PD IEC/TR 61400-24:2002

FOREWORD
INTRODUCTION
1 Scope
2 Definitions
3 Lightning and wind turbines
   3.1 The properties of lightning
   3.2 Lightning discharge formation and electrical
        parameters
   3.3 Cloud-to-ground flashes
   3.4 Upward initiated flashes
   3.5 Lightning protection of wind turbines - the generic
        problem
   3.6 Existing IEC standards and technical reports dealing
        with lightning protection
4 Damage statistics
   4.1 Data on wind turbine lightning damage
   4.2 Damage statistics
   4.3 Database merits and weaknesses
   4.4 Conclusions and recommendations
5 Evaluation of the risk of lightning damage to a wind turbine
   5.1 Introduction
   5.2 Assessing the lightning flash frequency to a wind
        turbine
   5.3 Use of IEC 61024-1-1
   5.4 Use of IEC 61662
   5.5 Analysis of blade lightning protection system costs
   5.6 Analysis of lightning protection costs for wind turbine
        control systems
6 Lightning protection of wind turbine blades
   6.1 Blade structure
   6.2 Blade damage mechanism
   6.3 Lightning protection for wind turbine blades
   6.4 Interception efficiency
   6.5 Sizing of materials
   6.6 Blade to hub connection
   6.7 Carbon reinforced plastic (CRP)
   6.8 Wiring inside blades
7 Protection of bearings and gearbox
   7.1 Damage to bearings due to AC and DC currents
   7.2 Damage to bearings due to lightning currents
   7.3 Laboratory investigations
   7.4 Lightning damage to gearbox
   7.5 Lightning protection of bearings and gearbox elements
8 Protection of electrical and control system
   8.1 Introduction
   8.2 Configuration of electrical equipment
   8.3 Lightning protection zones
   8.4 Surge coupling mechanisms
   8.5 Bonding and shielding
   8.6 Surge protection
   8.7 Summary
9 Earthing
   9.1 Lightning protection system earth termination for a
        single wind turbine
   9.2 Lightning protection system earth terminations in a
        wind farm
10 Personnel safety
   10.1 General
11 Conclusions and recommendations for further work
Annex A Typical lightning damage questionnaire
Bibliography
Figures
Tables

Aims to: identify the generic problems involved in lightning protection of wind turbines; collect and systematize existing experience with both older and new designs of wind turbines; describe appropriate methods for evaluating the risk of lightning damage to wind turbines, thereby making reliable cost-benefit evaluations of lightning protection efforts possible; describe and outline appropriate methods for lightning protection of wind turbine components, considering the special nature of wind turbines and the extensive use of composite materials; compile a technical report outlining problems and solutions as seen today.

Identifies the generic problems involved in lightning protection of wind turbines; describes appropriate methods for evaluating the risk of lightning damage to wind turbines; describes and outlines suitable methods for lightning protection of wind turbine components.