IEC TS 62271-316:2024

IEC TS 62271-316 ®
Edition 1.0 2024-11
TECHNICAL
SPECIFICATION
High-voltage switchgear and controlgear –
Part 316: Direct current by-pass switches and paralleling switches

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IEC TS 62271-316 ®
Edition 1.0 2024-11
TECHNICAL
SPECIFICATION
High-voltage switchgear and controlgear –

Part 316: Direct current by-pass switches and paralleling switches

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 29.130.10  ISBN 978-2-8322-9818-3

– 2 – IEC TS 62271-316:2024 © IEC 2024
CONTENTS
FOREWORD . 5
1 Scope . 7
2 Normative references . 7
3 Terms and definitions . 8
3.1 General terms and definitions . 8
3.2 Assemblies of switchgear and controlgear . 9
3.3 Parts of assemblies . 9
3.4 Switching devices . 9
3.5 Parts of switchgear and controlgear . 11
3.6 Operational characteristics of switchgear and controlgear . 13
3.7 Characteristic quantities . 15
3.8 Index of definitions . 20
4 Normal and special service conditions . 22
5 Ratings . 22
5.1 General . 22
5.2 Rated direct voltage (U ) . 23
rd
5.3 Rated insulation level (U , U , U ) . 24
dd p s
5.4 Rated continuous current (I ) . 24
rd
5.5 Rated values of short-time withstand current . 24
5.6 Rated supply voltage of auxiliary and control circuits (U ) . 24
a
5.7 Rated supply frequency of auxiliary and control circuits . 24
5.8 Rated pressure of compressed gas supply for controlled pressure systems . 24
5.101 Rated commutation current . 25
5.102 Rated operating sequence . 25
6 Design and construction . 25
6.1 Requirements for liquids in switchgear and controlgear . 25
6.2 Requirements for gases in switchgear and controlgear . 25
6.3 Earthing of switchgear and controlgear . 25
6.4 Auxiliary and control equipment and circuits . 25
6.5 Dependent power operation . 26
6.6 Stored energy operation . 26
6.7 Independent unlatched operation (independent manual or power operation) . 26
6.8 Manually operated actuators . 26
6.9 Operation of releases . 26
6.10 Pressure/level indication . 26
6.11 Nameplates. 26
6.12 Locking devices . 28
6.13 Position indication . 28
6.14 Degrees of protection provided by enclosures . 28
6.15 Creepage distances for outdoor insulators . 28
6.16 Gas and vacuum tightness . 28
6.17 Tightness for liquid systems . 28
6.18 Fire hazard (flammability) . 28
6.19 Electromagnetic compatibility (EMC) . 28
6.20 X-ray emission . 28
6.21 Corrosion . 28

6.22 Filling levels for insulation, switching and/or operation . 28
6.101 Design of BPSs and PSs . 29
6.102 General requirement for operation . 29
6.103 Pressure limits of fluids for operation . 30
6.104 Time quantities . 30
6.105 Static mechanical loads . 30
7 Type tests . 31
7.1 General . 31
7.2 Dielectric tests . 32
7.3 Resistance measurement . 35
7.4 Continuous current tests . 35
7.5 Short-time withstand current and peak withstand current tests . 36
7.6 Verification of the protection . 36
7.7 Tightness tests . 36
7.8 Electromagnetic compatibility tests (EMC) . 36
7.9 Additional tests on auxiliary and control circuits . 37
7.10 X-radiation test procedure for vacuum interrupters . 38
7.101 Mechanical and environmental tests . 38
7.102 Current commutation test . 47
8 Routine tests . 47
8.1 General . 47
8.2 Dielectric test on the main circuit . 47
8.3 Tests on auxiliary and control circuits . 48
8.4 Measurement of the resistance of the main circuit . 48
8.5 Tightness test . 48
8.6 Design and visual checks . 48
8.101 Mechanical operating tests . 48
9 Guide to the selection of switchgear and controlgear (informative) . 50
9.1 General . 50
9.2 Selection of rated values . 50
9.3 Cable-interface connections . 52
9.4 Continuous or temporary overload due to changed service conditions . 52
9.5 Environmental aspects . 53
10 Information to be given with enquiries, tenders and orders (informative) . 53
10.1 General . 53
10.2 Information with enquiries and orders . 53
10.3 Information to be given with tenders. 54
11 Transport, storage, installation, operation instructions and maintenance. 55
11.1 General . 55
11.2 Conditions during transport, storage and installation . 55
11.3 Installation . 55
11.4 Operating instructions . 61
11.5 Maintenance . 61
11.101 Resistors and capacitors . 61
12 Safety . 61
13 Influence of the product on the environment . 61
Annex A (normative) Tolerances on test quantities during type tests . 62
Annex B (normative) Records and reports of type tests . 65

– 4 – IEC TS 62271-316:2024 © IEC 2024
B.1 Information and results to be recorded . 65
B.2 Information to be included in type test reports . 65
Annex C (informative) Voltages associated with BPSs in different configurations . 67
C.1 General . 67
C.2 Case 1: BPS consisting of a single switching unit. 67
C.3 Case 2: BPS consisting of two series connected switching units . 69
Annex D (normative) Use of mechanical characteristics and related requirements . 71
Bibliography . 75

Figure 1 – Example of the location of BPSs in an HVDC transmission system . 10
Figure 2 – Example of the location of a CPS in an HVDC transmission system . 11
Figure 3 – Example of the location of a LPS in an HVDC transmission system . 11
Figure 4 – BPS and PS – Opening and closing operations . 15
Figure 5 – BPS and PS – Close-open cycle . 16
Figure 6 – BPS and PS – Open-close cycle . 17
Figure 7 – Example of two series connected BPSs. 29
Figure 8 – Test sequence for low temperature test . 42
Figure 9 – Test sequence for high temperature test . 44
Figure 10 – Humidity test . 46
Figure C.1 – HVDC system with 3 series connected converter units per pole . 67
Figure C.2 – Different ways to connect a BPS to the grid . 68
Figure C.3 – HVDC system with 2 series connected converter units per pole . 70
Figure D.1 – Example of reference mechanical characteristics (idealised curve) . 72
Figure D.2 – Reference mechanical characteristics of Figure D.1 with the envelopes
centred over the reference curve (+5 %, –5 %) . 72
Figure D.3 – Reference mechanical characteristics of Figure D.1 with the envelope
fully displaced upward from the reference curve (+10 %, –0 %) . 73
Figure D.4 – Reference mechanical characteristics of Figure D.1 with the envelope
fully displaced downward from the reference curve (+0 %, –10 %) . 74

Table 1 – Nameplate information . 27
Table 2 – Examples of static horizontal and vertical forces for static terminal load . 30
Table 3 – Mandatory type tests . 31
Table 4 – Test conditions in general case for BPSs according to Alternative 1 . 33
Table 5 – Test conditions in general case for BPSs according to Alternative 2 . 34
Table 6 – Test conditions in general case for PSs . 34
Table 7 – Number of operating sequences . 40
Table A.1 – Tolerances on test quantities for type tests . 63
Table C.1 – Voltage across the post insulator . 69

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
HIGH-VOLTAGE SWITCHGEAR AND CONTROLGEAR –

Part 316: Direct current by-pass switches and paralleling switches

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,
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preparation is entrusted to technical committees; any IEC National Committee interested in the subject dealt with
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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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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
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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) IEC draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). IEC takes no position concerning the evidence, validity or applicability of any claimed patent rights in
respect thereof. As of the date of publication of this document, IEC had not received notice of (a) patent(s), which
may be required to implement this document. However, implementers are cautioned that this may not represent
the latest information, which may be obtained from the patent database available at https://patents.iec.ch. IEC
shall not be held responsible for identifying any or all such patent rights.
IEC TS 62271-316 has been prepared by subcommittee 17A: Switching devices, of IEC
technical committee 17: High-voltage switchgear and controlgear. It is a Technical Specification.
The text of this Technical Specification is based on the following documents:
Draft Report on voting
17A/1407/DTS 17A/1414/RVDTS
Full information on the voting for its approval can be found in the report on voting indicated in
the above table.
The language used for the development of this Technical Specification is English.

– 6 – IEC TS 62271-316:2024 © IEC 2024
This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in
accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement, available
at www.iec.ch/members_experts/refdocs. The main document types developed by IEC are
described in greater detail at www.iec.ch/publications.
This document shall be read in conjunction with IEC TS 62271-5:2024, to which it refers, and
which is applicable unless otherwise specified in this document. In order to simplify the
indication of corresponding requirements, the same numbering of clauses and subclauses is
used as in IEC TS 62271-5. Modifications to these clauses and subclauses are given under the
same references whilst additional subclauses are numbered from 101.
A list of all parts in the IEC 62271 series, published under the general title High-voltage
switchgear and controlgear, can be found on the IEC website.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under webstore.iec.ch in the data related to the
specific document. At this date, the document will be
• reconfirmed,
• withdrawn, or
• revised.
HIGH-VOLTAGE SWITCHGEAR AND CONTROLGEAR –

Part 316: Direct current by-pass switches and paralleling switches

1 Scope
This part of IEC 62271, which is a Technical Specification, is applicable to direct current (DC)
by-pass switches (BPS) and paralleling switches (PS) designed for indoor or outdoor installation
and for operation on HVDC transmission systems having direct voltages of 100 kV and above.
Switches other than mechanical switching devices used for the same applications specified
here are not covered by this document.
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 60050-151, International Electrotechnical Vocabulary (IEV) – Part 151: Electrical and
magnetic devices, (available at www.electropedia.org)
IEC 60050-441, International Electrotechnical Vocabulary (IEV) – Part 441: Switchgear,
controlgear and fuses, (available at www.electropedia.org)
IEC 60050-442, International Electrotechnical Vocabulary (IEV) – Part 442: Electrical
accessories, (available at www.electropedia.org)
IEC 60050-461, International Electrotechnical Vocabulary (IEV) – Part 461: Electric cables,
(available at www.electropedia.org)
IEC 60050-601, International Electrotechnical Vocabulary (IEV) – Part 601: Generation,
transmission and distribution of electricity – General, (available at www.electropedia.org)
IEC 60050-614, International Electrotechnical Vocabulary – Part 614: Generation, transmission
and distribution of electricity – Operation, (available at www.electropedia.org)
IEC 60060-1, High-voltage test techniques – Part 1: General definitions and test requirements
IEC 60071-11:2022, Insulation coordination – Part 11: Definitions, principles and rules for
HVDC system
IEC 60071-12:2022, Insulation coordination – Part 12: Application guidelines for LCC HVDC
converter stations
IEC 60296, Fluids for electrotechnical applications – Mineral insulating oils for electrical
equipment
IEC 60376, Specification of technical grade sulphur hexafluoride (SF ) and complementary
gases to be used in its mixtures for use in electrical equipment

– 8 – IEC TS 62271-316:2024 © IEC 2024
IEC 60480, Specifications for the re-use of sulphur hexafluoride (SF ) and its mixtures in
electrical equipment
IEC 60633:2019, High-voltage direct current (HVDC) transmission – Vocabulary
IEC TS 62271-5:2024, High-voltage switchgear and controlgear – Part 5: Common
specifications for direct current switchgear
IEC 62271-102:2018, High-voltage switchgear and controlgear – Part 102: Alternating current
disconnectors and earthing switches
IEC 62271-102:2018/AMD1:2022
IEC TS 62271-315:2024, High-voltage switchgear and controlgear – Part 315: Direct current
(DC) transfer switches
3 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 60050-151,
IEC 60050-441, IEC 60050-442, IEC 60050-461, IEC 60050-601, IEC 60050-614,
IEC TS 62271-5 and IEC 60633, some of which are recalled hereunder, and the following apply.
ISO and IEC maintain terminology databases for use in standardization at the following
addresses:
• IEC Electropedia: available at https://www.electropedia.org/
• ISO Online browsing platform: available at https://www.iso.org/obp
NOTE Terms and definitions are classified in accordance with IEC 60050-441. Reference from other parts than
IEC 60050-441 are classified so as to be aligned with the classification used in IEC 60050-441.
3.1 General terms and definitions
3.1.101
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, 441-11-01]
3.1.102
indoor switchgear and controlgear
switchgear and controlgear designed solely for installation within a building or other housing,
where the switchgear and controlgear is protected against wind, rain, snow, abnormal dirt
deposits, abnormal condensation, ice and hoar frost
[SOURCE: IEC 60050-441:1984, 441-11-04]
3.1.103
outdoor switchgear and controlgear
switchgear and controlgear suitable for installation in the open air, i.e. capable of withstanding
wind, rain, snow, dirt deposits, condensation, ice and hoar frost
[SOURCE: IEC 60050-441:1984, 441-11-05]

3.1.104
ambient air temperature
temperature, determined under prescribed conditions, of the air surrounding the complete
switching device
Note 1 to entry: For switching devices installed inside an enclosure, it is the temperature of the air outside the
enclosure.
[SOURCE: IEC 60050-441:1984, 441-11-13, modified – "or fuses" removed in note 1 to entry]
3.1.105
temperature rise
difference between the temperature of the part under consideration and the ambient air
temperature
3.1.106
external insulation
distances in atmospheric air, and along the surfaces in contact with atmospheric air of solid
insulation of the equipment which are subject to dielectric stresses and to the effects of
atmospheric and other environmental conditions from the site
Note 1 to entry: Examples of environmental conditions are pollution, humidity, vermin, etc.
[SOURCE: IEC 60050-614:2016, 614-03-02]
3.1.107
internal insulation
internal distances of the solid, liquid or gaseous insulation of equipment which are protected
from the effects of atmospheric and other external conditions
[SOURCE: IEC 60050-614:2016, 614-03-03]
3.2 Assemblies of switchgear and controlgear
No particular definitions.
3.3 Parts of assemblies
No particular definitions.
3.4 Switching devices
3.4.101
switching device
device designed to make or break the current in one or more electric circuits
[SOURCE: IEC 60050-441:2000, 441-14-01]
3.4.102
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, for example, air, SF , oil.
[SOURCE: IEC 60050-441:1984, 441-14-02]

– 10 – IEC TS 62271-316:2024 © IEC 2024
3.4.103
by-pass switch
BPS
high-speed DC switch connected across each converter unit in HVDC schemes using more than
one independent converter unit per pole, designed to close rapidly to bypass a converter unit
that is being taken out of service and commutate the current back into a converter unit that is
being taken back in service
Note 1 to entry: A BPS may also be used for prolonged shunting of the converter unit(s).
Note 2 to entry: Figure 1 illustrates the position of the BPS.
Note 3 to entry: BPS are most commonly used in LCC HVDC schemes.

Key
BPS By-pass switch
BPD By-pass disconnector
NOTE Figure 1 shows an example of the location of the BPS for one polarity only.
Figure 1 – Example of the location of BPSs in an HVDC transmission system
[SOURCE: IEC 60633:2019, 9.30, modified – The wording "converter valve group" and "group"
replaced with "converter unit" in the definition; Notes 1 and 2 to entry changed; Note 3 to entry
and Figure 1 added.]
3.4.104
paralleling switch
PS
mechanical switching device intended for rapid configuration of a HVDC system
Note 1 to entry: A PS can either be a converter paralleling switch or a line paralleling switch.
3.4.105
converter paralleling switch
CPS
high-speed DC switch connected in series with each converter at the high-voltage DC terminal
in HVDC schemes where two or more converters are connected in parallel onto a common pole
conductor, designed to allow additional converter(s) to be connected in parallel or disconnected
without affecting the load current in the other converter
Note 1 to entry: Figure 2 illustrates the position of the CPS.

Key
CPS Converter paralleling switch
Figure 2 – Example of the location of a CPS in an HVDC transmission system
[SOURCE: IEC 60633:2019, 9.28, modified – Note 1 to entry changed and Figure 2 added.]
3.4.106
line paralleling switch
LPS
DC commutation switch placed in series with one or more high-voltage pole conductors,
allowing two or more lines to be connected in parallel or to revert to single-line operation while
conducting load current
Note 1 to entry: Figure 3 illustrates the position of the LPS.

Key
LPS Line paralleling switch
Figure 3 – Example of the location of a LPS in an HVDC transmission system
[SOURCE: IEC 60633:2019, 9.29, modified – Note 1 to entry changed and Figure 3 added.]
3.5 Parts of switchgear and controlgear
3.5.101
main circuit
all the conductive parts of a switching device included in the circuit
which it is designed to close or open
[SOURCE: IEC 60050-441:1984, 441-15-02]

– 12 – IEC TS 62271-316:2024 © IEC 2024
3.5.102
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, 441-15-07]
3.5.103
arcing contact
contact on which the arc is intended to be established
Note 1 to entry: An arcing contact may serve as a main contact; it may be a separate contact so designed that it
opens after and closes before another contact which it is intended to protect from injury.
[SOURCE: IEC 60050-441:1984, 441-15-08]
3.5.104
"a" contact
make contact
control or auxiliary contact which is closed when the main contacts of the mechanical switching
device are closed and open when they are open
[SOURCE: IEC 60050-441:1984, 441-15-12]
3.5.105
"b" contact
break contact
control or auxiliary contact which is open when the main contacts of a mechanical switching
device are closed and closed when they are open
[SOURCE: IEC 60050-441:1984, 441-15-13]
3.5.106
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, 441-15-17]
3.5.107
arc control device
device, surrounding the arcing contacts of a mechanical switching device, designed to confine
the arc and to assist in its extinction
[SOURCE: IEC 60050-441:1984, 441-15-18]
3.5.108
terminal
conductive part of a device, electric circuit or electric network, provided for connecting that
device, electric circuit or electric network to one or more external conductors
Note 1 to entry: The term "terminal" is also used for a connection point in circuit theory.
[SOURCE: IEC 60050-151:2001, 151-12-12]

3.5.109
enclosure
part of an assembly providing a specified degree of protection of equipment
against external influences and a specified degree of protection against approach to or contact
with live parts and against contact with moving parts
[SOURCE: IEC 60050-441:1984, 441-13-01]
3.5.110
operating mechanism
part of the BPS or PS that actuates the main contacts
3.6 Operational characteristics of switchgear and controlgear
3.6.101
operation
transfer of the moving contact(s) from one position to an
adjacent position
Note 1 to entry: For a BPS or PS, this may be a closing operation or an opening operation.
Note 2 to entry: If distinction is necessary, an operation in the electrical sense, for example make or break, is
referred to as a switching operation, and an operation in the mechanical sense, for example close or open, is referred
to as a mechanical operation.
[SOURCE: IEC 60050-441:1984, 441-16-01, modified – "Circuit-breaker" in Note 1 to entry
changed to "BPS or PS".]
3.6.102
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, 441-16-02]
3.6.103
operating sequence
succession of specified operations with specified time
intervals
[SOURCE: IEC 60050-441:1984, 441-16-03]
3.6.104
closing operation
operation by which the device is brought from the open
position to the closed position
[SOURCE: IEC 60050-441:1984, 441-16-08]
3.6.105
opening operation
operation by which the device is brought from the closed
position to the open position
[SOURCE: IEC 60050-441:1984, 441-16-09]

– 14 – IEC TS 62271-316:2024 © IEC 2024
3.6.106
dependent power operation
operation by means of energy other than manual, where
the completion of the operation is dependent upon the continuity of the power supply (to
solenoids, electric or pneumatic motors, etc.)
[SOURCE: IEC 60050-441:1984, 441-16-14]
3.6.107
stored energy operation
operation by means of energy stored in the mechanism itself prior to the completion of the
operation and sufficient to complete it under predetermined conditions
Note 1 to entry: This kind of operation can be subdivided according to:
a) The manner of storing the energy (spring, weight, etc.);
b) The origin of the energy (manual, electric, etc.);
c) The manner of releasing the energy (manual, electric, etc.).
[SOURCE: IEC 60050-441:1984, 441-16-15]
3.6.108
closed position
position in which the predetermined continuity of the main
circuit of the device is secured
[SOURCE: IEC 60050-441:1984, 441-16-22]
3.6.109
open position
position in which the predetermined clearance between
open contacts in the main circuit of the device is secured
[SOURCE: IEC 60050-441:2000, 441-16-23]
3.6.110
shunt release
release energised by a source of voltage
Note 1 to entry: The source of voltage may be independent of the voltage of the main circuit.
[SOURCE: IEC 60050-441:1984, 441-16-41]
3.6.111
anti-pumping device
device which
a) prevents reclosing after a close-open operation as long as the device initiating closing is
maintained in the position for closing
b) prevents re-opening after an open-close operation as long as the device initiating opening
is maintained in the position for opening
[SOURCE: IEC 60050-441:1984, 441-16-48, modified – item b) added.]
3.6.112
interlocking device
device which makes the operation of a switching device dependent upon the position or
operation of one or more other pieces of equipment
[SOURCE: IEC 60050-441:1984, 441-16-49]

3.6.113
switching
making and/or breaking operation of a mechanical switching device
3.7 Characteristic quantities
Figure 4, Figure 5 and Figure 6 illustrate some definitions of this subclause.
Time quantities, see definitions 3.7.106 through 3.7.113, are expressed in milliseconds.

Opening operation Closing operation
Key
1 Closed position 9 Instant of arc extinction
2 Contact travel 10 Arcing time,
3 Open position 11 Make-time, 3.7.110
4 Current flow 12 Pre-arcing time, 3.7.111
5 Opening time, 3.7.106 13 Closing time, 3.7.109
6 Commutation time, 3.7.108 14 Initiation of closing operation
7 Initiation of opening operation 15 Instant of start of current flow
8 Instant of separation of arcing contacts 16 Instant of contact touch

Figure 4 – BPS and PS – Opening and closing operations

– 16 – IEC TS 62271-316:2024 © IEC 2024

Key
1 Closed position 7 Initiation of closing operation
2 Contact travel 8 Instant of start of current flow
3 Open position 9 Instant of contact touch
4 Current flow 10 Initiation of opening operation
5 Close-open time, 3.7.112 11 Instant of separation of arcing contacts
6 Make-commutation time 12 Instant of arc extinction

Figure 5 – BPS and PS – Close-open cycle

Key
1 Closed position 8 Initiation of opening release
2 Contact travel 9 Separation of arcing contacts
3 Open position 10 Arc extinction
4 Current flow 11 Initiation of closing circuit
5 Open-close time, 3.7.113 12 Instant of start of current flow
6 Re-make time 13 Contact touch
7 Reclosing time
Figure 6 – BPS and PS – Open-close cycle
3.7.101
rated value
quantity value assigned, generally by the manufacturer, for a specified operating condition of a
component, device or equipment
[SOURCE: IEC 60050-441:2000, 441-18-35, modified – Note 1 to entry deleted.]
3.7.102
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, 441-17-17]
3.7.103
peak withstand current
value of peak current that a circuit or a switching device in the closed position can withstand
under prescribed conditions of use and behaviour
[SOURCE: IEC 60050-441:1984, 441-17-18]

– 18 – IEC TS 62271-316:2024 © IEC 2024
3.7.104
applied voltage
voltage which exists across the terminals of a switching device just
before the making of the current
[SOURCE: IEC 60050-441:1984, 441-17-24, modified – "of a pole" deleted from the definition.]
3.7.105
clearance
distance between two conductive parts along a string stretched the shortest way between these
conductive parts
[SOURCE: IEC 60050-441:1984, 441-17-31]
3.7.106
opening time
interval of time between the specified instant of initiation of
the opening operation and the instant when the arcing contacts have separated
Note 1 to entry: The instant of initiation of the opening operation, i.e. the application of the opening command (for
example energising the release, etc.) is given in the relevant specifications.
[SOURCE: IEC 60050-441:1984, 441-17-36, modified – "in all poles" deleted from the
definition.]
3.7.107
arcing time
interval of time between the instant of the initiation of the arc and the instant of final arc
extinction
[SOURCE: IEC 60050-441:1984, 441-17-37, modified – The domain "of a pole or a fuse"
deleted, and "in a pole or a fuse" and "in that pole or that fuse" deleted from the definition.]
3.7.108
commutation time
interval of time between the beginning of the opening time of a mechanical switching device
and the end of the arcing time
3.7.109
closing time
interval of time between the initiation of the closing operation and the instant when the contacts
touch
[SOURCE: IEC 60050-441:1984, 441-17-41, modified – "in all poles" deleted from the
definition.]
3.7.110
make-time
interval of time between the initiation of the closing operation and the instant when the current
begins to flow in the main circuit
[SOURCE: IEC 60050-441:1984, 441-17-40]

3.7.111
pre-arcing time
interval of time between the initiation of current flow during a closing operation and the instant
when the contacts touch
Note 1 to entry: The pre-arcing time depends on the instantaneous value of the applied voltage during a specific
closing operation and therefore can vary considerably.
3.7
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