IEC 62505-3-3:2009

IEC 62505-3-3 ®
Edition 1.0 2009-03
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Railway applications – Fixed installations – Particular requirements for a.c.
switchgear –
Part 3-3: Measurement, control and protection devices for specific use in a.c.
traction systems – Single-phase inductive voltage transformers

Applications ferroviaires – Installations fixes – Exigences particulières pour
appareillage à courant alternatif –
Partie 3-3: Dispositifs de mesure, de commande et de protection pour usage
spécifique dans les systèmes de traction à courant alternatif – Transformateurs
inductifs de tension monophasés

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IEC 62505-3-3 ®
Edition 1.0 2009-03
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Railway applications – Fixed installations – Particular requirements for a.c.
switchgear –
Part 3-3: Measurement, control and protection devices for specific use in a.c.
traction systems – Single-phase inductive voltage transformers

Applications ferroviaires – Installations fixes – Exigences particulières pour
appareillage à courant alternatif –
Partie 3-3: Dispositifs de mesure, de commande et de protection pour usage
spécifique dans les systèmes de traction à courant alternatif – Transformateurs
inductifs de tension monophasés

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
K
CODE PRIX
ICS 45.060 ISBN 978-2-88910-749-0
– 2 – 62505-3-3 © IEC:2009
CONTENTS
FOREWORD.3

INTRODUCTION.5

1 Scope.6

2 Normative references .6

3 Terms and definitions .6

4 Service conditions .7

5 Characteristics and use .7

6 Rating and design requirements .7
7 Withstand conditions .7
7.1 Primary side .7
7.2 Secondary side .7
8 Ferro-resonance.8
8.1 General .8
8.2 Prevention of the generation .8
8.3 Prevention of damages in the voltage transformer .8
8.4 Ferro-resonance withstand test .8
9 Particular design and construction characteristics .8
9.1 Pollution.8
9.2 External flashover test.8
9.3 Floating potentials and earthing.9
9.4 Electromagnetic compatibility .9
9.5 Secondary connection box .9
9.6 Information to be given by the purchaser.9
9.7 Information to be given by the supplier .9
10 Tests – General.9
11 Other requirements.10

62505-3-3 © IEC:2009 – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION

____________
RAILWAY APPLICATIONS –
FIXED INSTALLATIONS –
PARTICULAR REQUIREMENTS FOR AC SWITCHGEAR –

Part 3-3: Measurement, control and protection devices

for specific use in a.c. traction systems –

Single-phase inductive voltage transformers

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
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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 62505-3-3 has been prepared by IEC technical committee 9:
Electrical equipment and systems for railways. This standard is based on EN 50152-3-3.
The text of this standard is based on the following documents:
FDIS Report on voting
9/1223/FDIS 9/1236/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.

– 4 – 62505-3-3 © IEC:2009
A list of all parts of IEC 62505 series, under the general title Railway applications – Fixed

installations – Particular requirements for a.c. switchgear, can be found on the IEC website.

The committee has decided that the contents of this publication will remain unchanged until

the maintenance result 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.
62505-3-3 © IEC:2009 – 5 –
INTRODUCTION
Part 3 of IEC 62505, “Railway applications – Fixed installations – Particular requirements for

a.c. switchgear", concerning the measurement, control and protection devices for specific use

in a.c. traction systems, comprises:

IEC 62505-3-1: Application guide (informative document)

IEC 62505-3-2: Single-phase current transformers (normative document)

IEC 62505-3-3: Single-phase inductive voltage transformers (normative document)

This Standard applies to inductive voltage transformers used at traction voltages and

frequencies according to IEC 60850.
The requirements contained in this Standard complement those given in IEC 60044-2:1997.

– 6 – 62505-3-3 © IEC:2009
RAILWAY APPLICATIONS –
FIXED INSTALLATIONS –
PARTICULAR REQUIREMENTS FOR AC SWITCHGEAR –

Part 3-3: Measurement, control and protection devices

for specific use in a.c. traction systems –

Single-phase inductive voltage transformers

1 Scope
This part of IEC 62505 gives particular requirements for voltage transformers used in a.c.
single-phase railway applications, fixed installations.
This International Standard applies to inductive voltage transformers used at traction voltages
and frequencies according to IEC 60850.
The main uses of these voltage transformers are:
− voltage indication;
− measurement;
− protection.
2 Normative references
The following referenced documents are indispensable for the application of this document.
For dated references, only the edition cited applies. For undated references, the latest edition
of the referenced document (including any amendments) applies.
IEC 60044-2:1997, Instrument transformers – Part 2: Inductive voltage transformers
IEC 60529:2001, Degrees of protection provided by enclosures (IP Code)
IEC 60850, Railway applications – Supply voltages of traction systems
IEC 62236-5, Railway applications – Electromagnetic compatibility – Part 5: Emission and

immunity of fixed power supply installations and apparatus
IEC 62497-1, Railway applications – Insulation coordination – Part 1: Basic requirements –
Clearances and creepage distances for all electrical and electronic equipment
IEC 62505 (all parts), Railway applications – Fixed installations – Particular requirements for
a.c. switchgear
3 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 62505-1, Clause 3
and in IEC 60044-2:1997, Clause 2, apply.

62505-3-3 © IEC:2009 – 7 –
4 Service conditions
Where the equipment described in this part of the standard is mounted on circuit breakers to

IEC 62505-1, then the service conditions of that standard apply. Where they are separately

mounted and are used in association with switchgear then the same service conditions as the

switchgear apply.
5 Characteristics and use
The voltage transformer shall be:

a) either mounted inside the circuit breaker specified in IEC 62505-1; technical requirements
of this IEC 62505-3-3 apply together with the construction and test requirements (as
applicable) of IEC 62505-1;
b) or separately mounted, free standing; technical requirements of this IEC 62505-3-3 apply.
6 Rating and design requirements
Clauses 5 and 6 of IEC 60044-2:1997 apply with the following exceptions:
− In subclause 5.1.2 the following shall be added at the end of the subclause:
The secondary voltage values of 100 V or 110 V shall be preferred.
The rated ratio is given by the primary nominal voltage, as defined in IEC 60850, divided
by the rated secondary voltage.
− In Clause 6 the entire subclause 6.1.1 shall be replaced by:
6.1.1 Rated insulation levels for the primary winding
Voltage transformers covered by this standard shall have the same insulation ratings and
test values as the equipment into which they are installed. See Table 1 of IEC 62505-1
and IEC 62505-2. Free standing voltage transformers shall meet the same requirements.
− Subclause 6.1.5 of IEC 60044-2 is valid unless inconsistent with 9.1 of this International
Standard.
7 Withstand conditions
The following requirements, additional to those of IEC 60044-2:1997, apply:
7.1 Primary side
The voltage transformer shall withstand the overvoltage characteristics described in
IEC 60850, Annex A.
NOTE These events occur often and special attention should be paid to protect these voltage transformers.
7.2 Secondary side
The voltage transformer shall withstand the current produced in secondary winding for 1 s,
when its terminals are short circuited. The primary voltage shall be U for this condition.
max2
Where no U value is specified, U shall be used.
max2 max1
NOTE A rapid fuse or a miniature circuit breaker may be inserted at the load. On request, a slow-blow low-voltage
fuse should be inserted between secondary winding and secondary terminals.

– 8 – 62505-3-3 © IEC:2009
8 Ferro-resonance
8.1 General
The following requirements, additional to those of IEC 60044-2:1997, apply:

The structure of railway electrification network may easily generate ferro-resonance

phenomena. They occur mainly in 25 kV, 50 Hz systems.

When specified by the purchaser, the voltage transformer connected directly to the overhead

line shall have the following characteristics in order to avoid the generation of ferro-resonance

phenomena and withstand the overvoltages caused by the same.
8.2 Prevention of the generation
The following features shall be adopted:
− minimum resistance of the primary winding: shall be specified by the purchaser;
NOTE Typical resistance values are between 15 kΩ and 50 kΩ.
− flux density such that at U (see IEC 60850) the saturation point is not reached.
max2
8.3 Prevention of damages in the voltage transformer
The following features shall be adopted:
− ability to withstand without damage on the primary side a voltage wave obtained by
summing a sinusoidal wave at rated frequency with a square wave at 1/3 of the rated
frequency, with a total peak value of approximately 1,6 × U ;
n
− suitability to operate continuously at 1/3 of the rated frequency and rated voltage;
− voltage factor of 1,9 (1,9 × U for 8 h at rated frequency).
n
8.4 Ferro-resonance withstand test
The voltage transformer will be considered suitable to withstand ferro-resonance if these
characteristics are checked and tested, as a special type test named ferro-resonance
withstand test. This consists of a temperature-rise test at rated voltage, rated burden and 1/3
of rated frequency. The standard temperature rises shall not be exceeded.
9 Particular design and construction characteristics

The following requirements, additional to those of IEC 60044-2:1997, apply:
9.1 Pollution
The dust pollution on railway tracks (e.g. in tunnels and at the seaside) is often higher than on
high voltage transmission lines. For this reason the creepage distance shall not be less than
indicated in IEC 62497-1, Table A.7, for the appropriate pollution degree.
NOTE For the choice of the appropriate pollution degree, the degrees used in the associated switchgear (see
IEC 62505-1 and IEC 62505-2) should be taken into account.
9.2 External flashover test
When specified by the purchaser, outdoor units shall be able to withstand an external
flashover of the primary bushing and be capable of continued service. This will be tested as a
special type test named the external flashover test by repeating dielectric, partial discharge
and accuracy tests after a flashover. The flashover is made by creating a permanent

62505-3-3 © IEC:2009 – 9 –
conduction on the creepage distance of the insulator. The voltage applied shall be U the
max1
resulting fault current being maintained for 100 ms up to the following values:

− for 15 kV systems 50 kA r.m.s.;

− for 25 kV systems 16 kA r.m.s.

9.3 Floating potentials and earthing

No metallic part of the voltage transformer shall be left at floating potential. The earthing
connection shall be able to carry the rated short time withstand current for a duration of 1 s.

9.4 Electromagnetic compatibility
...