IEC TR 62271-312:2021

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

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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

– 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

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

– 4 – IEC TR 62271-312:2021 © IEC 2021
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 .
...