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Reply To: Protection Riddle No.13 – Setting of earth fault relay

#1336
AMIR KHASHAYAR

    If we assume , the voltage over winding is half and on the other hand the flux density is half , it means the number of winding is fix and hasn’t been reduced. U=4.44*N*(?)*F In this case we have used 2.3 times of copper in comparison with star winding . On the one hand , we state that the flux density is 1.7 T divided by two , while , this isn’t feasible and economical . If we assume the flux density is 1.7 T (as it is usual) , thus the current in one leg can’t be 5 AMP. It is 2.88 Amp. And if flux density is 0.85 T , so, it isn’t surprising if it can transfer 1.73 S.