IEC 61558-2-10:2014

Safety of transformers, reactors, power supply units and combinations thereof - Part 2-10: Particular requirements and tests for separating transformers with high insulation level and separating transformers with output voltages exceeding 1 000 V

IEC 61558-2-10:2014 deals with the safety of separating transformers with high insulation level and separating transformers with output voltages exceeding 1 000 V. Transformers incorporating electronic circuits are also covered by this standard. This first edition cancels and replaces Chapter ll Section Three of IEC 60989 published in 1991. It constitutes a technical revision. The main changes consist of
a) updating this part in accordance with IEC 61558-1:2005, and
b) adding power supply units to the scope. 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. The transitional period is not longer than 3 years after the publication of this standard.
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 2-10: Règles particulières et essais pour les transformateurs d'isolement à enroulements séparés à niveau d'isolement élevé et pour les transformateurs d'isolement à enroulements séparés à tensions secondaires supérieures à 1 000 V

L'IEC 61558-2-10:2014 traite de la sécurité des transformateurs d'isolement à enroulements séparés à niveau d'isolement élevé et des transformateurs d'isolement à enroulements séparés à tensions secondaires supérieures à 1 000 V. Les transformateurs incorporant des circuits électroniques sont également couverts par la présente norme. La présente première édition annule et remplace le Chapitre ll Section trois de l'IEC 60989 publiée en 1991. Elle constitue une révision technique. Les principales modifications consistent en
a) la mise à jour de la présente partie, conformément à l'IEC 61558-1:2005, et
b) l'ajout des blocs d'alimentation dans le domaine d'application. 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 IEC, 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. La période transitoire ne dépasse pas 3 ans après la publication de la présente norme.
Cette publication doit être lue conjointement avec la CEI 61558-1:2005.

General Information

• Status: Published
• Publication Date: 09-Apr-2014
• ICS: 29.035.20 - Plastics and rubber insulating materials
• ICS: 29.180 - Transformers. Reactors
• Technical Committee: TC 96 - Transformers and reactors
• Current Stage: DELPUB - Deleted Publication
• Start Date: 07-Jun-2024
• Completion Date: 29-Jul-2022

Relations

• Revised: IEC 61558-2-10:2024 - Safety of transformers, reactors, power supply units and combinations thereof - Part 2-10: Particular requirements and tests for separating transformers with high insulation level and separating transformers with output voltages exceeding 1 000 V
• Effective Date: 05-Sep-2023

Overview

IEC 61558-2-10:2014 is an international standard developed by the International Electrotechnical Commission (IEC) that sets the safety requirements for separating transformers with a high insulation level and those with output voltages exceeding 1,000 V. This standard extends coverage to transformers incorporating electronic circuits as well as power supply units. It replaces the earlier IEC 60989 standard from 1991, providing a comprehensive technical revision aligned with IEC 61558-1:2005.

The purpose of IEC 61558-2-10 is to ensure that these high-voltage transformers meet rigorous safety criteria related to electrical insulation, thermal management, mechanical construction, and protection against electric shock. It is intended for use in the design, testing, and certification of stationary or portable transformers used across a variety of industries.

Key Topics

• High Insulation Level Requirements
  Defines strict safety margins for electrical insulation to prevent breakdown and ensure operator safety under high-voltage conditions.

• Output Voltage Limits
  Applies to transformers with output voltages exceeding 1,000 V AC or 1,500 V DC, setting special requirements to handle increased electrical stresses.

• Safety Testing Protocols
  Comprehensive test methods including dielectric strength tests, insulation resistance measurements, heating and overload tests, mechanical strength, and short circuit assessments.

• Power Supply Units Inclusion
  Expands the scope to cover power supply units integrated with transformers, addressing emerging technologies.

• Design and Construction Guidelines
  Specifies protective earthing, creepage distances, clearances, and use of fire-resistant materials to enhance durability and safety.

• Labeling and Marking
  Requirements for clear identification of transformer ratings, insulation level, voltage settings, and safety instructions to support proper use and maintenance.

• Compatibility with IEC 61558-1:2005
  This standard supplements and modifies Part 1 to address particular issues relevant to high insulation and high voltage transformers.

Applications

IEC 61558-2-10 is critical for industries and applications where high-voltage transformers are essential:

• Industrial Manufacturing
  Transformers used in machinery and process control equipment requiring reliable isolation and high voltage operation.

• Power Generation and Distribution
  Separation transformers for high-voltage systems to ensure safety and prevent electrical faults.

• Medical Equipment
  Power supply units and transformers needing enhanced insulation to protect sensitive devices and patient safety.

• Renewable Energy Systems
  High-voltage transformers in wind turbines, solar inverters, or energy storage solutions requiring certified insulation integrity.

• Testing and Certification Laboratories
  Provides the framework for testing separating transformers to meet international safety standards before market release.

Related Standards

• IEC 61558-1:2005
  General requirements and tests for transformers and power supply units. IEC 61558-2-10 serves as a particular part expanding on these base requirements for high insulation and high voltage.

• IEC 60989 (1991)
  Predecessor to IEC 61558-2-10, now cancelled and replaced; previously addressed similar transformer safety aspects.

• IEC 60076 Series
  Covers power transformers more broadly but may be complementary depending on application.

• IEC 61727
  Relates to grid-connected photovoltaic inverters, which may include high-voltage transformer components.

Practical Value

Adopting IEC 61558-2-10 ensures compliance with internationally accepted safety benchmarks for separating transformers operating at high voltages. Manufacturers can design transformers that minimize risks of electric shock, overheating, and mechanical failure, protecting both end users and equipment. Regulatory bodies and certification agencies utilize this standard to evaluate products for market approval, while end users gain confidence in the safety and reliability of their electrical systems.

The standard also facilitates global trade by harmonizing technical requirements across national borders, encouraging innovation in transformer and power supply design with robust safety assurance.

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Keywords: IEC 61558-2-10, safety standard, separating transformers, high insulation level, high voltage transformers, power supply units, electrical insulation, dielectric testing, transformer safety, IEC standards, electrical safety, transformer testing, power transformers, international electrotechnical commission.

Standards Content (Sample)

IEC 61558-2-10 ®
Edition 1.0 2014-04
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Safety of transformers, reactors, power supply units and combinations thereof –
Part 2-10: Particular requirements and tests for separating transformers with
high insulation level and separating transformers with output voltages
exceeding 1 000 V
Sécurité des transformateurs, bobines d'inductance, blocs d'alimentation et des
combinaisons de ces éléments –
Partie 2-10: Règles particulières et essais pour les transformateurs d'isolement à
enroulements séparés à niveau d'isolement élevé et pour les transformateurs
d'isolement à enroulements séparés à tensions secondaires supérieures
à 1 000 V
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IEC 61558-2-10 ®
Edition 1.0 2014-04
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Safety of transformers, reactors, power supply units and combinations thereof –

Part 2-10: Particular requirements and tests for separating transformers with

high insulation level and separating transformers with output voltages

exceeding 1 000 V
Sécurité des transformateurs, bobines d'inductance, blocs d'alimentation et des

combinaisons de ces éléments –

Partie 2-10: Règles particulières et essais pour les transformateurs d'isolement

à enroulements séparés à niveau d'isolement élevé et pour les transformateurs

d'isolement à enroulements séparés à tensions secondaires supérieures

à 1 000 V
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
CODE PRIX Q
ICS 29.180 ISBN 978-2-8322-1513-5

– 2 – IEC 61558-2-10:2014 © IEC 2014
CONTENTS
FOREWORD . 3
1 Scope . 5
2 Normative references . 6
3 Terms and definitions . 6
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 . 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 . 11
16 Mechanical strength . 11
17 Protection against harmful ingress of dust, solid objects and moisture . 11
18 Insulation resistance, dielectric strength and leakage current . 11
19 Construction . 12
20 Components . 13
21 Internal wiring . 13
22 Supply connection and other external flexible cable or cords . 13
23 Terminals for external conductors . 13
24 Provisions for protective earthing . 13
25 Screws and connections . 13
26 Creepage distances, clearances and distances through insulation . 13
27 Resistance to heat, fire and tracking . 15
28 Resistance to rusting . 15
Annexes . 15

Table 101 – Output voltage difference . 11
Table 102 – Table of dielectric strength test voltages . 12
Table 103 – Clearances distances for homogenous fields and inhomogeneous fields . 14
Table 104 – Creepage distances for material group III a, II and I (CTI > 175) for basic
or supplementary insulation . 15

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
SAFETY OF TRANSFORMERS, REACTORS, POWER
SUPPLY UNITS AND COMBINATIONS THEREOF –

Part 2-10: Particular requirements and tests for separating
transformers with high insulation level and separating
transformers with output voltages exceeding 1 000 V

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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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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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
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.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
members of its technical committees and IEC National Committees for any personal injury, property damage or
other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
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 61558-2-10 has been prepared by IEC technical committee 96:
Transformers, reactors, power supply units, and combinations thereof.
This first edition cancels and replaces Chapter ll Section Three of IEC 60989 published in
1991.
It constitutes a technical revision. The main changes consist of
a) updating this part in accordance with IEC 61558-1:2005, and
b) adding power supply units to the scope.

– 4 – IEC 61558-2-10:2014 © IEC 2014
The text of this standard is based on the following documents:
FDIS Report on voting
96/407/FDIS 96/408/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 2-10 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 and its
Amendement 1 (2009).
This Part 2-10 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 separating
transformers with high insulation level and separating transformers with output voltages
exceeding 1 000 V.
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.
When 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 adopted accordingly.
In this part, the following print types are used:
− requirements proper: in roman type;
− test specifications: in italic type;
− explanatory matters: 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.
The transitional period is not longer than 3 years after the publication of this standard.

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

Part 2-10: Particular requirements and tests for separating
transformers with high insulation level and separating
transformers with output voltages exceeding 1 000 V

1 Scope
Replacement:
This part of IEC 61558 deals with the safety of separating transformers with high insulation
level and separating transformers with output voltages exceeding 1 000 V. 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 separating
transformers with high insulation level and separating transformers with output voltages
exceeding 1 000 V a.c or 1 500 V d.c .
This Part 2-10 is applicable to stationary or portable, single-phase or polyphase, air-cooled
(natural or forced) independent or associated dry-type transformers. The windings may be
encapsulated or non-encapsulated.
This standard is applicable to transformers and power supply (linear) with internal
operational frequencies not exceeding 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 operational 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., and the rated supply frequency and
the internal operating frequency do not exceed 500 Hz.
The rated output does not exceed:
– 25 kVA for single-phase transformers;
– 40 kVA for polyphase transformers.
This Part 2-10 is applicable to transformers without limitation of the rated output subject to
an agreement between the purchaser and the manufacturer.
Where applicable the no-load output voltage or the rated output voltage:
– does not exceed 1 000 V a.c. or 1 500 V d.c. for separating transformers with high
insulation level;
– does exceed 1 000 V a. c or 1 500 V d.c. and does not exceed 15 000 V a.c. or 15 000 V
d.c. for separating transformer with output voltage exceed 1 000 V.
This Part 2-10 is not applicable to:
– transformers covered by IEC 60076-11;

– 6 – IEC 61558-2-10:2014 © IEC 2014
– neon transformers covered by IEC 61050 and
– power supplies and converters for use with or in products according to IEC 61347-2-10.
This Part 2-10 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 2-10 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.
NOTE 2 Normally, the transformers are intended to be used with equipment to provide voltages different from the
supply voltage for the functional requirements of the equipment. The protection against electric shock can be
provided (or completed) by other features of the equipment, such as the body. Parts of output circuits can be
connected to the input circuits or to protective earth.
This Part 2-10 is applicable to transformers associated with specific equipment, to the extent
decided upon by the relevant IEC technical committees.
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.) can 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 can also be considered;
– the different conditions for transportation, storage, and operation of the can also be considered;
– additional requirements in accordance with other appropriate standards and national rules can be applicable to
transformers intended for use in special environments, such as tropical environment.
NOTE 4 Future technological development of transformers can necessitate a need to increase the upper limit of
the frequencies, until then this Part 2-10 can be used as a guidance document.
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
Amendment 1:2009
IEC 61558-2-16, Safety of transformers, reactors, power supply units and similar products for
supply voltages up to 1 100 V – Part 2-16: Particular requirements and tests for switch mode
power supply units and transformers for switch mode power supply units
3 Terms and definitions
This clause of Part 1 is applicable except as follows:
The third paragraph is not applicable.
3.1 Transformers
Addition:
3.1.101
separating transformer with high insulation level
a separating transformer where the output voltage does not exceed 1 000 V a.c or
1 500 V d.c and does exceed 50 V a.c or d.c for independent transformer
Note 1 to entry: The output winding(s) are isolated from both, input winding(s) and body for a working voltage
exceeding 1 000 V. a.c or 1 500 V d.c but not exceeding 15 000 V a.c or 15 000 V d.c.
3.1.102
separating transformer with output voltages exceeding 1 000 V
a separating transformer the output circuits of which are designed to give voltages
exceeding 1 000 V a.c or 1 500 V d.c and not exceeding 15 000 V a.c or 15 000 V d.c
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 not applicable.
Replacement:
6.101 The rated output voltage is limited as follows:
For separating transformers with high insulation level:
– the no-load output voltage or the rated output voltage shall not exceed 1 000 V a.c. or
1 500 V d.c.;
for independent transformers the rated output voltage shall exceed 50 V a.c. or d.c. and
this output voltage applies even when output windings, not intended for interconnection, are
connected in series.
For separating transformers with no load output voltages exceeding 1 000 V:
– the rated output voltage shall exceed 1 000 V a.c. or 1 500 V d.c. and shall not exceed
15 000 V a.c. or 15 000 V d.c.;
– for independent transformers this output voltage limitations applies even when output
windings, not intended for interconnection, are connected in series.
6.102 The rated output shall not exceed:
– 25 kVA for single-phase transformers;
– 40 kVA for polyphase transformers;
Transformers without limitation of the rated output shall be subject to agreement between the
purchaser and the manufacturer.
6.103 The rated supply frequency and the internal operating frequencies shall not exceed
500 Hz.
– 8 – IEC 61558-2-10:2014 © IEC 2014
6.104 The rated supply voltage shall not exceed 1 000 V a.c.
Compliance with the requirements of 6.101 to 6.104 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 h) Replacement:
Replace the first sentence by the following: relevant graphical symbols shown in 8.11 indicating
the kind of transformer;
The voltage of the insulation level, expressed in kV is not a part of the symbol
8.11 Addition:
Symbol or graphical symbol Explanation or title Identification
IEC 60417-6063
Separating transformer, high insulation
level, general
To identify the separating transformer with
high insulation level, where the letter "F"
may be used adjacent to the symbol to
indicate a fail-safe function.
The voltage of the insulation level,
expressed in kV, may be added adjacent to
the symbol.
IEC 60417-6064
Separating transformer, high insulation
level, non-short-circuit-proof
To identify the non-short-circuit-proof
separating transformer with high insulation
level.
The voltage of the insulation level,
expressed in kV, may be added adjacent to
the symbol
Symbol or graphical symbol Explanation or title Identification
Separating transformer, high insulation IEC 60417-6065
level, short-circuit-proof
To identify the short-circuit-proof (inherently
or non-inherently) separating transformer
with high insulation level.
The voltage of the insulation level,
expressed in kV, may be added adjacent to
the symbol.
Separating transformer, output voltages IEC 60417-6066
exceeding 1 kV, general
To identify the separating transformer with
output voltages exceeding 1 000 V and not
exceeding 15 000 V, where the letter "F"
may be used adjacent to the symbol to
indicate a fail-safe function.

IEC 60417-6067
Separating transformer, output voltages
exceeding 1 kV, non-short-circuit-proof
To identify the non-short-circuit-proof
separating transformer with output voltages
exceeding 1 000 V and not exceeding
15 000 V.
IEC 60417-6068
Separating transformer, output voltages
exceeding 1 kV, short-circuit-proof
To identify the short-circuit-proof (inherently
or non-inherently) separating transformer
with output voltages exceeding 1 000 V and
not exceeding 15 000 V.
– 10 – IEC 61558-2-10:2014 © IEC 2014

Addition:
8.101 Separating transformers with high insulation level shall be marked with the voltage
of the insulation level, expressed in kV on the right side of the symbol.
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 voltage is measured when the transformer is connected to the rated supply
voltage at the rated supply frequency at ambient temperature.
12.101 For separating transformers with high insulation level:
– the no load output voltage shall not exceed 1 000 V a.c. or 1 500 V d.c. For independent
transformers the no-load output voltage shall exceed 50 V a.c. or d.c. This limitation
applies even when independent output windings, not intended for interconnection, are
connected in series;
12.102 For separating transformers with output voltages exceeding 1 000 V:
– the no-load output voltage shall exceed 1 000 V a.c. or 1 500 V d.c. and shall not exceed
15 000 V a.c. or d.c. For independent transformers this limitation applies even when
independent output windings, not intended for interconnection, are connected in series;
12.103 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:
U −U
no−load load
×100 [%]
U
load
where U is the no-load output voltage and U is the output voltage under load. The

no-load load
difference shall not exceed the values shown in Table 101.

Table 101 – Output voltage difference
Type of transformer Difference between no-load output voltage and
Rated output 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 630 20
– over 630 15
Compliance with the requirements of 12.101, 12.102 and 12.103 shall be checked by
measuring the no-load output voltage at ambient temperature when the transformer is
connected to the rated supply voltage at the rated supply frequency.
13 Short-circuit voltage
This clause of Part 1 is applicable.
14 Heating
This clause of Part 1 is applicable.
15 Short-circuit and overload protection
This clause of Part 1 is applicable.
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:
18.3 Dielectric strength test
Replacement:
Immediately after the test of 18.2 the insulation is subjected for 1 min to a dielectric strength
voltage of substantially sinusoidal wave form at 50 Hz or 60 Hz. The value of the dielectric
strength test voltage and the points of application are given in Table 102.
Resistors, capacitors and other components are disconnected before carrying out the test.

– 12 – IEC 61558-2-10:2014 © IEC 2014
Table 102 – Table of dielectric strength test voltages
Application of dielectric strength test voltage Working voltage
over 1 000 V, up to
and including 15 000 V
1) Between live parts of input circuits and live parts of output circuits basic 2 x working voltage
insulation + 1 000 V
2) Over basic insulation or supplementary insulation between:
a) live parts of different polarity. Test is not applicable within the same winding
b) life parts and the body, if intended to be connected to the protective earth
c) accessible conductive parts and a metal rod of the same diameter as the
2 x working voltage
flexible cable or cord (or metallic foil wrapped round the cord) inserted inside
+ 1 000 V
inlet bushing, cord guards and anchorage, and the like
d) live parts and an intermediate conductive part
e) conductive parts and the body
f) each input circuit and all other input circuits connected together

19 Construction
This clause of Part 1 is applicable except as follows:
Replacement:
19.1 The input and output circuits shall be electrically separated from each other, and the
construction shall be such that there is no possibility of any connection between these circuits,
either directly or indirectly, through other conductive parts, except by deliberate action.
Compliance is checked by inspection and measurements, taking Clauses 18 and 26 into
consideration.
Addition:
19.1.101 The insulation between input and output winding(s) shall consist of at least basic
insulation (rated for the working voltage).
In addition, the following applies:
– for class I transformers, the insulation between the input windings and the body, and
between the output windings and the body, shall consist of basic insulation (both basic
insulations rated for the working voltage);
– for class II transformers, the insulation between the input windings and the body, and
between the output windings and the body, shall consist of double or reinforced
insulation (both double or reinforced insulations rated for the working voltage).
19.1.102 For transformers with intermediate conductive parts (e.g. the iron core) not
connected to the body and located between the input and output windings, the insulation
between the intermediate conductive parts and the input windings, and between the
intermediate conductive parts and the output windings shall consist of basic insulation
(rated for the working voltage).
NOTE An intermediate conductive part not separated from the input or output windings or the body by at least
basic insulation is considered to be connected to the relevant part(s).
In addition, the following applies:

– for class I transformers, the insulation between the input and output windings via the
intermediate conductive parts shall consist of at least basic insulation (rated for the
working voltage);
– for class II transformers, the insulation between the input windings and the body, and
between the output windings and the body via the intermediate conductive parts shall
consist of double or reinforced insulation (rated for the input and output voltage).
Addition:
19.101 Parts of output circuits may be connected to protective earth.
19.102 There shall be no connection between the output circuits and the body, unless – for
associated transformers – allowed by the relevant equipment standard.
Compliance is checked by inspection.
20 Components
This clause of Part 1 is applicable.
21 Internal wiring
This clause of Part 1 is applicable.
22 Supply connection and other external flexible cable or cords
This clause of Part 1 is applicable.
23 Terminals for external conductors
This clause of Part 1 is applicable.
24 Provisions for protective earthing
This clause of Part 1 is applicable.
25 Screws and connections
This clause of Part 1 is applicable.
26 Creepage distances, clearances and distances through insulation
This clause of Part 1 is applicable except as follows:
Replacements:
26.1 Replacement of the first and second paragraph by the following:
For working voltages up to and including 1 000 V the creepage distances, clearances and
distances through insulation shall not be less than the values shown in Table 13 for insulating
materials of group III a (see IEC 60664-1)

– 14 – IEC 61558-2-10:2014 © IEC 2014
For working voltages over 1 000 V, up to and including 15 000 V the creepage distances,
clearances and distances through insulation shall not be less than the values shown in
Table 103 for insulating materials of at least group III a (see IEC 60664-1)
Compliance is checked by measurements under the provisions of 26.2 and 26.3
NOTE 1
– For working voltages up to and including 1 000 V: For materials of groups I and II , see Tables C.1 and D.1.
– For working voltages exceeding 1 000 V and up to and including 15 000 V: For material groups II and I see
Table 103.
NOTE 2 Table 13, Table C.1 and Table D.1 and Table 102 are applicable only for frequencies up to and including
30 kHz.
Replacement of NOTE 7 by the following:
NOTE 7 Table 13, Table C.1 and Table D.1 take into consideration over voltage category II for basic insulation
and over voltage category III for double or reinforced insulation.
Addition:
26.1.101
Table 103 – Clearances distances
for homogenous fields and inhomogeneous fields
Minimum clearances in air up to 2 000 m above sea level
Working voltage Inhomogeneous field Homogeneous field
V
1 000 8,0 3,0
1 500 11,5 4,0
3 000 21,0 6,5
6 000 47,0 14,0
10 000 78,0 23,0
15 000 117,0 35,0
NOTE 1 The values from EN 50178 and IEC 62103 are also applicable.
NOTE 2 Interpolation is allowed.

Creepage distances, clearances and distances through insulation shall not be less than the
values shown in Table 104.
Table 104 – Creepage distances
for material group III a, II and I (CTI > 175)
for basic or supplementary insulation
Minimum creepage distance
Pollution degree
Working
1 2  3
voltage
All material Material Material Material Material Material Material
groups group I group II group III a group I group II group III a
V mm mm mm mm mm mm mm
1 000 3,2 5,0 7,1 10,0 12,5 14,0 16,0
1 250 4,2 6,3 9,0 12,5 16,0 18,0 20,0
1 600 5,6 8,0 11,0 16,0 20,0 22,0 25,0
2 000 7,5 10,0 14,0 20,0 25,0 28,0 32,0
2 500 10,0 12,5 18,0 25,0 32,0 36,0 40,0
3 200 12,5 16,0 22,0 32,0 40,0 45,0 50,0
4 000 16,0 20,0 28,0 40,0 50,0 56,0 63,0
5 000 20,0 25,0 36,0 50,0 63,0 71,0 80,0
6 300 25,0 32,0 45,0 63,0 80,0 90,0 100,0
8 000 32,0 40,0 56,0 80,0 100,0 110,0 125,0
10 000 40,0 50,0 71,0 100,0 125,0 140,0 160,0
12 500 50,0 63,0 90,0 125,0 155,0 180,0 200,0
15 000 59,0 75,0 103,2 150,0 200,0 230,0 240,0
NOTE 1 P1 = pollution degree 1; P2 = pollution degree 2; P3 = pollution degree 3.
NOTE 2 When a numeric figure is replaced with a dash in a column of the table, it means that no value is given.
NOTE 3 The minimum values of clearance in this table are applicable in air up to 2000 m above sea level.
NOTE 4 Material groups III b is not allowed.
NOTE 5 Interpolation is allowed.
NOTE 6 The values in IEC 60664-1:2007, Table F4 are also applicable.
NOTE 7 Creepage distance for double or reinforced insulation is twice the creepage distance for basic
insulation from this tables.
27 Resistance to heat, fire and tracking
This clause of Part 1 is applicable.
28 Resistance to rusting
This clause of Part 1 is applicable.
Annexes
The annexes of Part 1 are applicable.

– 16 – IEC 61558-2-10:2014 © IEC 2014
Bibliography
Addition:
IEC 60076-11, Power transformers – Part 11: Dry-type transformers
IEC 61050, Transformers for tubular discharge lamps having a no-load output voltage
exceeding 1000 V (generally called neon-transformers) – General and safety requirements
IEC 61347-2-10:2000, Lamp controlgear – Part 2-10: Particular requirements for electronic
invertors and convertors for high-frequency operation of cold start tubular discharge lamps
(neon tubes)
IEC 62103, Electronic equipment for use in power installations

EN 50178, Electronic equipment for use in power installations

_____________
– 18 – IEC 61558-2-10:2014 © IEC 2014
SOMMAIRE
AVANT-PROPOS . 19
1 Domaine d’application . 22
2 Références normatives . 23
3 Termes et définitions . 24
4 Exigences générales . 24
5 Généralités sur les essais . 24
6 Caractéristiques assignées . 24
7 Classification . 25
8 Marquage et indications . 25
9 Protection contre les chocs électriques . 27
10 Changement de la tension primaire d’alimentation . 27
11 Tension secondaire et courant secondaire en charge . 27
12 Tension secondaire à vide . 27
13 Tension de court-circuit . 28
14 Echauffements . 28
15 Protection contre les courts-circuits et les surcharges . 28
16 Résistance mécanique . 28
17 Protection contre les effets nuisibles dus à la pénétration de poussière, d’objets
solides et de l’humidité . 29
18 Résistance d'isolement, rigidité diélectrique et courant de fuite . 29
19 Construction . 29
20 Composants . 30
21 Conducteurs internes . 30
22 Raccordement à l’alimentation et câbles souples externes . 31
23 Bornes pour conducteurs externes . 31
24 Dispositions en vue de la mise à la terre . 31
25 Vis et connexions . 31
26 Lignes de fuite, distances d’isolement et distances à travers l’isolation . 31
27 Résistance à la chaleur, au feu et aux courants de cheminement . 33
28 Protection contre la rouille. 33
Annexes . 33

Tableau 101 – Différence de tensions secondaires . 28
Tableau 102 – Tableau des tensions d'essai de rigidité diélectrique . 29
Tableau 103 – Distances d'isolement pour champs homogènes et champs non
ho
...