A three-phase, 600-V generator feeds a load via single-phase feeder and 50-kVA, single-phase 600/120-V step-down transformer with series impedances of 2 + j6% as shown in the figure below. The single-phase feeder on the generator side has 0.003 + j0.025 Ω impedance. The generator rating is much greater than 50 kVA, making it an infinitely stiff bus with zero internal impedance. Determine the symmetrical rms current rating of the transformer circuit breaker on the load side, assuming the fault location close to the breaker LV terminals.

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Gen 1-phase cable 0.003 + j0.025 02 Fault 1-ph, 25-kVA Transformer 3-ph 600-V infinite bus 120-V loads Other loads