IEC 61992-2:2006

IEC 61992-2 ®
Edition 2.1 2014-04
CONSOLIDATED VERSION
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Railway applications – Fixed installations – DC switchgear –
Part 2: DC circuit-breakers
Applications ferroviaires – Installations fixes – Appareillage à courant continu –
Partie 2: Disjoncteurs en courant continu

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IEC 61992-2 ®
Edition 2.1 2014-04
CONSOLIDATED VERSION
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Railway applications – Fixed installations – DC switchgear –

Part 2: DC circuit-breakers
Applications ferroviaires – Installations fixes – Appareillage à courant continu –

Partie 2: Disjoncteurs en courant continu

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 45.060 ISBN 978-2-8322-1555-5

IEC 61992-2 ®
Edition 2.1 2014-04
CONSOLIDATED VERSION
REDLINE VERSION
VERSION REDLINE
colour
inside
Railway applications – Fixed installations – DC switchgear –
Part 2: DC circuit-breakers
Applications ferroviaires – Installations fixes – Appareillage à courant continu –
Partie 2: Disjoncteurs en courant continu

– 2 – IEC 61992-2:2006
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CONTENTS
FOREWORD . 4

1 Scope . 6
2 Normative references . 6
3 Terms and definitions. 6
4 Service requirements . 6
5 Characteristics of the circuit-breaker . 6
5.1 Enumeration of the characteristics. 6
5.2 Type of circuit-breaker . 7
5.3 Rated values and limit values for the main circuit . 9
5.4 Control circuits . 12
5.5 Auxiliary contacts and circuits . 12
5.6 Releases . 13
5.7 Arc voltage . 13
6 Construction . 14
6.1 General . 14
6.2 Materials . 14
6.3 Arcing contacts . 14
6.4 Clearances and creepage distances . 14
6.5 Primary connections . 14
6.6 Location of the primary connections . 14
6.7 Earthing terminal . 14
6.8 Manual operation for maintenance . 15
6.9 Circuit-breaker enclosures . 15
6.10 Temperature-rises . 15
6.11 Dielectric strength . 15
6.12 Electrical and mechanical endurance . 15
6.13 Operation . 16
6.14 Corrosion protection . 16
6.15 Noise emission . 17
6.16 Cooling . 17
6.17 Servo-control (where applicable) . 17
6.18 Other facilities . 17
7 Information and marking . 17
7.1 Information . 17
7.2 Marking . 17
8 Tests . 18
8.1 General . 18
8.2 Applicable tests and test sequence . 18
8.3 Performance of tests . 19

Annex A (informative) Information required . 28
Annex B (normative) AC short-circuit test method . 31
Bibliography . 35

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Figure B.1 – Test circuit . 31
Figure B.2 – Typical voltage and current waveforms of the AC short-circuit test . 32
Figure B.3 – Making phase angle (current waveform). 33
Figure B.4 – Method of measuring the circuit inductance L . 34

Table 1 – Shortened type designation . 9
Table 2 – Circuit-breaker duties . 11
Table 3 – Test duty cycles . 11
Table 4 – List of applicable tests and sequence . 19
Table 5 – Verification of the behaviour of the circuit-breaker when performing test
duties f, ff and fr . 26
Table 6 – Limits of the cut-off current of C circuit-breakers during maximum fault test . 8
Table 7 – Verification of the behaviour of the circuit-breaker when performing test
duties f, ff and fr . 24

– 4 – IEC 61992-2:2006
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INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
RAILWAY APPLICATIONS –
FIXED INSTALLATIONS –
DC SWITCHGEAR –
Part 2: DC circuit-breakers
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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agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
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3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
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5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
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6) All users should ensure that they have the latest edition of this publication.
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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.
This consolidated version of the official IEC Standard and its amendment has been prepared
for user convenience.
IEC 61992-2 edition 2.1 contains the second edition (2006-02) [documents 9/887/FDIS and
9/909/RVD] and its amendment 1 (2014-04) [documents 9/1791/CDV and 9/1851/RVC].
In this Redline version, a vertical line in the margin shows where the technical content is
modified by amendment 1. Additions and deletions are displayed in red, with deletions being
struck through. A separate Final version with all changes accepted is available in this
publication.
+AMD1:2014 CSV  IEC 2014
International Standard IEC 61992-2 has been prepared by IEC technical committee 9:
Electrical equipment and systems for railways.
This edition includes the following significant technical changes with respect to the previous
edition:
– all requirements applying to more than one part of the IEC 61992 series are now specified
in Part 1 and consequently the related clauses in this part of the series now make
reference to Part 1;
– specification of the characteristics of the circuit-breaker has been improved.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
IEC 61992 consists of the following parts, under the general title Railway applications – Fixed
installations – DC switchgear:
Part 1: General
Part 2: DC circuit-breakers
Part 3: Indoor d.c. disconnectors, switch-disconnectors and earthing switches
Part 4: Outdoor d.c. disconnectors, switch-disconnectors and earthing switches
Part 5: Surge arresters and low-voltage limiters for specific use in d.c. systems
Part 6: DC switchgear assemblies
Part 7-1: Measurement, control and protection devices for specific use in d.c. traction
systems – Application guide
Part 7-2: Measurement, control and protection devices for specific use in d.c. traction
systems – Isolating current transducers and other current measuring devices
Part 7-3: Measurement, control and protection devices for specific use in d.c. traction
systems – Isolating voltage transducers and other voltage measuring devices
The committee has decided that the contents of the base publication and its amendment 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.
IMPORTANT – The “colour inside” logo on the cover page of this publication indicates
that it contains colours which are considered to be useful for the correct understanding
of its contents. Users should therefore print this publication using a colour printer.

– 6 – IEC 61992-2:2006
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RAILWAY APPLICATIONS –
FIXED INSTALLATIONS –
DC SWITCHGEAR –
Part 2: DC circuit-breakers
1 Scope
This part of IEC 61992 specifies requirements for d.c. circuit-breakers for use in fixed
installations of traction systems.
NOTE Switchgear assemblies, electromagnetic compatibility (EMC) and dependability are not covered in this
standard, but by other parts of this standard or by other standards, as indicated in IEC 61992-1.
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 60850:2000, Railway applications – Supply voltage of traction systems
IEC 61992-1:2006+ A1:2014, Railway applications – Fixed installations – DC switchgear –
Part 1: General
IEC 61992-6:2006, Railway applications – Fixed installations – DC switchgear – Part 6:
DC switchgear assemblies
EN 50124-1:2001, Railway applications – Insulation coordination – Part 1: Basic requirements
– Clearances and creepage distances for electrical and electronic equipment
3 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 61992-1 apply.
4 Service requirements
Environmental conditions applicable to the equipment discussed in this standard are covered
in 4.1 of IEC 61992-1.
5 Characteristics of the circuit-breaker
5.1 Enumeration of the characteristics
The characteristics of a circuit-breaker and its assigned designations and values (where
applicable) are covered below as follows:
– type of circuit-breaker (5.2);
– rated values and limit values of the main circuit and short-circuit characteristics (5.3);
– control circuits (5.4);
– auxiliary circuits (5.5);
+AMD1:2014 CSV  IEC 2014
– releases (5.6);
– arc voltages (5.7).
5.2 Type of circuit-breaker
A circuit-breaker is defined by the following details, as applicable.
NOTE 1 As far as applicable, the following requirements also apply to single-pole circuit-breakers electrically or
mechanically interlocked in multiple systems.
a) Interruption:
– in air;
– via a semiconductor;
– in vacuum bulb.
NOTE 2 In this standard, only interruption in air or via a semiconductor is addressed. This standard may be
used for other specified interrupting media, as far as applicable, where clearly specified by mutual agreement
between purchaser and supplier.
b) Breaking characteristics (class designation):
1) circuit-breakers without intended limitation of current rise during maximum fault test
– high speed current limiting circuit-breaker H;
the H circuit-breaker has an opening time not greater than 5 ms and a total break time
not greater than 20 ms, when the current to be interrupted has a prospective sustained
value of at least 7 times the circuit-breaker setting and

di
 
 5 kA/ms
 
dt
 
t0
– very-high speed current limiting circuit-breaker V;
the V circuit-breaker in which the opening time is has a total break time not greater
than 2 ms, irrespective of the other parameters of the circuit;
– semi-high speed circuit-breaker S;
the S circuit-breaker has an opening time not greater than 15 ms and a total break
time not greater than 30 ms, when the current to be interrupted has a prospective
sustained value of at least 3,5 times the circuit-breaker setting and

di
 
 1,7 kA/ms
 
dt
 
t0
2) circuit-breakers with intended limitation of current rise during maximum fault test
– cut-off current limiting circuit-breaker C;
the C circuit-breaker limits the cut-off current before the short-circuit current to be
interrupted reaches its maximum value; the C circuit breaker can be an air circuit
breaker or a hybrid circuit breaker;
Table 6 gives the maximum values of the cut-off current depending on the preferred
values of rated short-circuit current together with the maximum allowable value of
initial current rise;
Table 6 applies to C circuit-breakers for nominal voltages up to and including 1 500 V.

– 8 – IEC 61992-2:2006
+AMD1:2014 CSV  IEC 2014
Table 6 – Limits of the cut-off current of C circuit-breakers during maximum fault test
Short circuit current characteristics Maximum cut-off current
Rated short-circuit Initial rate of rise Circuit time Class C1 Class C2
current constant
I
Nss
kA kA/ms ms kA kA
20 1,5 13,3 15 17
50 3 16,7 25 30
75 10 7,5 50 60
100 10 10,0 55 70
Smoothing reactors should be installed for substations in order to realize an initial rate of rise
equal to or less than the applicable value given in Table 6.
c) Use (installation point) in the system:
– interconnector circuit-breaker I (also called bus-section or section circuit-breaker);
– line circuit-breaker L;
– rectifier circuit-breaker R.
d) Current interruption direction:
– unidirectional U;
– fitted with a series unidirectional release U ;
– fitted with a series bidirectional release U ;
NOTE 3 U circuit-breakers are used for application where the reverse fault current is low (distant fault
current) and cannot operate the overload protection for normal discrimination purposes (i.e. substations where
adjacent substations are a far distance away).
– bidirectional B.
e) Duty of the main circuit
NOTE 4 To be specified when different from 5.3.4.2 and Table 2.
f) Actuating of the closing and opening operations:
– stored energy operation;
– independent manual operation;
– independent power operation;
– use of magnet;
– type of automatic tripping due to a release or relay;
– interlocks for opening and/or closing operations;
– trip-free provision;
– anti-pumping device.
g) Relay or release type:
– type of the relay(s) or release(s) involved.
h) Provision of an enclosure:
– without provision of an enclosure O (see 3.3.16 of IEC 61992-1);
– with provision of an integral enclosure E (see 3.3.17 of IEC 61992-1);
– with provision of a separate protection enclosure P.

+AMD1:2014 CSV  IEC 2014
The purchaser shall indicate which characteristics are to be present in the required circuit-
breaker(s) and only those tests which relate to the chosen type are applicable to the selected
type of circuit-breaker.
The above designations are used in this standard and may be used elsewhere adopting the
conventional grouping as given in Table 1.
Table 1 – Shortened type designation
a a
Items above b) c) D d) H h)
H / I / U / O
V / L / U / E
Options
S / R / B / P
C
Examples H/L/B/E
V/I/P S/R/O
b
H/R and L/U
NOTE When a circuit-breaker is not suitable to perform all duties as given
in 5.3.4.2, this fact will be indicated by means of the lower case letter(s)
designating actual capability according to Table 2, first column (for example,
H1/I ff, fr/P).
a
Optional designations.
b
When a circuit-breaker is or shall be suitable for multiple alternate
functions, the indication of these functions shall be preceded by an "and".

Where semiconductor circuit-breakers are only designed for use in rectifier equipped
substations, they shall be clearly so marked. If they may also be used as track paralleling
circuit-breakers, when the substation rectifier circuit-breakers are out of service, they shall
also be clearly so marked.
5.3 Rated values and limit values for the main circuit
5.3.1 General
The rated characteristic values shall be specified by the purchaser. Nominal voltage values
shall be selected from the values indicated in Table 1 of IEC 61992-1; current values and
track time constant (based on the track configuration which gives the largest track time
constant) should have one of the preferred values listed in 5.1.2 of IEC 61992-1.
These values should be confirmed by the supplier, who should indicate the rated values for
the type of circuit-breaker proposed and supply any other relevant data.
All these values shall be stipulated in accordance with 5.3.2 to 5.3.4. Definitions are given in
IEC 61992-1. Some data may be omitted by agreement.
5.3.2 Voltages
A circuit-breaker is identified by the following voltages:
– system voltages and limits (see 3.2.1 and 5.1.3 of IEC 61992-1);
(see IEC 60850);
– nominal voltage U
n
– rated voltage U (see 3.2.1.4 of IEC 61992-1);
Ne
– rated insulation voltage U (see 3.2.1.3 of IEC 61992-1). It shall be equal to or higher
Nm
than U ;
max
– 10 – IEC 61992-2:2006
+AMD1:2014 CSV  IEC 2014
– rated impulse withstand voltage U (see 3.2.1.7 of IEC 61992-1);
Ni
– power-frequency voltage withstand level (dry) U (see 3.2.1.8 and Table 1 of IEC 61992-1);
a
– maximum arc voltage (see 3.2.1.10 of IEC 61992-1);
– rated auxiliary and control supply voltages (see 3.2.1.5 of IEC 61992-1).
5.3.3 Currents
A circuit-breaker is defined by the following currents:
– conventional thermal current I , I (see 3.2.3 and 3.2.4 of IEC 61992-1);
th the
– rated service current I (see 3.2.5 of IEC 61992-1);
Ne
– rated short-circuit current I (see 3.2.10 of IEC 61992-1);
Nss
– rated short-time withstand current I (see 3.2.7 of IEC 61992-1);
Ncw
NOTE 1 Short-time ratings only apply to circuit-breakers not fitted with series trip devices, or in a
unidirectional device where a series trip is inoperative. In practice, this would apply to a rectifier circuit-breaker
in the forward direction where a series trip only acts in the reverse direction.
NOTE 2 Rated short-time currents do not need to have the same value as the rated short-circuit current I .
Nss
– overload capability: the purchaser shall inform the supplier of the load cycle requirements
(see 3.2.5, Note 2 of IEC 61992-1).
5.3.4 Short-circuit characteristics
5.3.4.1 Rated short-circuit breaking and making capacities
These values are defined in 3.2.19 and 3.2.23 of IEC 61992-1 and are associated with the
rated voltage U , the rated service current I , the rated short-circuit current I , the rated
Ne Ne Nss
track time constant T and the class designation H or , V or , S or C.
Nc
The rated short-circuit making capacity is the prospective peak value of the rated short-circuit
current I (see 3.2.10 of IEC 61992-1).
Nss
A rated short-circuit breaking capacity requires the circuit-breaker to be able to interrupt any
short-circuit current of a value lower than or equal to this rated breaking capacity at the circuit
time constant stipulated.
A H, V and S circuit-breakers having a breaking capacity at a rated track time constant T is
Nc
are capable of the same breaking capacity at all lower values of track circuit time constant T
c
t . For Type C circuit breakers the initial rate of rise shall not exceed the limits given in
c
Table 6.
The prospective maximum short-circuit current is the sum of the prospective short-circuit
currents from all sources connected to the system, including rectifier converters and
regenerative trains.
When fixing the maximum short-circuit current and the above track time constant, Clause 5 of
IEC 61992-1 shall be considered.
5.3.4.2 Duties and test duty cycles
The duties required of a circuit-breaker for each of the three uses are listed in Table 2. The
test duty cycles applying to the duties are shown in Table 3.
NOTE Where the circuit-breaker chosen by the manufacturer or offered by the supplier has been designed with
short-circuit breaking characteristics in excess of those actually required in the installation, it may be agreed
between purchaser and supplier to perform additional tests in accordance with 8.3.8 for duties f) and/or e) and/or
d) using the test current actually required. These tests may be performed either at a standard test duty cycle (duty
1 or , duty 2 or duty 3) or at an agreed duty cycle and may be repeated a number of times upon agreement
between purchaser and supplier.

+AMD1:2014 CSV  IEC 2014
Table 2 – Circuit-breaker duties
Duty Use Conditions Test current Prospective peak Time constant
f L Maximum fault I Type H, V and S: By consequence of
Nss
other circuit parameters
 1,42  I
Nss
See Table 6
Type C:  I
Nss
a
e L Maximum energy 0,5  I By consequence of 0,5  T
Nss Nc
other circuit parameters
d L Distant fault By consequence of T
2  I
Nc
Ne
other circuit parameters
l L Low current I Not applicable
 0,01 s
c
ff I Maximum fault forward I Type H, V and S: By consequence of
Nss
other circuit parameters
 1,42  I
Nss
See Table 6
Type C:  I
Nss
I
fr I Maximum fault reverse Type H, V and S: By consequence of
Nss
other circuit parameters
 1,42  I
Nss
See Table 6
Type C:  I
Nss
lr I Forward low current after I Not applicable
 0,01 s
c
reverse short circuit
b
R
c
r R Maximum fault reverse I
 1,42  I
Nss
Nss
with paralleled converters
c
s R Short time current forward I
 1,42  I
Ncw
Ncw
NOTE 1 For substations equipped with smoothing reactors of high value, the maximum energy condition may
correspond to the maximum fault condition.
NOTE 2 I is to be determined for each type of actual circuit situation. Therefore, I may be different for Line
Nss Nss
L, Interconnector I and Rectifier R circuit-breakers.
a
The factor affecting both I and T for maximum energy fault position is taken for practical reasons as 0,5.
Nss Nc
For low values of T , see Table 2 of IEC 61992-1.
Nc
b
R only when explicitly required by the purchaser.

c
The coefficient is 1 with regard to the C circuit-breaker.

Table 3 – Test duty cycles
Duty Breaking Test cycle
characteristics
a
a
f, e, d H,V,S Duty 1 O – 15 s – CO – 15 s – CO – 60 s – CO
Duty 1 Duty 2 O – 7 s – CO – 10 s – CO – 60 s – CO
Duty 2
b c
C Duty 3 O – 10 s – CO
ff, fr, r H,V,S,C O – 15 s – CO
l, lr H,V,S,C 10 times (O – 120 s – CO)
s H,V,S,C Carrying for 0,25 s
NOTE 1 O = opening operation; CO = closing operation.
NOTE 2 First opening is made on a short circuit being established.
a
The choice of Duty 1 or 2 is left to the purchaser. If no choice is made, then the duty cycle required is Duty 1.
b
In the case of C, the test cycle of duty e and d are subject to agreement between purchaser and supplier.
c
The standard duty is O – 10 s – CO. However, if AC short-circuit test method is applied, the duration between
O and CO may be reduced to less than 10 s.

– 12 – IEC 61992-2:2006
+AMD1:2014 CSV  IEC 2014
Circuit-breakers designed to comply with more than one duty shall be fully tested for each
duty; unless otherwise agreed between purchaser and supplier, these tests shall be carried
out on a single circuit-breaker which may be maintained between duty cycles. Any further duty
cycles on the same circuit-breaker shall not be performed unless a sufficient time to cool
down the circuit-breaker components is allowed.
The tests shall be performed with the series overcurrent release set at the maximum setting,
for example four times I , I or I for test duties f, e, ff, fr, and 0,5 times for test duties
Ne th the
r and s.
For test duties d) and l), the circuit-breaker shall be set to trip when the sustained value is
reached. For test duty d), when the track time constants are long, the trip shall be initiated at
0,15 s.
5.4 Control circuits
The control circuits are identified by the following characteristics as a minimum:
– the voltage of the control circuits;
– the kind of current (d.c. or a.c.);
– the current frequency, in case of an a.c. current.
The voltage of the supply source and its frequency are the values on which the performances,
the thermal behaviour and the insulation characteristics are based.
Unless otherwise required, the voltage shall be in accordance with 5.2 of IEC 61992-1 and
rated insulation voltage shall be in accordance with EN 50124-1.
The supply voltage shall be within a range between 85 % and 110 % of the voltage in
accordance with 5.2 of IEC 61992-1.
Where the control voltage is the same as in the main circuit, the same variations as in the
main circuit apply.
The manufacturer shall indicate the value(s) of the current drawn by the control circuits at the
rated voltage. In the case of control circuits which draw current intermittently, the duration of
the current flow shall be given.
5.5 Auxiliary contacts and circuits
Auxiliary circuits are mainly defined by the number of contacts provided, by their rating
(thermal current and voltage) and by their characteristics (NO, NC or commutation). Unless
otherwise required, the rated voltage shall be in accordance with 5.2 of IEC 61992-1, and the
rated insulation voltage shall be in accordance with EN 50124-1.
The purchaser shall specify the minimum number of auxiliary contacts required.
The auxiliary wiring connected to a circuit at 1 000 V a.c. or at 1 500 V d.c. or above shall be
physically separated from those connected to a circuit at a voltage below these limits.
For other characteristics of the auxiliary circuits, the requirements of 5.4 apply.

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5.6 Releases
5.6.1 Type
Classification of the releases comprises
– series (direct or indirect) overcurrent releases,
– shunt releases,
– under-voltage releases,
– other releases.
5.6.2 Characteristics
The following requirements apply to direct or indirect releases which are part of the circuit-
breaker.
A release may be instantaneous, time-lagged or time-dependant, or a combination of all three.
Other characteristics are as follows:
a) for overcurrent (d.c.) releases:
– type (overcurrent direct or indirect);
– rated current;
– the setting current (or setting range);
– the direction of the main carrying current in the case of a unidirectional circuit-breaker;
– characteristics of the operating time which the release gives the circuit-breaker as a
function of the rate of rise of the current.
The release shall be capable of withstanding this current under the test conditions
specified in Clause 8, without the temperature-rise exceeding the values specified in
Clause 6 of IEC 61992-1.
For circuit-breakers provided with interchangeable or adjustable releases, the current
setting (or the setting range, if applicable) shall be indicated on the release or on its
setting scale. The indication may be either in amperes or in multiples of the current
indicated on the release. The purchaser shall specify the required setting range. The ratio
of the minimum and maximum values shall not exceed 1:2 in normal conditions.
b) for the shunt release:
– the rated voltage;
– the power taken at the rated voltage for a specified time.
5.7 Arc voltage
The manufacturer shall specify the maximum value of the arc voltage Û caused by the
arc
operation of the circuit-breaker when it is tested in accordance with Clause 8.
NOTE This maximum voltage is the peak voltage measured during any test duty and is not necessarily seen with
maximum current.
This value shall not exceed both that of the rated impulse withstand voltage of the equipment
and four times the nominal voltage. If lower arc voltages are required, these shall be specified
by the purchaser.
– 14 – IEC 61992-2:2006
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6 Construction
6.1 General
All apparatus and connections required for the safe and satisfactory operation, control and
protection of the equipment concerned shall be provided, whether or not specifically
mentioned, unless otherwise agreed between the circuit-breaker manufacturer and the
switchgear assembly manufacturer. Unless otherwise specified, the equipment shall be
earthed, insulated, screened or enclosed as may be appropriate to ensure the protection of
the equipment and safety of those concerned in its operation and maintenance.
Control and auxiliary circuits and contacts shall comply with the requirements of 5.2 of
IEC 61992-1.
6.2 Materials
No materials containing asbestos shall be used in the construction of the circuit-breaker.
NOTE Special attention should be paid to the ability of the material used to resist moisture and fire: materials
used should be of the self-extinguishing type, such that the risk of propagation of fire from one cubicle to another is
minimised. See Annex B of IEC 61992-1.
6.3 Arcing contacts
Arcing contacts, if any, which are liable to be consumed during arc interruption shall be easy
to replace.
6.4 Clearances and creepage distances
Clearances and creepage distances shall not be lower than those indicated in Table 1 in
IEC 61992-1 and in Annex D of IEC 61992-1 respectively.
NOTE Clearances and creepage distances may be increased to take into account the presence of foreign
substances after the number of operations, in normal and short-circuit conditions, that occur during the normal life-
span between cleaning procedures.
Where applicable, ribs shall be provided in order to break the continuity of conducting deposit
which occurs during operation.
6.5 Primary connections
The circuit-breakers shall be equipped with fixed, removable (bolted or clamped) or plug-in
coupling connections.
6.6 Location of the primary connections
For non-withdrawable circuit-breakers, the terminals for the primary connections shall be
accessible with the circuit-breaker in its normal operating position. The position of the
terminals shall be agreed between purchaser and supplier, unless covered by an International
Standard.
For withdrawable circuit-breakers, the terminals for the primary connections shall be
accessible in the conditions detailed in IEC 61992-6.
6.7 Earthing terminal
The frames, the structure and the fixed parts of the metallic enclosures shall be connected to
each other and to a suitable earthing terminal, placed in an accessible position, in order to
allow earthing.
NOTE 1 This condition may be fulfilled by normal construction elements, ensuring an adequate electric continuity.

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For withdrawable circuit-breakers, the earth connection shall be made before the shutters are
opened, and the shutters shall be closed before the earth connection is disconnected.
NOTE 2 The purchaser may require a dedicated earth connection for this purpose. For a non-dedicated earth
connection, where bolts or similar fixings are used for earth continuity, the maintenance instructions should state
the requirements for cleaning the surfaces and ensuring tightness.
The earthing terminal shall be protected against corrosion. The standard earth symbol shall
be permanently marked.
The earth terminal shall be capable of carrying the rated earth fault current I for 0,25 s.
Ncwe
6.8 Manual operation for maintenance
NOTE A handle may be required by the purchaser or provided by the supplier for closing during maintenance. The
handle may be fixed or removable.
Where a fixed handle is provided, it shall not be accessible to the operator until the circuit-
breaker is fully withdrawn from its enclosure, if any, or until all primary connections are
opened.
6.9 Circuit-breaker enclosures
Circuit-breaker enclosures shall conform to IEC 61992-6.
6.10 Temperature-rises
6.10.1 Limits
The temperature shall not rise by more than the values given in Clause 6 of IEC 61992-1.
6.10.2 Main circuit
The main circuit of a circuit-breaker, including the series releases and the associated relays,
shall withstand its rated currents I , I or I . It shall also comply with the load cycle which
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may be specified by the purchaser, see Note 2 in 3.2.5 of IEC 61992-1.
6.10.3 Control circuit
The control circuits, as well as the control devices, used for the opening and closing
operations of a circuit-breaker shall not excee
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