A 200MVA 345kV D/34.5 kV Y substation transformer has an 8% leakage
reactance. The transformer links 345kV transmission and 34.5 kV
distribution. Neglect winding R and magnetizing current and source
impedance. Use Tx ratings as base and find
(a) per unit magnitude of voltage drop and low side voltage when rated
current at 0.8 pf lagging enters HV terminals,
(b) For a bolted 3 phase fault (impedance = 0) on LV side, find Fault
MVA (p.u.) (=fault current x nom volts). Note bolted fault means a
short circuit bolted on to the wires at zero impedance.
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