Question

what is the fault current in the bus 2? Answer most be in _________kA


Question 2 Para el sistema representado a continuación: z'Bus Z'Bus BUS 1 05 .01 03 .02 1 10 J06 .04 .06 jol İ.06 j.04 j.03 2 .06 07 j01 J01 4 J06 .01 01 10 La corriente de falla linea, linea en la barra 2 (11Sw) es de_--kA

Answer 1

Z^+_Bus = Z^-_Bus = 1 2 3 4 [1 j 0.05 j 0.01 j 0.02 j 0.02 2 j 0.01 j 0.06 j 0.04 j 0.03 3 j 0.03 j 0.04 j 0.05 j 0.02 4 j 0.02 j 0.03 j 0.02 j 0.05] Z^0_Bus = 1 2 3 4 [1 j 0.10 j 0.06 j 0.04 j 0.06 2 j 0.06 j 0.07 j 0.01 j 0.01 3 j 0.04 j 0.01 j 0.03 j 0.01 4 j 0.06 j 0.01 j 0.01 j 0.10] Consider line to ground fault happened in Bus 2 and let the system base is = 100 MVA Now, the sequence current I_af = Total voltage (V_Tn)/Z^+_22 Z^-_22 + Z^0_22 = 1 angle 0 degree /10.06 + j 0.06 + j 0.07 = 1 angle 0 degree /j 0.19 = 5.26 angle - 90 degree p.u Now, we know the fault current I_f = 3 I_af = 3 times 5.26 p.u. = 15.78 p.u. = 15.78 times 100 times 10^6/squareroot times 115 times 10^3 [Because Actual value = p.u. value = p.u. value times MVA/squareroot 3 times KV] = 7.92 times 10^3 Amp Therefore I_f = 7.92 kA