Power installations exceeding 1 kV AC and 1,5 kV DC - Part 1: AC

IEC 61936-1:2021 provides requirements for the design and the erection of electrical power installations in systems with nominal voltages exceeding 1 kV AC and nominal frequency up to and including 60 Hz, so as to provide safety and proper functioning for the use intended.
This document does not apply to the design and erection of any of the following:
– overhead and underground lines between separate electrical power installations;
– electrified railway tracks and rolling stock;
– mining equipment and installations;
– fluorescent lamp installations;
– installations on ships according to IEC 60092 (all parts) and offshore units according to IEC 61892 (all parts), which are used in the offshore petroleum industry for drilling, processing and storage purposes;
– electrostatic equipment (e.g. electrostatic precipitators, spray-painting units);
– test sites;
– medical equipment, e.g. medical X-ray equipment.
This document does not apply to the design of prefabricated, type-tested switchgear and high voltage/low voltage prefabricated substation, for which separate IEC standards exist.
This edition includes the following significant technical changes with respect to the previous edition:  
introduction has been rewritten to reflect the status when this document is produced;
the scope has been improved to clarify the application of this document;
missing and obsolete terms and definitions have been updated including improvement of existing terms;
Table 1 has been updated where agreements between supplier and user are needed;
requirements of electromagnetic compatibility have been clarified;
insulation coordination clause (Clause 5) has improved wording for better clarity and the technical content has an updated coordination to the latest versions of the insulation coordination standards;
wording regarding electrical equipment has been improved and made clearer;
subclause for fuses has been improved and reworded;
requirements have been added for labelling when multiple sources are required to be disconnected;
missing requirements for GIS have been reintroduced;
subclause regarding ventilation (HVAC) has been improved;
figures in Clause 7 have been updated and moved to the corresponding subclause;
requirements for transformer installations have been improved including adjustment of editorial typing-errors;
clause on protection, automation and auxiliary systems has been restructured and improved;
protection against lightning strokes has been extended;
clarification of content due to the distinction between erection (and providing electrical safety for the intended use of the electrical power installation) and subsequent activities such as maintenance and repair with safe working procedures;
where no provincial, national or regional regulations are available for safe working procedures, an informative guideline is provided in Annex F. This replaces the former parts of Figure 3 in Clause 7.

Installations électriques de puissance de tension supérieure à 1 kV en courant alternatif et 1,5 kV en courant continu - Partie 1: Courant alternatif

L’IEC 61936-1:2021 fournit des exigences relatives à la conception et au montage des installations électriques dans des systèmes dont les tensions nominales sont supérieures à 1 kV en courant alternatif et la fréquence nominale inférieure ou égale à 60 Hz, afin d'assurer la sécurité et le fonctionnement correct pour l'utilisation prévue.
L'installation électrique comprend notamment les matériels suivants:
machines électriques tournantes;
appareillage;
transformateurs et réactances;
convertisseurs;
câbles;
canalisations électriques;
batteries;
condensateurs;
installations de mise à la terre;
bâtiments et clôtures qui font partie d'une installation électrique fermée;
systèmes associés de protection, de commande et auxiliaires;
réactance élevée à noyau d’air.  Le présent document ne s'applique pas à la conception des appareillages préfabriqués soumis à un essai de type et des postes préfabriqués à haute tension/basse tension, pour lesquels des normes IEC spécifiques existent.
Cette édition inclut les modifications techniques majeures suivantes par rapport à l'édition précédente:  
l’introduction a été remaniée pour refléter la réalité au moment de la rédaction du présent document;
le domaine d’application a été amélioré pour clarifier l’application du présent document;
les termes et définitions manquants et obsolètes ont été mis à jour, et les termes existants ont été améliorés;
le Tableau 1 a été mis à jour pour tenir compte des situations qui nécessitent des accords entre le fournisseur et l’utilisateur;
les exigences en matière de compatibilité électromagnétique ont été clarifiées;
la formulation de l’Article 5) relatif à la coordination de l’isolement a été améliorée et la coordination de son contenu technique avec les dernières versions des normes de coordination de l’isolement a été mise à jour;
la formulation concernant les matériels électriques a été améliorée et clarifiée;
le paragraphe relatif aux fusibles a été amélioré et reformulé;
des exigences en matière d’étiquetage ont été introduites lorsque des sources multiples doivent être déconnectées;
les exigences manquantes pour les postes sous enveloppe métallique (PSEM) ont été réintroduites;
amélioration du paragraphe relatif à la ventilation (CVC, chauffage, ventilation et climatisation);
mise à jour des chiffres dans l'Article 7 et leur déplacement vers le paragraphe correspondant;
les exigences relatives aux installations de transformateurs ont été améliorées, et les fautes de frappe ont été corrigées;
restructuration et amélioration de l’article relatif aux systèmes de protection, d’automatisation et auxiliaires;
la protection contre les coups de foudre a été étendue;
clarification du contenu en raison de la distinction entre les activités de montage (et l’assurance de la sécurité électrique pour l’utilisation prévue de l’installation électrique) et les activités consécutives (par exemple, la maintenance et la réparation) avec des procédures de travail sûres;
présence d’une ligne directrice informative dans l’Annexe F en l’absence de réglementation locale, nationale ou régionale sur les procédures de travail sûres. Cette modification se substitue aux anciennes parties de la Figure 3 à l'Article 7.

General Information

Status
Published
Publication Date
06-Jul-2021
Current Stage
PPUB - Publication issued
Completion Date
07-Jul-2021
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IEC 61936-1
Edition 3.0 2021-07
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Power installations exceeding 1 kV AC and 1,5 kV DC –
Part 1: AC
Installations électriques de puissance de tension supérieure à 1 kV en courant
alternatif et 1,5 kV en courant continu –
Partie 1: Courant alternatif
IEC 61936-1:2021-07(en-fr)
---------------------- Page: 1 ----------------------
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---------------------- Page: 2 ----------------------
IEC 61936-1
Edition 3.0 2021-07
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Power installations exceeding 1 kV AC and 1,5 kV DC –
Part 1: AC
Installations électriques de puissance de tension supérieure à 1 kV en courant
alternatif et 1,5 kV en courant continu –
Partie 1: Courant alternatif
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 29.020; 29.080.01 ISBN 978-2-8322-9887-9

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

Attention! Veuillez vous assurer que vous avez obtenu cette publication via un distributeur agréé.

® Registered trademark of the International Electrotechnical Commission
Marque déposée de la Commission Electrotechnique Internationale
---------------------- Page: 3 ----------------------
– 2 – IEC 61936-1:2021 © IEC 2021
CONTENTS

FOREWORD ........................................................................................................................... 8

INTRODUCTION ................................................................................................................... 11

1 Scope ............................................................................................................................ 12

2 Normative references .................................................................................................... 13

3 Terms and definitions .................................................................................................... 15

3.1 General definitions ................................................................................................ 15

3.2 Definitions concerning electrical power installations .............................................. 17

3.3 Definitions concerning types of electrical power installations................................. 18

3.4 Definitions concerning safety measures against electric shock .............................. 18

3.5 Definitions concerning clearances ......................................................................... 19

3.6 Definitions concerning control and protection ........................................................ 21

3.7 Definitions concerning earthing ............................................................................. 21

4 Fundamental requirements ............................................................................................ 25

4.1 General ................................................................................................................. 25

4.1.1 General requirements .................................................................................... 25

4.1.2 Agreements between supplier and user ......................................................... 26

4.2 Electrical requirements ......................................................................................... 28

4.2.1 Methods of neutral earthing ........................................................................... 28

4.2.2 Voltage classification ..................................................................................... 28

4.2.3 Current in normal operation ........................................................................... 28

4.2.4 Short-circuit current ....................................................................................... 28

4.2.5 Rated frequency ............................................................................................ 29

4.2.6 Corona .......................................................................................................... 29

4.2.7 Electric and magnetic fields ........................................................................... 29

4.2.8 Overvoltages ................................................................................................. 30

4.2.9 Harmonics ..................................................................................................... 30

4.2.10 Electromagnetic compatibility ........................................................................ 30

4.3 Mechanical requirements ...................................................................................... 30

4.3.1 General ......................................................................................................... 30

4.3.2 Tension load .................................................................................................. 31

4.3.3 Erection load ................................................................................................. 31

4.3.4 Ice load ......................................................................................................... 31

4.3.5 Wind load ...................................................................................................... 31

4.3.6 Switching forces ............................................................................................ 31

4.3.7 Short-circuit forces ........................................................................................ 31

4.3.8 Loss of conductor tension .............................................................................. 31

4.3.9 Seismic loads ................................................................................................ 31

4.3.10 Dimensioning of structures ............................................................................ 32

4.4 Climatic and environmental conditions .................................................................. 32

4.4.1 General ......................................................................................................... 32

4.4.2 Normal conditions .......................................................................................... 32

4.4.3 Special conditions ......................................................................................... 34

4.5 Particular requirements ......................................................................................... 35

4.5.1 Effects of small animals and micro-organisms................................................ 35

4.5.2 Noise level ..................................................................................................... 35

4.5.3 Transport ....................................................................................................... 35

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IEC 61936-1:2021 © IEC 2021 – 3 –

5 Insulation ....................................................................................................................... 35

5.1 General ................................................................................................................. 35

5.2 Selection of insulation level................................................................................... 36

5.2.1 General ......................................................................................................... 36

5.2.2 Consideration of methods of neutral earthing ................................................. 36

5.2.3 Consideration of rated withstand voltages ...................................................... 36

5.3 Verification of withstand values ............................................................................. 36

5.4 Minimum clearances of live parts .......................................................................... 37

5.4.1 General ......................................................................................................... 37

5.4.2 Minimum clearances in voltage range I .......................................................... 37

5.4.3 Minimum clearances in voltage range II ......................................................... 37

5.5 Minimum clearances between parts under special conditions ................................ 40

5.6 Tested connection zones ...................................................................................... 40

6 Electrical equipment ...................................................................................................... 40

6.1 General requirements ........................................................................................... 40

6.1.1 Electrical equipment safety ............................................................................ 40

6.1.2 User safety .................................................................................................... 40

6.2 Specific requirements ........................................................................................... 41

6.2.1 Switching devices .......................................................................................... 41

6.2.2 Power transformers and reactors ................................................................... 41

6.2.3 Prefabricated type-tested switchgear ............................................................. 42

6.2.4 Instrument transformers ................................................................................. 42

6.2.5 Surge arresters .............................................................................................. 43

6.2.6 Capacitors ..................................................................................................... 43

6.2.7 Line traps ...................................................................................................... 44

6.2.8 Insulators ...................................................................................................... 44

6.2.9 Insulated cables ............................................................................................ 44

6.2.10 Conductors and accessories .......................................................................... 47

6.2.11 Rotating electrical machines .......................................................................... 47

6.2.12 Generating units ............................................................................................ 48

6.2.13 Generating unit main connections .................................................................. 48

6.2.14 Static converters ............................................................................................ 48

6.2.15 Fuses ............................................................................................................ 49

6.2.16 Electrical and mechanical interlocking ........................................................... 49

7 Electrical power installations ......................................................................................... 49

7.1 General ................................................................................................................. 49

7.1.1 Common requirements ................................................................................... 49

7.1.2 Circuit arrangement ....................................................................................... 50

7.1.3 Documentation .............................................................................................. 51

7.1.4 Transport routes ............................................................................................ 51

7.1.5 Aisles and access areas ................................................................................ 52

7.1.6 Lighting ......................................................................................................... 53

7.1.7 Operational safety ......................................................................................... 53

7.1.8 Labelling ........................................................................................................ 53

7.2 Outdoor electrical power installations of open design ............................................ 53

7.2.1 General ......................................................................................................... 53

7.2.2 Protective barrier clearances ......................................................................... 54

7.2.3 Protective obstacle clearances ...................................................................... 54

7.2.4 Boundary clearances ..................................................................................... 55

---------------------- Page: 5 ----------------------
– 4 – IEC 61936-1:2021 © IEC 2021

7.2.5 Minimum height over access area .................................................................. 56

7.2.6 Clearances to buildings ................................................................................. 57

7.2.7 External fences or walls and access doors .................................................... 59

7.3 Indoor electrical power installations of open design .............................................. 59

7.4 Installation of prefabricated type-tested switchgear ............................................... 60

7.4.1 General ......................................................................................................... 60

7.4.2 Additional requirements for gas-insulated metal-enclosed switchgear ............ 60

7.5 Requirements for buildings ................................................................................... 62

7.5.1 General ......................................................................................................... 62

7.5.2 Structural provisions ...................................................................................... 62

7.5.3 Rooms for switchgear .................................................................................... 63

7.5.4 Maintenance and operating areas .................................................................. 63

7.5.5 Doors ............................................................................................................ 63

7.5.6 Draining of insulating liquids .......................................................................... 64

7.5.7 Heating, ventilation and air conditioning (HVAC) ............................................ 64

7.5.8 Buildings which require special consideration ................................................ 65

7.6 High voltage/low voltage prefabricated substations ............................................... 65

7.7 Electrical power installations on mast, pole and tower ........................................... 65

8 Safety measures ............................................................................................................ 65

8.1 General ................................................................................................................. 65

8.2 Protection against direct contact ........................................................................... 66

8.2.1 General ......................................................................................................... 66

8.2.2 Measures for protection against direct contact ............................................... 66

8.2.3 Protection requirements ................................................................................. 67

8.3 Means to protect persons in case of indirect contact ............................................. 68

8.4 Means to protect persons working on or near electrical power installations ........... 68

8.4.1 General ......................................................................................................... 68

8.4.2 Electrical equipment for isolating installations or apparatus ........................... 68

8.4.3 Devices to prevent reclosing of isolating devices ........................................... 69

8.4.4 Devices for determining the de-energized state ............................................. 69

8.4.5 Devices for earthing and short-circuiting ........................................................ 69

8.4.6 Equipment acting as protective barriers against adjacent live parts ............... 70

8.4.7 Storage of personal protection equipment ...................................................... 71

8.5 Protection from danger resulting from arc fault ...................................................... 71

8.6 Protection against direct lightning strokes ............................................................. 71

8.7 Protection against fire ........................................................................................... 72

8.7.1 General ......................................................................................................... 72

8.7.2 Transformers, reactors .................................................................................. 73

8.7.3 Cables ........................................................................................................... 79

8.7.4 Other equipment with flammable liquid .......................................................... 79

8.8 Protection against leakage of insulating liquid and SF ......................................... 80

8.8.1 Insulating liquid leakage and subsoil water protection .................................... 80

8.8.2 SF leakage .................................................................................................. 82

8.8.3 Failure with loss of SF and its decomposition products ................................ 83

8.9 Identification and marking ..................................................................................... 83

8.9.1 General ......................................................................................................... 83

8.9.2 Information plates and warning plates ............................................................ 84

8.9.3 Electrical hazard warning ............................................................................... 84

---------------------- Page: 6 ----------------------
IEC 61936-1:2021 © IEC 2021 – 5 –

8.9.4 Electrical power installations with incorporated capacitors ............................. 84

8.9.5 Emergency signs for emergency exits ............................................................ 84

8.9.6 Cable identification marks .............................................................................. 84

9 Protection, automation and auxiliary systems ................................................................ 84

9.1 Protection systems................................................................................................ 84

9.2 Automation systems .............................................................................................. 85

9.3 Auxiliary systems .................................................................................................. 86

9.3.1 AC and DC supply circuits ............................................................................. 86

9.3.2 Compressed air systems ................................................................................ 87

9.3.3 SF gas handling plants ................................................................................ 88

9.3.4 Hydrogen handling plants .............................................................................. 88

9.4 Basic rules for electromagnetic compatibility of control systems ............................ 88

9.4.1 General ......................................................................................................... 88

9.4.2 Electrical noise sources in electrical power installations ................................ 89

9.4.3 Measures to be taken to reduce the effects of high frequency

interference ................................................................................................... 89

9.4.4 Measures to be taken to reduce the effects of low frequency

interference ................................................................................................... 89

9.4.5 Measures related to the selection of electrical equipment .............................. 90

9.4.6 Other possible measures to reduce the effects of interference ....................... 91

10 Earthing systems ........................................................................................................... 91

10.1 General ................................................................................................................. 91

10.2 Fundamental requirements .................................................................................... 91

10.2.1 Safety criteria ................................................................................................ 91

10.2.2 Functional requirements ................................................................................ 92

10.2.3 High and low voltage earthing systems .......................................................... 92

10.3 Design of earthing systems ................................................................................... 93

10.3.1 General ......................................................................................................... 93

10.3.2 Power system faults....................................................................................... 94

10.3.3 Lightning and transient overvoltages.............................................................. 94

10.4 Construction work on earthing systems ................................................................. 95

10.5 Measurements ...................................................................................................... 95

10.6 Maintainability ....................................................................................................... 95

10.6.1 Inspections .................................................................................................... 95

10.6.2 Measurements ............................................................................................... 95

11 Inspection and testing .................................................................................................... 96

11.1 General ................................................................................................................. 96

11.2 Verification of specified performances ................................................................... 96

11.3 Tests during installation and commissioning ......................................................... 97

11.4 Trial running ......................................................................................................... 97

12 Operation and maintenance manual .............................................................................. 97

Annex A (informative) Values of rated insulation levels and minimum clearances

based on current practice in some countries ......................................................................... 98

Annex B (normative) Method of calculating permissible touch voltages .............................. 101

Annex C (normative) Permissible touch voltage according to IEEE 80 ................................ 102

Annex D (normative) Earthing system design flow chart ..................................................... 103

---------------------- Page: 7 ----------------------
– 6 – IEC 61936-1:2021 © IEC 2021

Annex E (informative) Protection measures against direct lightning strokes ....................... 104

E.1 General ............................................................................................................... 104

E.2 Shield wires ........................................................................................................ 104

E.3 Lightning rods ..................................................................................................... 104

Annex F (informative) Considerations of design for safe working ....................................... 107

Annex G (informative) List of notes concerning particular conditions in certain

countries ............................................................................................................................. 109

Bibliography ........................................................................................................................ 115

Figure 1 – Minimum approach distance for transport within closed electrical operating

areas .................................................................................................................................... 52

Figure 2 – Protection against direct contact by protective barriers or protective

obstacles within closed electrical operating areas ................................................................. 55

Figure 3 – Boundary distances and minimum height at the external fence/wall ...................... 56

Figure 4 – Minimum heights within closed electrical operating areas ..................................... 57

Figure 5 – Approaches with buildings within closed electrical operating areas ...................... 5

...

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