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.

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Status
Published
Publication Date
26-Jan-2011
Current Stage
PPUB - Publication issued
Start Date
27-Jan-2011
Completion Date
27-Jan-2011
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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
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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

---------------------- Page: 4 ----------------------
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

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

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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

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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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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.

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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 61558-2-12 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.
---------------------- Page: 5 ----------------------
– 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.
---------------------- Page: 6 ----------------------
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;
---------------------- Page: 7 ----------------------
– 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.
---------------------- Page: 8 ----------------------
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:
---------------------- Page: 11 ----------------------
– 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:
...

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