IEC 62305-2:2006

IEC 62305-2
Edition 1.0 2006-01
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Protection against lightning –
Part 2: Risk management
Protection contre la foudre –
Partie 2: Evaluation des risques

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IEC 62305-2
Edition 1.0 2006-01
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Protection against lightning –
Part 2: Risk management
Protection contre la foudre –
Partie 2: Evaluation des risques

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
XE
CODE PRIX
ICS 29.020; 91.120.40 ISBN 2-8318-8364-4

62305-2  IEC:2006 –– 2 – 3 – 62305-2 © IEC:2006

CONTENTS
FOREWORD.7

INTRODUCTION.9

1 Scope.11

2 Normative references .11

3 Terms, definitions, symbols and abbreviations.11
4 Explanation of terms.21
4.1 Damage and loss .21
4.2 Risk and risk components.23
4.3 Composition of risk components related to a structure.25
4.4 Composition of risk components related to a service .27
4.5 Factors influencing the risk components.28
5 Risk management.29
5.1 Basic procedure .29
5.2 Structure to be considered for risk assessment .29
5.3 Service to be considered for risk assessment .29
5.4 Tolerable risk R .30
T
5.5 Specific procedure to evaluate the need of protection.30
5.6 Procedure to evaluate the cost effectiveness of protection .31
5.7 Protection measures .33
5.8 Selection of protection measures.33
6 Assessment of risk components for a structure.36
6.1 Basic equation.36
6.2 Assessment of risk components due to flashes to the structure (S1).36
6.3 Assessment of the risk component due to flashes near the structure (S2) .36
6.4 Assessment of risk components due to flashes to a line connected to the
structure (S3) .37
6.5 Assessment of risk component due to flashes near a line connected to the
structure (S4) .37
6.6 Summary of risk components in a structure .39

6.7 Partitioning of a structure in zones Z .39
S
6.8 Assessment of risk components in a structure with zones Z .40
S
7 Assessment of risk components for a service .41
7.1 Basic equation.41
7.2 Assessment of components due to flashes to the service (S3).41
7.3 Assessment of risk component due to flashes near the service (S4) .41
7.4 Assessment of risk components due to flashes to structures to which the
service is connected (S1) .42
7.5 Summary of risk components for a service .42
7.6 Partitioning of a service into sections S .43
S
62305-2 © IEC:200662305-2  IEC:2006 –– 3 – 5 –

Annex A (informative) Assessment of annual number N of dangerous events.44

Annex B (informative) Assessment of probability P of damage for a structure.53

X
Annex C (informative) Assessment of amount of loss L in a structure.59
X
Annex D (informative) Assessment of probability P′ of damage to a service .64
X
Annex E (informative) Assessment of the amount of loss L′ in a service.68

X
Annex F (informative) Switching overvoltages.70

Annex G (informative) Evaluation of costs of loss .71

Annex H (informative) Case study for structures .72

Annex I (informative) Case study for services – Telecommunication line.99
Annex J (informative)  Simplified software for risk assessment for structures.105

Bibliography.110

Figure 1 – Procedure for deciding the need of protection .31
Figure 2 – Procedure for evaluating the cost-effectiveness of protection measures.32
Fiigure 3 – Procedure for selecting protection measures in structures.34
Figure 4 – Procedure for selecting protection measures in services .35
Figure 5 – Structures at line ends: at “b” end the structure to be protected (structure b)
and at “a” end an adjacent structure(structure a) .38
Figure A.1 – Collection area A of an isolated structure .45
d
Figure A.2 – Complex shape structure .46
Figure A.3 – Different methods to determine the collection area for the structure of
Figure A.2.47
Figure A.4 – Structure to be considered for evaluation of collection area A .48
d
Figure A.5 – Collection areas (A , A , A , A ) .52
d m i l
Figure I.1 – Telecommunication line to be protected .99
Figure J.1 – Example for a country house (see Clause H.1 – no protection measures
provided) .108
Figure J.2 – Example for a country house (see Clause H.1 – protection measures
provided) .109

Table 1 – Sources of damage, types of damage and types of loss selected according
to the point of strike .22
Table 2 – Risk in a structure for each type of damage and of loss.23
Table 3 – Risk components to be considered for each type of loss in a structure .26
Table 4 – Risk components to be considered for each type of loss in a service.27
Table 5 – Factors influencing the risk components in a structure .28
Table 6 – Factors influencing the risk components in a service .29
Table 7 – Typical values of tolerable risk R .30
T
Table 8 – Parameters relevant to the assessment of risk components for a structure.38
Table 9 – Risk components for a structure for different types of damage caused by
different sources .39

62305-2  IEC:2006 –– 4 – 7 – 62305-2 © IEC:2006

Table 10 – Parameters relevant to the assessment of risk components for a service.42

Table 11 – Risk components for a service for different types of damage caused by

different sources .43

Table A. 1 – Values of collection area depending on the evaluation method.46

Table A.2 – Location factor C .49
d
Table A.3 – Collection areas A and A depending on the service characteristics.50
l i
Table A.4 – Tran
...