Three single-phase two-winding transformers, each rated 25 MVA, 34.5/13.8 kV, are connected to form a three-phase bank. Balance positive-sequence voltages are applied the high voltage terminals, and a balanced, resistive Y load connected to the low-voltage terminals absorbs 75 MW at 13.8 kV. If one of the single-phase transformers is removed (resulting in an open- conection) and the balanced load is simultaneously reduced to 43.3 MW (57.7% of the original value), determine:
(a) the load voltages Van, Vbn and Vcn (in polar coordinates)
(b) load currents Ia, Ib, and Ic (in polar coordinate)
(c) the MVA supplied by each of the remaining two transformers. (in polar coordinates) Are balanced voltages still applied to the load? Is the open transformer overloaded?