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SLOVENSKI STANDARD
01-september-2023
Nizkonapetostne naprave za zaščito pred prenapetostnimi udari - 12. del: Naprave
za zaščito pred prenapetostnimi udari za nizkonapetostne sisteme - Izbira in
načela za uporabo (IEC 61643-12:2020)
Low-voltage surge protective devices - Part 12: Surge protective devices connected to
low-voltage power systems - Selection and application principles (IEC 61643-12:2020)
Parafoudres à basse tension - Partie 12: Parafoudres connectés aux réseaux à basse
tension - Principes de choix et de mise en œuvre (IEC 61643-12:2020)
Ta slovenski standard je istoveten z: IEC 61643-12:2020
ICS:
29.240.10 Transformatorske postaje. Substations. Surge arresters
Prenapetostni odvodniki
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
IEC 61643-12
Edition 3.0 2020-05
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Low-voltage surge protective devices –
Part 12: Surge protective devices connected to low-voltage power systems –
Selection and application principles
Parafoudres à basse tension –
Partie 12: Parafoudres connectés aux réseaux à basse tension –
Principes de choix et de mise en œuvre
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 29.240.10 ISBN 978-2-8322-7914-4
– 2 – IEC 61643-12:2020 © IEC 2020
CONTENTS
FOREWORD . 10
INTRODUCTION . 12
0.1 General . 12
0.2 Keys to understanding the structure of this document . 12
1 Scope . 14
2 Normative references . 14
3 Terms, definitions and abbreviated terms . 15
3.1 Terms and definitions . 15
3.2 List of abbreviated terms and acronyms used in this document . 28
4 Need for protection . 29
5 Low-voltage power systems and equipment to be protected . 30
5.1 General . 30
5.2 Low-voltage power systems . 30
5.2.1 General . 30
5.2.2 Lightning overvoltages and surge currents . 30
5.2.3 Switching overvoltages . 31
5.2.4 Temporary overvoltages U . 32
TOV
5.3 Characteristics of the equipment to be protected. 33
6 Surge protective devices . 33
6.1 Basic functions of SPDs . 33
6.2 Additional requirements . 34
6.3 Classification of SPDs . 34
6.3.1 SPD: classification . 34
6.3.2 Typical design and topologies . 35
6.4 Characteristics of SPDs . 36
6.4.1 Service conditions as described in IEC 61643-11 . 36
6.4.2 List of parameters for SPD selection . 37
6.5 Additional information on characteristics of SPDs . 38
6.5.1 Information related to power-frequency voltages . 38
6.5.2 Information related to surge currents . 39
6.5.3 Information related to voltage protection level provided by SPDs . 40
6.5.4 Information related to the SPD’s status at its end of life . 42
6.5.5 I : Short-circuit current rating and I : Follow current interrupt
SCCR fi
rating . 43
6.5.6 I : Rated load current and ΔU: Voltage drop (for two-port SPDs or one-
L
port SPDs with separate input and output terminals) . 43
6.5.7 Information related to change of characteristics of SPDs . 44
7 Application of SPDs in low-voltage power systems . 44
7.1.1 General . 44
7.1.2 Consideration regarding location of the SPD depending on the classes
of test . 46
7.1.3 SPD modes of protection and installation . 46
7.1.4 Need for additional protection . 48
7.2 Selection of SPD characteristics . 55
7.2.1 General . 55
7.2.2 Selection of U , U , I , I , I , I , I and U of the SPD . 56
c T n imp max SCCR fi oc
7.2.3 Protective distance . 62
7.2.4 Expected lifetime . 62
7.2.5 Interaction between SPDs and other devices . 62
7.2.6 Choice of the voltage protection level U . 63
p
7.2.7 Coordination between the chosen SPD and other SPDs . 63
7.3 Characteristics of auxiliary devices . 66
7.3.1 Disconnecting devices . 66
7.3.2 Surge and event counters . 66
7.3.3 Status indicator . 67
Annex A (informative) Typical information required before selecting an SPD and
explanation of testing procedures . 68
A.1 Typical Information required before selecting an SPD . 68
A.1.1 System data . 68
A.1.2 SPD application considerations . 68
A.1.3 Characteristics of SPD . 69
A.1.4 Additional equipment and fittings . 69
A.2 Explanation of testing procedures used in IEC 61643-11 . 70
A.2.1 General Principles . 70
A.2.2 Test sequences and tests description . 70
Annex B (informative) Examples of relationship between U and nominal system voltage
c
and example of relationship between U and U for Metal oxide varistors (MOV) . 78
p c
B.1 Relationship between U and the nominal voltage of the system . 78
c
B.2 Relationship between U and U for Metal oxide varistors (MOV) . 78
p c
Annex C (informative) Environment – Surge voltages in LV systems . 80
C.1 General . 80
C.2 Lightning overvoltages . 80
C.2.1 General . 80
C.2.2 Surges transferred from MV to the LV system . 81
C.2.3 Overvoltages caused by direct flashes to LV distribution systems . 81
C.2.4 Induced overvoltages in LV distribution systems . 82
C.2.5 Overvoltages caused by flashes to a Lightning Protection System or to
a structure in close vicinity. 82
C.3 Switching overvoltages . 83
C.3.1 General . 83
C.3.2 General description . 84
C.3.3 Circuit-breaker and switch operations . 84
C.3.4 Fuse operations (current-limiting fuses) . 85
Annex D (informative) Partial lightning current calculations . 87
Annex E (informative) TOV in the low-voltage system due to faults between high-
voltage system and earth . 90
E.1 General . 90
E.2 References . 91
E.3 Symbols . 91
E.4 Overvoltages in LV-systems during a high-voltage earth fault . 91
E.5 Example of a TT-system – Calculation of the possible temporary
overvoltages . 93
E.5.1 Possible stresses on equipment in low-voltage installations due to earth
faults in a high-voltage system . 93
E.5.2 Characteristics of the high-voltage system . 94
– 4 – IEC 61643-12:2020 © IEC 2020
E.6 Temporary power-frequency overvoltages depending on different LV-
systems and different kinds of earthing configurations . 94
E.6.1 General . 94
E.6.2 Conclusion – Worst case SPDs stress current for SPDs HV-TOV
behaviour. . 96
E.6.3 Conclusion – Worst case test source for SPDs HV-TOV behaviour, if the
SPD is connected to ground between N-PE and / or L-PE: . 96
E.6.4 Examples of different LV-systems and their possible earthing
configurations . 97
E.7 Values of the temporary overvoltages for the US TN C system. 101
E.8 Values of temporary overvoltages used in IEC 61643-11 with explanations . 103
E.8.1 General . 103
E.8.2 Values of temporary overvoltages for US systems . 106
E.8.3 Values of temporary overvoltages for Japanese systems . 109
Annex F (informative) Coordination rules and principles . 114
F.1 General . 114
F.2 Energy coordination . 114
F.2.1 General . 114
F.2.2 Analytical studies: simple case of the coordination of two metal oxide
varistors (MOV) based SPDs . 114
F.2.3 Analytical study: ca
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