IEC TS 62271-318:2024

IEC TS 62271-318 ®
Edition 1.0 2024-09
TECHNICAL
SPECIFICATION
High-voltage switchgear and controlgear –
Part 318: DC gas-insulated metal-enclosed switchgear for rated voltages
including and above 100 kV
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IEC TS 62271-318 ®
Edition 1.0 2024-09
TECHNICAL
SPECIFICATION
High-voltage switchgear and controlgear –

Part 318: DC gas-insulated metal-enclosed switchgear for rated voltages

including and above 100 kV
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 29.130.10  ISBN 978-2-8322-9674-5

– 2 – IEC TS 62271-318:2024 © IEC 2024
CONTENTS
FOREWORD . 8
1 Scope . 10
2 Normative references . 10
3 Terms and definitions . 12
4 Normal and special service conditions . 16
4.1 Normal service conditions . 16
4.2 Special service conditions . 16
4.101 General . 17
5 Ratings . 17
5.1 General . 17
5.2 Rated direct voltage (U ) . 17
rd
5.3 Rated insulation level (U , U , U ) . 18
dd p s
5.4 Rated continuous current (I ) . 18
rd
5.5 Rated values of short-time withstand current . 18
5.5.1 Typical waveform of short-circuit current . 18
5.5.2 Rated short-time withstand direct current (I ) . 18
kd
5.5.3 Rated peak withstand current (I ) . 18
pd
5.5.4 Rated duration of short-circuit (t ) . 18
kd
5.6 Rated supply voltage of auxiliary and control circuits (U ) . 18
a
5.7 Rated supply frequency of auxiliary and control circuits . 18
5.8 Rated pressure of compressed gas supply for controlled pressure systems . 18
6 Design and construction . 19
6.1 Requirements for liquids in switchgear and controlgear . 19
6.2 Requirements for gases in switchgear and controlgear . 19
6.3 Earthing of switchgear and controlgear . 19
6.3.101 Earthing of the main circuit . 19
6.3.102 Earthing of the enclosure . 19
6.4 Auxiliary and control equipment and circuits . 19
6.5 Dependent power operation . 19
6.6 Stored energy operation . 19
6.7 Independent unlatched operation (independent manual or power operation) . 19
6.8 Manually operated actuators . 20
6.9 Operation of releases . 20
6.10 Pressure/level indication . 20
6.11 Nameplates. 20
6.12 Locking devices . 21
6.13 Position indication . 21
6.14 Degrees of protection provided by enclosures . 21
6.15 Creepage distances for outdoor insulators . 21
6.16 Gas and vacuum tightness . 21
6.16.1 General . 21
6.16.2 Controlled pressure systems for gas . 21
6.16.3 Closed pressure systems for gas . 21
6.16.4 Sealed pressure systems . 22
6.16.101 Leakage . 22

6.16.102 Gas handling . 22
6.17 Tightness for liquid systems . 22
6.18 Fire hazard (flammability) . 22
6.19 Electromagnetic compatibility (EMC) . 22
6.20 X-Ray emission . 22
6.21 Corrosion . 23
6.22 Filling levels for insulation, switching and/or operation . 23
6.101 General requirements for DC GIS . 23
6.102 Pressure coordination . 23
6.103 Internal arc fault . 24
6.103.1 General . 24
6.103.2 External effects of the arc . 25
6.103.3 Internal fault location . 26
6.104 Enclosures . 26
6.104.1 General . 26
6.104.2 Design of enclosures . 26
6.105 Partitions . 27
6.105.1 Design of partitions . 27
6.105.2 Partitioning . 27
6.106 Pressure relief . 29
6.106.1 General . 29
6.106.2 Non-reclosing pressure relief device . 29
6.106.3 Pressure relief valve . 29
6.106.4 Limitation of pressure rise in the case of an internal fault. 30
6.107 Noise . 30
6.108 Interfaces . 30
6.108.1 General . 30
6.108.2 Cable connections . 30
6.108.3 Direct transformer connections . 31
6.108.4 Bushings . 31
6.108.5 Interfaces for future extensions. 31
6.109 Interlocking . 32
7 Type tests . 32
7.1 General . 32
7.1.1 General remarks . 32
7.1.2 Information for identification of test objects . 33
7.1.3 Information to be included in type-test reports . 33
7.2 Dielectric tests . 33
7.2.1 General . 33
7.2.2 Ambient air conditions during tests . 34
7.2.3 Wet test procedure . 34
7.2.4 Arrangement of the equipment . 34
7.2.5 Criteria to pass the test . 34
7.2.6 Application of the test voltage and test conditions . 34
7.2.7 Tests of switchgear and controlgear . 35
7.2.8 Artificial pollution tests for outdoor insulators . 36
7.2.9 Partial discharge tests . 36
7.2.10 Dielectric tests on auxiliary and control circuits . 38
7.2.11 Voltage test as condition check . 38

– 4 – IEC TS 62271-318:2024 © IEC 2024
7.2.101 DC insulation system test . 38
7.2.102 Long-term energized test . 41
7.3 Resistance measurement . 41
7.3.1 Measurement of the resistance of auxiliary contacts class 1 and class 2. 41
7.3.2 Measurement of the resistance of auxiliary contacts class 3 . 41
7.3.3 Electrical continuity of earthed metallic parts test . 41
7.3.4 Resistance measurement of contacts and connections in the main
circuit as a condition check . 42
7.4 Continuous current tests . 42
7.4.1 Conditions of the test object . 42
7.4.2 Arrangement of the equipment . 42
7.4.3 Test current and duration . 42
7.4.4 Temperature measurement during test . 42
7.4.5 Resistance of the main circuit . 43
7.4.6 Criteria to pass test . 43
7.5 Short-time withstand current and peak withstand current tests . 43
7.5.1 General . 43
7.5.2 Arrangement of the equipment and of the test circuit . 43
7.5.3 Test current and duration . 43
7.5.4 Conditions of the test object after test . 43
7.5.101 Tests on the main circuits . 43
7.5.102 Tests on earthing circuits . 44
7.6 Verification of the protection . 44
7.6.1 General . 44
7.6.2 Verification of the IP coding . 44
7.6.3 Verification of the IK coding . 44
7.7 Tightness tests . 44
7.7.1 General . 44
7.7.2 Controlled pressure systems for gas . 44
7.7.3 Closed pressure systems for gas . 45
7.7.4 Sealed pressure systems . 45
7.7.5 Liquid tightness tests . 45
7.8 Electromagnetic compatibility tests (EMC) . 45
7.9 Additional tests on auxiliary and control circuits . 45
7.10 X-radiation test for vacuum interrupters . 45
7.101 Verification of making and breaking capacities . 45
7.102 Mechanical and environmental tests . 45
7.102.1 General . 45
7.102.2 Mechanical operation test at ambient temperature . 45
7.102.3 Low- and high-temperature test . 46
7.103 Proof tests for enclosures . 46
7.103.1 General . 46
7.103.2 Burst test procedure . 46
7.103.3 Strain measurement test . 47
7.104 Pressure test on partitions . 47
7.105 Test under conditions of arcing due to an internal fault . 48
7.106 Insulator tests . 48
7.106.1 General . 48
7.106.2 Thermal performance . 48

7.106.3 Tightness test for partitions . 49
7.107 Corrosion test on earthing connections . 49
7.107.1 General . 49
7.107.2 Test procedure . 49
7.107.3 Criteria to pass the test . 49
7.108 Corrosion tests on sealing systems of enclosures and auxiliary equipment . 50
7.108.1 General . 50
7.108.2 Test procedure . 50
7.108.3 Criteria to pass the test . 50
8 Routine tests . 50
8.1 General . 50
8.2 Dielectric test on the main circuit . 51
8.2.101 Alternating or direct voltage tests on the main circuit . 51
8.2.102 Partial discharge measurement . 51
8.3 Tests on auxiliary and control circuits . 51
8.4 Measurement of the resistance of the main circuit . 52
8.5 Tightness test . 52
8.6 Design and visual checks . 52
8.101 Pressure tests of enclosures . 52
8.102 Mechanical operation tests . 52
8.103 Tests on auxiliary circuits, equipment and interlocks in the control

mechanism . 53
8.104 Pressure test on partitions . 53
9 Guide to the selection of switchgear and controlgear (informative) . 53
9.1 General . 53
9.2 Selection of rated values . 53
9.3 Cable-interface considerations . 53
9.4 Continuous or temporary overload due to changed service conditions . 53
9.5 Environmental aspects . 53
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 . 54
11 Transport, storage, installation, operating instructions and maintenance. 54
11.1 General . 54
11.2 Conditions during transport, storage and installation . 54
11.3 Installation . 54
11.4 Operating instructions . 54
11.5 Maintenance . 54
11.101 Tests after installation on-site . 54
11.101.1 General . 54
11.101.2 Dielectric tests on the main circuits . 55
11.101.3 Dielectric tests on auxiliary circuits . 59
11.101.4 Measurement of the resistance of the main circuit . 59
11.101.5 Gas tightness tests . 59
11.101.6 Checks and verifications . 59
11.101.7 Gas quality verifications . 59
12 Safety . 60

– 6 – IEC TS 62271-318:2024 © IEC 2024
13 Influence of the product on the environment . 60
Annex A (normative) Methods for alternating current testing of DC gas-insulated
metal-enclosed switchgear under conditions of arcing due to an internal fault . 61
A.1 General . 61
A.2 Short-circuit current arcing test . 61
A.2.1 Test arrangements . 61
A.2.2 Current and voltage applied . 61
A.2.3 Test procedure . 62
A.2.4 Criteria to pass the test . 62
A.2.5 Test report . 63
A.2.6 Extension of the test results . 63
A.3 Composite verification by calculation and separate tests . 63
Annex B (informative) Technical and practical considerations of site testing . 64
B.1 Test voltage generators . 64
B.2 Locating discharges . 64
B.3 Special test procedures . 64
B.3.1 General . 64
B.3.2 Testing at reduced voltage. 65
B.3.3 Testing at reduced gas density . 65
B.4 Partial discharge measurements . 65
B.5 Electrical conditioning . 65
B.6 Repetition tests . 65
B.6.1 General . 65
B.6.2 Recommended procedure . 66
B.7 Partial discharge detection method . 66
B.7.1 General . 66
B.7.2 Conventional method according to IEC 60270 . 66
B.7.3 VHF/UHF method . 66
B.7.4 Acoustic method . 67
B.7.5 Sensitivity verification of acoustic and UHF method . 68
Annex C (informative) Calculation of pressure rise due to an internal fault . 69
Annex D (informative) Information to be given with enquiries, tenders and orders . 70
D.1 General . 70
D.2 Normal and special service conditions . 70
D.3 Ratings . 71
D.4 Design and construction . 72
D.5 Bus ducts . 72
D.6 Disconnector and earthing switch . 73
D.7 Bushing . 73
D.8 Cable connection . 73
D.9 Transformer connection . 74
D.10 Current transducer . 74
D.11 Voltage transducer . 74
D.12 Metal-oxide surge arrester . 74
D.13 Documentation for enquiries and tenders . 75
Annex E (informative) List of notes concerning certain countries . 76
Annex F (informative) Long-term energized test . 77
F.1 Test objects . 77

F.2 Test sequence . 77
F.3 Pre-test . 79
F.4 Condition check . 79
F.5 Success criteria, re-testing and interruptions . 79
Annex G (informative) Application of DC GIS under composite voltage of alternating

and direct voltage components . 81
G.1 General . 81
G.2 Composite voltage consisting of alternating and direct voltage components . 81
G.3 Recommendation for application of DC GIS in bipolar DC schemes under

composite voltage stress . 82
Annex H (informative) DC switchgear located on neutral buses . 83
Bibliography . 84

Figure 1 – Pressure coordination . 24
Figure 2 – Example of arrangement of enclosures and gas compartments . 29
Figure G.1 – Composite phase-to-earth voltage at midpoint of converter pole including
third harmonic content and simplified voltage curve . 81

Table 1 – Reference table of service conditions relevant to DC GIS . 17
Table 2 – Performance criteria . 25
Table 3 – Type tests . 33
Table 4 – Test voltage for measuring PD intensity . 37
Table 5 – Sequence of DC insulation system test . 40
Table 6 – On-site test voltages . 57
Table D.1 – Normal and special service conditions . 70
Table D.2 – Ratings . 71
Table D.3 – Design and construction. 72
Table D.4 – Bus ducts . 72
Table D.5 – Bushing . 73
Table D.6 – Cable connection . 73
Table D.7 – Transformer connection . 74
Table D.8 – Current transducer . 74
Table D.9 – Voltage transducer . 74
Table D.10 – Documentation for enquiries and tenders . 75
Table F.1 – Test sequence for long-term energized test . 77
Table F.2 – Test sequence for long-term energized test with combined switching and
lightning impulse voltage tests and changed sequence . 78
Table F.3 – Test procedure for the long-term energized test . 79
Table F.4 – Condition check for the long-term energized test . 79

– 8 – IEC TS 62271-318:2024 © IEC 2024
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
HIGH-VOLTAGE SWITCHGEAR AND CONTROLGEAR –

Part 318: DC gas-insulated metal-enclosed switchgear
for rated voltages including and above 100 kV

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
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6) All users should ensure that they have the latest edition of this publication.
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8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) 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
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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 62271-318 has been prepared by subcommittee 17C: Assemblies, 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
17C/930/DTS 17C/937/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.

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/standardsdev/publications.
The list of all parts of the IEC 62271 series under the general title, High-voltage switchgear and
controlgear, may be found on the IEC website.
This document should be read in conjunction with IEC TS 62271-5:2024, to which it refers and
which is applicable unless otherwise specified. In order to simplify the indication of
corresponding requirements, the same numbering of clauses and subclauses is used as in
IEC TS 62271-5:2024. Amendments to these clauses and subclauses are given under the same
numbering, whilst additional subclauses, are numbered from 101.
The reader's attention is drawn to the fact that Annex E lists all of the "in-some-country" clauses
on differing practices of a less permanent nature relating to the subject of this document.
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.
IMPORTANT – The "colour inside" logo on the cover page of this document indicates
that it contains colours which are considered to be useful for the correct understanding
of its contents. Users should therefore print this document using a colour printer.

– 10 – IEC TS 62271-318:2024 © IEC 2024
HIGH-VOLTAGE SWITCHGEAR AND CONTROLGEAR –

Part 318: DC gas-insulated metal-enclosed switchgear
for rated voltages including and above 100 kV

1 Scope
This part of IEC 62271 specifies requirements for gas-insulated metal-enclosed switchgear in
which the insulation is obtained, at least partly, by an insulating gas or gas mixture other than
air at atmospheric pressure, for direct current of rated voltages including and above 100 kV, for
indoor and outdoor installation. This document includes rules for service conditions, ratings,
design, and construction requirements. Test requirements and criteria for proof for passing type
and routine tests are defined in this document for development and manufacturing of DC
switchgear.
For the purpose of this document, the terms "DC GIS" and "DC switchgear" are used for "DC
gas-insulated metal-enclosed switchgear".
This specification is applicable for both Line Commutated Converter (LCC) and Voltage Sourced
Converter (VSC) for HVDC systems.
The DC gas-insulated metal-enclosed switchgear covered by this document consists of
individual components intended to be directly connected together and able to operate only in
this manner.
This document completes and amends, if applicable, the various relevant documents applying
to the individual components constituting DC gas-insulated metal-enclosed switchgear.
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 60060-1:2010, High-voltage test techniques – Part 1: General definitions and test
requirements
IEC 60085:2007, Electrical insulation – Thermal evaluation and designation
IEC 60068-2-11:2021, Environmental testing – Part 2-11: Tests – Test Ka: Salt mist
IEC 60068-2-17:2023, Environmental testing – Part 2-17: Tests – Test Q: Sealing
IEC/IEEE 60076-57-129:2017, Power transformers – Part 57-129: Transformers for HVDC
applications
IEC 60099-4:2014, Surge arresters – Part 4: Metal-oxide sur
...