IEC TR 62271-312:2021

High-voltage switchgear and controlgear - Part 312: Guidance for the transferability of type tests of high-voltage/low-voltage prefabricated substations

IEC TR 62271-312:2021(E) refers to high-voltage / low-voltage prefabricated substations (hereinafter prefabricated substations) as specified in IEC 62271-202:2014.
This document, among other options as agreed between manufacturer and user, can be used for the transferability of type tests performed on one or more prefabricated substations with a defined set of ratings and arrangement of components to another prefabricated substation with a different set of ratings or different arrangement of components. It supports the selection of appropriate representative test objects for that purpose in order to optimize the type testing procedure for a consistent conformity assessment.
This document utilises a combination of sound technical and physical principles, manufacturer and user experience and mutually agreed upon methods of calculation to establish pragmatic guidance for the transferability of type test results, covering various design and rating aspects.

General Information

• Status: Published
• Publication Date: 04-Jan-2021
• ICS: 29.130.10 - High voltage switchgear and controlgear
• Technical Committee: SC 17C - Assemblies
• Current Stage: PPUB - Publication issued
• Completion Date: 05-Jan-2021

Standards Content (sample)

IEC TR 62271-312
Edition 1.0 2021-01
TECHNICAL
REPORT
colour
inside
High-voltage switchgear and controlgear –
Part 312: Guidance for the transferability of type tests of high-voltage/
low-voltage prefabricated substations
IEC TR 62271-312:2021-01(en)
---------------------- Page: 1 ----------------------
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---------------------- Page: 2 ----------------------
IEC TR 62271-312
Edition 1.0 2021-01
TECHNICAL
REPORT
colour
inside
High-voltage switchgear and controlgear –
Part 312: Guidance for the transferability of type tests of high-voltage/
low-voltage prefabricated substations
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 29.130.10 ISBN 978-2-8322-9228-0

Warning! Make sure that you obtained this publication from an authorized distributor.

® Registered trademark of the International Electrotechnical Commission
---------------------- Page: 3 ----------------------
– 2 – IEC TR 62271-312:2021 © IEC 2021
CONTENTS

FOREWORD ........................................................................................................................... 6

1 Scope .............................................................................................................................. 8

2 Normative references ...................................................................................................... 8

3 Terms and definitions ...................................................................................................... 9

4 Use of transferability criteria .......................................................................................... 11

4.1 General ................................................................................................................. 11

4.2 Design parameters for transferability criteria ......................................................... 12

4.3 Use of calculations ................................................................................................ 12

4.3.1 General ......................................................................................................... 12

4.3.2 Temperature rise calculations ........................................................................ 13

4.3.3 Electric field calculations ............................................................................... 13

4.3.4 Electromagnetic field calculations .................................................................. 13

4.3.5 Mechanical stress calculations....................................................................... 13

4.3.6 Short-circuit current calculations .................................................................... 13

4.3.7 Internal arc calculations ................................................................................. 14

4.4 Information needed for transferability of type test results ...................................... 14

5 Application of transferability criteria ............................................................................... 15

5.1 General ................................................................................................................. 15

5.2 Temperature rise tests .......................................................................................... 15

5.3 Dielectric tests ...................................................................................................... 16

5.4 Electromagnetic field tests .................................................................................... 17

5.5 Mechanical tests ................................................................................................... 19

5.6 Short-time withstand current and peak withstand current tests .............................. 21

5.7 Internal arc tests ................................................................................................... 22

6 Transferability of type test reports ................................................................................. 24

6.1 General ................................................................................................................. 24

6.2 Transferability of a type test report to another prefabricated substation

(situation a)) ......................................................................................................... 24

6.3 Validation of a substation design by existing type test reports (situation b)) .......... 25

6.4 Validation of a design modification (situation c)) ................................................... 26

Annex A (informative) Rationale for the transferability criteria .............................................. 27

A.1 General ................................................................................................................. 27

A.2 Temperature rise .................................................................................................. 27

A.2.1 Layout and enclosure .................................................................................... 27

A.2.2 Ventilation openings (items 2.1, 2.2, 2.3 and 2.4 of Table 2) .......................... 30

A.2.3 Distances between ventilation openings and power transformer (items 3

and 5 of Table 2) ........................................................................................... 30

A.2.4 Clearance between low-voltage-switchgear and controlgear and the

power transformer (item 4 of Table 2) ............................................................ 32

A.2.5 Power transformer insulation type (item 6 of Table 2) .................................... 32

A.2.6 Power transformer total losses (item 7 of Table 2) ......................................... 32

A.2.7 Current of the low-voltage circuit (items 8 and 9 of Table 2) .......................... 32

A.3 Dielectric .............................................................................................................. 33

A.3.1 General ......................................................................................................... 33

A.3.2 Clearances (items 2 and 3 of Table 3) ........................................................... 33

A.3.3 Insulating supports and material (items 4 and 5 of Table 3) ........................... 33

A.3.4 Live parts (items 6 and 7 of Table 3) .............................................................. 33

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IEC TR 62271-312:2021 © IEC 2021 – 3 –

A.4 Electromagnetic field ............................................................................................ 34

A.4.1 General ......................................................................................................... 34

A.4.2 Substation layout and distance from components to external surfaces of

the enclosure (items 1 and 2 of Table 4) ........................................................ 34

A.4.3 Rated voltages (item 3 of Table 4) ................................................................. 36

A.4.4 Rated normal currents (item 4 of Table 4) ...................................................... 36

A.4.5 Rated frequency (item 5 of Table 4) ............................................................... 37

A.4.6 Permeability and conductivity of the enclosure material(s) (items 6 and

12 of Table 4) ................................................................................................ 37

A.4.7 Interconnections (items 7, 8 and 9 of Table 4) ............................................... 38

A.4.8 Power transformer type of insulation (item 10 of Table 4) .............................. 39

A.4.9 Distance between main circuit phases of the low-voltage switchgear and

controlgear (item 11 of Table 4) ..................................................................... 40

A.5 Mechanical stress ................................................................................................. 40

A.5.1 General ......................................................................................................... 40

A.5.2 Common design parameters to be assessed for the key components ............. 40

A.5.3 Considerations for different enclosure materials, fasteners and

reinforcements (items 1, 2, 3 and 4 of Table 5) .............................................. 42

A.6 Short-time withstand current and peak withstand current ...................................... 43

A.6.1 General ......................................................................................................... 43

A.6.2 Rated short-time and peak currents (items 1 and 2 of Table 6) ...................... 43

A.6.3 Rated duration of short-circuit (item 3 of Table 6) .......................................... 43

A.6.4 Centre distance between phase conductors (item 4 of Table 6) ..................... 43

A.6.5 Conductors (items 5, 9 and 11 of Table 6) ..................................................... 43

A.6.6 Insulating conductor supports (items 6, 7 and 8 of Table 6) ........................... 44

A.6.7 Type of high-voltage and low-voltage terminations (item 10 of Table 6) ......... 44

A.6.8 Temperature class of insulating material in contact with conductors

(item 12 of Table 6) ....................................................................................... 44

A.7 Internal arc ........................................................................................................... 44

A.7.1 General ......................................................................................................... 44

A.7.2 Rated arc fault current, arc fault peak current and arc fault duration

(items 1 and 2 of Table 7) .............................................................................. 45

A.7.3 High-voltage switchgear family (item 3 of Table 7) ......................................... 45

A.7.4 Layout of the prefabricated substation (item 4 of Table 7) .............................. 46

A.7.5 Expansion volumes (items 5, 6 and 7 of Table 7) ........................................... 46

A.7.6 Cross-section of ventilation openings (item 8 of Table 7) ............................... 51

A.7.7 Design, position, cross-section of the cooling device(s) and gas flow

(item 9 of Table 7) ......................................................................................... 51

A.7.8 Distances between high-voltage switchgear and controlgear assembly
and the prefabricated substation enclosure (walls and roof) (item 10 of

Table 7) ......................................................................................................... 53

A.7.9 Mechanical strength of the enclosure (item 11 of Table 7) ............................. 54

A.7.10 The shortest path length of hot gases in the last compartment to the
closest ventilation opening before leaving the substation (item 12 of

Table 7) ......................................................................................................... 54

A.7.11 Type of high-voltage interconnection and electrical protection of the

circuit (items 13 and 14 of Table 7) ................................................................ 54

Annex B (informative) Collection of design parameters for the assessment of

transferability of type test results .......................................................................................... 56

B.1 General ................................................................................................................. 56

B.2 Information needed for the assessment of the temperature-rise test ..................... 56

B.3 Information needed for the assessment of the dielectric test ................................. 57

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B.4 Information needed for the assessment of the electromagnetic field test ............... 58

B.5 Information needed for the assessment of the mechanical stress test ................... 59

B.6 Information needed for the assessment of the short-circuit current test ................. 59

B.7 Information needed for the assessment of the internal arc test .............................. 60

Bibliography .......................................................................................................................... 61

Figure 1 – Transferability of one type test report ................................................................... 25

Figure 2 – Validation of a prefabricated substation by existing test reports ........................... 26

Figure A.1 – Different examples of non-walk-in type-tested prefabricated substation

and related prefabricated substation under consideration ..................................................... 28

Figure A.2 – Different examples of walk-in type-tested prefabricated substation and

related prefabricated substation under consideration ............................................................ 29

Figure A.3 – Types of ventilation opening designs ................................................................ 30

Figure A.4 – Distance from air inlet and air outlet ventilation openings .................................. 31

Figure A.5 – Difference in height between power transformer and air outlet ventilation

openings ............................................................................................................................... 31

Figure A.6 – Clearance between low-voltage-switchgear and controlgear and the

power transformer ................................................................................................................. 32

Figure A.7 – Prefabricated substation not acceptable alternative layouts .............................. 35

Figure A.8 – Distances from main components to external surfaces of the enclosure ............ 36

Figure A.9 – Frequency influence on magnetic field .............................................................. 37

Figure A.10 – Magnetic field behaviour under shielded technologies ..................................... 37

Figure A.11 – Example of magnetic field for different distributions of phase currents in

a three-phase interconnection having the same geometry and number of cables per

phase ................................................................................................................................... 39

Figure A.12 – Examples of different door designs ................................................................. 41

Figure A.13 – Examples of different roof designs .................................................................. 41

Figure A.14 – Different size of prefabricated substations with same layout ........................... 46

Figure A.15 – Gas flow in a non-walk-in type and walk-in type prefabricated

substations with separate high-voltage switchgear compartment ........................................... 48

Figure A.16 – Gas flow in a non-walk-in type and walk-in type prefabricated

substations without separate high-voltage switchgear compartment ...................................... 48

Figure A.17 – Gas flow in a walk-in type prefabricated substation with high-voltage

switchgear compartment without gas flow cooling device ...................................................... 49

Figure A.18 – Gas flow in a walk-in type prefabricated substation with high-voltage

switchgear compartment and high-voltage switchgear and controlgear with integrated

gas flow cooling device ......................................................................................................... 49

Figure A.19 – Gas flow in a walk-in type prefabricated substation and high-voltage

switchgear and controlgear with integrated gas flow cooling device without separate

high-voltage switchgear compartment ................................................................................... 50

Figure A.20 – Transferability according to volume-criteria items 5, 6 and 7 of Table 7 .......... 51

Figure A.21 – Layers with different transmittance for a multi-layer gas flow cooling

device ................................................................................................................................... 52

Figure A.22 – Top view of a prefabricated substation design with different gas flow

cooling device arrangements ................................................................................................ 53

Figure A.23 – Top view of one basic substation design with different positions of high-

voltage switchgear and controlgear within the high-voltage switchgear compartment ............ 53

Figure A.24 – Prefabricated substations with different length of hot gases flow path

with regard to ventilation openings ........................................................................................ 54

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IEC TR 62271-312:2021 © IEC 2021 – 5 –

Table 1 – Examples of design parameters............................................................................. 12

Table 2 – Transferability criteria for temperature rise performance ........................................ 15

Table 3 – Transferability criteria for dielectric withstand performance ................................... 17

Table 4 – Transferability criteria for electromagnetic field performance ................................. 18

Table 5 – Transferability criteria for the mechanical strength of the enclosure ....................... 19

Table 6 – Transferability criteria for short-time and peak withstand current performance ....... 21

Table 7 – Transferability criteria for internal arc fault withstand performance ........................ 23

Table A.1 – Material thermal conductivity .............................................................................. 29

Table B.1 – Information needed for the assessment of temperature-rise test ........................ 56

Table B.2 – Information needed for the assessment of dielectric test .................................... 58

Table B.3 – Information needed for the assessment of electromagnetic field test .................. 58

Table B.4 – Information needed for the assessment of mechanical test................................. 59

Table B.5 – Information needed for the assessment of short-circuit current test .................... 60

Table B.6 – Information needed for the assessment of internal arc test ................................. 60

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INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
HIGH-VOLTAGE SWITCHGEAR AND CONTROLGEAR –
Part 312: Guidance for the transferability of type tests
of high-voltage/low-voltage prefabricated substations
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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8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is

indispensable for the correct application of this publication.

9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of patent

rights. IEC shall not be held responsible for identifying any or all such patent rights.

The main task of IEC technical committees is to prepare International Standards. However, a

technical committee may propose the publication of a Technical Report when it has collected

data of a different kind from that which is normally published as an International Standard, for

example "state of the art".

IEC TR 62271-312, which is a Technical Report, has been prepared by subcommittee 17C:

Assemblies, of IEC technical committee 17: High-voltage switchgear and controlgear.

The text of this Technical Report is based on the following documents:
Draft TR Report on voting
17C/737/DTR 17C/753B/RVDTR

Full information on the voting for the approval of this Technical Report can be found in the

report on voting indicated in the above table.
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IEC TR 62271-312:2021 © IEC 2021 – 7 –

This document has been drafted in accordance with the ISO/IEC Directives, Part 2.

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 "http://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.

IMPORTANT – The 'colour inside' logo on the cover page of this publication 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.

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– 8 – IEC TR 62271-312:2021 © IEC 2021
HIGH-VOLTAGE SWITCHGEAR AND CONTROLGEAR –
Part 312: Guidance for the transferability of type tests
of high-voltage/low-voltage prefabricated substations
1 Scope

This document refers to high-voltage / low-voltage prefabricated substations (hereinafter

prefabricated substations) as specified in IEC 62271-202:2014.

This document, among other options as agreed between manufacturer and user, can be used

for the transferability of type tests performed on one or more prefabricated substations with a

defined set of ratings and arrangement of components to another prefabricated substation with

a different set of ratings or different arrangement of components. It supports the selection of

appropriate representative test objects for that purpose in order to optimize the type testing

procedure for a consistent conformity assessment.

This document utilises a combination of sound technical and physical principles, manufacturer

and user experience and mutually agreed upon methods of calculation to establish pragmatic

guidance for the transferability of type test results, covering various design and rating aspects.

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 60050-441:1984, International Electrotechnical Vocabulary (IEV) – Part 441: Switchgear,

controlgear and fuses
IEC 60050-441:1984/AMD1:2000
IEC 60076-1:2011, Power transformers – Part 1: General

IEC 60076-2, Power transformers – Part 2: Temperature rise for liquid-immersed transformers

IEC 60076-7, Power transformers – Part 7: Loading guide for mineral-oil-immersed power

transformers
IEC 60076-11, Power transformers – Part 11: Dry-type transformers

IEC 60076-12, Power transformers – Part 12: Loading guide for dry-type power transformers

IEC 60282-1:2020, High-voltage fuses – Part 1: Current-limiting fuses

IEC 61439-1:2020, Low-voltage switchgear and controlgear assemblies – Part 1: General rules

IEC 62271-1:2017, High-voltage switchgear and controlgear – Part 1: Common specifications

for alternating current switchgear and controlgear

IEC 62271-200:2011, High-voltage switchgear and controlgear – Part 200: AC metal-enclosed

switchgear and controlgear for rated voltages above 1 kV and up to and including 52 kV

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IEC TR 62271-312:2021 © IEC 2021 – 9 –

IEC 62271-202:2014, High-voltage switchgear and controlgear – Part 202: High-voltage/low-

voltage prefabricated substation

IEC TR 62271-208:2009, High-voltage switchgear and controlgear – Part 208: Methods to

quantify the steady state, power-frequency electromagnetic fields generated by HV switchgear

assemblies and HV/LV prefabricated substations
3 Terms and definitions

For the purposes of this document, the terms and definitions given in IEC 60050-441,

IEC 62271-202 and the following apply.

NOTE Some standard terms and definitions are recalled here for ease of reference.

ISO and IEC maintain terminological databases for use in standardization at the following

addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
3.1
prefabricated substation

prefabricated and type-tested assembly comprising an enclosure containing in general power

transformers, high-voltage and low-voltage switchgear and controlgear, high-voltage and low-

...