IEC 61558-2-23:2010

Safety of transformers, reactors, power supply units and combinations thereof - Part 2-23: Particular requirements and tests for transformers and power supply units for construction sites

IEC 61558-2-23:2010 deals with the safety of transformers for construction sites and power supply units incorporating transformers for construction sites. Transformers incorporating electronic circuits are also covered by this standard. This second edition cancels and replaces the first edition published in 2000. It constitutes a technical revision. The main changes consist of updating this Part 2-23 in accordance with IEC 61558-1:2005. 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.

Sécurité des transformateurs, bobines d'inductance, blocs d'alimentation et des combinaisons de ces élements - Partie 2-23: Règles particulières et essais pour les transformateurs et les blocs d'alimentation pour chantiers

La CEI 61558-2-23:2010 traite de la sécurité des transformateurs pour chantiers et des blocs d'alimentation incorporant des transformateurs pour chantiers. Les transformateurs incorporant des circuits électroniques sont également couverts par la présente norme. Cette deuxième édition annule et remplace la première édition publiée en 2000. Elle constitue une révision technique. Les principales modifications consistent en la mise à jour de la présente partie conformément à la CEI 61558-1:2005. 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 fabricants 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 oeuvre 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.

General Information

• Status: Published
• Publication Date: 30-Aug-2010
• ICS: 01 - GENERALITIES. TERMINOLOGY. STANDARDIZATION. DOCUMENTATION
• ICS: 29.180 - Transformers. Reactors
• 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: 30-Sep-2010
• Completion Date: 31-Aug-2010

Standards Content (Sample)

IEC 61558-2-23
®
Edition 2.0 2010-08
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
GROUP SAFETY PUBLICATION

PUBLICATION GROUPÉE DE SÉCURITÉ

Safety of transformers, reactors, power supply units and combinations thereof –
Part 2-23: Particular requirements and tests for transformers and power supply
units for construction sites

Sécurité des transformateurs, bobines d’inductance, blocs d'alimentation et des
combinaisons de ces élements –
Partie 2-23: Règles particulières et essais pour les transformateurs et les blocs
d'alimentation pour chantiers

IEC 61558-2-23:2010

---------------------- Page: 1 ----------------------
THIS PUBLICATION IS COPYRIGHT PROTECTED
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IEC 61558-2-23
®
Edition 2.0 2010-08
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
GROUP SAFETY PUBLICATION

PUBLICATION GROUPÉE DE SÉCURITÉ

Safety of transformers, reactors, power supply units and combinations thereof –
Part 2-23: Particular requirements and tests for transformers and power supply
units for construction sites

Sécurité des transformateurs, bobines d’inductance, blocs d'alimentation et des
combinaisons de ces élements –
Partie 2-23: Règles particulières et essais pour les transformateurs et les blocs
d'alimentation pour chantiers

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
S
CODE PRIX
ICS 29.180 ISBN 978-2-88912-162-5
® Registered trademark of the International Electrotechnical Commission
Marque déposée de la Commission Electrotechnique Internationale

---------------------- Page: 3 ----------------------
– 2 – 61558-2-23 © IEC:2010
CONTENTS

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

Figure 101 – Impact test for horizontal surface .18
Figure 102 – Impact test for vertical surface .18

Table 101 – Ratio of output voltages for safety isolating transformers .11
Table 102 – Ratio of output voltages for isolating transformers .11

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61558-2-23 © IEC:2010 – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
_____________

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

Part 2-23: Particular requirements and tests for transformers
and power supply units for construction sites


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,
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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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4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
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between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
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5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
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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.
International Standard IEC 61558-2-23 has been prepared by IEC Technical Committee 96:
Transformers, reactors, power supply units, and combinations thereof.
This second edition cancels and replaces the first edition published in 2000. It constitutes a
technical revision. The main changes consist of updating this Part 2-23 in accordance with
IEC 61558-1:2005.
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 – 61558-2-23 © IEC:2010
The text of this standard is based on the following documents:
FDIS Report on voting
96/359/FDIS 96/368/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 transformers and
power supply units for construction sites.
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 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.
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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61558-2-23 © IEC:2010 – 5 –
SAFETY OF TRANSFORMERS, REACTORS,
POWER SUPPLY UNITS AND COMBINATIONS THEREOF –

Part 2-23: Particular requirements and tests for transformers
and power supply units for construction sites



1 Scope
Replacement:
This part of IEC 61558 deals with the safety of transformers for construction sites and
power supply units incorporating transformers for construction sites. 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 transformers for
construction sites and power supply units incorporating transformers for construction
sites.
This part is applicable to stationary or portable, single-phase or polyphase, air-cooled (natural
or forced) independent or associated transformers, being isolating or safety isolating dry-
type transformers for the use on construction sites. The windings may be encapsulated or
non-encapsulated.
The rated supply voltage does not exceed 1 000 V a.c., and the rated supply frequency and
the internal operating frequencies do not exceed 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 operating frequencies higher than
500 Hz. Where the two requirements are in conflict the most severe take precedence
The rated output does not exceed:
– 25 kVA for single-phase transformers;
– 40 kVA for poly-phase 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.
Isolating transformers and power supply units incorporating isolating transformers for
construction sites have a no-load output voltage and a rated output voltage exceeding 50
V a.c. and not exceeding 250 V a.c.
Safety isolating transformers and power supply units incorporating safety isolating
transformers for construction sites have a no-load output voltage and a rated output
voltage not exceeding 50 V a.c.
NOTE 3 This standard is applicable to transformers for the supply of electricity in locations as specified in
IEC 60364-7-704. The latter also specifies the protection by using an earthed midpoint or starpoint of the output
winding.

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– 6 – 61558-2-23 © IEC:2010
Transformers and power supply units covered by this part are used in applications where it
is required by the installation rules or by the appliance specification for protection purposes.
When the transformers or power supply units are incorporated into low voltage switchgear
and controlgear assemblies for construction sites as specified in IEC 60439-4, the
additional requirements of IEC 60439-4 will apply to the assembly.
NOTE 4 For transformers filled with liquid dielectric or pulverised material, such as sand, additional requirements
are under consideration.
NOTE 5 Attention is drawn to the following:
– measures to protect the enclosure and the components inside the enclosure against external influences
like fungus, vermin, termites, solar-radiation and icing should also be considered;
– the different conditions for transportation, storage, and operation of the transformers and power supply
units should also be considered;
– additional requirements in accordance with other appropriate standards and national rules may be
applicable to transformers and power supply units intended for use in special environments such as
tropical environment.
NOTE 6 Future technological development of transformers may necessitate a need to increase the upper limit of
the frequencies, until then this standard may be used as a guidance document.
2 Normative references
This clause of Part 1 is applicable except as follows:
Addition:
IEC 60068-2-27, Environmental testing – Part 2-27: Tests – Test Ea and guidance: Shock
IEC 60439-4, Low-voltage switchgear and controlgear assemblies – Part 4: Particular
requirements for assemblies for construction sites (ACS)
IEC 61558-1:2005, Safety of power transformers, power supplies, reactors and similar products
– Part 1: General requirements and tests
3 Terms and definitions
This clause of Part 1 is applicable except as follows:
Addition:
3.101
low voltage switchgear and controlgear assembly for construction sites (ACS)
combination of one or several transforming or switching devices with associated control,
measuring, signalling, protective and regulating equipment complete with all their internal
electrical and mechanical connections and structural parts, designed and built for use on all
construction sites, indoors or outdoors.
4 General requirements
This clause of Part 1 is applicable.

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61558-2-23 © IEC:2010 – 7 –
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:
– 250 V a.c. for isolating transformers with a non-earthed mid-point (single-phase) or a
non-earthed star-point (three-phase) or delta connection (three-phase) and for power
supply units incorporating such transformers;
– 110 V a.c. for isolating transformers with a mid-point (single-phase) earthed in the
construction or a star-point (three-phase) earthed in the construction and for power
supply units incorporating such transformers;
– 50 V a.c. for safety isolating transformers and for power supply units incorporating
safety isolating transformers.
The rated output voltage shall exceed:
– 50 V a.c. for isolating transformers and for power supply units incorporating isolating
transformers.
Preferred values for the rated output voltage are
– 110 V and 230 V for portable, single-phase isolating transformers;
– 72 V, 110 V and 230 V for other isolating transformers;
– 6 V, 12 V, 24 V, 42 V and 48 V for safety isolating transformers.
6.102 The rated output shall not exceed:
– 25 kVA for single-phase isolating and safety isolating transformers and power
supply units incorporating such transformers;
– 40 kVA for polyphase isolating and safety isolating transformers and power supply
units incorporating such transformers;
Preferred values for the rated output are
– 25 VA, 40 VA, 63 VA, 100 VA, 160 VA, 250 VA, 400 VA, 630 VA, 1 000 VA, 1 600 VA,
– 2 500 VA, 4 000 VA, 6 300 VA, 10 kVA, 16 kVA and 25 kVA for single-phase
transformers;
– 630 VA, 1 000 VA, 1 600 VA, 2 500 VA, 4 000 VA, 6 300 VA, 10 kVA, 16 kVA, 25 kVA
and 40 kVA for poly-phase transformers.
Intermittent duty cycle may be assigned only to portable transformers and power supply
units having a rated output not exceeding 6,3 kVA.
6.103 The rated supply frequency shall not exceed 500 Hz.
6.104 The rated supply voltage shall not exceed 1 000 V a.c.
6.105 Transformers with intermittent duty cycle shall be intended for a rated operating
time of 5 min "on" and a resting time of 15 min "off".

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– 8 – 61558-2-23 © IEC:2010
6.106 The supply current is limited to a maximum of 125 A, and in the case of flexible cable
or socket outlet, to 63 A.
Compliance with 6.101 to 6.106 is checked by inspection of the marking.
7 Classification
This clause of Part 1 is applicable except as follows:
7.5 Replacement:
According to their duty type:
– continuous duty;
– intermittent duty cycle.
8 Marking and other information
This clause of Part 1 is applicable except as follows:
8.1 h) Replacement:
The transformers shall be marked with one of the graphical symbols shown in 8.11;
8.11 Addition:
Symbol or Explanation or title Identification
graphical symbol
Isolating transformer for construction site, fail-safe IEC 60417-
6010-1

Isolating transformer for construction site, fail- safe, IEC 60417-
safety 6010-2

Isolating transformer for construction site, fail-safe, IEC 60417-
mid-point or star-point earthed 6010-3

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61558-2-23 © IEC:2010 – 9 –
Symbol or Explanation or title Identification
graphical symbol
Isolating transformer for construction sites, non-short- IEC 60417-
circuit proof 6010-4

Isolating transformer for construction sites, non-short- IEC 60417-
circuit proof, safety 6010-5

Isolating transformer for construction sites, non-short- IEC 60417-
circuit proof, mid-point or star-point earthed 6010-6

Isolating transformer for construction sites, short- IEC 60417-
circuit proof 6010-7

Isolating transformer for construction sites, short- IEC 60417-
circuit proof, safety 6010-8

Isolating transformer for construction sites, short- IEC 60417-
circuit proof, mid-point or star-point earthed 6010-9

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– 10 – 61558-2-23 © IEC:2010
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.
12 No-load output voltage
This clause of Part 1 is applicable except as follows:
Addition:
12.101 The no-load output voltage shall not exceed:
– 250 V a.c. for isolating transformers with a non-earthed mid-point (single-phase) or a
non-earthed star-point (three-phase) or delta connection (three-phase) and for power
supply units incorporating such transformers;
– 116 V a.c. for isolating transformers with a mid-point (single-phase) earthed in the
construction or a star-point (three-phase) earthed in the construction and for power
supply units incorporating such transformers;
– 50 V a.c. for safety isolating transformers and for power supply units incorporating
safety isolating transformers.
For independent transformers, the no-load output voltage limitation applies even
when output windings, not intended for interconnection, are connected in series.
The no-load output voltage shall exceed:
– 50 V a.c. for isolating transformers and power supply units incorporating isolating
transformers.
12.102 The difference between the no-load output voltage and the output voltage under
load shall not be excessive.
Compliance with the requirements of 12.101 and 12.102 is checked by measuring the no-load
output voltage at the ambient temperature when the transformer is connected to the rated
supply voltage at the rated supply frequency.
The difference between the no-load output voltage measured in this clause and the output
voltage under load measured during the test of Clause 11, expressed as a percentage of the
latter voltage, shall not exceed the values shown in Table 101 or Table 102.
U – U
no-load
load
NOTE The ratio is defined as follows: × 100 %
U
load

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61558-2-23 © IEC:2010 – 11 –
Table 101 – Ratio of output voltages for safety isolating transformers
Type of transformer Ratio between no-load output voltage and output
Rated output voltage under load
VA %
Inherently short-circuit proof transformers:
-up to and including 63 100
-over 63 up to and including 630 50
-over 630 20

Other transformers:
-up to and including 10 100
-over 10 up to and including 25 50
-over 25 up to and including 63 20
-over 63 up to and including 250 15
-over 250 up to and including 630 10
-over 630 5

Table 102 – Ratio of output voltages for isolating transformers
Rated output Ratio between no-load output voltage and output
voltage under load

VA %
All type of transformers:
-up to and including 63 20
-over 63 up to and including 250 15
-over 250 up to and including 630 10
-over 630 5

For single phase transformers with earthed midpoint, the voltage between any pole of the
no - load output voltage
⎛ ⎞
output circuit and earth shall not exceed the ± 2,5 %.
⎜ ⎟
2
⎝ ⎠
For three phase transformers with earthed star-point, the voltage between any pole of the
no - load output voltage
⎛ ⎞
output circuit and earth shall not exceed the ⎜ ⎟ ± 2,5 %.
3
⎝ ⎠
13 Short-circuit voltage
This clause of Part 1 is applicable.
14 Heating
This clause of Part 1 is applicable.

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