IEC 60947-8:2021

Low-voltage switchgear and controlgear - Part 8: Control units for built-in thermal protection (PTC) for rotating electrical machines

IEC 60947-8:2021

Name:IEC 60947-8:2021   Standard name:Low-voltage switchgear and controlgear - Part 8: Control units for built-in thermal protection (PTC) for rotating electrical machines
Standard number:IEC 60947-8:2021   language:English and French language
Release Date:27-Jul-2021   technical committee:SC 121A - Low-voltage switchgear and controlgear
Drafting committee:   ICS number:29.130.20 - Low voltage switchgear and controlgear

IEC 60947-8
Edition 2.0 2021-07
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Low-voltage switchgear and controlgear –
Part 8: Control units for built-in thermal protection (PTC) for rotating electrical
machines
Appareillage à basse tension –
Partie 8: Unités de commande pour la protection thermique incorporée (CTP)
aux machines électriques tournantes





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IEC 60947-8
Edition 2.0 2021-07
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Low-voltage switchgear and controlgear –

Part 8: Control units for built-in thermal protection (PTC) for rotating electrical

machines
Appareillage à basse tension –

Partie 8: Unités de commande pour la protection thermique incorporée (CTP)

aux machines électriques tournantes

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 29.130.20 ISBN 978-2-8322-1009-4

– 2 – IEC 60947-8:2021 © IEC 2021
CONTENTS
FOREWORD . 5
INTRODUCTION . 7
1 Scope . 8
2 Normative references . 8
3 Terms and definitions, symbols and abbreviated terms . 9
3.1 Terms and definitions . 9
3.2 Symbols and abbreviated terms . 11
4 Void . 11
5 Characteristics of control units for built-in thermal protection (PTC) . 11
5.1 Summary of characteristics . 11
5.2 Type of equipment . 11
5.2.1 Operating temperatures of protection systems . 11
5.2.2 Rated PTC thermistor operating temperature . 11
5.2.3 Rated system operating temperature . 12
5.2.4 Maximum permissible rated operating temperature for the system . 12
5.2.5 Control unit with reset temperature . 12
5.2.6 Control unit with sensor short-circuit detection . 12
5.2.7 Control unit with sensor wire break detection . 12
5.3 Rated electrical values of the switching device of the control unit . 13
5.3.1 Rated electrical values of switching devices . 13
5.3.2 Rated voltages of a control unit . 13
5.3.3 Rated currents of a control unit . 13
5.3.4 Rated making and breaking capacities of a control unit . 13
5.4 Rated electrical values of characteristic variation related to PTC thermistors . 13
5.4.1 General . 13
5.4.2 Electrical data/ratings and characteristics related to the PTC thermistor . 13
5.4.3 Rated voltage of the PTC thermistor circuit of the control unit . 14
5.5 Control supply circuit . 14
5.6 Auxiliary circuits . 14
6 Product information . 14
6.1 Nature of information . 14
6.2 Marking . 15
6.3 Instructions for installation, operation and maintenance, decommissioning
and dismantling. 15
6.4 Environmental information . 15
7 Normal service, mounting and transport conditions . 15
8 Constructional and performance requirements . 16
8.1 Constructional requirements . 16
8.1.1 General . 16
8.1.2 Materials . 17
8.1.3 Current-carrying parts and their connections . 17
8.1.4 Clearances and creepage distances . 17
8.1.5 Vacant . 17
8.1.6 Vacant . 17
8.1.7 Vacant . 17
8.1.8 Terminals . 17

8.1.9 Vacant . 18
8.1.10 Provisions for protective earthing . 18
8.1.11 Dedicated enclosures for equipment . 18
8.1.12 Degrees of protection of enclosed equipment . 18
8.1.13 Conduit pull-out, torque and bending with metallic conduits . 18
8.1.14 Limited energy source . 18
8.1.15 Stored charge energy circuit . 20
8.1.16 Fault and abnormal conditions . 20
8.1.17 Short-circuit and overload protection of ports . 21
8.2 Performance requirements . 21
8.2.1 Operating conditions . 21
8.2.2 Abnormal conditions of service . 22
8.2.3 Dielectric properties . 22
8.2.4 Temperature rise . 22
8.2.5 Conditional short-circuit current . 22
8.2.6 Making and breaking capacities for control and auxiliary circuits . 22
8.2.7 Additional requirements and tests for equipment with protective

separation . 22
8.2.8 Operating temperature variation . 22
8.2.9 Damp heat . 22
8.2.10 Shock and vibration . 22
8.2.11 Requirements for short-circuit detection within the PTC thermistor
circuit . 23
8.2.12 Requirements for wire break detection within the PTC thermistor circuit . 23
8.3 Electromagnetic compatibility (EMC) . 23
8.3.1 General . 23
8.3.2 Immunity . 23
8.3.3 Emission . 24
9 Tests . 24
9.1 Kinds of tests .
...

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