IEC 61558-2-15:2011

Safety of transformers, reactors, power supply units and combinations thereof - Part 2-15: Particular requirements and tests for isolating transformers for the supply of medical locations

IEC 61558-2-15:2011 deals with safety aspects of isolating transformers for the supply of medical locations. This second edition cancels and replaces the first edition published in 1999. It constitutes a technical revision. The main changes consist of updating this part in accordance with IEC 61558-1:2005. This part has the status of a group safety publication in accordance with IEC Guide 104:2010. 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.
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 elements - Partie 2-15: Règles particulières et essais pour les transformateurs de séparation de circuits pour locaux à usages médicaux

La CEI 61558-2-15:2011 traite des aspects de sécurité des transformateurs de séparation de circuits pour locaux à usages médicaux. Cette deuxième édition annule et remplace la première édition parue en 1999. 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 104:2010. The preparation of safety publications and the use of basic safety publications and group safety publications (disponible en anglais seulement). L'attention des Comités Nationaux est attirée sur le fait que les fabricants d'appareils et les organismes d'essai peuvent avoir besoin d'une période transitoire après la publication d'une nouvelle publication CEI, ou d'une publication amendée ou révisée, pour fabriquer des produits conformes aux nouvelles exigences et pour adapter leurs équipements aux nouveaux essais ou aux essais révisés. Le comité recommande que le contenu de cette publication soit entériné au niveau national au plus tôt 12 mois après la date de publication.
Cette publication doit être lue conjointement avec la CEI 61558-1:2005.

General Information

• Status: Published
• Publication Date: 21-Nov-2011
• ICS: 01 - GENERALITIES. TERMINOLOGY. STANDARDIZATION. DOCUMENTATION
• ICS: 11.040.50 - Radiographic equipment
• 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: DELPUB - Deleted Publication
• Start Date: 31-Mar-2021
• Completion Date: 02-May-2022

Relations

• Revised: IEC 61558-2-15:2022 - Safety of transformers, reactors, power supply units and combinations thereof - Part 2-15: Particular requirements and tests for isolating transformers for medical IT systems for the supply of medical locations
• Effective Date: 05-Sep-2023

Standards Content (Sample)

IEC 61558-2-15
®

Edition 2.0 2011-11
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
GROUP SAFETY PUBLICATION
PUBLICATION GROUPÉE DE SÉCURITÉ

Safety of transformers, reactors, power supply units and combinations thereof –
Part 2-15: Particular requirements and tests for isolating transformers for the
supply of medical locations

Sécurité des transformateurs, bobines d’inductance, blocs d'alimentation et des
combinaisons de ces éléments –
Partie 2-15: Règles particulières et essais pour les transformateurs de
séparation de circuits pour locaux à usages médicaux

IEC 61558-2-15:2011

---------------------- 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 61558-2-15
®

Edition 2.0 2011-11
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
GROUP SAFETY PUBLICATION
PUBLICATION GROUPÉE DE SÉCURITÉ

Safety of transformers, reactors, power supply units and combinations thereof –
Part 2-15: Particular requirements and tests for isolating transformers for the
supply of medical locations

Sécurité des transformateurs, bobines d’inductance, blocs d'alimentation et des
combinaisons de ces éléments –
Partie 2-15: Règles particulières et essais pour les transformateurs de
séparation de circuits pour locaux à usages médicaux


INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
CODE PRIX R
ICS 29.180 ISBN 978-2-88912-790-0

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

---------------------- Page: 3 ----------------------
– 2 – 61558-2-15  IEC:2011
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 . 7
8 Marking and other information . 7
9 Protection against electric shock . 8
10 Change of input voltage setting . 8
11 Output voltage and output current under load . 8
12 No-load output voltage . 8
13 Short-circuit voltage and inrush currents . 9
14 Heating . 10
15 Short-circuit and overload protection . 10
16 Mechanical strength . 10
17 Protection against harmful ingress of dust, solid objects and moisture . 10
18 Insulation resistance, dielectric strength and leakage current . 10
19 Construction . 12
20 Components . 14
21 Internal wiring . 14
22 Supply connection and other external flexible cables or cords. 14
23 Terminals for external conductors . 14
24 Provisions for protective earthing . 15
25 Screws and connections . 15
26 Creepage distances, clearances and distances through insulation . 15
27 Resistance to heat, fire and tracking . 15
28 Resistance to rusting . 15
Annexes . 16
Annex H Electronic circuits . 16
Annex L Routine tests (production tests) . 16
Bibliography . 17
Index of defined terms . 18

Figure 101 – The required circuit for measuring the leakage current from the output
winding to earth. 11
Figure 102 – The required circuit for measuring the leakage current at the protective
earth conductor . 12

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61558-2-15  IEC:2011 – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
_____________

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

Part 2-15: Particular requirements and tests
for isolating transformers for the supply of medical locations

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
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. 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
Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
misinterpretation by any end user.
4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
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
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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 61558-2-15 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 1999. It constitutes a
technical revision. The main changes consist of updating this part in accordance with
IEC 61558-1:2005.
This part has the status of a group safety publication in accordance with IEC Guide 104:2010,
The preparation of safety publications and the use of basic safety publications and group
safety publications.

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– 4 – 61558-2-15  IEC:2011
The text of this standard is based on the following documents:
FDIS Report on voting
96/384/FDIS 96/385/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 isolating
transformers for the supply of medical locations.
A list of all parts of the IEC 61558 series, under the general title: Safety of transformers,
reactors, power supply units and combination 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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61558-2-15  IEC:2011 – 5 –
SAFETY OF TRANSFORMERS, REACTORS,
POWER SUPPLY UNITS AND COMBINATIONS THEREOF –

Part 2-15: Particular requirements and tests
for isolating transformers for the supply of medical locations



1 Scope
Replacement:
This part of IEC 61558 deals with safety aspects of isolating transformers for the supply of
medical locations.
NOTE 1 Safety includes electrical, thermal and mechanical aspects.
Unless otherwise specified, from here onward, the term transformer covers isolating
transformers for the supply of medical locations.
This part is applicable to stationary, single-phase or three-phase, air-cooled (natural or forced)
independent dry-type isolating transformers for the supply of medical IT systems for group
2 medical locations, designed to be permanently connected to the fixed wiring and intended to
form the IT power system on the secondary side. The windings may be encapsulated or non-
encapsulated.
NOTE 2 IT power systems are defined in IEC 60364-1.
NOTE 3 The installation rules for medical IT systems for group 2 medical locations are covered by
IEC 60364-7-710.
NOTE 4 Transformers covered by this standard are intended for the supply of medical locations. All other
transformers or equipments connected downstream from the transformer are not covered by this Part 2.
The rated supply voltage does not exceed 1 000 V a.c. The rated supply frequency and
internal operational frequency do not exceed 500 Hz.
The rated output does not be less than 0,5 kVA and does not exceed 10 kVA for single-phase
and three-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 5 Transformers intended to supply power to distribution networks are not covered by this standard.
The no-load output voltage and the rated output voltage does not exceed 250 V a.c. for
single-phase or three-phase transformer (phase-to-phase voltage).
This standard do not cover power supply unit.
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. Transformers covered by this
part are used in applications where double or reinforced insulation between circuits is
required by the installation rules or by the appliance specification.
NOTE 6 Attention is drawn to the following:

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– 6 – 61558-2-15  IEC:2011
– 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.
2 Normative references
This clause of Part 1 is applicable, except as follows:
Addition:
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:
3.1.101
isolating transformer for the supply of medical locations
isolating transformer used for the supply of medical IT systems for group 2 medical locations,
designed to be permanently connected and with double or reinforced insulation between
each part of the transformer (body, screen, circuits, thermal sensitive device) except between
the core and the body
3.4.101
functional screening
separation between two windings or between a winding and the core or shielding of a part or of
the whole transformer, by means of a conductive material for functional reasons
3.5.101
rated input current
unput current, when the transformer is loaded with rated output
3.6.101
no-load input current
input current when the transformer is connected to the rated supply voltage, at the rated
frequency, with no-load on the output
3.6.102
inrush current
the maximum instantaneous value of the no-load input current of the transformer (peak
value) when is switched on at rated supply voltage
4 General requirements
This clause of Part 1 is applicable.

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61558-2-15  IEC:2011 – 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:
Replacement:
6.1 The rated output voltage (phase-to-phase voltage) shall not exceed 250 V a.c. for
single-phase or three-phase transformers.
6.2 The rated output shall not be less than 0,5 kVA and it shall not exceed 10 kVA.
Transformers without limitation of the rated output shall be subject to agreement between the
purchaser and the manufacturer.
6.3 The rated frequency shall not exceed 500 Hz.
6.4 The rated supply voltage shall not exceed 1 000 V a.c.
Compliance with the requirements of 6.1 to 6.4 shall be verified by inspection of the marking.
7 Classification
This clause of Part 1 is applicable, except as follows:
7.2 Replacement:
According to short-circuit protection or protection against abnormal conditions:
– non-short-circuit proof transformer.
8 Marking and other information
This clause of Part 1 is applicable, except as follows:
8.1 h) Replacement:
Replace the first sentence by the following: Relevant graphical symbols shown in 8.11
indicating the type of transformer;
t) Addition:
Transformers shall be marked with the measured short-circuit voltage expressed as a
percentage of the rated supply voltage.
8.1.101 When the inrush current exceeds 8 times the peak value of the rated input current,
the resulting value shall be marked on the transformer.

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– 8 – 61558-2-15  IEC:2011
8.11 Addition:
Symbol or graphical symbol Explanation or title Identification
non-short-circuit proof isolating transformer for IEC 60417-5972
the supply of medical locations (DB 2010-08)


8.14 Addition:
The instruction sheet shall state: “Screens whose connection to earth is necessary for
compliance with the leakage current requirements of Clause 18 shall be connected to earth.”
The instruction sheet shall qualify the type of temperature sensor built in the transformer, if
any. The instruction sheet shall give the required value of the circuit of the transformer, when it
is allowed by national installation rules.
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:
The no-load output voltage shall be measured when the transformer is connected to the
rated supply voltage at the rated supply frequency and at the rated ambient temperature.
12.101 The no-load output voltage (phase-to-phase voltage) shall not exceed 250 V a.c.
single-phase or three-phase transformers.
12.102 The difference between the no-load output voltage, and the output voltage under
load shall not be excessive.
The difference is expressed as a percentage of the latter voltage calculated according to the
following formula:

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61558-2-15  IEC:2011 – 9 –
V −V
no-load load
× 100 (%)
V
load
where V is the no-load output voltage and V is the output voltage under load.
no-load load
Compliance with the requirements of 12.101 and 12.102 shall be verified by measuring the no-
load output voltage and output voltage under load, at the rated 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 and the output voltage under load shall
not exceed 5 %.
13 Short-circuit voltage
This clause of Part 1 is not applicable.
Replacement:
13 Short-circuit voltage and inrush currents
13.1 The short-circuit voltage shall be measured and marked on the transformer.
Compliance shall be verified by measurements
13.2 The no-load input current shall not exceed 3 % of the rated input current at the rated
supply voltage.
This requirement shall be fulfilled by construction of the transformer without the use of any
capacitors in the transformer circuits (input/output) or in the installation.
Compliance shall be verified by measurements.
13.3 The inrush current shall not exceed 8 times the peak value of the rated input current.
However, it is allowed to increase this value to 12 times the rated input current; provided the
latter value shall be reflected on the transformer marking.
This requirement shall be fulfilled by construction of the transformer without the use of any
electronic devices and additional measures in the transformer or in the installation.
Compliance shall be verified by the following test:
The transformer with no load is connected to the rated supply voltage. The test supply
voltage is then switched on and off 20 times at random intervals of approximately 20 s.
NOTE The switching-on and -off may be carried out only twice if a device is used to switch on at the most
unfavourable electrical angle of the supply voltage.
The supply source shall be such that the voltage drop does not exceed 2 % as a result of the
inrush current.
The inrush current shall not exceed 8 times or 12 times the peak value of the rated input
current, respectively, during any of the switching events.

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– 10 – 61558-2-15  IEC:2011
14 Heating
This clause of Part 1 is applicable, except as follows.
Addition:
14.101 Immediately after the test of 14.1 an additional heating test is required with 150 % of
the load for 30 min. After the test the temperature shall not exceed the values of Table 1
increased by 25 %.
15 Short-circuit and overload protection
This clause of Part 1 is applicable, except as follows:
Addition:
Isolating transformers for the supply of medical locations are non-short-circuit proof
transformers. The overload must be monitored by a temperature monitoring system. The test
of 15.3 of Part 1 will be carried out. When the circuit breaker is allowed by national installation
rules the value for a circuit-breaker shall be mentioned in the instruction sheet.
16 Mechanical strength
This clause of Part 1 is applicable.
17 Protection against harmful ingress of dust, solid objects and moisture
This clause of Part 1 is applicable.
18 Insulation resistance, dielectric strength and leakage current
This clause of Part 1 is applicable, except as follows:
18.2 Insulation resistance
th th
Table 7: Replacement of the 6 and 7 lines by the following:
Insulation to be tested Insulation resistance
MΩ
Between each input circuit and all other input circuits connected together 7
Between each output circuit and all other output circuits connected together 7
7
Between input and output circuits (double reinforced insulation)
NOTE In Australia, higher insulation resistance values are required.

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61558-2-15  IEC:2011 – 11 –
18.3 Dielectric strength test
Table 8a: Addition:
Application of dielectric strength test voltage Working voltage
V
< 50 150 300 600 1 000
500 2 800 4 200 5 000 5 500
5) Between live parts of adjacent input circuits not
intended to be connected together
6) Between live parts of adjacent output circuits not 500 2 800 4 200 5 000 5 500
intended to be connected together

Addition:
18.101 The leakage current of the output winding to earth shall n
...