IEC 61643-32:2017

IEC 61643-32 ®
Edition 1.0 2017-09
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Low-voltage surge protective devices –
Part 32: Surge protective devices connected to the d.c. side of photovoltaic
installations – Selection and application principles

Parafoudres basse tension –
Partie 32: Parafoudres connectés au côté courant continu des installations
photovoltaïques – Principes de choix et d'application

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IEC 61643-32 ®
Edition 1.0 2017-09
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Low-voltage surge protective devices –

Part 32: Surge protective devices connected to the d.c. side of photovoltaic

installations – Selection and application principles

Parafoudres basse tension –
Partie 32: Parafoudres connectés au côté courant continu des installations

photovoltaïques – Principes de choix et d'application

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 29.240.01; 29.240.10 ISBN 978-2-8322-4583-5

– 2 – IEC 61643-32:2017 © IEC 2017
CONTENTS
FOREWORD . 4
INTRODUCTION . 6
1 Scope . 7
2 Normative references . 7
3 Terms and definitions . 8
4 Systems and equipment to be protected . 12
5 Overvoltages in a PV installation . 12
6 Installation and location of SPDs . 13
6.1 General . 13
6.2 Requirements for different PV installations:. 15
6.2.1 PV installation without an external LPS . 15
6.2.2 PV installation with an external LPS when the separation distance (s) is
maintained (excluding multi-earthed solar systems, such as PV power
plants) . 16
6.2.3 PV installation with an external LPS where the separation distance (s)
cannot be maintained (including multi-earthed systems, such as PV
power plants) . 17
6.2.4 PV installation including communication and signalling circuits . 18
7 Equipotential bonding . 18
8 Requirements for the installation of surge protective devices (SPDs) in a
PV system . 19
9 Selection and installation of SPDs in PV installations . 19
9.1 Selection of SPDs on the AC side . 19
9.1.1 General . 19
9.1.2 Selection of SPDs with regard to nominal discharge current I and
n
impulse current I . 19
imp
9.1.3 Selection of SPDs with regard to voltage protection level U . 20
P
9.1.4 Installation of SPDs on the AC side . 20
9.2 Selection of SPDs installed on the DC side . 22
9.2.1 General . 22
9.2.2 Selection of SPDs with regard to nominal discharge current I and
n
impulse current I . 22
imp
9.2.3 Selection of U of SPDs on the DC side . 22
CPV
9.2.4 Selection of SPDs with regard to voltage protection level U . 22
p
9.2.5 Installation of SPDs on the DC side . 23
9.2.6 Cross-sections of connecting conductors for SPDs on the DC side . 24
9.2.7 Internal connection schemes of multipole SPDs or combinations of
SPDs with a single mode of protection on the DC side . 25
9.2.8 Selection of I of SPDs on the DC side . 26
SCPV
9.2.9 Coordination of SPDs . 27
10 Maintenance . 27
Annex A (normative) Determination of the value of I or I for SPDs according to
imp n
the simplified approach for different structures protected by an LPS . 28
A.1 General . 28
A.2 Building with a PV installation on the roof according to 6.2.3 . 29
A.3 Free- field PV power plant. 32
Annex B (informative) Characteristics of a PV source . 35

B.1 PV source characteristics. 35
B.2 Calculation of U . 36
OC MAX
B.3 Calculation of I . 37
SC MAX
Annex C (informative) Additional information to clause 6: Installation and location of
SPD and to clause 7: Equipotential bonding . 38
C.1 PV installation including communication and signalling circuits . 38
C.2 PV installation and dimensions of equipotential bonding conductors . 40
Annex D (informative) Exceptions in the USA related to Class I tested SPDs . 42
Bibliography . 43

Figure 1 – Installation of SPDs in the case of a building without an external LPS . 15
Figure 2 – Installation of SPDs in the case of a PV installation with an external LPS
where the separation distance (s) is maintained . 16
Figure 3 – Installation of SPDs in the case of a PV-installation with an external LPS
where the separation distance (s) cannot be maintained . 17
Figure 4 – Installation of SPDs on the AC side with a short distance between the
origin of the installation and the PV inverter (E < 10 m) . 21
Figure 5 – Installation of SPDs on the AC side with a long distance between the origin
of the installation and the PV inverter (E ≥ 10 m) . 21
Figure 6 – Example of overvoltage protection on the DC side of a PV installation . 24
Figure 7 – Example of SPD connections on the DC side of an unearthed PV source . 25
Figure 8 – Example of SPD connection on the DC side of a reliable earthed PV source . 26
Figure A.1 – Example of a structure with two external down conductors to determine
the value of the discharge current for the selection of SPDs . 30
Figure A.2 – Example of the structure of an extended PV installation. A PV power
plant with multiple earthing and a meshed earthing system . 33
Figure B.1 – Schematic of a PV current source .
...