>> P.108
TermsandDenitionsIECstandardsforlightningprotectionStandardnameStandardNumberAbstractProtectionagainstlightning–Part1:GeneralprinciplesIEC62305-1Protectionagainstlightning–Part2:RiskmanagementIEC62305-2IEC62305–1providesgeneralprinciplestobefollowedforprotectionofstructuresagainstlightning,includingtheirinstallationsandcontents,aswellaspersons.Thissecondeditioncancelsandreplacesthefirstedition,publishedin2006,andconstitutesatechnicalrevision.Thiseditionincludesthefollowingsignicanttechnicalchangeswithrespecttothepreviousedition:1)Itnolongercoversprotectionofservicesconnectedtostructures.2)Isolatedinterfacesareintroducedasprotectionmeasurestoreducefailureofelectricandelectronicsystems.3)Firstnegativeimpulsecurrentisintroducedasanewlightningparameterforcalculationpurposes.4)Expectedsurgeovercurrentsduetolightningflasheshavebeenmoreaccuratelyspeciedforlowvoltagepowersystemsandfortelecommunica-tionsystems.IEC62305-2isapplicabletoriskassessmentforastructureduetolightningashestoearth.Itspurposeistoprovideaprocedurefortheevaluationofsucharisk.Onceanuppertolerablelimitfortheriskhasbeenselected,thisprocedureallowstheselectionofappropriateprotectionmeasurestobeadoptedtoreducetherisktoorbelowthetolerablelimit.Thissecondeditioncancelsandreplacesthefirstedition,publishedin2006,andconstitutesatechnicalrevision.Thiseditionincludesthefollowingsignicanttechnicalchangeswithrespecttothepreviousedition:1)Riskassessmentforservicesconnectedtostructuresisexcludedfromthescope.2)Injuriesoflivingbeingscausedbyelectricshockinsidethestructureareconsidered.3)Tolerableriskoflossofculturalheritageisloweredfrom10-3to10-4.Thevalueoftolerableriskoflossofeconomicvalue(RT=10-3)isintroduced,tobeusedwhendataforcost/benetanalysisarenotavailable.4)Extendeddamagetosurroundingsstructuresortotheenvironmentisconsidered.5)Improvedequationsareprovidedforevaluationof------collectionareasrelevanttoflashesnearbyastructure,collectionareasrelevanttoflashestoandnearbyaline,probabilitiesthataashcancausedamage,lossfactorseveninstructureswithriskofexplosion,riskrelevanttoazoneofastructure,costofloss.6)Tablesareprovidedtoselecttherelativeamountoflossinallcases.7)Impulsewithstandvoltagelevelofequipmentswasextendeddownto1kV.108
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