Itdetectsthepresenceofharmonicsinthecircuitthatitisbeingmeasuredandittripswhentheyexceedathresholdthatcanbeadjustedbytheuser.Itreceivesthesignalfromacurrenttransfor-mer.Somemodelsh***ethetrans-formerincorporatedinthesamerelay,whileforcurrentshigherthan200A,thesignalhastobeprovidedexternally.Inpowercapacitors,itisusedtodisconnecttheminthecasethattheharmoniclevelexceedsanestablishedthreshold,***oidinginthiswaythemdamageduetoovercurrents.Theyincorporateatripdelayadjustmentandathresholdselectionadjustment.Outputismadebyonechange-overcontact./ModelWDH50A)