IEC TS 62257-5:2015

Recommendations for renewable energy and hybrid systems for rural electrification - Part 5: Protection against electrical hazards

IEC TS 62257-5:2015(E) specifies the general requirements for the protection of persons and equipment against electrical hazards to be applied in decentralised rural electrification systems. Requirements dealing with protection against electric shock are based on basic rules from IEC 61140 and IEC 60364. Decentralized Rural Electrification Systems are designed to supply electric power for sites which are not connected to a large interconnected system, or a national grid, in order to meet basic needs. Examples of such sites: isolated dwellings, village houses, community services, economic activities, etc. The main technical changes with regard to the previous edition are as follows:
- redefine the maximum AC voltage from 500 V to 1 000 V, the maximum DC voltage from 750 V to 1 500 V;
- removal of the limitation of 100 kVA system size.
This publication is to be read in conjunction with IEC 62257 series.

General Information

• Status: Published
• Publication Date: 10-Dec-2015
• ICS: 01 - GENERALITIES. TERMINOLOGY. STANDARDIZATION. DOCUMENTATION
• ICS: 27.160 - Solar energy engineering
• Technical Committee: TC 82 - Solar photovoltaic energy systems
• Drafting Committee: JWG 1 - TC 82/JWG 1
• Current Stage: PPUB - Publication issued
• Start Date: 29-Feb-2016
• Completion Date: 11-Dec-2015

Relations

• Revises: IEC TS 62257-5:2005 - Recommendations for small renewable energy and hybrid systems for rural electrification - Part 5: Protection against electrical hazards
• Effective Date: 05-Sep-2023

Standards Content (Sample)

IEC TS 62257-5 ®
Edition 2.0 2015-12
TECHNICAL
SPECIFICATION
colour
inside
Recommendations for renewable energy and hybrid systems for rural
electrification –
Part 5: Protection against electrical hazards
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IEC TS 62257-5 ®
Edition 2.0 2015-12
TECHNICAL
SPECIFICATION
colour
inside
Recommendations for renewable energy and hybrid systems for rural

electrification –
Part 5: Protection against electrical hazards

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 27.160 ISBN 978-2-8322-3070-1

– 2 – IEC TS 62257-5:2015  IEC 2015
CONTENTS
FOREWORD . 5
INTRODUCTION . 7
1 Scope . 8
2 Normative references . 8
3 Terms and definitions . 9
4 Classification of decentralised rural electrification systems . 11
5 Protection against electric shock . 11
5.1 General . 11
5.2 Requirements on the d.c. side of a DRES . 11
5.3 Requirements on the a.c. side of a DRES . 12
5.3.1 General . 12
5.3.2 TT system. 12
5.3.3 TN system . 12
6 Protection against overcurrent . 13
6.1 General . 13
6.2 Protection against overload currents . 13
6.3 Protection against short-circuits . 13
7 Protection against risk of fire . 13
8 Protection against effects of lightning . 14
8.1 Principle . 14
8.2 Examples . 14
8.3 Protection against overvoltage . 14
8.4 Protection against direct lightning . 14
9 Determination of the pick up area of a rod or wire (see IEC 62305-3:2010) . 14
9.1 General . 14
9.2 Operational conditions and external influences . 14
9.3 Wiring system . 15
9.4 Isolation and switching . 15
9.4.1 Isolation . 15
9.4.2 Over-current protective devices . 16
9.4.3 Residual Current Devices (RCD) . 17
9.5 Surge protective devices . 17
9.6 Earthing arrangement, protective conductors and protective bonding
conductors . 18
9.6.1 Earth electrodes . 18
9.6.2 Protective bonding conductors . 19
10 Verification . 19
11 Operation and maintenance . 19
Annex A (informative) Protection against electric shock in electrical installations . 20
A.1 Protection against electric shock . 20
A.2 Automatic disconnection of supply . 20
A.2.1 General . 20
A.2.2 In TN systems . 21
A.2.3 In TT systems . 21
A.3 Double or reinforced insulation . 22

A.4 Extra-low-voltage (SELV and PELV) . 22
A.5 Electrical separation . 22
A.6 Additional protection . 23
Annex B (informative) Types of LV distribution systems earthing . 24
B.1 Terms and definitions . 24
B.2 Types of system earthing used in DRES (Figures are from IEC 60364-1:2005) . 25
B.2.1 General . 25
B.2.2 AC TN systems . 27
B.2.3 AC TT systems . 34
B.2.4 DC distribution systems . 36
Annex C (informative) Classification of electrical equipment . 41
C.1 Classification of residual current devices (RCDs) (see IEC 61008,
IEC 61009, IEC 60755, IEC 60947-2, IEC 62423) . 41
C.2 Classification of circuit breakers for a.c. operation (see IEC 60898-1,
IEC 60947-2) . 42
C.3 Classification of surge protective devices (see IEC 61643-11) . 43
Annex D (informative)  General information concerning protection against lightning . 44
D.1 General . 44
D.2 Protection against lightning – Principles . 45
Bibliography . 46

Figure B.1 – General outline of the distribution system . 24
Figure B.2 – Distribution system of the smallest type . 25
Figure B.3 – TN-S system 3-phase, 4-wire with separate neutral conductor and
protective conductor throughout the distribution system . 28
Figure B.4 – TN-S system 3-phase, 3-wire with separate earthed line conductor and
protective conductor throughout the distribution system . 29
Figure B.5 – TN-S system 3-phase, 3-wire with protective conductor and no distributed
neutral conductor throughout the distribution system . 30
Figure B.6 – TN-C-S system 3-phase, 4-wire where the PEN conductor is separated
into the protective conductor PE and the neutral conductor N elsewhere in the
electrical installation . 31
Figure B.7 – TN-C-S system 3-phase, 4-wire where the PEN conductor is separated
into the protective conductor PE and the neutral conductor N at the origin of the
electrical installation . 32
Figure B.8 – TN-C-S system – single-phase, 2-wire where the PEN conductor is
separated into the protective conductor PE and the neutral conductor N at the origin of
the electrical installation . 32
Figure B.9 – TN-C system 3-phase, 4-wire with neutral and protective conductor
functions combined in a single conductor throughout the distribution system . 33
Figure B.10 – TN-S multiple source system 3-phase, 4-wire with separate protective
conductor and neutral conductor to current using equipment . 34
Figure B.11 – TT system 3-phase, 4-wire with earthed protective conductor and neutral
conductor throughout the distribution system . 35
Figure B.12 – TT system 3-phase, 3-wire with earthed protective conductor and no
distributed neutral conductor throughout the distribution system . 35
Figure B.13 – TN-S d.c. system . 37
Figure B.14 – TN-C d.c. system . 38
Figure B.15 – TN-C-S d.c. system . 39

– 4 – IEC TS 62257-5:2015  IEC 2015
Figure B.16 – TT d.c. system . 40
Figure D.1 – Example of effects of a lightning stroke . 44

Table 1 – Typology of decentralized electrification systems . 11
Table 2 – Rated operating residual current of the protec
...