2. a) A three-phase star-connected alternator with its neutral point solidly earthed is excited in such a way as to give 33kV on open circuit. Its positive, negative and zero sequence impedances are j5.0, j3.0 and j2.2 ohms/phase respectively. A resistive fault occurs between a single line and earth at the alternator terminals on phase 'a'. The resistance Rr of the fault is 0.502. Show that the fault resistance can be represented by a resistor of value 3Rf in series with the zero sequence impedances and calculate the (i) fault current and (ii) voltage of phase 'b'-earth at the fault point. [10 marks]

2. a) A three-phase star-connected alternator with its neutral point solidly earthed is excited in such a way as to give 33kV on open circuit. Its positive, negative and zero sequence impedances are j5.0, j3.0 and j2.2 ohms/phase respectively. A resistive fault occurs between a single line and earth at the alternator terminals on phase 'a'. The resistance Rr of the fault is 0.502. Show that the fault resistance can be represented by a resistor of value 3Rf in series with the zero sequence impedances and calculate the (i) fault current and (ii) voltage of phase 'b'-earth at the fault point. [10 marks]

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 3.36P: Three single-phase two-winding transformers, each rated 25MVA,34.5/13.8kV, are connected to form a...

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