To achieve AU the phase-shifting transformer must at its secondary terminal provide a voltage UT, which is higher than the primary voltage U1 and, in addition, displaced an angle ð. in the positive direction in relation to U1 (the positive direction defined counter-clockwise). ð can be calculated from the vector diagram to the right and is in this case 11,9°.If the total load current is only the half of 722A and the 50/50% distribution between system A and B still is desired, the voltage drops across ZA and ZB becomes only the half of those in the last example. The need for additional voltage to drive the desired current through ZB will then also be only the half, that is 0,5 • 97 470 V = 48 735 V. The displacement angle ð becomes now 6°.If ZB had been smaller than ZA, the direction of AU must the opposite to prevent that the current IB would be too high in relation to the desired load distribution.Also the power factor (cos ) .of the load current I influences the required displacement angle.
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