文档介绍：-,themaincircuit-'expenseofmuchtimeandmoney,theengineersfoundthattheinterruptionhadbeencausedbytheneutraloftheelectricitysupply,powerconductorofthebalancedthree-,buttheratingofitsprotectiverelayhadonly50per-centoftheratingoftherelaysprotectingthephaseconduc-tors.(Abalancedthree-phasesystemshouldhavezeroneutralcauseandremedyofthecurrent,sothe65percentwasquiteunexpected.)IntheUnitedStates,aMidwestutilityreportedthefailureharmonicpolIutionproblemofatransformerwhoseloaddidnotexceeditskilovoltam-pereratingbutconsistedprimarilyofvariable-,mutuallythroughthelineinductance,sothatlargeharmonica300-kVAtransformerfailed,althoughaclamp-onaverag-,exceedingitsrmsing-,soonafterinstallation,amoreappro-priatemeasurementwithatruermsammeterindicatedsignif-,IntheItalianAlps,nexttothemassifoftheMarmolada,namely,excessivedistortionofthecurrentorvoltageofthethemotivepowerplantforadouble-,designedtocarry3600per-