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Hello all: We have a Autotranformer with the data from FAT: Sn=300/300/1MVA, 400/115/10.5kV Connection: Yyod5 Short circuit imepedance: HV-LV u%=12.31 at 300MVA LV-MV, u%=0.28 at 1MVA HV-MV, u%=0.33 at 1MVA LV-MV, u%=84.86at 300MVA HV-MV, u%=100.08at 300MVA For short circuit calculation at...

Dear all Please has any body the book of "Numerical differential protection principles and applications By Gerhard Ziegler

If I understand well the neutral point of Transformer is earthed by impedance te reduce earth fault at value 200A. Than the line from transformer to bus load is short line.I dont know level of voltage for line. Of course distance protection will consider Arc resistance and resistance of tower...

We have two realay protection in HV lines Distance protection and overcurrent protection. The time settings of backup overcurrent protection for earth fualt is 1 sec. During single phase short circuit the trip issue by main distance protection and ARC start in progres. The dead time ARC is 1sec...

yes right Istab is angle. The differential current Id>kIstab, k=0.10-0.80. The question is wich factor "k" used for differential current/

Please can you inform based on experience settings Id and Istab of BB protection of type relay siprotec Low impedance numerical protection 7SS/ In the substation when there are different ratio of CT from the smalest 200/1A and bigest ratio 2000/1 in bus coupler there will be problem of...