Low-voltage surge protective devices - Part 32: Surge protective devices connected to the d.c. side of photovoltaic installations - Selection and application principles

IEC 61643-32:2017 describes the principles for selection, installation and coordination of SPDs intended for use in Photovoltaic (PV) systems up to 1 500 V DC and for the AC side of the PV system rated up to 1 000 V rms 50/60 Hz. The photovoltaic installation extends from a PV array or a set of interconnected PV-modules to include the associated cabling and protective devices and the inverter up to the connection point in the distribution board or the utility supply point. This part of IEC 61643 considers SPDs used in different locations and in different kinds of PV systems:PV systems located on the top of a building. PV systems located on the ground like free field power plants characterized by multiple earthing and a meshed earthing system. The term PV installation is used to refer to both kinds of PV systems. The term PV power plant is only used for extended free-field multi-earthed power systems located on the ground. For PV installations including batteries additional requirements may be necessary.
The contents of the corrigendum of June 2019 have been included in this copy.

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

IEC 61643-32:2017 décrit les principes de choix, d'installation et de coordination des parafoudres destinés à être utilisés dans les systèmes photovoltaïques (PV) jusqu'à une tension maximale de 1 500 V en courant continu, et en courant alternatif dans un système photovoltaïque d’une tension assignée maximale de 1 000 V en valeur efficace sous une fréquence de 50 Hz/60 Hz. Une installation photovoltaïque englobe à la fois un groupe photovoltaïque ou un ensemble de modules photovoltaïques interconnectés, des dispositifs de câblage et de protection associés, ainsi que l’onduleur et le point de connexion d'un tableau de distribution ou le point d'alimentation du réseau. La présente partie de l'IEC 61643 traite des parafoudres utilisés dans différents emplacements et avec différents types de systèmes photovoltaïques: Les systèmes photovoltaïques situés au sommet d'un bâtiment. Les systèmes photovoltaïques au sol comme les centrales électriques en champ libre caractérisées par plusieurs mises à la terre et un système de mise à la terre maillé. Le terme «installation photovoltaïque» fait référence aux deux types de systèmes photovoltaïques. Le terme «centrale photovoltaïque» s'applique uniquement aux réseaux d'alimentation étendus mis à la terre en des points multiples en champ libre au sol. Des exigences supplémentaires peuvent être nécessaires pour les installations photovoltaïques comportant des batteries.
Mots clés: SPD - surge protective device connectés aux installations photovoltaïques, parafoudres, PV
Le contenu du corrigendum de juin 2019 a été pris en considération dans cet exemplaire.

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Status
Published
Publication Date
19-Sep-2017
Current Stage
PPUB - Publication issued
Start Date
20-Sep-2017
Completion Date
20-Sep-2017
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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
IEC 61643-32:2017-07(en-fr)
---------------------- Page: 1 ----------------------
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---------------------- Page: 2 ----------------------
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

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 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

impulse current I ...................................................................................... 19

imp

9.1.3 Selection of SPDs with regard to voltage protection level U ......................... 20

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

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

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

---------------------- Page: 4 ----------------------
IEC 61643-32:2017 © IEC 2017 – 3 –

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 ..................................................................... 35

Figure B.2 – U/I characteristics of a non-linear PV current source ......................................... 35

Figure C.1 – Example of SPDs installed on a PV system protected by an external LPS

where the separation distance (s) is maintained – Installation includes data acquisition

and control system ................................................................................................................ 39

Figure C.2 – Example of a building with an external LPS – Dimensions of equipotential

bonding conductors when the separation distance (s) is maintained, or an isolated

LPS is used .......................................................................................................................... 40

Figure C.3 – Example of a building with an external LPS – Dimensions of equipotential

bonding conductors when the separation distance (s) is not maintained ................................ 41

Table 1 – Selection of SPD test class and cross section of bonding conductor ..................... 14

Table 2 – Rated impulse voltage U for equipment between PV array and inverter

(where no other information is available) ............................................................................... 23

Table A.1 – Values of I (I ) and I (I ) for voltage-limiting SPDs on the DC
imp 10/350 n 8/20

side of a PV installation mounted on the roof of a building with an external LPS if the

separation distance is not maintained ................................................................................... 31

Table A.2 – Values of I (I ) for voltage-switching SPDs on the DC side of a
imp 10/350
PV installation mounted on the roof of a building with an external LPS, if the

separation distance is not maintained ................................................................................... 31

Table A.3 – Values of I (I and I (I ) for SPDs used on the DC side in PV
imp 10/350) n 8/20

power plants with a central inverter, multiple earthing and a meshed earthing system........... 33

---------------------- Page: 5 ----------------------
– 4 – IEC 61643-32:2017 © IEC 2017
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
LOW-VOLTAGE SURGE PROTECTIVE DEVICES –
Part 32: Surge protective devices connected to the d.c. side of
photovoltaic installations – Selection and application principles
FOREWORD

1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising

all national electrotechnical committees (IEC National Committees). The object of IEC is to promote

international co-operation on all questions concerning standardization in the electrical and electronic fields. To

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governmental organizations liaising with the IEC also participate in this preparation. IEC collaborates closely

with the International Organization for Standardization (ISO) in accordance with conditions determined by

agreement between the two organizations.

2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international

consensus of opinion on the relevant subjects since each technical committee has representation from all

interested IEC National Committees.

3) IEC Publications have the form of recommendations for international use and are accepted by IEC National

Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC

Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any

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4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications

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between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in

the latter.

5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity

assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any

services carried out by independent certification bodies.

6) All users should ensure that they have the latest edition of this publication.

7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and

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expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC

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8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is

indispensable for the correct application of this publication.

9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of

patent rights. IEC shall not be held responsible for identifying any or all such patent rights.

International Standard IEC 61643-32 has been prepared by subcommittee 37A: Low-voltage

surge protective devices, of IEC technical committee 37: Surge arresters.
The text of this International Standard is based on the following documents:
FDIS Report on voting
37A/302/FDIS 37A/303/RVD

Full information on the voting for the approval of this International Standard can be found in

the report on voting indicated in the above table.

This document has been drafted in accordance with the ISO/IEC Directives, Part 2.

---------------------- Page: 6 ----------------------
IEC 61643-32:2017 © IEC 2017 – 5 –

The following differing practices of a less permanent nature exist in the countries indicated

below.
Annex D: Class I tested SPDs are not required (United States)

A list of all parts of the IEC 61643 series can be found, under the general title Low-voltage

surge protection devices, on the IEC website.

The committee has decided that the contents of this document will remain unchanged until the

stability date indicated on the IEC website under "http://webstore.iec.ch" in the data related to

the specific document. At this date, the document will be
 reconfirmed,
 withdrawn,
 replaced by a revised edition, or
 amended.
The contents of the corrigendum of June 2019 have been included in this copy.

IMPORTANT – The 'colour inside' logo on the cover page of this publication indicates

that it contains colours which are considered to be useful for the correct

understanding of its contents. Users should therefore print this document using a

colour printer.
---------------------- Page: 7 ----------------------
– 6 – IEC 61643-32:2017 © IEC 2017
INTRODUCTION

This part of IEC 61643 provides useful information for the selection of SPDs connected to

photovoltaic installations.

This part of IEC 61643 provides information to evaluate, with reference to the IEC 62305

series, IEC 60364 series and IEC 61643-12, the additional needs for surge protective devices

(SPDs) to be installed on the DC side of a photovoltaic (PV) system, to protect against

induced and direct lightning effects. It gives guidance for selection, operation and installation

of SPDs, including the selection of SPD test class, surge current values and cross section of

bonding conductors. Guidance for selection of SPDs connected to the AC side is also given.

The specific electrical parameters of a PV array or a PV source require specific SPDs on the

DC side.

This part of IEC 61643 considers SPDs used in different locations and in different kinds of PV

systems. It gives examples and provides a simplified and common approach to determine

impulse discharge current values for the DC side of different PV installations.
---------------------- Page: 8 ----------------------
IEC 61643-32:2017 © IEC 2017 – 7 –
LOW-VOLTAGE SURGE PROTECTIVE DEVICES –
Part 32: Surge protective devices connected to the DC side of
photovoltaic installations – Selection and application principles
1 Scope

This part of IEC 61643 describes the principles for selection, installation and coordination of

SPDs intended for use in Photovoltaic (PV) systems up to 1 500 V DC and for the AC side of

the PV system rated up to 1 000 V rms 50/60 Hz.

The photovoltaic installation extends from a PV array or a set of interconnected PV-modules

to include the associated cabling and protective devices and the inverter up to the connection

point in the distribution board or the utility supply point.

This part of IEC 61643 considers SPDs used in different locations and in different kinds of PV

systems:
– PV systems located on the top of a building.

– PV systems located on the ground like free field power plants characterized by multiple

earthing and a meshed earthing system.

The term PV installation is used to refer to both kinds of PV systems. The term PV power

plant is only used for extended free-field multi-earthed power systems located on the ground.

For PV installations including batteries additional requirements may be necessary.

NOTE 1 IEC 60364 series, IEC 62305 series and IEC 61643-12 also apply.

NOTE 2 This standard deals only with SPDs and not with surge protective components integrated inside

equipment (e.g. inverters, (PCE) power conversion equipment).
2 Normative references

The following documents are referred to in the text in such a way that some or all of their

content constitutes requirements of this document. For dated references, only the edition

cited applies. For undated references, the latest edition of the referenced document (including

any amendments) applies.

IEC 60364-4-44:2007, Low-voltage electrical installations – Part 4-44: Protection for safety –

Protection against voltage disturbances and electromagnetic disturbances
IEC 60364-4-44:2007/AMD1:2015

IEC 60364-5-53:2015, Electrical installations of buildings – Part 5-53: Selection and erection

of electrical equipment – Isolation, switching and control

IEC 60364-5-54, Low-voltage electrical installations – Part 5-54: Selection and erection of

electrical equipment – Earthing arrangements and protective conductors

IEC 60364-7-712:2017, Low voltage electrical installations – Part 7-712: Requirements for

special installations or locations – Solar photovoltaic (PV) power supply systems

IEC 60664-1:2007, Insulation coordination for equipment within low-voltage systems – Part 1:

Principles, requirements and tests
---------------------- Page: 9 ----------------------
– 8 – IEC 61643-32:2017 © IEC 2017
IEC 61000-4-5:2014, Electromagnetic compatibility (EMC) – Part 4-5: Testing and
measurement techniques – Surge immunity test

IEC 61643-11:2011, Low-voltage surge protective devices – Part 11: Surge protective devices

connected to low-voltage power systems – Requirements and test methods

IEC 61643-12, Low-voltage surge protective devices – Part 12: Surge protective devices

connected to low-voltage power distribution systems – Selection and application principles

IEC 61643-21, Low voltage surge protective devices – Part 21: Surge protective devices

connected to telecommunications and signalling networks – Performance requirements and

testing methods

IEC 61643-22, Low-voltage surge protective devices – Part 22: Surge protective devices

connected to telecommunications and signalling networks – Selection and application

principles

IEC 61643-31, Low-voltage surge protective devices – Part 31: Surge protective devices

connected to the DC side of photovoltaic installations – Requirements and test methods

IEC 62305-2, Protection against lightning – Part 2: Risk management

IEC 62305-3:2010, Protection against lightning – Part 3: Physical damage to structures and

life hazard

IEC 62305-4, Protection against lightning – Part 4: Electrical and electronic systems within

structures

ITU-T, Recommendation K.20, Resistibility of telecommunication equipment installed in a

telecommunications centre to overvoltages and overcurrents

ITU-T, Recommendation K.21, Resistibility of telecommunication equipment installed in

customer premises to overvoltages and overcurrents
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.

ISO and IEC maintain terminological databases for use in standardization at the following

addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
3.1
PV array
assembly of electrically interconnected PV modules, PV strings or PV sub-arrays

Note 1 to entry: For the purposes of this document a PV array is all components up to the d.c. input terminals of

the PCE or other power conversion equipment or DC loads. A PV array does not include its foundation, tracking

apparatus, thermal control and other such components.
___________
Under preparation: Stage at the time of publication: IEC/FDIS 61643-31:2017.
---------------------- Page: 10 ----------------------
IEC 61643-32:2017 © IEC 2017 – 9 –

Note 2 to entry: A PV array may consist of a single PV module, a single PV string, or several parallel-connected

strings, or several parallel-connected PV sub-arrays and their associated electrical components. For the purposes

of this standard the boundary of a PV array is the output side of the PV array disconnecting device.

[SOURCE: IEC 60364-7-712:2017, 712.3.4]
3.2
PV module
smallest complete environmentally protected assembly of interconnected cells
[SOURCE: IEC 60364-7-712:2017, 712.3.2]
3.3
PV string
circuit of one or more series-connected modules
[SOURCE: IEC 60364-7-712:2017, 712.3.3]
3.4
PV installation
erected equipment of a PV power supply installation
[SOURCE: IEC 60364-7-712:2017, 712.3.11]
3.5
origin of the electrical installation
point at which the electric energy is delivered to the electrical installation
[SOURCE: IEC 60050-826:2004, 826-10-02]
3.6
lightning protection system
LPS

complete system used to reduce physical damage due to lightning flashes to a structure

Note 1 to entry: It consists of both external and internal lightning protection systems.

[SOURCE: IEC 62305-1:2010, 3.42]
3.7
external LPS isolated from the structure to be protected
LPS with an air-termination system and down conductor system inst
...

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