EN 60077-2:2017

SLOVENSKI STANDARD
01-oktober-2018
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SIST EN 60077-2:2003
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Railway applications - Electric equipment for rolling stock - Part 2: Electrotechnical
components - General rules
Bahnanwendungen - Elektrische Betriebsmittel auf Bahnfahrzeugen - Teil 2:
Elektrotechnische Bauteile - Allgemeine Regeln
Applications ferroviaires - Equipements électriques du matériel roulant - Partie 2:
Composants électrotechniques - Règles générales
Ta slovenski standard je istoveten z: EN 60077-2:2017
ICS:
29.280 (OHNWULþQDYOHþQDRSUHPD Electric traction equipment
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD EN 60077-2
NORME EUROPÉENNE
EUROPÄISCHE NORM
November 2017
ICS 45.060.01 Supersedes EN 60077-2:2002
English Version
Railway applications - Electric equipment for rolling stock -
Part 2: Electrotechnical components - General rules
(IEC 60077-2:2017)
Applications ferroviaires - Equipements électriques du Bahnanwendungen - Elektrische Betriebsmittel auf
matériel roulant - Partie 2: Composants électrotechniques - Bahnfahrzeugen - Teil 2: Elektrotechnische Bauteile -
Règles générales Allgemeine Regeln
(IEC 60077-2:2017) (IEC 60077-2:2017)
This European Standard was approved by CENELEC on 2017-09-01. CENELEC members are bound to comply with the CEN/CENELEC
Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration.
Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN-CENELEC
Management Centre or to any CENELEC member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by translation
under the responsibility of a CENELEC member into its own language and notified to the CEN-CENELEC Management Centre has the
same status as the official versions.
CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus, the Czech Republic,
Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,
Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden,
Switzerland, Turkey and the United Kingdom.

European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2017 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.
Ref. No. EN 60077-2:2017 E
European foreword
The text of document 9/2267/FDIS, future edition 2 of IEC 60077-2, prepared by IEC/TC 9 "Electrical
equipment and systems for railways" was submitted to the IEC-CENELEC parallel vote and approved
by CENELEC as EN 60077-2:2017.

The following dates are fixed:
(dop) 2018-06-01
• latest date by which the document has to be
implemented at national level by
publication of an identical national
standard or by endorsement
• latest date by which the national (dow) 2020-09-01
standards conflicting with the
document have to be withdrawn
This document supersedes EN 60077-2:2002.

Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CENELEC shall not be held responsible for identifying any or all such patent rights.

Endorsement notice
The text of the International Standard IEC 60077-2:2017 was approved by CENELEC as a European
Standard without any modification.
In the official version, for Bibliography, the following notes have to be added for the standards indicated:

IEC 60077-3 NOTE Harmonized as EN 60077-3.
IEC 60077-4 NOTE Harmonized as EN 60077-4.
IEC 60077-5 NOTE Harmonized as EN 60077-5.
IEC 60947-1 NOTE Harmonized as EN 60947-1.
IEC 60947-4-1 NOTE Harmonized as EN 60947-4-1.
IEC 61140 NOTE Harmonized as EN 61140.
IEC 61373 NOTE Harmonized as EN 61373.
Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications

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.
NOTE 1  Where an International Publication has been modified by common modifications, indicated by (mod), the relevant
EN/HD applies.
NOTE 2  Up-to-date information on the latest versions of the European Standards listed in this annex is available here:
www.cenelec.eu.
Publication Year Title EN/HD Year

IEC 60050-811 2017 International Electrotechnical Vocabulary - -
(IEV) - Chapter 811: Electric traction
IEC 60068-2-1 -  Environmental testing - Part 2-1: Tests - EN 60068-2-1 -
Test A: Cold
IEC 60068-2-2 -  Environmental testing - Part 2-2: Tests - EN 60068-2-2 -
Test B: Dry heat
IEC 60068-2-30 -  Environmental testing - Part 2-30: Tests - EN 60068-2-30 -
Test Db: Damp heat, cyclic (12 h + 12 h
cycle)
IEC 60068-2-52 -  Environmental testing - Part 2-52: Tests - EN 60068-2-52 -
Test Kb: Salt mist, cyclic (sodium chloride
solution)
IEC 60068-2-78 -  Environmental testing - Part 2-78: Tests - EN 60068-2-78 -
Test Cab: Damp heat, steady state
IEC 60077-1 2017 Railway applications - Electric equipment EN 60077-1 2017
for rolling stock - Part 1: General service
conditions and general rules
IEC 60417-DB -  Graphical symbols for use on equipment - -
IEC 60529 -  Degrees of protection provided by EN 60529 -
enclosures (IP Code)
IEC/TR 60943 -  Guidance concerning the permissible - -
temperature rise for parts of electrical
equipment, in particular for terminals

IEC 60077-2 ®
Edition 2.0 2017-07
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Railway applications – Electric equipment for rolling stock –

Part 2: Electrotechnical components – General rules

Applications ferroviaires – Equipements électriques du matériel roulant –

Partie 2: Composants électrotechniques – Règles générales

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 45.060.01 ISBN 978-2-8322-4424-1

– 2 – IEC 60077-2:2017 © IEC 2017
CONTENTS
FOREWORD . 4
1 Scope . 6
2 Normative references . 7
3 Terms, definitions and abbreviated terms . 7
3.1 Components . 7
3.2 Component parts . 9
3.3 Operational features . 11
3.4 Abbreviated terms . 14
4 Classification . 15
5 Characteristics . 15
5.1 List of characteristics . 15
5.2 Type of component . 15
5.3 Rated and limiting values for the main circuit . 16
5.3.1 General . 16
5.3.2 Rated voltages . 16
5.3.3 Rated currents . 16
5.3.4 Rated time constants (for DC switchgear) . 16
5.3.5 Rated power factor (for AC switchgear) . 17
5.4 Operational frequencies . 17
5.5 Component categories . 17
5.6 Electric control circuits . 17
5.7 Pneumatic control circuits . 18
5.8 Manual control . 18
5.9 Electric auxiliary circuits . 18
5.10 Pneumatic auxiliary circuits . 19
5.11 Peak arc voltages . 19
6 Product information . 19
6.1 Nature of the information . 19
6.1.1 General . 19
6.1.2 Component documentation . 19
6.1.3 Other information . 20
6.2 Marking . 20
6.3 Instructions for storage, installation, operation and maintenance . 20
7 Normal service conditions . 21
8 Constructional and performance requirements . 21
8.1 Constructional requirements . 21
8.1.1 General . 21
8.1.2 Terminals and connecting capacity . 21
8.1.3 Protective bonding terminal . 21
8.2 Performance requirements . 21
8.2.1 Operating conditions . 21
8.2.2 Temperature limits . 22
8.2.3 Operation following inactivity . 23
8.2.4 Electromagnetic compatibility (EMC) . 23
8.2.5 Acoustic noise emission . 23

IEC 60077-2:2017 © IEC 2017 – 3 –
8.2.6 Clearances . 23
8.2.7 Creepage distances . 23
8.2.8 Switching overvoltages . 23
8.2.9 Operational performance capability . 23
8.2.10 Ability to withstand vibration and shock . 25
8.2.11 Ability to withstand short-time current . 25
9 Tests . 25
9.1 Kinds of tests . 25
9.2 Verification of constructional requirements . 26
9.3 Type tests . 26
9.3.1 Test sequences . 26
9.3.2 General test conditions . 26
9.3.3 Test sequence I: General performance characteristics . 27
9.3.4 Test sequence II: Rated service making and breaking capacities (if
appropriate) . 28
9.3.5 Test sequence III: Ability to withstand vibration and shock . 30
9.3.6 Test sequence IV: Critical currents range . 31
9.3.7 Test sequence V: Climatic conditions . 31
9.3.8 Test sequence VI: Other tests. 32
9.4 Routine tests. 32
9.4.1 General . 32
9.4.2 Functional test . 32
9.4.3 Measurement of resistance or impedance . 32
9.4.4 Air-tightness (for pneumatic components) . 32
9.4.5 Dielectric withstand . 32
9.4.6 Check on the setting and operation of protective equipment and relays
(calibration) . 32
Annex A (normative) Correspondence between auxiliary contacts and steady states of
switchgear . 33
Bibliography . 35

Figure A.1 – Relationship between auxiliary contacts and steady states of switchgear . 34

Table 1 – Rated time constants . 17
Table 2 – Temperature rise limits and temperature limits . 22
Table 3 – Operational performance capability for category A1 components . 24
Table 4 – Operational performance capability for category A2 components . 24
Table 5 – Operational performance capability for category A3 components . 25
Table 6 – Operational performance capability for category A4 components . 25
Table 7 – List of test sequences . 26
Table 8 – Tolerances on test values . 27
Table 9 – Test method and severity . 31

– 4 – IEC 60077-2:2017 © IEC 2017
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
RAILWAY APPLICATIONS –
ELECTRIC EQUIPMENT FOR ROLLING STOCK –

Part 2: Electrotechnical components – General rules

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 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 60077-2 has been prepared by IEC technical committee 9:
Electrical equipment and systems for railways.
This second edition cancels and replaces the first edition of IEC 60077-2, issued in 1999. It
constitutes a technical revision.
This edition includes the following main technical changes with regard to the previous edition:
a) Short circuit breaking capacity;
b) Rated short-time withstand current;
c) Critical currents range;
d) Climatic conditions are specified.
This standard is to be read in conjunction with IEC 60077-1.

IEC 60077-2:2017 © IEC 2017 – 5 –
The text of this standard is based on the following documents:
FDIS Report on voting
9/2267/FDIS 9/2279/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.
A list of all parts in the IEC 60077 series, published under the general title Railway
applications – Electric equipment for rolling stock, can be found on the IEC website.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
The committee has decided that the contents of this publication will remain unchanged until
the stability date indicated on the IEC website 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.
– 6 – IEC 60077-2:2017 © IEC 2017
RAILWAY APPLICATIONS –
ELECTRIC EQUIPMENT FOR ROLLING STOCK –

Part 2: Electrotechnical components – General rules

1 Scope
In addition to the rules given in IEC 60077-1, this part of IEC 60077 provides general rules for
all electrotechnical components installed in power circuits, auxiliary circuits, control and
indicating circuits, etc., on railway rolling stock.
The purpose of this document is to adapt the general rules given in IEC 60077-1 to all
electrotechnical components for rolling stock, in order to obtain uniformity of requirements
and tests for the corresponding range of components.
Electrotechnical components are mainly switchgear and controlgear, including also relays,
valves, resistors, fuses, etc., irrespective of the nature of their control.
The incorporation of electronic components or electronic subassemblies into electrotechnical
components is now common practice. Although this document is not applicable to electronic
equipment, the presence of electronic components does not give grounds to exclude such
electrotechnical components from the scope of this document.
Electronic subassemblies comply with the relevant standard.
Some of these rules, after agreement between the user and the manufacturer, are used for
electrotechnical components installed on vehicles other than railway rolling stock, such as
mine locomotives, trolleybuses, etc.
This document states:
a) the characteristics of the components;
b) the service conditions with which components have to comply;
c) the tests intended to confirm compliance of the components with these characteristics
under these service conditions, and the methods to be adopted for these tests;
d) the information to be marked on, or given with, the apparatus.
This document does not cover industrial electrotechnical components which comply with their
own product standard. In order to ensure satisfactory operation of these components for
rolling stock, this document is used to specify only the particular requirements for railway
application. In that case, a specific document would state the additional requirements with
which the industrial components are to comply, e.g.:
– to be adapted (for example for control voltage, environmental conditions, etc.); or
– to be installed and used so as not to have to endure specific railway conditions; or
– to be additionally tested to prove that these components can satisfactorily withstand
railway conditions.
In the event of there being a difference in requirements between this document and a railway
rolling stock relevant product standard, then the product standard requirements take
precedence.
IEC 60077-2:2017 © IEC 2017 – 7 –
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 60050-811:2017, International Electrotechnical Vocabulary (IEV) – Chapter 811: Electric
traction
IEC 60068-2-1, Environmental testing – Part 2-1: Tests – Test A: Cold
IEC 60068-2-2, Environmental testing – Part 2-2: Tests – Test B: Dry heat
IEC 60068-2-30, Environmental testing – Part 2-30: Tests – Test Db: Damp heat, cyclic (12 h
+ 12 h cycle)
IEC 60068-2-52, Environmental testing – Part 2-52: Test methods – Test Kb: Salt mist, cyclic
(sodium, chloride solution)
IEC 60068-2-78, Environmental testing – Part 2-78: Tests – Test Cab: Damp heat, steady
state
IEC 60077-1:2017, Railway applications – Electric equipment for rolling stock – Part 1:
General service conditions and general rules
IEC 60417, Graphical symbols for use on equipment (available at http://www.graphical-
symbols.info/equipment)
IEC 60529, Degrees of protection provided by enclosures (IP Code)
IEC TR 60943, Guidance concerning the permissible temperature rise for parts of electrical
equipment, in particular for terminals
3 Terms, definitions and abbreviated terms
For the purposes of this document, the terms and definitions given in IEC 60077-1 as well as
the following apply.
ISO and IEC maintain terminological databases for use in standardization at the following
addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
3.1 Components
3.1.1
active electrical component
simple device or assembly of devices which, in response to a control signal, executes a
function or various inseparable functions of logical or analogical nature by changing their
state, for which the control or the function is electrical (e.g. contactor, relay, etc.)
Note 1 to entry: Passive electical component is defined as the antonym of this term.

– 8 – IEC 60077-2:2017 © IEC 2017
3.1.2
passive electrical component
simple device or assembly of devices which are not included in the active electrical
components group and have at least one electrical function (e.g. mounting insulator,
permanent connection, resistor, capacitor, etc.)
3.1.3
switchgear and controlgear
general term covering switching devices and their combination with associated control,
measuring, protective and regulating equipment, also assemblies of such devices and
equipment with associated interconnections, accessories, enclosures and supporting
structures
[SOURCE: IEC 60050-441:1984 / AMD1:2007, 441-11-01]
3.1.4
switchgear
general term covering switching devices and their combination with associated control,
measuring, protective and regulating equipment, also assemblies of such devices and
equipment with associated interconnections, accessories, enclosures and supporting
structures, intended in principle for use in connection with generation, transmission,
distribution and conversion of electric energy
[SOURCE: IEC 60050-441:1984 / AMD1:2007, 441-11-02]
3.1.5
controlgear
general term covering switching devices and their combination with associated control,
measuring, protective and regulating equipment, also assemblies of such devices and
equipment with associated interconnections, accessories, enclosures and supporting
structures, intended in principle for the control of electric energy consuming equipment
[SOURCE: IEC 60050-441:1984 / AMD1:2007, 441-11-03]
3.1.6
switching device
device designed to make or break the current in one or more electric circuits
Note 1 to entry: A switching device may perform one or both of these operations.
[SOURCE: IEC 60050-441:1984 / AMD1:2007, 441-14-01, modified – Note 1 to entry has
been added.]
3.1.7
fuse
device that, by the fusing of one or more of its specially designed and proportioned
components, opens the circuit in which it is inserted by breaking the current when this
exceeds a given value for a sufficient time
Note 1 to entry: The fuse comprises all the parts that form the complete device.
[SOURCE: IEC 60050-441:1984 / AMD1:2007, 441-18-01, modified – The second sentence
has been changed to Note 1 to entry.]
3.1.8
switch
mechanical switching device capable of making, carrying and breaking currents under normal
circuit conditions which may include specified operating overload conditions and also carrying

IEC 60077-2:2017 © IEC 2017 – 9 –
for a specified time currents under specified abnormal circuit conditions such as those of
short-circuit
Note 1 to entry: A switch may be capable of making but not breaking short-circuit currents.
[SOURCE: IEC 60050-441:1984 / AMD1:2007, 441-14-10]
3.1.9
mechanical switching device
switching device designed to close and open one or more electric circuits by means of
separable contacts
Note 1 to entry: Any mechanical switching device may be designated according to the medium in which its
contacts open and close, e.g. air, SF6, oil.
[SOURCE: IEC 60050-441:1984 / AMD1:2007, 441-14-02]
3.1.10
circuit breaker
mechanical switching device, capable of making, carrying and breaking currents under normal
circuit conditions and also making, carrying for a specified time and breaking currents under
specified abnormal circuit conditions such as those of short-circuit
[SOURCE: IEC 60050-441:1984 / AMD1:2007, 441-14-20]
3.1.11
contactor
mechanical switching device having only one position of rest, operated otherwise than by
hand, capable of making, carrying and breaking currents under normal circuit conditions
including operating overload conditions
Note 1 to entry: Contactors may be designated according to the method by which the force for closing the main
contacts is provided.
Note 2 to entry: The definition is the same as”mechanical contactor”: IEC 60050-441:1984 / AMD1:2007, 441-14-
33.
3.1.12
disconnector
mechanical switching device which provides, in the open position, an isolating distance in
accordance with specified requirements
Note 1 to entry: A disconnector is capable of opening and closing a circuit only when negligible current is broken
or made, or when no significant change in the voltage across the terminals of each of the poles of the disconnector
occurs. It is also capable of carrying currents under normal circuit conditions and carrying for a specified time
currents under abnormal conditions such as those of short circuit.
[SOURCE: IEC 60050-811:2017, 811-29-17]
3.2 Component parts
3.2.1
pole of a switching device
portion of a switching device associated exclusively with one electrically separated conducting
path of its main circuit and excluding those portions which provide a means for mounting and
operating all poles together
Note 1 to entry: A switching device is called single-pole if it has only one pole. If it has more than one pole, it may
be called multipole (two-pole, three-pole, etc.) provided the poles are or can be coupled in such a manner as to
operate together.
[SOURCE: IEC 60050-441:1984 / AMD1:2007, 441-15-01]

– 10 – IEC 60077-2:2017 © IEC 2017
3.2.2
main circuit,
all the conductive parts of a switching device included in the circuit which it is designed to
close or open
Note 1 to entry: This does not include parts that are included in the auxiliary circuit of the switching device
(see 3.2.4).
[SOURCE: IEC 60050-441:1984 / AMD1:2007, 441-15-02, modified – Note 1 to entry has
been added.]
3.2.3
control circuit,
all the conductive parts (other than the main circuit) of a switching device which are included
in a circuit used for the closing operation or opening operation, or both, of the device
[SOURCE: IEC 60050-441:1984 / AMD1:2007, 441-15-03]
3.2.4
auxiliary circuit,
all the conductive parts of a switching device which are intended to be included in a circuit
other than the main circuit and the control circuits of the device
Note 1 to entry: Some auxiliary circuits fulfil supplementary functions such as signalling, interlocking, etc., and, as
such, they may be part of the control circuit of another switching device.
[SOURCE: IEC 60050-441:1984 / AMD1:2007, 441-15-04]
3.2.5
contact,
conductive parts designed to establish circuit continuity when they touch and which, due to
their relative motion during an operation, open or close a circuit or, in the case of hinged or
sliding contacts, maintain circuit continuity
[SOURCE: IEC 60050-441:1984 / AMD1:2007, 441-15-05]
3.2.6
main contact
contact included in the main circuit of a mechanical switching device, intended to carry, in the
closed position, the current of the main circuit
[SOURCE: IEC 60050-441:1984 / AMD1:2007, 441-15-07]
3.2.7
auxiliary contact
contact included in an auxiliary circuit and mechanically operated by the switching device
[SOURCE: IEC 60050-441:1984 / AMD1:2007, 441-15-10]
3.2.8
make contact
contact which is closed when the main contacts of the mechanical switching device are in
their operate condition and which is open when they are in their release condition
Note 1 to entry: See complementary information in Annex A of this document.
Note 2 to entry: “normally open contact” is a deprecated term.

IEC 60077-2:2017 © IEC 2017 – 11 –
[SOURCE: IEC 60050-811:2017, 811-31-03, modified – “relay” is replaced with “main contacts
of the mechanical switching device”. Note 1 to entry and Note 2 to entry have been added.]
3.2.9
break contact
contact which is open when the main contacts of the mechanical switching device are in their
operate condition and which is closed when they are in their release condition
Note 1 to entry: See complementary information in Annex A of this document.
Note 2 to entry: “normally closed contact” is a deprecated term.
[SOURCE: IEC 60050-811:2017, 811-31-04, modified – “relay” is replaced with “main contacts
of the mechanical switching device”. Note 1 to entry and Note 2 to entry have been added.]
3.2.10
relay
device designed to produce sudden predetermined changes in one or more electric output
circuits, when certain conditions are fulfilled in the electric input circuits controlling the device
Note 1 to entry: This definition may also be applied to relays for which the actuation is not electric.
[SOURCE: IEC 60050-151:2001, 151-13-31, modified – Note 1 to entry has been added.]
3.2.11
release,
device, mechanically connected to a mechanical switching device, which releases the holding
means and permits the opening or the closing of the switching device
[SOURCE: IEC 60050-441:1984 / AMD1:2007, 441-15-17]
3.3 Operational features
3.3.1
operation,
transfer of the moving contact(s) from one position to an adjacent position
Note 1 to entry: For a circuit-breaker, this may be a closing operation or an opening operation.
Note 2 to entry: If distinction is necessary, an operation in the electrical sense, e.g. make or break, is referred to
as a switching operation, and an operation in the mechanical sense, e.g. close or open, is referred to as a
mechanical operation.
[SOURCE: IEC 60050-441:1984 / AMD1:2007, 441-16-01]
3.3.2
operating cycle,
succession of operations from one position to another and back to the first position through all
other positions, if any
[SOURCE: IEC 60050-441:1984 / AMD1:2007, 441-16-02]
3.3.3
manual control
control of an operation by human intervention
[SOURCE: IEC 60050-441:1984 / AMD1:2007, 441-16-04]

– 12 – IEC 60077-2:2017 © IEC 2017
3.3.4
closed position,
position in which the predetermined continuity of the main circuit of the device is secured
[SOURCE: IEC 60050-441:1984 / AMD1:2007, 441-16-22]
3.3.5
open position,
position in which the predetermined dielectric withstand voltage requirements are satisfied
between open contacts in the main circuit of the device
Note 1 to entry: This definition differs from IEV 441-16-23 to meet the requirements of dielectric properties.
[SOURCE: IEC 60050-441:1984 / AMD1:2007, 441-16-23, modified – “clearance…is secured”
is changed to “dielectric withstand voltage requirements are satisfied”. Note 1 to entry has
been added.]
3.3.6
breaking current,
current in a pole of a switching device or in a fuse at the instant of initiation of the arc during a
breaking process
Note 1 to entry: For AC the current is expressed as the symmetrical RMS value of the AC component.
[SOURCE: IEC 60050-441:1984 / AMD1:2007, 441-17-07, modified. Note 1 to entry has been
added.]
3.3.7
prospective current,
current that would flow in the circuit if each pole of the switching device or the fuse were
replaced by a conductor of negligible impedance
Note 1 to entry: The method to be used to evaluate and to express the prospective current is to be specified in
the relevant publications.
[SOURCE: IEC 60050-441:1984 / AMD1:2007, 441-17-01]
3.3.8
prospective making current,
prospective current when initiated under specified conditions
Note 1 to entry: The specified conditions may relate to the method of initiation, e.g. by an ideal switching device,
or to the instant of initiation, e.g. leading to the maximum prospective peak current in an AC circuit, or to the
highest rate of rise. The specification of these conditions is given in the relevant publications.
[SOURCE: IEC 60050-441:1984 / AMD1:2007, 441-17-05]
3.3.9
prospective breaking current,
prospective current evaluated at a time corresponding to the instant of the initiation of the
breaking process
Note 1 to entry: Specifications concerning the instant of the initiation of the breaking process are to be found in
the relevant publications. For mechanical switching devices or fuses, it is usually defined as the moment of
initiation of the arc during the breaking process.
[SOURCE: IEC 60050-441:1984 / AMD1:2007, 441-17-06]

IEC 60077-2:2017 © IEC 2017 – 13 –
3.3.10
breaking capacity,
value of prospective breaking current that a switching device or a fuse is capable of breaking
at a stated voltage under prescribed conditions of use and behaviour
Note 1 to entry: The voltage to be stated and the conditions to be prescribed are dealt with in the relevant
publications.
Note 2 to entry: For AC, the current is expressed as the symmetrical RMS value of the AC component.
[SOURCE: IEC 60050-441:1984 / AMD1:2007, 441-17-08, modified – Note 2 to entry has
been changed.]
3.3.11
short circuit breaking capacity
breaking capacity for which the prescribed conditions include a short-circuit at the terminals of
the switching device
[SOURCE: IEC 60050-441:1984 / AMD1:2007, 441-17-11]
3.3.12
critical current
critical currents range
value (or range of values) of current at which the component is not capable of operating
without risk of failure to break
Note 1 to entry: For AC current only AC contactor is applicable.
3.3.13
making capacity,
value of prospective making current that a switching device is capable of making at a stated
voltage under prescribed conditions of use and behaviour
Note 1 to entry: The voltage to be stated and the conditions to be prescribed are dealt with in the relevant
publications.
[SOURCE: IEC 60050-441:1984 / AMD1:2007, 441-17-09, modified – In Note 1 to entry
“specifications” is replaced with “publications”.]
3.3.14
short circuit making capacity
making capacity for which the prescribed conditions include a short circuit at the terminals of
the switching device
[SOURCE: IEC 60050-441:1984 / AMD1:2007, 441-17-10]
3.3.15
short-time withstand current
current that a circuit or a switching device in the closed position can carry during a specified
short time under prescribed conditions of use and behaviour
[SOURCE: IEC 60050-441:1984 / AMD1:2007, 441-17-17]
3.3.16
recovery voltage
voltage which appears across the terminals of a pole of a switching device or a fuse after the
breaking of the current
– 14 – IEC 60077-2:2017 © IEC 2017
Note 1 to entry: This voltage may be considered in two successive intervals of time, one during which a transient
voltage exists, followed by a second one during which the power-frequency or the steady-state recovery voltage
alone exists.
Note 2 to entry: This definition applies to a single-pole device. For a multipole device it is the phase-to-phase
voltage across the supply terminals of the device.
[SOURCE: IEC 60050-441:1984 / AMD1:2007, 441-17-25, modified – Note 2 to entry has
been added.]
3.3.17
peak arc voltage,
maximum instantaneous value of voltage which, under prescribed conditions, appears across
the terminals of a pole of a switching device during the arcing time
[SOURCE: IEC 60050-441:1984 / AMD1:2007, 441-17-30]
3.3.18
opening time,
interval of time between the specified instant of initiation of the opening operation and the
instant when the arcing contacts have separated in all poles
Note 1 to entry: The instant of initiation of the opening operation, i.e. the application of the opening command
(e.g. energising the release, etc.) is given in the relevant publications.
Note 2 to entry: Closing time is defined as the antonym of this term.
[SOURCE: IEC 60050-441:1984 / AMD1:2007, 441-17-36, modified – Note 2 to entry has
been added.]
3.3.19
arcing time,
interval of time between the instant of the initiation of the arc in a pole or a fuse and the
instant of final arc extinction in that pole or that fuse
[SOURCE: IEC 60050-441:1984 / AMD1:2007, 441-17-37]
3.3.20
break time
interval of time between the beginning of the opening time of a mechanical switching device
(or the pre-arcing time of a fuse) and the end of the arcing time
[SOURCE: IEC 60
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