prEN IEC 62271-205:2026

Hochspannungs-Schaltgeräte und -Schaltanlagen - Teil 205: Kompakte Schaltgerätekombinationen für Bemessungsspannungen über 52 kV

Appareillage à haute tension - Partie 205: Ensembles d'appareillage compacts, postes mobiles et préfabriqués pour une tension nominale supérieure à 52 kv

Visokonapetostne stikalne in krmilne naprave - 205. del: Sestav omrežnih stikalnih naprav, mobilne in montažne postaje za naznačene napetosti nad 52 kV

General Information

• Status: Not Published
• Publication Date: 16-Jan-2028
• ICS: 29.130.10 - High voltage switchgear and controlgear
• ICS: 29.130.99 - Other switchgear and controlgear
• Technical Committee: CLC/TC 17AC - High-voltage switchgear and controlgear
• Drafting Committee: IEC/SC 17C - IEC_SC_17C
• Current Stage: 4020 - Enquiry circulated - Enquiry
• Start Date: 26-Jun-2026
• Due Date: 31-May-2024
• Completion Date: 26-Jun-2026
• Ref Project: oSIST prEN IEC 62271-205:2026 - High-voltage switchgear and controlgear - Part 205: Compact switchgear assemblies, mobile and prefabricated substations for rated voltage above 52 kv

Relations

• Revises: EN 62271-205:2008 - High-voltage switchgear and controlgear - Part 205: Compact switchgear assemblies for rated voltages above 52 kV
• Effective Date: 23-Jan-2023

Overview

prEN IEC 62271-205:2026 is a CLC-adopted international standard that specifies requirements for high-voltage switchgear and controlgear assemblies-specifically, compact switchgear, mobile substations, and prefabricated substations intended for rated voltages above 52 kV. This standard applies to systems for both indoor and outdoor installation, serving public utility, industrial, or emergency power supply needs where rapid deployment, modularity, and operational safety of high-voltage equipment are crucial.

This edition introduces significant updates:

• Expanding the scope to include both mobile and prefabricated substations
• New and clarified definitions for mobile and prefabricated substations
• Separation of requirements specific to compact assemblies, mobile, and prefabricated substations
• Updated references to the latest IEC publications

Key Topics

The standard covers several critical technical areas to ensure performance, safety, and adaptability:

• Definitions and Types:

  • Compact switchgear assemblies: Integration of switching devices, instrument transformers, and other elements for high-voltage switching in a single compact unit.
  • Prefabricated substations: Factory-built assemblies for permanent installation.
  • Mobile substations: Factory-built assemblies engineered for rapid deployment and relocatability.

• Service Conditions:

  • Applicable for installations with rated voltages above 52 kV and frequencies up to 60 Hz.
  • Guidance for both indoor (containerized/enclosed) and outdoor environments.

• Design and Construction:

  • Requirements for earthing, corrosion resistance, sealing, position indication, and safety labeling.
  • Modular approach, allowing combinations of modules: high-voltage, transformer, medium-voltage, and protection/control.

• Testing and Ratings:

  • Type and routine testing procedures to demonstrate dielectric strength, resistance, current-carrying capability, tightness, and operational reliability.
  • Ratings encompass voltage, insulation, frequency, short-time withstand current, and more.

• Safety and Environmental Aspects:

  • Specialized provisions for maintenance, safety interlocks, and minimizing environmental impact throughout the product lifecycle.

Applications

The standard is relevant for organizations involved in the design, procurement, and operation of high-voltage substations, ensuring that products conform to internationally accepted safety, performance, and interoperability criteria in the following scenarios:

• Electric Utilities: Rapidly deployable mobile substations for grid emergencies, planned maintenance, or network expansion.
• Industrial Facilities: Compact switchgear and prefabricated substations where space, installation time, or relocation flexibility are key factors.
• Construction Projects: Temporary high-voltage substations for short- and intermediate-term power supply on sites.
• Disaster Recovery and Grid Reliability: Quick restoration of power using mobile substations after natural disasters or major faults.

Benefits include:

• Reduced installation time and costs due to off-site fabrication and pre-testing
• Modular solutions enable scalability and relocation as operational needs evolve
• Consistent safety and quality across international projects

Related Standards

The prEN IEC 62271-205:2026 is designed for use alongside other essential IEC publications in the high-voltage domain, including:

• IEC 62271-1: Common specifications for switchgear and controlgear
• IEC 62271-203: Requirements for gas-insulated metal-enclosed switchgear above 52 kV
• IEC 60068-2-17: Environmental testing - Sealing tests
• IEC 61936-1: Power installations exceeding 1 kV AC and 1.5 kV DC - General requirements
• IEC 62271-4: Handling procedures for gases in insulating and/or switching devices

By harmonizing requirements with these related standards, prEN IEC 62271-205:2026 streamlines compliance, supports effective risk management, and enhances operational efficiency in high-voltage power systems worldwide.

---

For further details and the full requirements, refer to the official publication of prEN IEC 62271-205:2026 High-voltage switchgear and controlgear - Part 205: Compact switchgear assemblies, mobile and prefabricated substations for rated voltage above 52 kV.

Standards Content (Sample)

SLOVENSKI STANDARD
01-september-2026
Visokonapetostne stikalne in krmilne naprave - 205. del: Sestav omrežnih stikalnih
naprav, mobilne in montažne postaje za naznačene napetosti nad 52 kV
High-voltage switchgear and controlgear - Part 205: Compact switchgear assemblies,
mobile and prefabricated substations for rated voltage above 52 kv
Hochspannungs-Schaltgeräte und -Schaltanlagen - Teil 205: Kompakte
Schaltgerätekombinationen für Bemessungsspannungen über 52 kV
Appareillage à haute tension - Partie 205: Ensembles d'appareillage compacts, postes
mobiles et préfabriqués pour une tension nominale supérieure à 52 kv
Ta slovenski standard je istoveten z: prEN IEC 62271-205:2026
ICS:
29.130.10 Visokonapetostne stikalne in High voltage switchgear and
krmilne naprave controlgear
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

17C/1001/CDV
COMMITTEE DRAFT FOR VOTE (CDV)
PROJECT NUMBER:
IEC 62271-205 ED2
DATE OF CIRCULATION: CLOSING DATE FOR VOTING:
2026-06-26 2026-09-18
SUPERSEDES DOCUMENTS:
17C/984/CD, 17C/997/CC
IEC SC 17C : ASSEMBLIES
SECRETARIAT: SECRETARY:
Germany Mr Mark Kuschel
OF INTEREST TO THE FOLLOWING COMMITTEES: HORIZONTAL FUNCTION(S):
SC 17A, TC 28, TC 36, TC 57, TC 99
ASPECTS CONCERNED:
Electromagnetic Compatibility, Safety
SUBMITTED FOR CENELEC PARALLEL VOTING NOT SUBMITTED FOR CENELEC PARALLEL VOTING
Attention IEC-CENELEC parallel voting
The attention of IEC National Committees, members of CENELEC,
is drawn to the fact that this Committee Draft for Vote (CDV) is
submitted for parallel voting.
The CENELEC members are invited to vote through the CENELEC
online voting system.
This document is still under study and subject to change. It should not be used for reference purposes.
Recipients of this document are invited to submit, with their comments, notification of any relevant patent rights of which t hey are aware
and to provide supporting documentation.
Recipients of this document are invited to submit, with their comments, notification of any relevant “In Some Countries” clau ses to be
included should this proposal proceed. Recipients are reminded that the CDV stage is the final stage for submitting ISC c lauses. (SEE
AC/22/2007 OR NEW GUIDANCE DOC).

TITLE:
High-voltage switchgear and controlgear – Part 205: AC compact switchgear assemblies, mobile and
prefabricated substations for rated voltage above 52 kV

PROPOSED STABILITY DATE: 2032
NOTE FROM TC/SC OFFICERS:
electronic file, to make a copy and to print out the content for the sole purpose of preparing National Committee positions.
You may not copy or "mirror" the file or printed version of the document, or any part of it, for any other purpose without
permission in writing from IEC.

IEC CDV 62271-205 © IEC 2026
CONTENTS
FOREWORD . 3
INTRODUCTION . 5
1 Scope . 6
1.1 General . 6
1.2 Compact switchgear assemblies . 6
1.3 Prefabricated substation and mobile substation . 7
2 Normative references . 7
3 Terms and definitions . 7
3.1 General terms . 7
4 Normal and special service conditions . 9
5 Ratings . 10
5.1 Compact switchgear assemblies . 10
5.2 Mobile substations and prefabricated substations . 11
6 Design and construction . 13
6.1 General . 13
6.2 Earthing of compact switchgear assemblies, mobile and prefabricated
substations . 15
6.3 Nameplates . 16
6.4 Locking devices . 16
6.5 Position indication . 16
6.6 Gas and vacuum tightness . 16
6.7 X-ray emission . 17
6.8 Corrosion . 17
6.9 Filling levels for insulation, switching and/or operation . 17
6.10 Pressure relief devices . 17
6.11 Movement of pressurized devices . 17
6.12 Isolating distance for maintenance . 17
7 Type test . 17
7.1 General . 17
7.2 Dielectric tests . 20
7.3 Radio interference voltage (RIV) test . 20
7.4 Resistance measurement . 20
7.5 Continuous current tests . 21
7.6 Short-time withstand current and peak withstand current tests . 21
8 Routine tests . 24
8.1 General . 24
8.2 Dielectric test on the main circuit . 24
8.3 Tests on auxiliary and control circuits . 25
8.4 Measurement of the resistance of the main circuit . 25
8.5 Tightness test . 25
8.6 Design and visual checks . 26
8.7 Additional functional tests of mobile substations and prefabricated
substations . 26
8.8 Test after assembly at site of mobile substations and prefabricated
substations . 26
9 Guide to the selection of an equipment (informative) . 27
IEC CDV 62271-205 © IEC 2026
9.1 Compact switchgear assembly . 27
9.2 Mobile substations and prefabricated substations . 27
10 Information to be given with enquiries, tenders and orders (informative) . 27
10.1 Compact switchgear assemblies . 27
10.2 Mobile substations and prefabricated substations . 28
11 Transport, storage, installation, operating instructions and maintenance . 28
11.1 General . 28
11.2 Compact switchgear assemblies . 28
11.3 Mobile substations and prefabricated substations . 29
12 Safety . 29
13 Influence of the product on the environment . 29
Annex A (informative) Explanations of compact switchgear assemblies . 30
A.1 Explanations of the scope of compact switchgear assemblies . 30
A.2 Examples of compact switchgear assemblies . 30
B.1 Background of mobile substations . 33
B.2 Explanation of the scope of a mobile substation . 33
Annex C (informative) Explanation of prefabricated substations . 35
C.1 Background of prefabricated substations . 35
C.2 Explanation of the scope of prefabricated substation . 35
Bibliography . 37

Figure A.1 – Combination coverd by this document . 30
Figure A.2 – Example for Type 1 . 31
Figure A.4 – Example for Type 3 . 32
Figure A.5 – Example for Type 4 (highly integrated) . 32
Figure B.1 – Simplified lifetime of a mobile substation . 33
Figure B.2 – Combination of prefabricated hgh-voltage, transformer, medium-voltage,
protection & control module and vehicle . 33
Figure B.3 Mobile substation consisting of separate mobile modules . 34
Figure B.4 – Example of a mobile substation with high-voltage and transformer module
installed on a vehicle . 34
Figure C.1 – Simplified lifetime of prefabricated substation . 35
Figure C.2 – Combination of prefabricated high voltage-, transformer-, medium
voltage- and protection & control-module . 35
Figure C.3 – Combination of separated high voltage-, transformer-, medium voltage-
and protection & control-module . 35
Figure C.4 – Example of prefabricated substation with high-voltage- and protection &
control-module . 36
Figure C.5 – Example of prefabricated substation with medium-voltage- and power
supply module . 37

Table 1 – Type tests on the compact switchgear assembly . 18

IEC CDV 62271-205 © IEC 2026
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
HIGH-VOLTAGE SWITCHGEAR AND CONTROLGEAR –

Part 205: AC compact switchgear assemblies, mobile and prefabricated
substations for rated voltage above 52 kV

FOREWORD
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8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
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9) IEC draws attention to the possibility that the implementation of this document may involve the use of (a)
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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 62271-205 has been prepared by subcommittee 17C: Assemblies, of IEC technical
committee 17: High-voltage switchgear and controlgear. It is an International Standard.
This second edition cancels and replaces the first edition published in 2008. This edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) Scope has been enlarged to include prefabricated substations and mobile substations
b) New terms “mobile substation” and “prefabricated substation” have been defined
c) References to actual IEC publications have been updated
IEC CDV 62271-205 © IEC 2026
d) Clauses and subclauses have been re-organized to distinguish between compact
switchgear assemblies, mobile substations and prefabricated substations where needed
The text of this International Standard is based on the following documents:
Draft Report on voting
XX/XX/FDIS XX/XX/RVD
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 International Standard 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/publications.
This document is to be read in conjunction with IEC 62271-1 to which it refers and which is
applicable, unless otherwise specified. A list of all parts of the IEC 62271 series can be found,
under the general title High-voltage switchgear and controlgear, 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,
• replaced by a revised edition, or
• amended.
IEC CDV 62271-205 © IEC 2026
1 INTRODUCTION
2 This standard uses the terms compact switchgear assemblies, prefabricated substations and
3 mobile substations. Even if these terms suggest a clear distinction, the real applications show
4 a wide overlap and also a mixture of these terms. This is, among other things, due to the fact,
5 that compact switchgear assemblies, prefabricated substations and mobile substations are
6 generally highly customized and thus almost each application can be considered individual.
7 A prefabricated substation is basically designed for installation without further relocation. It is
8 pre-built off-site e.g., in a factory, and then transported to its final installation site.
9 A mobile substation is designed for temporary installations and relocations. It is pre-built off-
10 site, e.g., in a factory, and then transported to its location for use.
11 Compact switchgear assemblies consist of at least one mechanical switching device directly
12 connected to, or sharing components, with one or more other devices (e.g., instrument
13 transformers, bushings etc.). In general, they are designed for fixed installation and in most
14 cases transported to site as a whole.
15 A combination of above-described terms is possible. For instance, a compact switchgear
16 assembly may also form a part of a mobile substation.
17 Within mobile or prefabricated substations with rated voltages above 52 kV, switching devices
18 rated up to 52 kV (e.g., medium-voltage switching devices at 36 kV) as well as high-voltage
19 switching devices (e.g., 145 kV) may be used. For a better understanding in reading this
20 document the term “medium-voltage” will be used where necessary.
21 Mobile substations and prefabricated substations usually, but not exclusively, consist of the
22 following modules:
23 – High-voltage module;
24 – Power transformer module;
25 – Medium-voltage module;
26 – Protection and control module;
27 Mobile substations require additional suitable vehicles for transportation.
28 The CIGRE Technical Brochure 907 [1] “Mobile substations incorporating HV GIS” provides
29 guidance for mobile substation applications, which extend from those intended for rapid
30 deployment in an emergency through relocatable designs to prefabricated or ’build off-site’
31 solutions. Three cases for mobile/prefabricated substation are defined:
32 – Substation for short term (emergency) use – typically 1 week ÷ 6 months;
33 – Substation for intermediate term use – typically 6 months ÷ 3 years;
34 – Substation for long term use – typically more than 3 years.
35 More explanatory information could be found in CIGRE Technical Brochure 907 [1].
IEC CDV 62271-205 © IEC 2026
37 HIGH-VOLTAGE SWITCHGEAR AND CONTROLGEAR-
39 Part 205: AC compact switchgear assemblies, mobile and prefabricated
40 substations for rated voltage above 52 kV
43 1 Scope
44 1.1 General
45 This part of IEC 62271 series applies to service conditions, rated characteristics, general
46 structural requirements and test methods of compact switchgear assemblies, mobile
47 substations and prefabricated substations, for indoor and/or outdoor installations in systems
48 having rated voltages above 52 kV and service frequencies up to and including 60 Hz.
49 1.2 Compact switchgear assemblies
50 In general, compact switchgear assemblies consist of at least one mechanical switching device
51 directly connected to or sharing components with one or more other devices such that there is
52 an interaction between the functions of the individual devices.
53 The devices, defined by IEC standards, which can be a part of a compact switchgear assembly
54 are exemplary listed below and is not be limited to:
55 NOTE To simplify the reading of this document, the term "switching device" is used instead of the term "mechanical
56 switching device".
57 Switching devices:
58 – Circuit-breakers
59 – Disconnectors/Earthing switches
60 – Switch-disconnectors
61 – Disconnecting circuit-breakers
62 Devices:
63 – Instrument transformers
64 – Surge arresters
65 – Bushings
66 – Insulators
67 – Cable connections
68 – Transformer connections
69 The interaction between devices might be due to proximity, sharing of components or a
70 combination of both. The assemblies can contain devices of air insulated switchgear (AIS) only
71 or a combination of part of AIS and part of gas-insulated metal-enclosed switchgear (GIS), so
72 called mixed technology switchgear (MTS) and can be delivered entirely prefabricated or
73 partially assembled.
74 Each switching device forming a part of a compact switchgear assembly shall comply with the
75 relevant individual standard. If a part of the compact switchgear assembly is formed by gas-
76 insulated metal-enclosed switchgear devices, the requirements of IEC 62271-203:2022 apply.
77 The parts of this document relevant for compact switchgear assemblies do not apply to
78 switchgear assemblies (for fixed or mobile purpose) consisting solely of GIS which are covered
79 by IEC 62271-203.
IEC CDV 62271-205 © IEC 2026
80 It is not possible to define all potential arrangements of compact switchgear assemblies. Four
81 examples are shown for information in Annex A.
83 1.3 Prefabricated substation and mobile substation
84 In general, a prefabricated substation is a high-voltage assembly, comprising of different
85 functional type-tested modules, assembled off-site in a factory and then transported to its final
86 location for installation. The majority of the assembly and testing operations which are normally
87 carried out at site are completed before delivery in order to shorten site works. A prefabricated
88 substation is based on functional modules and consists at least of a power transformer module
89 and/or a high-voltage switchgear and controlgear module. Further functional modules, which
90 may be part of a prefabricated substation, are listed below but shall not be seen as conclusive:
91 – Protection and control module
92 – Medium-voltage module
93 – Lightning protection
94 – Power cable
95 Compact switchgear assemblies can be an integral part of the high-voltage switchgear and
96 controlgear module and can be therefore part of a prefabricated substation.
97 A mobile substation is a prefabricated substation designed and intended to be transported
98 during lifetime by use of an adequate vehicle. Requirements for the vehicle can be linked to
99 local regulations and are not in the scope of this document.
100 In general, it is not feasible to specify every possible configuration of prefabricated and mobile
101 substations. Annex B provides more information on mobile substations and Annex C on
102 prefabricated substations.
103 NOTE For the use of this document high voltage (IEC 60050-601:1985 [2], 601-01-27) is the rated voltage above
104 1 000 V. However, medium voltage (IEC 60050-601:1985 [2], 601-01-28) is commonly used for distribution systems
105 with voltages above 1 000 V and generally applied up to and including 52 kV. For a better understanding in reading
106 this document the term “medium voltage” will be used where necessary.
107 2 Normative references
108 The following publications are referred to in the text in such a way that some or all of their
109 content constitutes requirements of this document. For dated references, only the edition cited
110 applies. For undated references, the latest edition of the referenced publication (including any
111 amendments) applies.
112 IEC 60068-2-17 Environmental testing - Part 2-17: Tests - Test Q: Sealing
113 IEC 61936-1 Power installations exceeding 1 kV AC and 1,5 kV DC - Part 1: AC
114 IEC 62271-1 High-voltage switchgear and controlgear – Part 1: Common specifications for
115 alternating current switchgear and controlgear
116 IEC 62271-4 High-voltage switchgear and controlgear – Part 4: Handling procedures for gases
117 for insulating and/or switching
118 IEC 62271-203 High-voltage switchgear and controlgear – Part 203: Gas-insulated metal-
119 enclosed switchgear for rated voltages above 52 kV
120 3 Terms and definitions
121 3.1 General terms
122 For the purposes of this document, the terms and definitions given in IEC 62271-1:2017 and
123 IEC 62271-1:2017/AMD1:2021, the publications mentioned in clause 2 and the following apply.
IEC CDV 62271-205 © IEC 2026
124 ISO and IEC maintain terminology databases for use in standardization at the following
125 addresses:
126 – IEC Electropedia: available at https://www.electropedia.org/
127 – ISO Online browsing platform: available at https://www.iso.org/obp
128 3.1.1
129 agreement between user and manufacturer
130 documented understanding between the user and/or customer and the manufacturer defining
131 responsibilities, technical requirements, and conditions applicable to the product or system.
132 3.2 Assemblies of switchgear and controlgear
133 3.2.1
134 compact switchgear assembly
135 assembly of high-voltage devices consisting of at least one switching device directly connected
136 to, or sharing components with, one or more other devices such that there is an interaction
137 between the functions of the individual devices
138 Note 1 to entry: Assembly of high-voltage devices can be made of “air insulated/air insulated” or “air insulated/gas
139 insulated” devices. Annex A provides examples of compact switchgear assemblies.
140 Note 2 to entry: A compact switchgear assembly may be mounted on one or more structures, but it is only intended
141 for installation and operation as a single, complete unit.
142 Note 3 to entry: Interaction is the transfer of stresses (e.g., electrical, mechanical and thermal) between the
143 individual devices.
144 3.2.2
145 prefabricated substation
146 prefabricated high-voltage assembly comprising at least a power transformer and/or a high-
147 voltage switchgear and controlgear, and usually one or several of the following devices:
148 medium-voltage switchgear and controlgear, high-voltage interconnection, medium-voltage
149 interconnection, auxiliary and control equipment and circuits
150 Note 1 to entry: A prefabricated substation includes all main and earthing circuits to be connected through
151 appropriate interfaces to external high-voltage and medium-voltage cables and to external earthing system and
152 (protective) bonding conductor (if any).
153 Note 2 to entry: A prefabricated substation may be partially or completely protected by an enclosure.
154 Note 3 to entry: A prefabricated substation is normally not designed for relocation to alternative sites during it s
155 lifetime.
156 Note 4 to entry: Annex C provides some more information of prefabricated substations.
157 [SOURCE: IEC 62271-202:2022 [3], 3.2.101, modified - change from “low-voltage” to “medium-
158 voltage”; “and type-tested” deleted; “an enclosure containing” deleted; Note 2, Note 3 and
159 Note 4 to entry added]
160 3.2.3
161 mobile substation
162 pre-fabricated electrical substation which is designed to be relocated to alternative sites during
163 lifetime and connectable to the grid itself or via a substation.
164 Note 1 to entry: Mobile substations are normally mounted as an integral part of a vehicle for road or train
165 transportation. Alternatively, they can also be mounted on e.g., a platform or rack which is at site unloaded and
166 placed on ground until relocation.
167 Note 2 to entry: According to the intended usage of the mobile substation ( e.g., short term emergency use or
168 intermediate use during renovation/reconstruction of an existing substation) the design and requirements e.g., on
169 type-tests and site acceptance tests may differ.
170 Note 3 to entry: A mobile substation can consist of different transportation units
171 Note 4 to entry: Annex B provides more information and examples of mobile substations.
172 3.2.4
173 high-voltage module
174 functional unit with a rated voltage above 52 kV, may consisting of, but not limited for, switching
175 devices, instrument transformers including their associated auxiliary and control devices,
176 establishing the connection to the existing grid by either overhead line or cable connection
IEC CDV 62271-205 © IEC 2026
177 Note 1 to entry: The functional unit may be prefabricated.
178 Note 2 to entry: The functional unit may be based on compact switchgear assemblies or e.g., GIS (covered by
179 IEC 62271-203).
180 3.2.5
181 transformer module
182 functional unit for a power transformer and additional windings if applicable and/or a shunt
183 reactor, as well as associated auxiliary, protection and control devices .
184 3.2.6
185 medium-voltage module
186 functional unit with a rated voltage up to and including 52 kV, may consisting of, but not limited
187 to, switching devices, instrument transformers, medium-voltage / low-voltage power
188 transformer, reactive power compensation device including their associated auxiliary and
189 control devices
190 Note 1 to entry: The functional unit may be prefabricated.
191 3.2.7
192 protection & control module
193 functional unit which may integrate automation system, scheduling automation system,
194 communication system, protection relay and safety automatic device, AC and DC power supply
195 system, time synchronization device, auxiliary facilities intelligent control and other equipment
196 Note 1 to entry: The functional unit may be a combination of protection & control system and local power supply
197 system.
198 3.2.8
199 vehicle
200 transportation system designed to relocate mobile substation or parts of it ( e.g., trailer)
201 4 Normal and special service conditions
202 Clause 4 of IEC 62271-1:2017 and IEC 62271-1:2017/AMD1:2021 is applicable with the
203 following additions:
204 Unless otherwise specified in this document, a prefabricated or mobile substation is intended
205 to be used in accordance with its rated characteristics and at locations compliant with the
206 normal service conditions defined for outdoor switchgear and controlgear in IEC 62271-1:2017
207 and IEC 62271-1:2017/AMD1:2021.
208 Inside an enclosed installation (e.g., inside a container or indoor installation) of a prefabricated
209 or mobile substation, it is assumed that the normal indoor service conditions defined for indoor
210 switchgear and controlgear in IEC 62271-1:2017 and IEC 62271-1:2017/AMD1:2021 prevail.
211 The air temperature inside an enclosed installation of a prefabricated or mobile substation might
212 differ from the ambient air temperature. If the air temperature inside the enclosed installation is
213 higher than the limits defined for the devices in their respective product standards, de -rating
214 can be necessary
215 Generally, as compact switchgear assemblies, prefabricated substations and mobile
216 substations can contain devices that are not covered by IEC 62271-1 (e.g., voltage
217 transformers), the normal and special service conditions of these devices shall at least meet
218 Clause 4 of IEC 62271-1:2017 and IEC 62271-1:2017/AMD1:2021 without the need for derating.
IEC CDV 62271-205 © IEC 2026
221 5 Ratings
222 5.1 Compact switchgear assemblies
223 5.1.1 General
224 Subclause 5.1 of IEC 62271-1:2017 and IEC 62271-1:2017/AMD1:2021 is applicable, except
225 as follows.
226 The ratings of a compact switchgear assembly are the following:
227 a) rated voltage (Ur);
228 rated insulation level (Up, Ud, and US where applicable);
229 b) rated frequency (fr)
230 c) rated continuous current (I ) (for main circuits);
r
231 d) rated short-time withstand current (Ik) (for main and earthing circuits);
232 e) rated peak withstand current (I ) (for main and earthing circuits);
p
233 f) rated duration of short-circuit (t ) (for main and earthing circuits);
k
234 and as applicable
235 g) Individual rated values of the high-voltage devices forming the compact switchgear
236 assembly, including their operating devices (supply voltage and frequency), auxiliary and
237 control circuits
238 The ratings of the compact switchgear assembly shall be assigned ensuring that operation of
239 the compact switchgear assembly within its assigned ratings does not expose any individual
240 device to conditions which are outside its rated capabilities.
241 Further ratings are subjected to agreement between user and manufacturer.
242 5.1.2 Rated voltage (Ur)
243 Subclause 5.2 of IEC 62271-1:2017 and IEC 62271-1:2017/AMD1:2021 is applicable with the
244 following addition:
245 The compact switchgear assembly shall be suitable for the rated voltage.
246 For the purposes of this document, the rated voltage (U ) defined in IEC 62271-1:2017 and
r
247 IEC 62271-1:2017/AMD1:2021 is the rated voltage of the compact switchgear assembly (U )
r
248 NOTE 1: Devices forming part of the compact switchgear assembly can have individual values of rated voltage in
249 accordance with the relevant product standards.
250 5.1.3 Rated insulation level (Up, Ud, and Us)
251 Subclause 5.3 of IEC 62271-1:2017 and IEC 62271-1:2017/AMD1:2021 is applicable with the
252 following addition:
253 The compact switchgear assembly shall be suitable for the rated insulation level.
254 5.1.4 Rated frequency (fr)
255 Subclause 5.4 of IEC 62271-1:2017 and IEC 62271-1:2017/AMD1:2021 is applicable with the
256 following addition:
257 The compact switchgear assembly shall be suitable for the rated frequency.
258 5.1.5 Rated continuous current (Ir)
259 Subclause 5.5 of IEC 62271-1:2017 and IEC 62271-1:2017/AMD1:2021 is applicable with the
260 following addition:
IEC CDV 62271-205 © IEC 2026
261 The compact switchgear assembly shall be suitable for the rated continuous current.
262 5.1.6 Rated short-time withstand current (Ik)
263 Subclause 5.6 of IEC 62271-1:2017 and IEC 62271-1:2017/AMD1:2021 is applicable with the
264 following addition:
265 The compact switchgear assembly shall be suitable for the rated short-time withstand current.
266 An earthing switch may be assigned a rating different from the rating of the related main circuit
267 (if applicable).
268 An earthing switch forming an integral part of a combined function earthing switch may be
269 assigned to a rating different from the rating of its main circuit.
270 5.1.7 Rated peak withstand current (Ip)
271 Subclause 5.7 of IEC 62271-1:2017 and IEC 62271-1:2017/AMD1:2021 is applicable with the
272 following addition:
273 The compact switchgear assembly shall be suitable for the rated peak withstand current.
274 An earthing switch may be assigned a rating different from the rating of the related main circuit
275 (if applicable).
276 An earthing switch forming an integral part of a combined disconnecting-earthing switch may
277 be assigned a rating different from the rating of its main circuit.
278 5.1.8 Rated duration of short-circuit (tk)
279 Subclause 5.8 of IEC 62271-1:2017 and IEC 62271-1:2017/AMD1:2021 is applicable with the
280 following addition:
281 The compact switchgear assembly shall be suitable for the rated duration of short -circuit.
282 An earthing switch may be assigned a rating different from the rating of the related main circuit .
283 An earthing switch forming an integral part of a combined disconnecting-earthing switch may
284 be assigned to a rating different from the rating of its main circuit.
285 5.1.9 Rated supply voltage of auxiliary and control circuits (U )
a
286 Subclause 5.9 of IEC 62271-1:2017 and IEC 62271-1:2017/AMD1:2021 is applicable.
287 5.1.10 Rated supply frequency of auxiliary circuits
288 Subclause 5.10 of IEC 62271-1:2017 and IEC 62271-1:2017/AMD1:2021 is applicable.
289 5.2 Mobile substations and prefabricated substations
290 5.2.1 General
291 Subclause 5.1 of IEC 62271-1:2017 and IEC 62271-1:2017/AMD1:2021 is applicable, except
292 as follows.
293 Mobile and prefabricated substations comprise usually of high-voltage and medium-voltage
294 assemblies and/or devices. Therefore, the ratings of the high-voltage and medium-voltage
295 assemblies and/or devices shall be defined separately, where applicable.
296 A clear distinction should be ensured when choosing abbreviations for a rated value (e.g.,
297 voltage) but for different voltage levels (e.g., high-voltage and medium-voltage). Additional
298 suffixes (e.g., Ur1) may be used and may be agreed between user and manufacturer.
299 The ratings of mobile substations and prefabricated substations are the following. Where
300 applicable, differentiation shall be made between high-voltage and medium-voltage assemblies
301 and/or devices.
IEC CDV 62271-205 © IEC 2026
302 a) rated voltage (U );
r
303 b) rated insulation level(U , U and U , where applicable);
p d s
304 c) rated frequency (f );
r
305 d) rated continuous current (I ) (for main circuits);
r
306 e) rated short-time withstand current (I ) (for main and earthing circuits);
k
307 f) rated peak withstand current (I ) (for main and earthing circuits);
p
308 g) rated duration of short-circuit (t ) (for main and earthing circuits);
k
309 and as applicable
310 h) individual rated values of the high-voltage and medium-voltage devices forming the mobile
311 and prefabricated substation, including their operating devices (supply voltage and
312 frequency), auxiliary and control equipment.
313 Further ratings are subjected to agreement between user and manufacturer.
314 The ratings of the mobile and prefabricated substation shall be assigned to ensure that
315 operation of the mobile and prefabricated substation is within its assigned ratings and does not
316 expose any individual device to conditions which are outside its rated capabilities.
317 Mobile substations and prefabricated substations can include devices not covered by
318 IEC 62271. Where applicable, such devices shall be suitable for the ratings defined in
319 subclauses 5.2.2 to 5.2.10. of this document. Additional ratings may apply in accordance with
320 relevant ISO/IEC documents.
321 5.2.2 Rated voltage (Ur)
322 Subclause 5.2 of IEC 62271-1:2017 and IEC 62271-1:2017/AMD1:2021 is applicable with the
323 following addition:
324 The mobile or prefabricated substation shall be suitable for the rated voltages.
325 NOTE 1: Devices forming part of the mobile or prefabricated substation can have individual values of rated voltage
326 in accordance with the relevant standards.
327 5.2.3 Rated insulation level (Up, Ud, and Us)
328 Subclause 5.5 of IEC 62271-1:2017 and IEC 62271-1:2017/AMD1:2021 is applicable with the
329 following addition:
330 The mobile or prefabricated substation shall be suitable for the rated insulation levels.
331 5.2.4 Rated frequency (f )
r
332 Subclause 5.4 of IEC 62271-1:2017 and IEC 62271-1:2017/AMD1:2021 is applicable with the
333 following addition:
334 The mobile or prefabricated substation shall be suitable for the rated frequency.
335 5.2.5 Rated continuous current (I )
r
336 Subclause 5.5 of IEC 62271-1:2017 and IEC 62271-1:2017/AMD1:2021 is applicable with the
337 following addition:
338 The mobile or prefabricated substation shall be suitable for the rated continuous currents.
339 5.2.6 Rated short-time withstand current （I）
k
340 Subclause 5.6 of IEC 62271-1:2017 and IEC 62271-1:2017/AMD1:2021 is applicable with the
341 following addition:
342 The mobile or prefabricated substation be suitable the rated short-time withstand currents.
IEC CDV 62271-205 © IEC 2026
343 An earthing switch may be assigned a rating different from the rating of the related main circuit
344 (if applicable).
345 An earthing switch forming an integral part of a combined function earthing switch may be
346 assigned to a rating different from the rating of its main circuit.
347 5.2.7 Rated peak withstand current (I )
p
348 Subclause 5.7 of IEC 62271-1:2017 and IEC 62271-1:2017/AMD1:2021 is applicable with the
349 following addition:
350 The mobile or prefabricated substation shall be suitable for the rated peak withstand currents.
351 An earthing switch may be assigned a rating different from the rating of the related main circuit.
352 An earthing switch forming an integral part of a combined function earthing switch may be
353 assigned a rating different from the rating of its main circui
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