence by the following:
relevant graphical symbols shown in 8.11 indicating the kind of transformer;

---------------------- Page: 10 ----------------------
61558-2-12  IEC:2011 – 9 –
8.11 Addition:
Symbol or graphical symbol Explanation or title Identification
Fail-safe constant voltage separating transformer IEC 60417-6011

Non-short-circuit-proof constant voltage
IEC 60417-6011
separating transformer

Short-circuit-proof constant voltage separating
IEC 60417-6011
transformer

Fail-safe constant voltage isolating transformer IEC 60417-6012

Non-short-circuit-proof constant voltage isolating
IEC 60417-6012
transformer

Short-circuit-proof constant voltage isolating
IEC 60417-6012
transformer

Fail-safe constant voltage safety isolating
IEC 60417-6013
transformer

Non-short-circuit-proof constant voltage safety
IEC 60417-6013
isolating transformer

Short-circuit-proof constant voltage safety
IEC 60417-6013
isolating transformer

Fail-safe constant voltage auto-transformer IEC 60417-6017

Non-short-circuit-proof constant voltage auto-
IEC 60417-6017
transformer

Short-circuit-proof constant voltage auto-
IEC 60417-6017
transformer


9 Protection against electric shock
This clause of Part 1 is applicable.
10 Change of input voltage setting
This clause of Part 1 is applicable.
11 Output voltage and output current under load
This clause of Part 1 is applicable except as follows:
11.1 Replacement:

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– 10 – 61558-2-12  IEC:2011
11.1 When the transformer is connected to the rated supply voltage plus or minus the
input voltage variation declared by the manufacturer, at the rated supply frequency, and
loaded with an impedance resulting in the rated output at the rated output voltage and, for
a.c., at the rated power factor, the output voltage shall not differ from the rated value by
more than the regulation tolerance.
Compliance is checked by measuring the output voltage when steady-state conditions are
established. During the test, the transformer is connected to the rated supply voltage, plus
or minus the highest input voltage variation, at the rated supply frequency, and loaded with
an impedance resulting in the rated output at the rated output voltage and the rated power
factor.
For transformers incorporating a rectifier, the output voltage shall be measured at the
terminals of the d.c. circuit by means of a voltmeter giving the arithmetical mean value, unless
the effective (r.m.s.) value is specifically stated (see 8.1).
For transformers with more than one rated supply voltage, the requirement is applicable for
each of the rated supply voltages.
For transformers with multiple output windings, the loads are applied to every multiple
section simultaneously, unless otherwise declared.
12 No-load output voltage
This clause of Part 1 is applicable except as follows:
...