IEC 62505-3-3:2020

IEC 62505-3-3 ®
Edition 2.0 2020-01
INTERNATIONAL
STANDARD
Railway applications – Fixed installations – Particular requirements for AC
switchgear –
Part 3-3: Measurement, control and protection devices for specific use in AC
traction systems – Voltage transformers

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IEC 62505-3-3 ®
Edition 2.0 2020-01
INTERNATIONAL
STANDARD
Railway applications – Fixed installations – Particular requirements for AC

switchgear –
Part 3-3: Measurement, control and protection devices for specific use in AC

traction systems – Voltage transformers

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 45.060.01 ISBN 978-2-8322-7668-6

– 2 – IEC 62505-3-3:2020 © IEC 2020
CONTENTS
FOREWORD . 3
INTRODUCTION . 5
1 Scope . 6
2 Normative references . 6
3 Terms, definitions and abbreviated terms . 7
3.1 Terms and definitions . 7
3.2 Abbreviated terms . 8
4 Service conditions . 8
5 Rating. 8
5.1 General . 8
5.2 Nominal voltage (U ) . 8
n
5.3 Rated voltage (U ) . 8
Ne
5.4 Insulation coordination . 9
5.4.1 General . 9
5.4.2 Rated insulation level . 9
5.5 Rated frequency . 10
5.6 Rated output . 10
5.7 Rated accuracy class . 10
5.8 Standard values of rated voltages . 10
5.9 Standard values of rated voltage factor . 10
5.10 Ferroresonance . 11
6 Design and construction . 11
6.1 General . 11
6.2 Transformer construction . 11
6.3 Requirements for the external insulation . 11
6.4 Nameplates. 12
7 Tests . 12
7.1 General . 12
7.2 Ferroresonance withstand test . 12
7.3 Partial discharge test . 12
8 Rules for transport, storage, erection, operation and maintenance . 13
9 Safety . 13
10 Influence of the product on the environment . 13
11 Information to be given with enquiries, tenders and orders . 13
Bibliography . 14

Table 1 – Nominal voltages (U ), rated voltages (U ), rated impulse voltages (U )
n Ne Ni
and power-frequency withstand voltage (U ) for circuits connected to the contact line . 9
d
Table 2 – Partial discharge test voltages and permissible levels . 13

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
RAILWAY APPLICATIONS – FIXED INSTALLATIONS –
PARTICULAR REQUIREMENTS FOR AC SWITCHGEAR –

Part 3-3: Measurement, control and protection devices
for specific use in AC traction systems – 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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8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
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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 second edition cancels and replaces the first edition published in 2009. This edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
– This standard was revised to reflect the latest versions of standards referenced and to
remove text already included in the IEC 61869 series.
– The structure of the document was adapted to that of IEC 62505‑1 and IEC 62505‑2.
– Ratings have been added to provide designations in line with other railway standards, for
example IEC 62497.
– 4 – IEC 62505-3-3:2020 © IEC 2020
– Tests requirements have been detailed to meet operating conditions of railway
applications.
– Partial discharge voltages have been specified in Table 2.
The text of this International Standard is based on the following documents:
FDIS Report on voting
9/2556/FDIS 9/2562/RVD
Full information on the voting for the approval of this International Standard can be found in
the report on voting indicated in the above table.
This document has been drafted in accordance with the ISO/IEC Directives, Part 2.
This document has to be read in conjunction with IEC 61869‑1:2007 and IEC 61869‑3:2011
(see Introduction).
A list of all parts in the IEC 62505 series, published under the general title Railway
applications – Fixed installations – Particular requirements for AC switchgear, can be found
on the IEC website.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under "http://webstore.iec.ch" in the data related to
the specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
A bilingual version of this publication may be issued at a later date.

INTRODUCTION
Where a particular clause/subclause of IEC 61869‑3 is not mentioned in this standard, that
clause/subclause applies as far as reasonable. Where requirements relate exclusively to
three-phase systems or to voltages outside those in use in traction systems, they are not
applicable. Where this standard states "addition" or "replacement", the relevant text of
IEC 61869‑3 is to be adapted accordingly.
The numbering of clauses in the IEC 61869 series is similar to that in the IEC 62505 series.
Where terms defined in IEC 61869‑1 and IEC 61869‑3 conflict with definitions of the same
terms as given in IEC 60050‑811:2017 or of the other railway applications documents listed in
the normative references, the definitions in IEC 61869‑1 and IEC 61869‑3 are to be used.
NOTE The suffix N which appears in this standard for rated values is not present in IEC 61869‑1 and
IEC 61869‑3.
References in subclauses of IEC 61869‑1 and IEC 61869‑3 have to be replaced by references
to applicable subclauses in this standard as far as reasonably possible.

– 6 – IEC 62505-3-3:2020 © IEC 2020
RAILWAY APPLICATIONS – FIXED INSTALLATIONS –
PARTICULAR REQUIREMENTS FOR AC SWITCHGEAR –

Part 3-3: Measurement, control and protection devices
for specific use in AC traction systems – Voltage transformers

1 Scope
This part of IEC 62505 is applicable to new voltage transformers which are:
– intended for use in indoor or outdoor fixed installations in tractions systems, and
– operated with an AC line voltage and frequency as specified in IEC 60850.
NOTE 1 IEC 60850 specifies the AC traction systems:
15 kV 16,7 Hz,
12 kV 25 Hz,
12,5 kV, 20 kV also 25 kV with 50 Hz and
12,5 kV, 20 kV, 25 kV also 50 kV with 60 Hz.
NOTE 2 As rails of AC traction systems are typically connected to earth and included in the return current path,
all phase to earth voltages are subject to the limits as given in IEC 60850. Nevertheless, conductor to conductor
voltages are sometimes higher, e.g. in autotransformer systems.
This document does not provide specific requirements for AC traction systems supplied with a
frequency of 25 Hz or with a nominal voltage of 12,5 kV or 50 kV. Nevertheless, requirements
set out in this document can be used as a guidance also for these systems.
Voltage transformers are mainly used with:
– measuring instruments,
– protective devices.
This document also applies to voltage transformers other than inductive types as far as
reasonably possible. Requirements of this document have priority.
NOTE 3 Combined current and voltage transformers, also capacitive voltage transformers are typically not used in
fixed installations in traction systems.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their
content constitutes requirements 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 60850:2014, Railway applications – Supply voltages of traction systems
IEC 61869-1:2007, Instrument transformers – Part 1: General requirements
IEC 61869-3:2011, Instrument transformers – Part 3: Additional requirements for inductive
voltage transformers
IEC 62497-1:2010, Railway applications – Insulation coordination – Part 1: Basic
requirements – Clearances and creepage distances for all electrical and electronic equipment
IEC 62497-1:2010/AMD1:2013
3 Terms, definitions and abbreviated terms
3.1 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 61869‑1:2007 and
IEC 61869‑3:2011, except 3.2.1 to 3.2.9, and the following apply.
ISO and IEC maintain terminological databases for use
...