Power transformers are used in the power system to change the voltage levels to a level suitable for generation, or transmission or distribution. They are three-phase transformers, and can either be constructed as a single-unit or a bank of three single-phase units. In a hydro power station, a number of synchronous generators are used to generate electricity at 17.5 kV. The voltage is stepped up to 330 kV for transmission by parallel connected three-phase transformers. Each three-phase transformer consists of a bank of three single-phase units with each unit rated 100 MVA, 50 Hz, 330/17.5 kV. (a) With good reasons, explain the most suitable connection of the windings on the high-voltage side and the low-voltage side of each three-phase transformer, respectively. (b) What are the advantages of using a bank of single-phase transformers for each three-phase unit? (c) What are the disadvantages of using a bank of single-phase transformers for each three-phase unit?

Power transformers are used in the power system to change the voltage levels to a level suitable for generation, or transmission or distribution. They are three-phase transformers, and can either be constructed as a single-unit or a bank of three single-phase units. In a hydro power station, a number of synchronous generators are used to generate electricity at 17.5 kV. The voltage is stepped up to 330 kV for transmission by parallel connected three-phase transformers. Each three-phase transformer consists of a bank of three single-phase units with each unit rated 100 MVA, 50 Hz, 330/17.5 kV. (a) With good reasons, explain the most suitable connection of the windings on the high-voltage side and the low-voltage side of each three-phase transformer, respectively. (b) What are the advantages of using a bank of single-phase transformers for each three-phase unit? (c) What are the disadvantages of using a bank of single-phase transformers for each three-phase unit?

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 3.33P: Consider the three single-phase two-winding transformers shown in Figure 3.37. The high-voltage...

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Consider the three single-phase two-winding transformers shown in Figure 3.37. The high-voltage windings are connected in Y. (a) For the low-voltage side, connect the windings in , place the polarity marks, and label the terminals a, b, and c in accordance with the American standard. (b) Relabel the terminals a, b, and c such that VAN is 90 out of phase with Va for positive sequence.
Determine the positive- and negative-sequence phase shifts for the three- phase transformers shown in Figure 3.36.
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