IEC_62305-2_213_CD.pdf

81/213/CDCOMMITTEE DRAFT(CD)IEC/TC or SC:TC 81Project numberIEC 62305-2,Ed.1Title of TC/SC:Lightning protectionDate of circulation2003-03-14Closing date for comments2003-06-20Also of interest to the following committeesSC 37A,TC 64,TC 77Supersedes documents81/173/NP 81/180/RVNFunctions concerned:Safety EMC Environment Quality assuranceSecretary:Mr.G.B.Lo Piparo(Italy)E-mail:lopiparorai.itTHIS DOCUMENT IS STILL UNDER STUDY AND SUBJECT TO CHANGE.ITSHOULD NOT BE USED FOR REFERENCE PURPOSES.RECIPIENTS OF THIS DOCUMENT ARE INVITED TO SUBMIT,WITH THEIRCOMMENTS,NOTIFICATION OF ANY RELEVANT PATENT RIGHTS OFWHICH THEY ARE AWARE AND TO PROVIDE SUPPORTINGDOCUMENTATION.Title:IEC 62305-2,Ed.1:Protection against lightning-Part 2:Risk management(Titre):Introductory noteThis document was elaborated by TC 81/WG 9 in close cooperation with TC 81 secretary.Coherence of this document with:IEC 62305-1;IEC 62305-3;IEC 62305-4;was checked and assured by TC 81 Secretariat.FORM CD(IEC)2002-08-08Copyright 2003 International Electrotechnical Commission,IEC.All rights reserved.It is permitted todownload this electronic file,to make a copy and to print out the content for the sole purpose of preparingNational Committee positions.You may not copy or mirror the file or printed version of the document,orany part of it,for any other purpose without permission in writing from IEC.2 81/213/CDIEC 62305-2,Ed.1:Protection against lightningPart 2:Risk managementContentsINTRODUCTION1.SCOPE AND OBJECT2.NORMATIVE REFERENCES3.TERMS AND DEFINITIONS4.RISK ASSESSMENT METHOD4.1 General approach4.1.1 Source of damage4.1.2 Types of damage4.1.3 Types of loss4.2 Risk components4.2.1 Risk components for a structure4.2.2 Factors influencing the risk components in a structure4.2.3 Risk components for a service4.2.4 Factors influencing the risk components in a service4.3 Risk management4.3.1 Structure to be considered for risk assessment4.3.2 Service to be considered for risk assessment4.3.3 Tolerable risk RT4.3.4 Procedure to evaluate the need of protection4.3.5 Procedure to evaluate the economic convenience of protection4.3.6 Protection measures4.3.7 Selection of protection measures5.ASSESSMENT OF RISK COMPONENTS FOR STRUCTURES5.1 Partitioning of a structure in zones ZS5.2 Parameters to assess risk components5.3 Risk due to flashes to the structure5.3.1 Assessment of risk components due to lightning flashes to the structure5.4 Risk due to flashes not to the structure5.4.1 Assessment of the risk component due to lightning flashes near the structure5.4.2 Assessment of risk components due to lightning flashes to an incoming line5.4.3 Assessment of risk component due to lightning flashes near an incoming line5.4 Summary of risk components in a structure 6.ASSESSMENT OF RISK COMPONENTS FOR SERVICES6.1 Partitioning of a service in sections SS6.2 Parameters relevant to the assessment of risk components6.3 Assessment of risk components related to lightning flashes to the service6.4 Assessment of the risk component due to lightning flashes near the service6.5 Assessment of risk components due to lightning flashes to the structures to which the service is connected6.6 Summary of risk components in a serviceANNEX A(Informative)Assessment of annual number of dangerous eventsANNEX B(Informative)Assessment of probability of damage for a structureANNEX C(Informative)Assessment of amount of loss for a structureANNEX D:(Informative)Assessment of probability of damage for a service 3 81/213/CDANNEX E:(Informative)Assessment of amount of loss for a serviceANNEX F:(Informative)Switching overvoltagesANNEX G:(Informative)Evaluation of costs of lossANNEX H:(Informative)Case study for structuresANNEX I:(Informative)Case study for services 4 81/213/CDINTRODUCTIONCloud-to-ground discharges are hazardous to structures and services and to persons,installationsand other equipment in or on the structures or around them.The hazard can result in damages of theentire structure,its parts and contents,of services as well as in failures of equipment and especiallyof the electrical and electronic systems.Consequential effects of the damages and failures may beextended to the surroundings of the structure or may involve its environment.To reduce the loss due to lightning,protection measures may be required.Whether they are neededand to which extend should be determined by risk assessment.The risk,defined in this standard as the probable average annual loss in a structure and in a servicedue to lightning flashes,depends on:-the annual number of lightning flashes influencing the structure and the service,-the probability of damage by one of the influencing lightning flashes-the mean amount of consequential loss Lightning flashes influencing the structure may be divided into:-flashes striking the structure-flashes striking near the structure and/or near the incoming lines and services and/or theincoming lines(power,telecommunication lines)or other services.Lightning flashes influencing the service m