IEC 60947-5-1:2024

IEC 60947-5-1 ®
Edition 5.0 2024-03
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Low- voltage switchgear and controlgear –
Part 5-1: Control circuit devices and switching elements – Electromechanical
control circuit devices
Appareillage à basse tension –
Partie 5-1: Appareils et éléments de commutation pour circuits de commande –
Appareils électromécaniques pour circuits de commande
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IEC 60947-5-1 ®
Edition 5.0 2024-03
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Low- voltage switchgear and controlgear –

Part 5-1: Control circuit devices and switching elements – Electromechanical

control circuit devices
Appareillage à basse tension –

Partie 5-1: Appareils et éléments de commutation pour circuits de commande –

Appareils électromécaniques pour circuits de commande

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 29.120.40, 29.130.20 ISBN 978-2-8322-8326-4

– 2 – IEC 60947-5-1:2024 © IEC 2024
CONTENTS
FOREWORD . 9
1 Scope . 11
2 Normative references . 12
3 Terms, definitions, symbols and abbreviated terms . 14
3.1 Terms and definitions . 14
3.1.1 General . 14
3.1.2 Basic terms and definitions . 14
3.1.3 Terms and definitions concerning automatic control switches . 16
3.1.4 Terms and definitions concerning manually operated control switches . 16
3.1.5 Terms and definitions concerning parts of control switches . 18
3.1.6 Terms and definitions concerning operation of contactor relays . 21
3.1.7 Terms and definitions concerning operation of pilot switches . 21
3.1.8 Terms and definitions concerning operation of rotary switches. 22
3.1.9 Terms and definitions concerning operation of mechanically operated
control switches . 22
3.1.10 Terms and definitions concerning reed contact magnetic switches . 25
3.1.11 Terms and definitions concerning Class II control circuit devices . 26
3.1.12 Terms and definitions concerning control circuit devices with integrally
connected cables . 26
3.1.13 Terms and definitions concerning semiconductor switching elements . 27
3.1.14 Terms and definitions concerning indicator lights, indicating towers and
audible signalling devices . 27
3.1.15 Terms and definitions concerning control switches with direct opening
action . 28
3.1.16 Terms and definitions concerning digital communication interface . 28
3.1.17 Alphabetical index of definitions. 29
3.2 Symbols and abbreviated terms . 33
4 Classification . 33
4.1 Contact elements . 33
4.2 Control switches . 35
4.3 Control circuit devices . 35
4.4 Time delay switching elements. 35
4.5 Control switch mounting . 35
5 Characteristics . 35
5.1 Summary of characteristics . 35
5.1.1 General . 35
5.1.2 Operation of a control switch . 35
5.2 Type of control circuit device or switching element . 36
5.2.1 Kind of control circuit device . 36
5.2.2 Kind of switching elements . 36
5.2.3 Number of poles . 36
5.2.4 Kind of current . 36
5.2.5 Interrupting medium . 36
5.2.6 Operating conditions . 37
5.3 Rated and limiting values for switching elements . 37
5.3.1 General . 37
5.3.2 Rated voltages (of a switching element). 37

5.3.3 Currents . 37
5.3.4 Rated frequency . 38
5.3.5 Vacant . 38
5.3.6 Characteristics under normal and abnormal load conditions . 38
5.3.7 Short-circuit characteristics – Rated conditional short-circuit current . 40
5.4 Utilization categories for switching elements . 40
5.5 Control circuits . 40
5.6 Vacant . 41
5.7 Vacant . 41
5.8 Vacant . 41
5.9 Vacant . 41
5.10 Electrically separated contact elements . 41
5.11 Actuating quantities for pilot switches . 41
5.12 Pilot switches having two or more contact elements . 41
6 Product information . 41
6.1 Nature of information . 41
6.2 Marking . 43
6.2.1 General . 43
6.2.2 Terminal identification and marking . 43
6.2.3 Functional markings. 43
6.2.4 Emergency stop . 43
6.2.5 Operating diagram . 43
6.2.6 Time delay markings . 44
6.3 Instructions for installation, operation and maintenance, decommissioning
and dismantling. 45
6.4 Environmental information . 45
6.4.1 Environmentally conscious design process (ECD process) . 45
6.4.2 Procedure to establish material declaration . 45
6.5 Additional information . 45
7 Normal service, mounting and transport conditions . 46
7.1 Normal service conditions . 46
7.1.1 Ambient air temperature . 46
7.1.2 Altitude . 46
7.1.3 Atmospheric conditions . 46
7.1.4 Shock and vibration . 46
7.2 Conditions during transport and storage . 46
7.3 Mounting . 46
7.3.1 General . 46
7.3.2 Mounting of single hole mounted devices . 46
8 Constructional and performance requirements . 48
8.1 Constructional requirements . 48
8.1.1 General . 48
8.1.2 Materials . 48
8.1.3 Current-carrying parts and their connections . 49
8.1.4 Clearances and creepage distances . 49
8.1.5 Actuator . 49
8.1.6 Indication of the contact position . 50
8.1.7 Conditions for control switches suitable for isolation . 50
8.1.8 Terminals . 50

– 4 – IEC 60947-5-1:2024 © IEC 2024
8.1.9 Vacant . 50
8.1.10 Provisions for protective earthing . 50
8.1.11 Enclosures for equipment . 50
8.1.12 Degrees of protection of enclosed equipment . 50
8.1.13 Conduit pull-out, torque and bending with metallic conduits . 50
8.1.14 Requirements for control circuit devices with artificial optical radiation . 50
8.1.15 Biological and chemical effects . 51
8.1.16 Hygienic design . 51
8.1.17 Security aspects . 51
8.1.18 Limited energy source . 51
8.1.19 Fault and abnormal conditions . 53
8.1.20 Stored charge energy circuit . 54
8.1.21 Embedded software . 54
8.2 Performance requirements . 54
8.2.1 Operating conditions . 54
8.2.2 Temperature-rise . 54
8.2.3 Dielectric properties . 54
8.2.4 Ability to make and break under normal and abnormal load conditions. 54
8.2.5 Conditional short-circuit current . 55
8.2.6 Vacant . 55
8.2.7 Additional requirements for control switches suitable for isolation . 55
8.3 Electromagnetic compatibility (EMC) . 55
8.3.1 General . 55
8.3.2 Immunity . 56
8.3.3 Emission . 56
8.4 Special requirements . 56
8.4.1 Additional requirements for reed contact magnetic switches . 56
8.4.2 Class II control circuit devices . 57
8.4.3 Additional requirements for control circuit devices with integrally

connected cables . 57
8.4.4 Additional requirements for semiconductor switching elements for
control circuit devices . 57
8.4.5 Special requirements for indicator lights, indicating towers and their
optional audible functions . 57
8.4.6 Special requirements for control switches with direct opening action . 57
8.4.7 Special requirements for mechanically linked contact elements . 57
8.4.8 Additional requirements for control circuit devices incorporating a built-
in communication interface (SDCI) . 57
9 Tests . 57
9.1 Kinds of test . 57
9.1.1 General . 57
9.1.2 Type tests . 57
9.1.3 Routine tests . 58
9.1.4 Sampling tests . 58
9.1.5 Special tests . 58
9.2 Compliance with constructional requirements . 59
9.2.1 General . 59
9.2.2 Test of materials to abnormal heat and fire . 59
9.2.3 Equipment . 59
9.2.4 Degrees of protection . 59

9.2.5 Mechanical and electrical properties of terminals . 60
9.2.6 Verification of actuating force (or torque) . 62
9.2.7 Verification of limitation of rotation (of a rotary switch) . 62
9.2.8 Conduit pull-out test, torque test and bending test with metallic conduits . 62
9.2.9 Test of earth continuity for protective earth . 62
9.2.10 Limited energy source test . 62
9.2.11 Breakdown of components . 63
9.2.12 Artificial optical radiation test . 63
9.2.13 Stored charge energy test . 64
9.3 Performance . 64
9.3.1 Test sequences . 64
9.3.2 General test conditions . 65
9.3.3 Performance under no-load, normal load and abnormal load conditions . 66
9.3.4 Performance under conditional short-circuit current . 70
9.4 Tests for EMC . 72
9.4.1 General . 72
9.4.2 Immunity . 72
9.4.3 Emission . 74
9.4.4 Test results and test report . 75
Annex A (normative) Electrical ratings based on utilization categories (see 4.1) . 76
Annex B (informative) Example of inductive test loads for DC contacts . 78
B.1 General . 78
B.2 Construction . 78
Annex C (normative) Special tests – Durability tests . 80
C.1 General . 80
C.1.1 Durability declaration . 80
C.1.2 Test procedures . 80
C.1.3 Failure criteria . 80
C.2 Mechanical durability . 81
C.2.1 General . 81
C.2.2 Test procedures . 81
C.3 Electrical durability . 81
C.3.1 General . 81
C.3.2 Test procedures . 81
Annex D (normative) Additional requirements for reed contact magnetic switches . 84
Annex E (informative) Items subject to agreement between manufacturer and user . 87
Annex F (normative) Class II control circuit devices – Requirements and tests . 88
Annex G (normative) Additional requirements for control circuit devices with integrally
connected cables . 93
Annex H (normative) Additional requirements for semiconductor switching elements
for control circuit devices . 97
Annex I (informative) . 103
Annex J (normative) Special requirements for indicator lights, indicating towers and
audible signalling devices . 104
Annex K (normative) Special requirements for control switches with direct opening

action. 110
Annex L (normative) Special requirements for mechanically linked contact elements . 115

– 6 – IEC 60947-5-1:2024 © IEC 2024
Annex M (normative) Terminal marking, distinctive number and distinctive letter for
control circuit devices . 118
M.1 General . 118
M.2 Terminal marking rule . 118
M.2.1 General . 118
M.2.2 Function digit . 118
M.2.3 Sequence digit . 118
M.2.4 Numbering method . 119
M.3 Distinctive number and distinctive letter . 119
M.3.1 General . 119
M.3.2 Distinctive number . 119
M.3.3 Distinctive letter . 119
M.4 Terminal numbering sequence . 120
M.5 Contactor relays designated by the distinctive letter E . 120
M.6 Contactor relays designated by distinctive letters X, Y or Z . 122
M.6.1 Contactor relays designated by the distinctive letter Z . 122
M.6.2 Contactor relays designated by the distinctive letter X . 122
M.6.3 Contactor relays designated by the distinctive letter Y . 122
Annex N (normative) Procedure to determine reliability data for electromechanical
devices in control circuits used in functional safety applications . 123
N.1 General . 123
N.1.1 Overview . 123
N.1.2 Object . 123
N.1.3 General requirements . 123
N.2 Terms, definitions and symbols . 123
N.3 Method based on durability test results . 123
N.3.1 General method . 123
N.3.2 Test requirements . 123
N.3.3 Number of samples . 124
N.3.4 Characterization of a failure mode . 124
N.3.5 Weibull modelling . 124
N.3.6 Useful life and upper limit of failure rate . 124
N.3.7 Reliability data . 124
N.4 Data information . 124
N.5 Example. 124
Annex O (normative) Additional requirements for control circuit devices incorporating
a built-in communication interface complying with IEC 61131-9 . 125
Bibliography . 127

Figure 1 – Operation of push-buttons . 23
Figure 2 – Difference e between the over-travel of the actuator and that of the contact

element. 23
Figure 3 – Examples of contact elements (schematic sketches) . 34
Figure 4 – Examples of the recommended method for drawing an operating diagram of
a rotary switch . 44
Figure 5 – Mounting hole diameter and dimensions of the key recess (if any) . 47
Figure 6 – Voltage drop measurement at contact point of the clamping unit or terminal . 61
Figure 7 – Test circuits for multi-pole control switches – Contacts of same polarity, not
electrically separated . 68

Figure 8 – Test circuits for multi-pole control switches – Electrically separated . 68
Figure 9 – Load L details for test conditions requiring different values of make and
d
break current and/or power factor (time constant) . 69
Figure 10 – Current/time limits for DC test loads . 69
Figure 11 – Test circuit, conditional short-circuit current . 71
Figure B.1 – Construction of load for DC contacts . 79
Figure C.1 – Normal circuit (see C.3.2.2) . 83
Figure C.2 – Simplified circuit (see C.3.2.2) . 83
Figure F.1 – Device insulated by encapsulation . 88
Figure F.2 – Device insulated by double and reinforced insulation . 89
Figure F.3 – Test apparatus . 91
Figure H.1 – Relationship between U and U . 98
e B
Figure H.2 – Example of test circuit for the verification of voltage drop, minimum

operational current and OFF-state current . 100
Figure H.3 – Short-circuit testing. 101
Figure J.1 – Mounting dimensions for indicating tower socket . 105
Figure J.2 – Mounting dimensions for temperature-rise tests . 107
Figure K.1 – Verification of robustness of the actuating system . 114
Figure L.1 – Example of representation of NO and NC contacts which are mechanically
linked and NC non-linked contact . 116
Figure L.2 – Symbol for device containing mechanically linked contacts . 116

Table 1 – Utilization categories for switching elements . 36
Table 2 – Verification of making and breaking capacities of switching elements under
normal load conditions corresponding to the utilization categories . 39
Table 3 – Verification of making and breaking capacities of switching elements under
abnormal conditions corresponding to the utilization categories . 40
Table 4 – Mounting hole diameter and dimensions of the key recess (if any) . 47
Table 5 – Preferred minimum distances between centres of mounting holes . 47
Table 6 – Test conditions for glow-wire test . 49
Table 7 – Limits for limited energy sources without an overcurrent protective device . 52
Table 8 – Limits for limited energy sources with an overcurrent protective device . 52
Table 9 – Limits for limited energy source with limited current impedance . 53
Table 10 – Acceptance criteria . 56
Table 11 – Test values for electrical performance and ageing test of screwless-type
clamping units . 61
Table 12 – Immunity tests . 73
Table A.1 – Examples of contact rating designation based on utilization categories . 76
Table A.2 – Examples of semiconductors switching element ratings for 50 Hz and/or
60 Hz . 77
Table A.3 – Examples of semiconductors switching element ratings for direct current . 77
Table B.1 – DC loads . 79
Table C.1 – Making and breaking conditions for electrical durability . 82
Table F.1 – Acceptance criteria for Annex F . 90
Table G.1 – Material characteristics (informative) . 94

– 8 – IEC 60947-5-1:2024 © IEC 2024
Table G.2 – Examples of standard cable types (informative) . 95
Table G.3 – Tensile forces . 95
Table M.1 – Diagrams of control switches . 120
Table M.2 – Diagrams of contactor relays designated by the distinctive letter E . 121
Table M.3 – Diagrams of contactor relays designated by the distinctive letter Y . 122

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
LOW-VOLTAGE SWITCHGEAR AND CONTROLGEAR –

Part 5-1: Control circuit devices and switching elements –
Electromechanical control circuit devices

FOREWORD
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IEC 60947-5-1 has been prepared by subcommittee 121A: Low-voltage switchgear and
controlgear, of IEC technical committee 121: Switchgear and controlgear and their assemblies
for low voltage. It is an International Standard.
This fifth edition cancels and replaces the fourth edition published in 2016. This edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) update of the scope structure and exclusions;
b) requirements for control circuits;
c) update of the normal service conditions (e.g. shock and vibration);
d) update of information and marking requirements including environmental information
requirements referencing IEC TS 63058:2021;

– 10 – IEC 60947-5-1:2024 © IEC 2024
e) update of the constructional requirements and the corresponding tests considering safety
aspects (e.g. artificial optical radiation, security aspects, limited energy source, stored
charge energy circuit);
f) update of the EMC requirements acco
...