IEC TS 62271-313:2025

High-voltage switchgear and controlgear - Part 313: Direct current circuit-breakers

IEC TS 62271-313:2025 is applicable to direct current circuit-breakers (hereafter termed DC circuit-breakers) for indoor or outdoor installation having direct voltages of 100 kV and above for operation on DC transmission and distribution systems. This document includes the (mechanical) switching devices, including the residual current interruption devices, and their operating devices, power electronic switches, primary auxiliary circuits and energy dissipation systems, as well as their controls. Depending on design and system needs, operation can be for one current direction only (unidirectional) or for both directions (bidirectional).

General Information

• Status: Published
• Publication Date: 30-Mar-2025
• ICS: 29.130.10 - High voltage switchgear and controlgear
• Technical Committee: SC 17A - Switching devices
• Drafting Committee: WG 64 - TC 17/SC 17A/WG 64
• Current Stage: PPUB - Publication issued
• Start Date: 31-Mar-2025
• Completion Date: 03-Jan-2025

Overview

IEC TS 62271-313:2025 is a Technical Specification from the IEC covering direct current circuit-breakers (DC circuit-breakers) for indoor or outdoor installation at direct voltages of 100 kV and above. It applies to equipment used in DC transmission and distribution systems (HVDC) and addresses the full switching assembly - mechanical switching devices (including residual current interruption devices), power electronic switches, operating and control devices, primary and auxiliary circuits, energy dissipation systems and associated controls. Designs may be unidirectional or bidirectional depending on system needs.

Key topics and requirements

• Scope and definitions: comprehensive terms and definitions specific to DC circuit-breakers and associated assemblies.
• Ratings and selection: guidance on rated direct voltage, rated insulation levels, rated continuous current, and rated short-circuit breaking/making currents.
• Design and construction: requirements for liquids and gases, earthing, auxiliary/control circuits, stored-energy and power-operated mechanisms, enclosures, creepage distances, EMC, X‑ray limits, corrosion and fire hazard considerations.
• Components covered: mechanical interrupters, power electronic devices, residual current interruption devices, MOSA, cooling and liquid systems, and potential grading devices.
• Type and routine tests: dielectric, partial discharge, continuous current, short-time and peak withstand, making/breaking tests, mechanical/environmental tests, seismic qualification, EMC tests, vacuum interrupter X‑radiation tests, and inspection procedures.
• Verification, commissioning and maintenance: routine tests, resistance measurement, tightness tests, installation and operating instructions, and maintenance data for fluids/gases.
• Informative guidance: selection guide (rated values, insulation coordination, cable interfaces, environmental aspects) and detailed information required for enquiries, tenders and orders.

Applications and users

Who uses IEC TS 62271-313:

• Utility HVDC transmission and distribution engineers specifying DC circuit-breakers for grid protection and switching.
• Manufacturers and designers of high-voltage switchgear and DC interruption systems.
• Test laboratories and certification bodies conducting type and routine tests.
• Asset owners, procurement teams and consultants preparing technical specifications, tenders and installation/maintenance procedures. Practical applications include HVDC converter stations, DC transmission lines, DC distribution substations, and industrial DC networks requiring high-voltage interruption and protection.

Related standards

• IEC 62271 series (high-voltage switchgear and controlgear) - for complementary AC/DC switchgear requirements and general testing methodologies.
• Relevant EMC, seismic and electrical safety IEC publications for system-level coordination and conformity.

Keywords: IEC TS 62271-313, DC circuit-breakers, direct current circuit-breaker, high-voltage switchgear, HVDC, power electronic switches, insulation coordination, short-circuit breaking current, type tests, ratings, installation and maintenance.

Standards Content (Sample)

IEC TS 62271-313 ®
Edition 1.0 2025-03
TECHNICAL
SPECIFICATION
High-voltage switchgear and controlgear –
Part 313: Direct current circuit-breakers

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IEC TS 62271-313 ®
Edition 1.0 2025-03
TECHNICAL
SPECIFICATION
High-voltage switchgear and controlgear –

Part 313: Direct current circuit-breakers

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 29.130.10  ISBN 978-2-8327-0292-5

– 2 – IEC TS 62271-313:2025 © IEC 2025
CONTENTS
FOREWORD . 7
INTRODUCTION . 9
1 Scope . 10
2 Normative references . 10
3 Terms and definitions . 11
3.1 General terms and definitions . 11
3.2 Assemblies of switchgear and controlgear . 12
3.3 Parts of assemblies . 12
3.4 Switching devices . 12
3.5 Parts of switchgear and controlgear . 16
3.6 Operational characteristics of DC circuit-breaker . 20
3.7 Characteristic quantities . 21
3.8 Index of definitions . 26
4 Normal and special service conditions . 28
5 Ratings . 28
5.1 General . 28
5.2 Rated direct voltage (U ) . 29
rd
5.2.1 General . 29
5.2.2 Rated voltages . 29
5.3 Rated insulation level (U , U , U ) . 29
dd p s
5.4 Rated continuous current (I ) . 29
rd
5.5 Rated values of short-time withstand current . 29
5.5.1 Typical waveform of short-circuit current . 29
5.5.2 Rated short-time withstand direct current (I ) . 29
kd
5.5.3 Rated peak withstand current (I ) . 29
pd
5.5.4 Rated duration of short circuit (t ) . 29
kd
5.6 Rated supply voltage of auxiliary and control circuits (U ) . 29
a
5.6.1 General . 29
5.6.2 Rated supply voltage (U ) . 29
a
5.7 Rated supply frequency of auxiliary and control circuits . 29
5.101 Rated operating sequence . 30
5.102 Rated short-circuit breaking current (I ) . 30
scd
5.103 Rated short-circuit making current . 30
5.104 Rated dissipated energy during breaking operation . 30
6 Design and construction . 30
6.1 Requirements for liquids in DC circuit-breaker . 30
6.2 Requirements for gases in DC circuit-breaker . 30
6.3 Earthing of DC circuit-breaker . 30
6.4 Auxiliary and control equipment and circuits . 31
6.5 Dependent power operation . 31
6.6 Stored energy operation . 31
6.7 Independent unlatched operation (independent manual or power operation) . 31
6.8 Manually operated actuators . 31
6.9 Operation of releases . 31

6.10 Pressure/level indication . 31
6.11 Nameplates. 31
6.12 Locking devices . 32
6.13 Position indication . 33
6.14 Degrees of protection provided by enclosures . 33
6.15 Creepage distances for outdoor insulators . 33
6.16 Gas and vacuum tightness . 33
6.17 Tightness for liquid systems . 33
6.18 Fire hazard (flammability) . 33
6.19 Electromagnetic compatibility (EMC) . 33
6.20 X-ray emission . 33
6.21 Corrosion . 33
6.22 Filling levels for insulation, switching and/or operation . 33
6.101 Static mechanical load . 33
6.102 Metal oxide surge arrester (MOSA) . 34
6.103 Power to potential device (if applicable) . 34
6.104 Liquid cooling system (if applicable) . 34
6.105 Power electronic devices (if applicable) . 34
6.106 Other components (if applicable) . 35
7 Type tests . 35
7.1 General . 35
7.1.1 Basics . 35
7.1.2 Information for identification of test objects . 36
7.1.3 Information to be included in type-test reports . 36
7.1.4 Invalid tests . 36
7.2 Dielectric tests . 36
7.2.1 General . 36
7.2.2 Ambient air conditions during tests . 36
7.2.3 Wet test procedure . 36
7.2.4 Arrangement of the equipment . 36
7.2.5 Criteria to pass the tests . 36
7.2.6 Application of the test voltage and test conditions . 36
7.2.7 Tests of switchgear and controlgear . 36
7.2.8 Artificial pollution tests for outdoor insulators . 37
7.2.9 Partial discharge tests . 37
7.2.10 Dielectric tests on auxiliary and control circuits . 37
7.2.11 Voltage test as condition check . 38
7.3 Resistance measurement . 38
7.4 Continuous current tests . 38
7.5 Short-time withstand current and peak withstand current tests . 38
7.6 Verification of the protection . 38
7.7 Tightness tests . 38
7.8 Electromagnetic compatibility (EMC) tests . 38
7.9 Additional tests on auxiliary and control circuits . 38
7.10 X-radiation test for vacuum interrupters . 38
7.101 Mechanical and environmental test . 39
7.101.1 Miscellaneous provisions for mechanical and environmental tests . 39
7.101.2 Mechanical operation test at ambient air temperature . 41
7.101.3 Low and high-temperature test . 43

– 4 – IEC TS 62271-313:2025 © IEC 2025
7.102 Short-circuit making and breaking tests. 44
7.102.1 General . 44
7.102.2 Making tests . 45
7.102.3 Breaking tests. 45
7.102.4 Unit testing . 47
7.102.5 Multi-part testing . 50
7.103 Seismic qualification tests . 51
7.104 Communication conformance tests . 51
7.105 Cooling equipment tests . 51
8 Routine tests . 51
8.1 General . 51
8.2 Dielectric test on the main circuit . 51
8.3 Tests on auxiliary and control circuits . 51
8.4 Measurement of the resistance of the main circuit . 51
8.5 Tightness test . 51
8.6 Design and visual checks . 51
8.101 Connection inspection . 51
8.102 Voltage-grading circuit inspection . 51
8.103 Voltage withstand test . 52
8.104 Mechanical operating tests . 52
8.105 MOSA current distribution test . 52
8.106 Verification of other components . 52
9 Guide to the selection of DC circuit-breakers (informative) . 52
9.1 General . 52
9.2 Selection of rated values . 53
9.2.101 Selection of the rated direct voltage . 53
9.2.102 Insulation coordination . 53
9.2.103 Selection of the rated continuous current . 53
9.2.104 Local service conditions. 53
9.2.105 Selection of the rated short-circuit breaking current . 53
9.2.106 Operating sequence in service . 53
9.3 Cable-interface considerations . 54
9.4 Continuous or temporary overload due to changed service conditions . 54
9.5 Environmental aspects . 54
10 Information to be given with enquiries, tenders and orders (informative) . 54
10.1 General . 54
10.2 Information with enquiries and orders . 54
10.3 Information with tenders . 55
11 Transport, storage, installation, operation instructions and maintenance. 56
11.1 General . 56
11.2 Conditions during transport, storage and installation . 56
11.3 Installation . 57
11.4 Operating instructions . 57
11.5 Maintenance . 57
11.5.1 General . 57
11.5.2 Information about fluids and gas to be included in maintenance manual . 57
11.5.3 Recommendations for the manufacturer . 57
11.5.4 Recommendations for the user . 57

11.5.5 Failure report . 58
12 Safety . 58
12.1 General . 58
12.2 Precautions by manufacturers . 58
12.3 Precautions by users . 58
12.101 High energy capacitor . 58
12.102 High-voltage switchgear . 58
12.103 High power laser . 58
12.104 MOSA . 58
12.105 Cooling system . 58
12.106 Power electronic devices . 59
13 Influence of the product on the environment . 59
Annex A (informative) Calculation of the duration of the transient interruption voltage

(TIV) and the dissipated energy in type tests . 60
A.1 General . 60
A.2 Stresses during fault current suppression . 60
A.2.1 Test circuit with negligible resistance . 60
A.2.2 Test circuit with appreciable resistance . 61
A.3 Direct recovery voltage after current interruption . 63
Annex B (informative) Test-circuits for testing the breaking capability of DC circuit-
breakers . 64
Annex C (informative) Layout examples of a test object for unit testing . 69
C.1 General . 69
C.2 Example of a unit testing layout using one of the common units of a
mechanical DC circuit-breaker with current injection composed of multiple

vacuum interrupters in series in the case of a modular design. 69
C.3 Example of a concept of unit testing layout using a partial unit for a
mechanical DC circuit-breaker with current injection composed of multiple
vacuum interrupters in series in the case of the combined design . 69
Annex D (normative) Tolerances on test quantities during type tests . 72
Bibliography . 73

Figure 1 – Schematic of two-branch DC circuit-breaker . 12
Figure 2 – Schematic of three-branch DC circuit-breaker . 13
Figure 3 – Schematic of power electronic DC circuit-breaker . 14
Figure 4 – Schematic of mechanical DC circuit-breaker . 14
Figure 5 – Schematic of hybrid DC circuit-breaker . 15
Figure 6 – Schematic of DC circuit-breaker electronic valve, section, and level . 19
Figure 7 – Schematic of a fault interruption process . 22
Figure A.1 – Schematic diagram of current interruption process . 60
Figure A.2 – Schematic of DC circuit when the current has been commutated into the
DC circuit-breaker's energy dissipation branch . 62
Figure A.3 – Schematic diagram of current interruption process in a slightly resistive

circuit . 62
Figure B.1 – Schematic diagrams of test-circuits for DC circuit-breakers . 64
Figure B.2 – Current for breaking test . 65
Figure B.3 – Example of test oscillogram with test-circuit type C . 66
Figure B.4 – Example of generator supplied test-circuit (type C) . 67

– 6 – IEC TS 62271-313:2025 © IEC 2025
Figure B.5 – Simulation of a direct current interruption with test-circuit type B . 67
Figure B.6 – Example of test oscillogram with test-circuit type B . 68
Figure B.7 – Example of pre-charged capacitor supplied test-circuit (type B) . 68
Figure C.1 – Layout of unit for unit testing for a series-connected module design . 69
Figure C.2 – Example of a unit for unit testing of the combined design to take out the
necessary components . 70

Table 1 – Nameplate information . 32
Table 2 – Type test items . 35
Table 3 – Invalid tests . 36
Table 4 – Number of operating sequences . 42
Table 5 – Making and breaking test duties . 45
Table 6 – Minimum number of DC-CB electronic valve levels per DC-CB electronic

valve to be operational type tested. 50
Table A.1 – Examples of DC circuit-breaker parameters and related interruption
parameters . 63
Table C.1 – Calculation example of a unit for unit testing . 71
Table D.1 – Tolerances on test quantities during type tests . 72

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
HIGH-VOLTAGE SWITCHGEAR AND CONTROLGEAR –

Part 313: Direct current 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 this end and
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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) 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, which
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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 62271-313 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/1413/DTS 17A/1416/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.

– 8 – IEC TS 62271-313:2025 © IEC 2025
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 is to 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 if applicable. 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.
INTRODUCTION
This document mainly refers to IEC TS 62271-5. In addition, some findings and considerations
from CIGRE are referred to in this document [1],[2] .

___________
Numbers in square brackets refer to the Bibliography.

– 10 – IEC TS 62271-313:2025 © IEC 2025
HIGH-VOLTAGE SWITCHGEAR AND CONTROLGEAR –

Part 313: Direct current circuit-breakers

1 Scope
This part of IEC 62271 is applicable to direct current circuit-breakers (hereafter termed DC
circuit-breakers) for indoor or outdoor installation having direct voltages of 100 kV and above
for operation on DC transmission and distribution systems.
This document includes the (mechanical) switching devices, including the residual current
interruption devices, and their operating devices, power electronic switches, primary auxiliary
circuits and energy dissipation systems, as well as their controls. Depending on design and
system needs, operation can be for one current direction only (unidirectional) or for both
directions (bidirectional).
This document does not cover:
Series reactors described in IEC TS 63014-1 for reducing the rate-of-rise of fault current.
Although these are often installed with the operation of DC circuit-breakers, they are typically
and specifically system-dependent.
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 60050-441, International Electrotechnical Vocabulary (IEV) – Part 441: Switchgear,
controlgear and fuses
IEC 60059, IEC standard current ratings
IEC 60099-9:2014, Surge arresters – Part 9: Metal-oxide surge arresters without gaps for HVDC
converter stations
IEC 60700-1, Thyristor valves for high voltage direct current (HVDC) power transmission –
Part 1: Electrical testing
IEC 60825-1, Safety of laser products – Part 1: Equipment classification and requirements
IEC 60825-2, Safety of laser products –Part 2: Safety of optical fibre communication systems
(OFCSs)
IEC 61071:2017, Capacitors for power electronics
IEC 61850-10, Communication networks and systems for power utility automation – Part 10:
Conformance testing
IEC TS 62271-5:2024, High-voltage switchgear and controlgear – Part 5: Common
specifications for direct current switchgear

IEC 62271-100:2021, High-voltage switchgear and controlgear – Part 100: Alternating-current
circuit-breakers
IEC TR 62271-300, High-voltage switchgear and controlgear – Part 300: Seismic qualification
of alternating current circuit-breakers
IEC 62501, Voltage sourced converter (VSC) valves for high-voltage direct current (HVDC)
power transmission – Electrical testing
IEC 62751-1, Power losses in voltage sourced converter (VSC) valves for high-voltage direct
current (HVDC) systems – Part 1: General requirements
IEC 62751-2, Power losses in voltage sourced converter (VSC) valves for high-voltage direct
current (HVDC) systems – Part 2: Modular multilevel converters
IEC TR 63259:2022, Water cooling systems for power electronics used in electrical
transmission and distribution systems
3 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 60050-441 and
IEC TS 62271-5 apply.
NOTE Some terms and definitions are recalled here for ease of reference. Additional terms and definitions are
classified so as to be aligned with the classification used in IEC 60050-441.
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
3.1 General terms and definitions
3.1.101
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]
3.1.102
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]
3.1.103
short-circuit current
overcurrent resulting from a short circuit due to a fault or an incorrect connection in an electric
circuit
[SOURCE: IEC 60050-441:1984, 441-11-07]

– 12 – IEC TS 62271-313:2025 © IEC 2025
3.1.104
temperature rise
difference between the temperature of the part and the ambient
air temperature
3.1.105
overvoltage
any voltage between one pole and earth having a peak value or values exceeding
the highest voltage for equipment
3.1.106
unit test
test carried out on a unit or group of units at the making current or the breaking current, specified
for the test on the complete DC circuit-breaker and at the appropriate fraction of the applied
voltage, or the recovery voltage, specified for the test on the complete DC circuit-breaker
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
DC circuit-breaker
DC-CB
type of switchgear used on an HVDC scheme, capable of making, carrying and breaking direct
currents and also making, carrying for a specified time and breaking in a specified time direct
currents under specified abnormal circuit conditions such as those of short-circuit
Note 1 to entry: DC circuit-breakers typically consist of a residual current interruption device in series with a parallel
combination of two or three branches, depending on their scheme (Figure 1 to Figure 5).
[SOURCE: IEC TS 62271-5:2024, 3.4.2, modified – “DC-CB” has been added as a second
preferred term, and the Note to entry has been added.]
3.4.102
two-branch DC circuit-breaker
DC circuit-breaker, consisting of a residual current interruption device in series with a parallel
combination of a main branch, including one or more branch devices (MBD), and an energy
dissipation branch
SEE: Figure 1.
Figure 1 – Schematic of two-branch DC circuit-breaker

Note 1 to entry: The power electronic DC circuit-breaker using a DC-CB electronic valve as main branch device
(MBD) is a typical two-branch DC circuit-breaker.
3.4.103
three-branch DC circuit-breaker
DC circuit-breaker, consisting of a residual current interruption device in series with a parallel
combination of a main branch, including a mechanical switching device and potential additional
main branch devices (MBD), a temporary branch, imbedding one or more temporary branch
devices (TBD), which is normally activated for short periods during turn-off and in some designs
also during turn-on operations, and an energy dissipation branch
SEE: Figure 2.
Figure 2 – Schematic of three-branch DC circuit-breaker
Note 1 to entry: Mechanical DC circuit-breakers and hybrid DC circuit-breakers are typical three-branch DC circuit-
breakers.
Note 2 to entry: For mechanical DC circuit-breakers a counter current device (CCD) is typically used as temporary
branch device (TBD) during turn-off operations only. In such DC circuit-breakers typically no main branch device
(MBD) is used.
Note 3 to entry: For hybrid DC circuit-breakers a DC-CB electronic valve is used as a temporary branch device
(TBD) during turn-off and turn-on operations, and often also as main branch device (MBD).
3.4.104
power electronic DC circuit-breaker
two-branch DC circuit-breaker consisting of a residual current interruption device in series with
a parallel combination of a DC-CB electronic valve as main branch device (MBD) in the main
branch and the energy dissipation device
SEE: Figure 3.
– 14 – IEC TS 62271-313:2025 © IEC 2025

Figure 3 – Schematic of power electronic DC circuit-breaker
Note 1 to entry: Power electronic DC circuit-breakers produce high losses in on-state, which is why they are not
often used.
3.4.105
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, SF , oil.
[SOURCE: IEC 60050-441:1984, 441-14-02]
3.4.106
mechanical DC circuit-breaker
three-branch DC circuit-breaker in which the main branch consists solely of mechanical
switching devices and the temporary branch includes a counter current device (CCD) to produce
a counter current in the main branch, where the current interruption takes place in the
mechanical switching device only
SEE: Figure 4
Figure 4 – Schematic of mechanical DC circuit-breaker
Note 1 to entry: The typical scheme of a mechanical DC circuit-breaker consists of a mechanical switching device
in the main branch connected in parallel with a current injection branch (active) or an oscillating branch (passive)
being a combination of inductance and capacitance, and energy dissipation device.

3.4.107
passive mechanical DC circuit-breaker
mechanical DC circuit-breaker using an oscillating circuit without charging device as counter
current device (CCD) in the temporary branch
Note 1 to entry: The time needed during current oscillation to reach the value of fault current is not adequate to
meet the requirements of modern HVDC transmission systems. Therefore, passive mechanical DC circuit-breakers
are not often used.
Note 2 to entry: Passive mechanical DC circuit-breakers are sometimes also named as oscillation mechanical DC
circuit-breaker.
3.4.108
active mechanical DC circuit-breaker
mechanical DC circuit-breaker using a current generator as counter current device (CCD) in the
temporary branch, which provides a counter current in the main branch
Note 1 to entry: The current generator could provide a bi-polar current oscillation or a unipolar current peak with
opposite polarity to the current in the main branch.
Note 2 to entry: Active mechanical DC circuit-breakers are sometimes also named as current injection mechanical
DC circuit-breaker.
3.4.109
hybrid DC circuit-breaker
three-branch DC circuit-breaker consisting of a residual current interruption device in series
with a parallel combination of a switchable low resistance main branch, a temporary branch
which is normally activated only for short periods during turn-off and turn-on operations, and
the energy dissipation device
SEE: Figure 5.
Figure 5 – Schematic of hybrid DC circuit-breaker
Note 1 to entry: The typical scheme of a hybrid DC circuit-breaker consists of a mechanical switching device in the
main branch connected in parallel with a DC-CB elect
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