IEC_61400-24_Lightning_protection_TR_JULIO_2002.pdf

TECHNICALREPORTIEC TR 61400-24First edition2002-07Wind turbine generator systems Part 24:Lightning protectionReference numberIEC/TR 61400-24:2002(E)Publication numberingAs from 1 January 1997 all IEC publications are issued with a designation in the60000 series.For example,IEC 34-1 is now referred to as IEC 60034-1.Consolidated editionsThe IEC is now publishing consolidated versions of its publications.For example,edition numbers 1.0,1.1 and 1.2 refer,respectively,to the base publication,thebase publication incorporating amendment 1 and the base publication incorporatingamendments 1 and 2.Further information on IEC publicationsThe technical content of IEC publications is kept under constant review by the IEC,thus ensuring that the content reflects current technology.Information relating tothis publication,including its validity,is available in the IEC Catalogue ofpublications(see below)in addition to new editions,amendments and corrigenda.Information on the subjects under consideration and work in progress undertakenby the technical committee which has prepared this publication,as well as the listof publications issued,is also available from the following:IEC Web Site(www.iec.ch)Catalogue of IEC publicationsThe on-line catalogue on the IEC web site(www.iec.ch/catlg-e.htm)enablesyou to search by a variety of criteria including text searches,technicalcommittees and date of publication.On-line information is also available onrecently issued publications,withdrawn and replaced publications,as well ascorrigenda.IEC Just PublishedThis summary of recently issued publications(www.iec.ch/JP.htm)is alsoavailable by email.Please contact the Customer Service Centre(see below)forfurther information.Customer Service CentreIf you have any questions regarding this publication or need further assistance,please contact the Customer Service Centre:Email:custserviec.chTel:+41 22 919 02 11Fax:+41 22 919 03 00TECHNICALREPORTIECTR 61400-24First edition2002-07Wind turbine generator systems Part 24:Lightning protectionPRICE CODE IEC 2002 Copyright-all rights reservedNo part of this publication may be reproduced or utilized in any form or by any means,electronic ormechanical,including photocopying and microfilm,without permission in writing from the publisher.International Electrotechnical Commission,3,rue de Varemb,PO Box 131,CH-1211 Geneva 20,SwitzerlandTelephone:+41 22 919 02 11 Telefax:+41 22 919 03 00 E-mail:inmailiec.ch Web:www.iec.chVFor price,see current catalogueCommission Electrotechnique InternationaleInternational Electrotechnical Commission 2 TR 61400-24 IEC:2002(E)CONTENTSFOREWORD.5INTRODUCTION.71Scope.82Definitions.83Lightning and wind turbines.123.1The properties of lightning.123.2Lightning discharge formation and electrical parameters.123.3Cloud-to-ground flashes.133.4Upward initiated flashes.173.5Lightning protection of wind turbines the generic problem.193.6Existing IEC standards and technical reports dealing with lightning protection.204Damage statistics.214.1Data on wind turbine lightning damage.214.2Damage statistics.214.3Database merits and weaknesses.274.4Conclusions and recommendations.285Evaluation of the risk of lightning damage to a wind turbine.295.1Introduction.295.2Assessing the lightning flash frequency to a wind turbine.295.3Use of IEC 61024-1-1.305.4Use of IEC 61662.325.5Analysis of blade lightning protection system costs.345.6Analysis of lightning protection costs for wind turbine control systems.356Lightning protection of wind turbine blades.366.1Blade structure.366.2Blade damage mechanism.386.3Lightning protection for wind turbine blades.386.4Interception efficiency.406.5Sizing of materials.416.6Blade to hub connection.436.7Carbon reinforced plastic(CRP).436.8Wiring inside blades.437Protection of bearings and gearbox.447.1Damage to bearings due to AC and DC currents.447.2Damage to bearings due to lightning currents.447.3Laboratory investigations.447.4Lightning damage to gearbox.457.5Lightning protection of bearings and gearbox elements.458Protection of electrical and control system.468.1Introduction.468.2Configuration of electrical equipment.468.3Lightning protection zones.508.4Surge coupling mechanisms.528.5Bonding and shielding.53TR 61400-24 IEC:2002(E)3 8.6Surge protection.568.7Summary.589Earthing.589.1Lightning protection system earth termination for a single wind turbine.589.2Lightning protection system earth terminations in a wind farm.6010Personnel safety.6110.1 General.6111Conclusions and recommendations for further work.62Annex A Typical lightning damage questionnaire.64Bibliography.66Figure 1 Processes involved in the formation of a cloud-to-ground flash 4.14Figure 2 Typical profile of a negative cloud-to-ground flash(not to scale).15Figure 3 Typical profiles of negative cloud-to-ground flashes(not to scale).16Figure 4 Typical profile of a positive cloud-to-ground flash.17Figure 5 Typical profile of a negative upward-initiated flash.17Figure 6 Different profiles of negative upward initi