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 6.4.6 Touch voltages and step voltages 3436.4.6.1 Touch voltages 3436.4.6.2 Stepvoltages 3446.4.8 Measurement of soil resistivity and earth resistances 3456.4.8.1 Measurement of soil resistivity 3456.4.8.2 Measurement of earth resistances3486.5 Selection of materials 348Acknowledgements 352References 3537 Internal lightning protection system 355Peter Hasse and Peter Zahlmann7.1 Damage due to lightning and other surges 3557.1.1 Damage in hazardous areas3577.1.2 Lightning damage in city areas 3577.1.3 Damage to airports 3607.1.4 Consequences of lightning damage 3617.2 Protective measures 3617.2.1 Internal lightning protection 3637.2.1.1 Equipotential bonding in accordancewith IEC 60364-4-41 and -5-543637.2.1.2 Equipotential bonding for a low-voltagesystem3647.2.1.3 Equipotential bonding for informationtechnology system3647.2.2 Lightning protection zones concept 3657.2.3 Basic protection measures: earthing magneticshielding and bonding3667.2.3.1 Magnetic shielding 3667.2.3.2 Cable shielding 3697.2.3.3 Equipotential bonding network 3717.2.3.4 Equipotential bonding on the boundariesoflightning protection zones3737.2.3.5 Equipotential bonding at the boundaryof LPZ 0Aand LPZ 23807.2.3.6 Equipotential bonding on the boundaryof LPZ 1 and LPZ 2 andhigher 3837.2.3.7 Coordination of the protective measuresat various LPZ boundaries3857.2.3.8 Inspection and maintenance of LEMP protection 3887.3 Surge protection for power systems: power supplysystems (within the scope of the lightning pro

tectionzones concept according to IEC 62305-4)3897.3.1 Technical characteristicsof SPDs 3917.3.1.1 Maximum continuous voltageUC391xiiContents 7.3.1.2 Impulse currentIimp3927.3.1.3 Nominal discharge currentIn

3927.3.1.4 Voltage protection levelUp3927.3.1.5 Short-circuit withstand capability 3927.3.1.6 Follow current extinguishing capabilityatUC(I)3927.3.1.7 Follow current limitation (for spark-gap based SPDs class I)3937.3.1.8 Coordination 3937.3.1.9 Temporary overvoltage 3937.3.2 Use of SPDs in varioussystems 3937.3.3 Use of SPDs in TN systems 3967.3.4 Use of SPDs in TT systems 3

987.3.5 Use of SPDs in IT systems 4017.3.6 Rating the lengths of connecting leads for SPDs 4017.3.6.1 Series connection (V-shape) in accordancewith IEC 60364-5-534027.3.6.2 Parallel connection system in accordancewith IEC 60364-5-534037.3.6.3 Design of the connecting lead on the earth side 4057.3.6.4 Design of the phase-side connecting cables 4067.3.7 Rating of cross-sectional areas and backup protection of SPDs4107.3.7.1 Selectivity to the protection of the installation 4167.4 Surge protection for telecommunication systems 4177.4.1 Procedure for selection and installation of arresters:example BLITZDUCTOR CT4177.4.1.1 Technical data4187.4.2 Measuring and control systems 4217.4.2.1 Electrical isolation using optocouplers 4227.5 Examples for application 4237.5.1 Lightning and surge protecti

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on of wind turbines 4237.5.1.1 Positive prognoses 4247.5.1.2 Danger resulting from lightning effects 4247.5.1.3 Frequency of lightning strokes 4247.5.1.4 Standardization 4257.5.1.5 Protection measures 4257.5.1.6 Shielding measures 4267.5.1.7 Earth-termination system 4267.5.2 Lightning and surge protection for photovoltaicsystems and solar power plants4287.5.2.1 Lightning and surge protection forphotovoltaic systems4287.5.2.2 Lightning and surge protection for solar power plants434Contentsxiii 7.5.3 Surge protection for video surveillance systems 4387.5.3.1 Video surveillance systems 4397.5.3.2 Choice of SPDs 439Bibliography 4418 Risk analysis 443Z. Flisowski and C. Mazzetti8.1 General considerations 4438.2 General concept of risk due to lightning 4458.3 Number of strikes to a selected location 4478.4 Damage probabilities 4528.5 Simplied practical approach to damage probability 4578.6 Question of relative lossassessment 4588.7 Concept of risk components 4598.8 Standardized procedure of risk assessment 4618.8.1 Basic relations 4618.8.2 Evaluation of risk components 4648.8.3 Risk reduction criteria 4688.9 Meaning of subsequent strokes in a ash 4708.10 Final remarks and conclusions 471References 4729 Low-frequency grounding resistance and lightning protection 475Silverio Visacro9.1 Introduction 4759.2 Basic considerations about grounding systems 4759.3 The

concept of grounding resistance 4769.4 Grounding resistance of some simple electrode arrangements 4799.5 Relation of the grounding resistance to the experimentalresponse of electrodes to lightning currents4829.6 Typical arrangements of grounding electrodes for some relevant applications and their lightning-protection-related requirements4879.6.1 Transmission lines 4879.6.2 Substations 4909.6.3 Lightning protection systems 4949.6.4 Overhead distribution lines 4969.7 Conclusion497References 49910 High-frequency grounding 503Leonid Grcev10.1 Introduction 50310.2 Basic circuit concepts 50310.3 Basic eld considerations50610.4 Frequency-dependent characteristics of the soil 509