EN 61558-2-12:2001

SLOVENSKI SIST EN 61558-2-12:2002
prva izdaja
STANDARD
september 2002
Safety of power transformers, power supply units and similar devices - Part 2-12:
Particular requirements for constant voltage transformers
ICS 29.180 Referenčna številka
©  Standard je založil in izdal Slovenski inštitut za standardizacijo. Razmnoževanje ali kopiranje celote ali delov tega dokumenta ni dovoljeno

EUROPEAN STANDARD EN 61558-2-12
NORME EUROPÉENNE
EUROPÄISCHE NORM October 2001
ICS 29.180
English version
Safety of power transformers, power supply units and similar devices
Part 2-12: Particular requirements for constant voltage transformers
(IEC 61558-2-12:2001)
Sécurité des transformateurs, blocs Sicherheit von Transformatoren,
d'alimentation et dispositifs analogues Netzgeräten und dergleichen
Partie 2-12: Règles particulières pour Teil 2-12: Besondere Anforderungen an
les transformateurs à tension constante magnetische Spannungskonstanthalter
(CEI 61558-2-12:2001) (IEC 61558-2-12:2001)
This European Standard was approved by CENELEC on 2001-09-01. 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 Central Secretariat 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 Central Secretariat has the same status as the official versions.
CENELEC members are the national electrotechnical committees of Austria, Belgium, Czech Republic,
Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Malta, Netherlands,
Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom.
CENELEC
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
Central Secretariat: rue de Stassart 35, B - 1050 Brussels
© 2001 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.
Ref. No. EN 61558-2-12:2001 E
Foreword
The text of document 96/168/FDIS, future edition 1 of IEC 61558-2-12, prepared by IEC TC 96, Small
power transformers, reactors and power supply units: Safety requirements, was submitted to the IEC-
CENELEC parallel vote and was approved by CENELEC as EN 61558-2-12 on 2001-09-01.
This part 2-12 is to be used in conjunction with EN 61558-1:1997.
This part 2-12 supplements or modifies the corresponding clauses of EN 61558-1. When a particular
subclause of part 1 is not mentioned in this part 2-12, that subclause applies as far as is reasonable.
Where this part 2-12 states "addition", "modification" or "replacement", the relevant text of part 1 is to
be adapted accordingly.
In this standard, the following print types are used:
- requirements: in roman type;
- test specifications: in italic type;
- explanatory matter: in smaller roman type.
The words in bold in the text of the standard are defined in clause 3.
Subclauses which are additional to those in part 1 are numbered starting from 101.
The following dates were fixed:
– latest date by which the EN has to be implemented
at national level by publication of an identical
national standard or by endorsement (dop) 2002-06-01
– latest date by which the national standards conflicting
with the EN have to be withdrawn (dow) 2004-09-01
__________
Endorsement notice
The text of the International Standard IEC 61558-2-12:2001 was approved by CENELEC as a
European Standard without any modification.
__________
NORME CEI
INTERNATIONALE IEC
61558-2-12
INTERNATIONAL
Première édition
STANDARD
First edition
2001-06
PUBLICATION FONDAMENTALE DE SÉCURITÉ
BASIC SAFETY PUBLICATION
Sécurité des transformateurs, blocs d'alimentation
et dispositifs analogues –
Partie 2-12:
Règles particulières pour les transformateurs
à tension constante
Safety of power transformers, power supply
units and similar devices –
Part 2-12:
Particular requirements for constant voltage
transformers
 IEC 2001 Droits de reproduction réservés  Copyright - all rights reserved
Aucune partie de cette publication ne peut être reproduite ni No part of this publication may be reproduced or utilized in
utilisée sous quelque forme que ce soit et par aucun procédé, any form or by any means, electronic or mechanical,
électronique ou mécanique, y compris la photocopie et les including photocopying and microfilm, without permission in
microfilms, sans l'accord écrit de l'éditeur. writing from the publisher.
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Telefax: +41 22 919 0300 e-mail: inmail@iec.ch IEC web site http://www.iec.ch
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Pour prix, voir catalogue en vigueur
For price, see current catalogue

61558-2-12 © IEC:2001 – 3 –
CONTENTS
FOREWORD . 3
1 Scope . 9
2 Normative references . 11
3 Definitions. 11
4 General requirements. 13
5 General notes on tests . 13
6 Ratings . 13
7 Classification . 15
8 Marking and other information . 15
9 Protection against accessibility to hazardous live parts . 17
10 Change of input voltage setting . 17
11 Output voltage and output current under load . 19
12 No-load output voltage . 19
13 Short-circuit voltage . 21
14 Heating . 21
15 Short-circuit and overload protection . 21
16 Mechanical strength . 25
17 Protection against harmful ingress of dust, solid objects and moisture . 25
18 Insulation resistance and dielectric strength. 25
19 Construction. 25
20 Components. 33
21 Internal wiring . 33
22 Supply connection and other external flexible cables or cords . 33
23 Terminals for external conductors. 33
24 Provision for protective earthing . 35
25 Screws and connections. 35
26 Creepage distances, clearances and distances through insulation . 35
27 Resistance to heat, abnormal heat, fire and tracking. 35
28 Resistance to rusting. 35
Annexes . 19

61558-2-12 © IEC:2001 – 5 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
SAFETY OF POWER TRANSFORMERS, POWER SUPPLY UNITS
AND SIMILAR DEVICES –
Part 2-12: Particular requirements for constant
voltage transformers
FOREWORD
1) The IEC (International Electrotechnical Commission) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of the 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, the IEC publishes International Standards. 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. The 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 the 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 National Committees.
3) The documents produced have the form of recommendations for international use and are published in the form
of standards, technical specifications, technical reports or guides and they are accepted by the National
Committees in that sense.
4) In order to promote international unification, IEC National Committees undertake to apply IEC International
Standards transparently to the maximum extent possible in their national and regional standards. Any
divergence between the IEC Standard and the corresponding national or regional standard shall be clearly
indicated in the latter.
5) The IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for any
equipment declared to be in conformity with one of its standards.
6) Attention is drawn to the possibility that some of the elements of this International Standard may be the subject
of patent rights. The 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:
Small power transformers, reactors and power supply units: Safety requirements.
It 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 (1997).
The text of this standard is based on the following documents:
FDIS Report on voting
96/168/FDIS 96/175/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 3.
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 revision.

61558-2-12 © IEC:2001 – 7 –
This part 2-12 is intended to be used in conjunction with IEC 61558-1. It was established on the
basis of the first edition (1997) of that standard.
This part 2-12 supplements or modifies the corresponding clauses in IEC 61558-1, so as to
convert that publication into the IEC standard: Particular requirements for constant voltage
transformers.
When a particular subclause of part 1 is not mentioned in this part 2-12, that subclause applies
as far as is reasonable. Where this standard states "addition", "modification" or "replacement",
the relevant text of part 1 shall be adapted accordingly.
In this standard, 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 the standard the words in bold are defined in clause 3.
Subclauses which 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 2004. At this date, the publication will be
reconfirmed;
withdrawn;
replaced by a revised edition, or
amended.
61558-2-12 © IEC:2001 – 9 –
SAFETY OF POWER TRANSFORMERS, POWER SUPPLY UNITS
AND SIMILAR DEVICES –
Part 2-12: Particular requirements for constant
voltage transformers
1 Scope
Replacement:
This International Standard deals with all aspects of safety such as electrical, thermal and
mechanical.
This part of IEC 61558 applies to stationary or portable, single-phase or polyphase, air-
cooled (natural or forced), associated or independent:
– constant voltage auto-transformers
– constant voltage separating transformers
– constant voltage isolating transformers
– constant voltage safety isolating transformers
having a rated supply voltage not exceeding 1 000 V a.c., a rated frequency not exceeding
500 Hz, an internal operational frequency not exceeding 30 kHz and no limitation of the
rated output.
NOTE 1 The technological development of transformers might imply a need to increase the higher limit of the
internal operational frequency; until such time, this standard may be used as a guide.
Constant voltage independent auto-transformers
– have a no-load output voltage and a rated output voltage exceeding 50 V a.c. or
...