IEC 62505-1:2009

IEC 62505-1 ®
Edition 1.0 2009-03
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Railway applications – Fixed installations – Particular requirements for a.c.
switchgear –
Part 1: Single-phase circuit-breakers with U above 1 kV
n
Applications ferroviaires – Installations fixes – Exigences particulières pour
appareillage à courant alternatif –
Partie 1: Disjoncteurs monophasés avec U supérieur à 1 kV
n
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by
any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from either IEC or
IEC's member National Committee in the country of the requester.
If you have any questions about IEC copyright or have an enquiry about obtaining additional rights to this publication,
please contact the address below or your local IEC member National Committee for further information.

Droits de reproduction réservés. Sauf indication contraire, aucune partie de cette publication ne peut être reproduite
ni utilisée sous quelque forme que ce soit et par aucun procédé, électronique ou mécanique, y compris la photocopie
et les microfilms, sans l'accord écrit de la CEI ou du Comité national de la CEI du pays du demandeur.
Si vous avez des questions sur le copyright de la CEI ou si vous désirez obtenir des droits supplémentaires sur cette
publication, utilisez les coordonnées ci-après ou contactez le Comité national de la CEI de votre pays de résidence.

IEC Central Office
3, rue de Varembé
CH-1211 Geneva 20
Switzerland
Email: inmail@iec.ch
Web: www.iec.ch
About the IEC
The International Electrotechnical Commission (IEC) is the leading global organization that prepares and publishes
International Standards for all electrical, electronic and related technologies.

About IEC publications
The technical content of IEC publications is kept under constant review by the IEC. Please make sure that you have the
latest edition, a corrigenda or an amendment might have been published.
ƒ Catalogue of IEC publications: www.iec.ch/searchpub
The IEC on-line Catalogue enables you to search by a variety of criteria (reference number, text, technical committee,…).
It also gives information on projects, withdrawn and replaced publications.
ƒ IEC Just Published: www.iec.ch/online_news/justpub
Stay up to date on all new IEC publications. Just Published details twice a month all new publications released. Available
on-line and also by email.
ƒ Electropedia: www.electropedia.org
The world's leading online dictionary of electronic and electrical terms containing more than 20 000 terms and definitions
in English and French, with equivalent terms in additional languages. Also known as the International Electrotechnical
Vocabulary online.
ƒ Customer Service Centre: www.iec.ch/webstore/custserv
If you wish to give us your feedback on this publication or need further assistance, please visit the Customer Service
Centre FAQ or contact us:
Email: csc@iec.ch
Tel.: +41 22 919 02 11
Fax: +41 22 919 03 00
A propos de la CEI
La Commission Electrotechnique Internationale (CEI) est la première organisation mondiale qui élabore et publie des
normes internationales pour tout ce qui a trait à l'électricité, à l'électronique et aux technologies apparentées.

A propos des publications CEI
Le contenu technique des publications de la CEI est constamment revu. Veuillez vous assurer que vous possédez
l’édition la plus récente, un corrigendum ou amendement peut avoir été publié.
ƒ Catalogue des publications de la CEI: www.iec.ch/searchpub/cur_fut-f.htm
Le Catalogue en-ligne de la CEI vous permet d’effectuer des recherches en utilisant différents critères (numéro de référence,
texte, comité d’études,…). Il donne aussi des informations sur les projets et les publications retirées ou remplacées.
ƒ Just Published CEI: www.iec.ch/online_news/justpub
Restez informé sur les nouvelles publications de la CEI. Just Published détaille deux fois par mois les nouvelles
publications parues. Disponible en-ligne et aussi par email.
ƒ Electropedia: www.electropedia.org
Le premier dictionnaire en ligne au monde de termes électroniques et électriques. Il contient plus de 20 000 termes et
définitions en anglais et en français, ainsi que les termes équivalents dans les langues additionnelles. Egalement appelé
Vocabulaire Electrotechnique International en ligne.
ƒ Service Clients: www.iec.ch/webstore/custserv/custserv_entry-f.htm
Si vous désirez nous donner des commentaires sur cette publication ou si vous avez des questions, visitez le FAQ du
Service clients ou contactez-nous:
Email: csc@iec.ch
Tél.: +41 22 919 02 11
Fax: +41 22 919 03 00
IEC 62505-1 ®
Edition 1.0 2009-03
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Railway applications – Fixed installations – Particular requirements for a.c.
switchgear –
Part 1: Single-phase circuit-breakers with U above 1 kV
n
Applications ferroviaires – Installations fixes – Exigences particulières pour
appareillage à courant alternatif –
Partie 1: Disjoncteurs monophasés avec U supérieur à 1 kV
n
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
XB
CODE PRIX
ICS 45.060 ISBN 978-2-88910-745-2
– 2 – 62505-1 © IEC:2009
CONTENTS
FOREWORD.6
INTRODUCTION.8
1 Scope.9
2 Normative references .9
3 Terms and definitions .9
4 Service conditions .10
5 Rating .10
5.1 General .10
5.2 Rated voltage (U ).11
Ne
5.3 Nominal voltage (U ).11
n
5.4 Rated insulation voltage (U ) [4.2] .11
Nm
5.5 Rated frequency [4.3] .12
5.6 Rated normal current and temperature rise [4.4].12
5.7 Rated short-time withstand current [4.5] .13
5.8 Rated peak withstand current [4.6] .13
5.9 Rated duration of short-circuit [4.7] .13
5.10 Rated supply voltage of closing and opening devices and auxiliary circuit
[4.8] .13
5.11 Rated supply frequency of closing and opening devices and auxiliary circuits
[4.9] .13
5.12 Rated pressures of compressed gas supply for operation and for interruption
[4.10].13
5.13 Rated short-circuit breaking current (I ) [4.101].13
Nss
5.13.1 General [4.101].13
5.13.2 AC component of the rated short-circuit breaking current [4.101.1].14
5.13.3 DC component of the rated short-circuit breaking current [4.101.2].14
5.14 Rated transient recovery voltage for terminal faults [4.102] .15
5.14.1 General .15
5.14.2 Representation of transient recovery voltage waves [4.102.1].15
5.14.3 Representation of rated TRV [4.102.2].15
5.14.4 Standard values of rated TRV [4.102.3] .15
5.15 Standard values of initial transient recovery voltage [4.102.4] .16
5.16 Rated short-circuit making current [4.103] .16
5.17 Rated operating sequence [4.104] .16
5.18 Rated out-of-phase breaking current [4.106].17
5.19 Rated line-charging breaking current [4.107.1] .19
5.20 Rated cable-charging breaking current [4.107.2] .19
5.21 Rated single capacitor bank breaking current [4.107.3] .19
5.22 Rated back-to-back capacitor bank breaking current [4.107.4].19
5.23 Rated capacitor bank inrush making current [4.107.5] .20
5.24 Rated time quantities [4.109].20
5.24.1 General .20
5.24.2 Rated break time [4.109.1] .21
5.25 Co-ordination of rated values .21
6 Design and construction [5] .22
6.1 Requirements for liquids in circuit-breakers [5.1] .22

62505-1 © IEC:2009 – 3 –
6.2 Requirements for gases in circuit-breakers [5.2].22
6.3 Earthing of circuit-breakers [5.3].22
6.4 Auxiliary equipment [5.4] .23
6.5 Dependent power closing [5.5] .23
6.6 Stored energy closing [5.6].23
6.7 Operation of releases [5.8] .23
6.7.1 General .23
6.7.2 Over-current release [5.8.101] .23
6.7.3 Multiple releases [5.8.102].24
6.8 Low and high pressure interlocking devices [5.9].24
6.9 Nameplates [5.10] .24
6.10 Requirements for simultaneity of poles [5.101] .24
6.11 General requirement for operation [5.102] .24
6.12 Pressure limits of compressed gas for interruption in gas blast circuit-
breakers [5.103] .25
6.13 Vent outlet [5.104].25
6.14 Safety overpressure device .25
7 Type tests [6] .25
7.1 General .25
7.2 Dielectric tests [6.2].26
7.2.1 Ambient air conditions during tests [6.2.1] .26
7.2.2 Wet test procedure [6.2.2] .26
7.2.3 Condition of circuit-breaker during dielectric tests [6.2.3].26
7.2.4 Application of test voltage and test conditions [6.2.5].26
7.2.5 Test voltages [6.2.6] .26
7.2.6 Lightning and switching impulse voltage tests [6.2.7.2, 6.2.7.3] .26
7.2.7 Power-frequency voltage tests [6.2.7.1] .27
7.2.8 Artificial pollution tests [6.2.8].27
7.2.9 Partial discharge tests [6.2.9] .27
7.2.10 Tests on auxiliary and control circuits [6.2.10] .27
7.3 Radio interference voltage (r.i.v.) tests [6.3] .27
7.4 Temperature-rise tests [6.5] .28
7.4.1 Conditions of the circuit-breaker to be tested [6.5.1] .28
7.4.2 Arrangement of the equipment [6.5.2].28
7.4.3 Measurement of the temperature and the temperature rise [6.5.3] .28
7.4.4 Ambient air temperature [6.5.4] .28
7.4.5 Temperature-rise tests of the auxiliary equipment [6.5.5].28
7.4.6 Interpretation of the temperature-rise tests [6.5.6] .28
7.5 Measurement of the resistance of the main circuit [6.4.1] .28
7.6 Short-time withstand current and peak withstand current tests [6.6] .28
7.6.1 Arrangement of the circuit-breaker and of the test circuit [6.6.1] .28
7.6.2 Test current and duration [6.6.2].29
7.6.3 Behaviour of circuit-breaker during test [6.6.3] .29
7.6.4 Conditions of circuit-breaker after test [6.6.4] .29
7.7 Mechanical and environmental tests [6.101] .29
7.7.1 Miscellaneous provisions for mechanical and environmental tests
[6.101.1] .29
7.7.2 Mechanical operation test at ambient air temperature [6.101.2] .31
7.7.3 Low and high temperature tests [6.101.3] .32

– 4 – 62505-1 © IEC:2009
7.7.4 Humidity test [6.101.4].35
7.7.5 Test to prove the operation under severe ice conditions [6.101.5].36
7.7.6 Guide for static terminal load test [6.101.6].36
7.8 Miscellaneous provisions for making and breaking tests [6.102] .37
7.8.1 General [6.102.1].37
7.8.2 Particular requirements for single–pole circuit-breaker tests .37
7.8.3 Arrangement of circuit-breaker for tests [6.102.3] .37
7.8.4 General considerations concerning test methods [6.102.4] .38
7.8.5 Synthetic tests [6.102.5] .38
7.8.6 No-load operations before tests [6.102.6] .38
7.8.7 Alternative closing mechanisms [6.102.7] .39
7.8.8 Behaviour of circuit-breaker during tests [6.102.8] .39
7.8.9 Condition of circuit-breaker after tests [6.102.9] .40
7.8.10 Circuit-breaker with short arcing times.41
7.9 Test circuit for short circuit making and breaking tests [6.103].43
7.9.1 Power factor [6.103.1] .43
7.9.2 Frequency [6.103.2].43
7.9.3 Earthing of test circuit for single phase tests of a single-pole circuit-
breaker [6.103.3] .43
7.9.4 Connection of test circuit to circuit-breaker [6.103.4] .43
7.10 Short-circuit test quantities [6.104] .44
7.10.1 Applied voltage before short-circuit making tests [6.104.1] .44
7.10.2 Short-circuit making current [6.104.2] .44
7.10.3 Short-circuit breaking current [6.104.3].45
7.10.4 DC component of short-circuit breaking current [6.104.4].45
7.10.5 Transient recovery voltage (TRV) for terminal fault test [6.104.5].46
7.10.6 Measurement of transient recovery voltage [6.104.6] .48
7.10.7 Power frequency recovery voltage [6.104.7] .48
7.11 Short-circuit test procedure [6.105].48
7.11.1 Time interval between tests [6.105.1] .48
7.11.2 Application of auxiliary power to the opening release – Breaking tests
[6.105.2] .49
7.11.3 Application of auxiliary power to the opening release – Make-break
tests [6.105.3] .49
7.11.4 Latching on short-circuit [6.105.4].49
7.11.5 Invalid tests [6.105.5] .49
7.12 Basic short-circuit test-duties [6.106].50
7.12.1 General .50
7.12.2 Test-duty T10 [6.106.1] .50
7.12.3 Test-duty T30 [6.106.2] .50
7.12.4 Test-duty T60 [6.106.3] .50
7.12.5 Test-duty T100s [6.106.4].50
7.12.6 Test-duty T100a [6.106.5].51
7.13 Critical current tests [6.107] .51
7.13.1 Applicability [6.107.1] .51
7.13.2 Tests current [6.107.2].51
7.13.3 Critical current test-duties [6.107.3] .52
7.14 Out-of-phase making and breaking tests [6.110].52
7.15 Capacitive current switching tests [6.111].52
7.15.1 Applicability [6.111.1] .52

62505-1 © IEC:2009 – 5 –
7.15.2 General [6.111.2] .52
7.15.3 Characteristics of supply circuits [6.111.3] .52
7.15.4 Earthing of the supply circuit [6.111.4] .52
7.15.5 Characteristics of the capacitive circuit to be switched [6.111.5].53
7.15.6 Wave form of the current [6.111.6] .53
7.15.7 Test voltage [6.111.7].54
7.15.8 Test duties [6.111.9].54
7.15.9 Test with specified TRV [6.111.9] .54
7.15.10 Test results [6.111.11].54
8 Routine tests [7] .55
8.1 General .55
8.2 Power frequency voltage withstand dry on the main circuit [7.1] .55
8.3 Voltage withstand tests on control and auxiliary circuits [7.2] .55
8.4 Measurement of the resistance of the main circuit [7.3] .55
8.5 Mechanical operating tests [7.101] .55
8.6 Design and visual check [7.102] .56
9 Guidance to the selection of circuit-breakers for service [8] .57
10 Information to be given with enquiries, tenders and orders [9] .57
Bibliography.58

Table 1 – Nominal voltages (U ), rated impulse voltages (U ) and short-duration
n Ni
power-frequency (AC) test levels U for circuits connected to the contact line .12
a
Table 2 – Standard values of rated transient recovery voltage – Representation by two
parameters – Single pole circuit-breaker.16
Table 3 – Standard values of prospective transient recovery voltage for 120° out-of-
phase breaking–Representation by two parameters – Single pole circuit-breaker.18
Table 4 – Standard values of prospective transient recovery voltage for 180° out-of-
phase breaking – Representation by two parameters – Single pole circuit-breaker.18
Table 5 – Suggested values of maximum permissible switching overvoltage to earth .20
Table 6 – Co-ordination table of rated values for circuit-breakers.22
Table 7 – Mechanical operation test at ambient temperature.32
Table 8 – Standard values of prospective transient recovery voltage for test-duty T60 –
Representation by two parameters – Single pole circuit-breaker .46
Table 9 – Standard values of prospective transient recovery voltage for test-duty T30 –
Representation by two parameters – Single pole circuit-breaker .47
Table 10 – Test values for tests with specified TRV .54

– 6 – 62505-1 © IEC:2009
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
RAILWAY APPLICATIONS –
FIXED INSTALLATIONS –
PARTICULAR REQUIREMENTS FOR AC SWITCHGEAR –

Part 1: Single-phase circuit-breakers with U above 1 kV
n
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 provides no marking procedure to indicate its approval and cannot be rendered responsible for any
equipment declared to be in conformity with an IEC Publication.
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 62505-1 has been prepared IEC technical committee 9: Electrical
equipment and systems for railways. This standard is based on EN 50152-1.
The text of this standard is based on the following documents:
FDIS Report on voting
9/1219/FDIS 9/1232/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.

62505-1 © IEC:2009 – 7 –
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.
– 8 – 62505-1 © IEC:2009
INTRODUCTION
The IEC Standard series 62505 is divided as follows.
Part 1: Single-phase circuit-breakers with U above 1 kV.
n
Part 2: Single-phase disconnectors, earthing switches and switches with U above 1 kV.
n
Part 3-1: Measurement, control and protection devices for specific use in a.c. traction
systems – Application guide
Part 3-2: Measurement, control and protection devices for specific use in a.c. traction
systems – Single-phase current transformers
Part 3-3: Measurement, control and protection devices for specific use in a.c. traction
systems – Single-phase inductive voltage transformers
IEC 62505-1 is to be used in conjunction with IEC 62271-100 (2008).
The essential requirements of IEC 62271-100 have been transcribed in this International
Standard. Other complementary clauses of IEC 62271-100 are mentioned in this Standard.
Where a particular clause of IEC 62271-100 is not mentioned, but is not referred as "not
applicable" in this Standard, that clause applies as far as reasonable. Where this Standard
states "addition" or "replacement", the relevant text of IEC 62271-100 is to be adapted
accordingly.
The numbering of clauses in the IEC 62271 series is not used in this Standard. The
numbering in square brackets refers to the numbering of clauses in IEC 62271.
NOTE 1 Where terms defined in IEC 62271-100 conflict with definitions of the same terms as given in IEC 60050-
811:1991 or of the other railway applications documents listed in the normative references, the definitions used in
IEC 62271-100 are to be used.
NOTE 2 The suffix N which appears in this Standard for rated values is not present in IEC 62271-100.

62505-1 © IEC:2009 – 9 –
RAILWAY APPLICATIONS –
FIXED INSTALLATIONS –
PARTICULAR REQUIREMENTS FOR AC SWITCHGEAR –

Part 1: Single-phase circuit-breakers with U above 1 kV
n
1 Scope
This part of IEC 62505 is applicable to single-phase a.c. one-pole circuit-breakers designed
for indoor or outdoor fixed installations for operation at frequencies of 16,7 Hz, 50 Hz and
60 Hz on traction systems having an U above 1 kV up to 52 kV.
Nm
This International Standard is also applicable to two-pole circuit-breakers when connected in
the following manner: one pole supplying the connection to the contact line of the track, the
second pole supplying the connection to the feeder cable which runs alongside the same
track and which is used to boost the track voltage at regular intervals in combination with
autotransformers. The centre of this circuit is connected to earth.
This Standard is also applicable to the operating devices of circuit-breakers and to their
auxiliary equipment.
This Standard does not address circuit-breakers with dependent manual operating
mechanism.
NOTE A rated short-circuit making current cannot be specified for these circuit-breakers and the use of these
mechanisms may give reasons for the objection based on their safety in operation.
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 60044-1:1999, Instrument transformers – Part 1: Current transformers
IEC 60850:2007, Railway applications – Supply voltages of traction systems
IEC 62271-1:2007, High-voltage switchgear and controlgear – Part 1: Common specifications
IEC 62271-100:2008, High-voltage switchgear and controlgear – Part 100: Alternating-current
circuit-breakers
IEC 62271-102:2003, High-voltage switchgear and controlgear – Part 102: Alternating-current
disconnectors and earthing switches
IEC 62497-1, Railway applications – Insulation co-ordination – Part 1: Basic requirements –
Clearances and creepage distances for all electrical and electronic equipment
3 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 62271-1 and
IEC 62271-100, and the following apply:

– 10 – 62505-1 © IEC:2009
3.1
single-pole circuit-breaker
circuit-breaker with one electrically separated conducting path for the main circuit suitable for
use in a single phase circuit
NOTE The construction arrangement of this device is in principle identical to one phase of a three-phase circuit-
breaker.
3.2
two-pole circuit-breaker
circuit-breaker with two independent electrically separated conducting paths for the main
circuit
NOTE 1 The two paths may be connected in series for use in a single phase circuit where the establishment and
the seperation of the two paths are simultaneous.
NOTE 2 The construction arrangement of this device is in principle identical to two phases of a three phase
circuit-breaker.
3.3
index of definitions
same as in 3.8 of IEC 62271-100, but amended according to the definitions above
4 Service conditions
Clause 2 of IEC 62271-1:2007 is applicable with the following addition:
The equipment covered by this Standard shall be suitable for installation in trackside locations
subject to vibrations from passing trains, airborne iron dust contamination from train brakes
and shall meet the electromagnetic compatibility (EMC) requirements.
For special service conditions, agreement shall be made between purchaser and supplier.
5 Rating
5.1 General
A circuit-breaker in correct condition of maintenance and adjustment shall be able to
withstand all stresses that occur in service provided that these do not exceed its rated
characteristics.
The characteristics of a circuit-breaker, including its operating devices and auxiliary
equipment, that shall be used to determine the rating are the following:
Rated characteristics to be given for all circuit-breakers:
a) rated voltage;
b) rated insulation level;
c) rated frequency;
d) rated normal current;
e) rated short-time withstand current;
f) rated peak withstand current;
g) rated duration of short circuit, for circuit-breakers not fitted with direct over-
current release;
h) rated supply voltage of closing and opening devices and of auxiliary circuits;
i) rated supply frequency of closing and opening devices and of auxiliary circuits;

62505-1 © IEC:2009 – 11 –
j) rated pressures of compressed gas supply for operation and for interruption, if applicable;
k) rated gas pressure for sealed gas pressure devices;
l) rated short-circuit breaking current;
m) rated transient recovery voltage for terminal faults;
n) rated short-circuit making current;
o) rated operating sequence.
5.2 Rated voltage (U )
Ne
The rated voltage U shall be chosen taking into consideration the maximum voltage level
Ne
suitable to be permanently applied to the circuit-breaker (i.e. highest permanent voltage
U as defined in IEC 60850).
max1
NOTE This standard makes reference to the values U and U , taken from IEC 60850. These values are
max1 max2
used to express the values of U , which are expected to be equal or higher than U . The insulation
Ne max1
characteristics are also expected to be suitable to allow, when required in Clause 5 and Clause 7, the highest non-
permanent voltage U .
max2
5.3 Nominal voltage (U )
n
The nominal voltage U shall be one of the voltages listed in Table 1 of IEC 60850.
n
5.4 Rated insulation voltage (U ) [4.2]
Nm
The value of the rated insulation voltage U , of the rated impulse withstand voltage U and
Nm Ni
of the power-frequency withstand voltage U shall be as given in Table 1, taken from the
a
values listed in IEC 62497-1.
– 12 – 62505-1 © IEC:2009
Table 1 – Nominal voltages (U ), rated impulse voltages (U ) and short-duration
n Ni
power-frequency (AC) test levels U for circuits connected to the contact line
a
a
OV
U U U U U
n Nm Ni a
(1,2/50 μs)
kV kV kV kV kV
IEC 60850 IEC 62497-1 (IEC 62271-1) IEC 62497-1
b
15 17,25 (24,0) 3 95 38 or 50
4 125 50
(36,0) 3 145 70
b
4 170 70 or 95
20 24 N/A 3
4 150 50
c b
25 27,5 N/A 3 170 70 or 95
c
4 200 95
c
(52,0) 3 200 95
4 250 95
30 N/A 3
4 200 70
See Note 3 52,0 (72,5) 3 250 95
4 300 140
NOTE 1 The choice of the different values of U given for the same U , depends upon the highest non-permanent
Ni n
voltages (such as U of IEC 60850) actually appearing in the system.
max2
NOTE 2 OV3 and OV4 are overvoltage categories depending on the system configuration and degree of overvoltage
control (inherent control or protective control) as given in IEC 62497-1.
NOTE 3 Take care that in those cases in which for circuit reasons it may happen that a higher voltage is applied to the
device terminals in transient conditions, a higher rated insulation voltage between contacts might be necessary (e. g.
U = 52 kV for U = 25 kV).
Nm n
a
The values in brackets give the rated voltages according to Table 1a of IEC 62271-1 having the nearest equivalence
in test withstand voltages with the test values for single-phase voltages given in this Table.
b
At purchaser’s choice or by agreement
c
These values are used in railway application only and are not of wide industrial use.

5.5 Rated frequency [4.3]
Subclause 4.3 of IEC 62271-1 is applicable.
5.6 Rated normal current and temperature rise [4.4]
Subclauses 4.4.1 and 4.4.2 of IEC 62271-1 are applicable with the following additions:
The values of rated currents shall be selected from the following standard values:
400 A; 630 A; 800 A; 1 250 A; 1 600 A; 2 000 A; 2 500 A; 4 000 A.
NOTE The above values are selected from the R 10 series, and, if required, higher values than those shown
should also be selected from this series.
If the circuit-breaker is fitted with a series connected accessory, such as a direct over-current
release, the rated normal current of the accessory is the r.m.s. value of the current which the

62505-1 © IEC:2009 – 13 –
accessory shall be able to carry continuously without deterioration at its rated frequency, with
a temperature rise not exceeding the values specified in Table 3 of IEC 62271-1.
Current transformers shall comply with IEC 60044-1.
5.7 Rated short-time withstand current [4.5]
Subclause 4.5 of IEC 62271-1 is applicable with the following addition:
The rated short-time withstand current is equal to the rated short-circuit breaking current
(see 5.13).
5.8 Rated peak withstand current [4.6]
Subclause 4.6 of IEC 62271-1 is applicable with the following addition:
The rated peak withstand current is equal to the rated short-circuit making current (see 5.16).
5.9 Rated duration of short-circuit [4.7]
Subclause 4.7 of IEC 62271-1 is applicable with the following addition:
A rated duration of a short-circuit need not be assigned to a circuit-breaker fitted with a direct
over-current release provided that, when connected in a circuit the prospective breaking
current of which is equal to its rated short-circuit breaking current, the circuit-breaker shall be
capable of carrying the resulting current for the break-time required by the circuit-breaker with
the over-current release set for the maximum setting and maximum time delay if adjustable,
when operating in accordance with its rated operating sequence (see 7.6.1).
5.10 Rated supply voltage of closing and opening devices and auxiliary circuit [4.8]
Subclause 4.8 of IEC 62271-1 is applicable.
5.11 Rated supply frequency of closing and opening devices and auxiliary circuits
[4.9]
Subclause 4.9 of IEC 62271-1 is applicable.
5.12 Rated pressures of compressed gas supply for operation and for interruption
[4.10]
The value of the pressures to which the circuit-breaker is filled.
Subclause 4.10 of IEC 62271–1 is applicable to the pressure of the compressed gas supply
for operation.
No standard values are given for rated pressure of compressed gas supply for interruption.
The rated pressures of compressed gas shall be given by the manufacturer of the circuit-
breaker.
5.13 Rated short-circuit breaking current (I ) [4.101]
Nss
5.13.1 General [4.101]
The rated short-circuit breaking current (I ) is the highest short-circuit current which the
Nss
circuit-breaker shall be capable of breaking under the conditions of use and behaviour
prescribed in this standard in a circuit having a power-frequency recovery voltage

– 14 – 62505-1 © IEC:2009
corresponding to the rated voltage of the circuit-breaker and having a transient recovery
voltage equal to the rated value specified in 5.14.1.
Short-line fault interruption is not a requirement for circuit-breakers to this standard. Such a
requirement shall be deemed to be special and subject to agreement between purchaser and
supplier.
The rated short-circuit breaking current is characterized by two values:
– the r.m.s. value of its a.c. component, termed "rated short-circuit current" for shortness,
and
– the percentage d.c. component.
NOTE 1 If the d.c. component does not exceed 20 %, the rated short-circuit breaking current is characterized only
by the r.m.s. value of its a.c. component.
For determination of the a.c. and d.c. components, see Figure 8 of IEC 62271-100.
The circuit-breaker shall be capable of breaking any short-circuit current up to its rated short-
circuit breaking current containing any a.c. component up to the rated value and associated
with it any percentage d.c. component up to that specified, under the conditions mentioned
above.
The following applies to a standard circuit-breaker:
a) At voltages below the rated voltage, it will be capable of breaking its rated short-circuit
breaking current.
NOTE 2 For circuit-breakers having proved rated short-circuit breaking currents I at two different rated
Nss
voltages U , intermediate characteristics may be assigned from the straight line drawn between the two proved
Ne
rating points on a plot of log U versus log I. In case of doubt, tests should be carried out to check the validity of the
interpolation.
b) At voltages above the rated voltage, no short-circuit breaking current is guaranteed
except to the extent provided for in 5.18.
5.13.2 AC component of the rated short-circuit breaking current [4.101.1]
The r.m.s. value of the a.c. component of the rated short-circuit breaking current shall be
selected from the values shown in Table 6.
NOTE The values in Table 6 are selected from the R 10 series, and, if required, higher values than those shown
should also be selected from this series.
5.13.3 DC component of the rated short-circuit breaking current [4.101.2]
The value
...