(30) Assume that a distribution substation, shown below, has a 4000 kVA 69/12.47 kV LTC transformer...

 

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(30) Assume that a distribution substation, shown below, has a 4000 kVA 69/12.47 kV LTC transformer feeding a three-phase four-wire 12.47 kV distribution system. The transformer has a reactance of 0.065 pu. Assume that fault impedance is 40 Q and that the maximum and minimum power generations of the system are 600 and 360 MVA, respectively. Use 1 MVA as the three-phase power base: a) Under the maximum (system) power generation conditions, determine the available three- phase, L-L, and SLG fault currents at buses 1 and 2 in per units, in amperes, and in MVA. b) Under the minimum (system) power generation conditions, determine the available three- phase, L-L, and SLG fault currents at buses 1 and 2 in per units, in amperes, and in MVA. V1 Substation V2 transformer Feeders To urban distribution System (source) 3 To rural distribution A- (30) Assume that a distribution substation, shown below, has a 4000 kVA 69/12.47 kV LTC transformer feeding a three-phase four-wire 12.47 kV distribution system. The transformer has a reactance of 0.065 pu. Assume that fault impedance is 40 Q and that the maximum and minimum power generations of the system are 600 and 360 MVA, respectively. Use 1 MVA as the three-phase power base: a) Under the maximum (system) power generation conditions, determine the available three- phase, L-L, and SLG fault currents at buses 1 and 2 in per units, in amperes, and in MVA. b) Under the minimum (system) power generation conditions, determine the available three- phase, L-L, and SLG fault currents at buses 1 and 2 in per units, in amperes, and in MVA. V1 Substation V2 transformer Feeders To urban distribution System (source) 3 To rural distribution A-