QUESTION ONE A three-phase 20 MVA, 11 kV generator has a reactance of 10% and is connected via a bank of three single-phase transformers to a transmission line whose series reactance is 100 2. The transmission line is supplying a load of 10 MVA at 10 kV and 0.8 power factor. The transformer bank at the generator end is connected in delta on the generator side and in star on the transmission line side and the transformer on the load side is star-star connected. Each of the single phase transformers in the bank of transformers is rated at 10 MVA, 11/110 kV with a reactance of 8%. Draw the pu circuit diagram for a system base of 10 MVA, 15 kV in the load circuit. Calculate the voltage at the generator terminals.

QUESTION ONE A three-phase 20 MVA, 11 kV generator has a reactance of 10% and is connected via a bank of three single-phase transformers to a transmission line whose series reactance is 100 2. The transmission line is supplying a load of 10 MVA at 10 kV and 0.8 power factor. The transformer bank at the generator end is connected in delta on the generator side and in star on the transmission line side and the transformer on the load side is star-star connected. Each of the single phase transformers in the bank of transformers is rated at 10 MVA, 11/110 kV with a reactance of 8%. Draw the pu circuit diagram for a system base of 10 MVA, 15 kV in the load circuit. Calculate the voltage at the generator terminals.

Power System Analysis and Design (MindTap Course List)

6th Edition

ISBN:9781305632134

Author:J. Duncan Glover, Thomas Overbye, Mulukutla S. Sarma

Publisher:J. Duncan Glover, Thomas Overbye, Mulukutla S. Sarma

Chapter3: Power Transformers

Section: Chapter Questions

Problem 3.45P: Figure 3.39 shows a oneline diagram of a system in which the three-phase generator is rated 300 MVA,...

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Three single-phase two-winding transformers, each rated 25MVA,34.5/13.8kV, are connected to form a three-phase bank. Balanced positive-suence voltages are applied to 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 connection) and the balanced load is simultaneously reduced to 43.3 MW (57.7 of the original value), determine (a) the load voltages Va,Vb, and Vc; (b) load currents Ia,Ib, and Ic; and (c) the MVA supplied by each of the remaining two transformers. Are balanced voltages still applied to the load? Is the open transformer overloaded?
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