Q4: The single line diagram of an unloaded power system is shown in Fig. below. Reactances of the two sections of the transmission line are shown on the diagram. The generators and transformers are rated as follows: Generator 1: 20 MVA, 13.8 kV, X=0.2 pu Generator 2: 30 MVA, 18 kV, X = 0.2 pu Generator 3: 30 MVA, 20 kV, X«=0.2 pu Tị: 25 MVA, 220 Y:13.8 AkV, X = 10% T;: single-phase units, each rated 10 MVA, 127 Y:18 A kV, X = 10% T;: 35 MVA, 220 Y:22 Y kV, X= 10% a. Draw the impedance diagram with all reactances marked in per uint with letters to indicate points corresponding to the single line diagram. Choose a base of 50 MVA, 13.8 kV in the circuit of generator 1. b. Suppose that the system is unloaded and that the voltage throughout the system is I per unit on bases chosen in part a. If a three-phase short circuit occurs from bus C to ground, find the phasor value of the short circuit current (in amperes) if each generator is represented by its subtransient reactance. j 80 Q -머

Q4: The single line diagram of an unloaded power system is shown in Fig. below. Reactances of the two sections of the transmission line are shown on the diagram. The generators and transformers are rated as follows: Generator 1: 20 MVA, 13.8 kV, X=0.2 pu Generator 2: 30 MVA, 18 kV, X = 0.2 pu Generator 3: 30 MVA, 20 kV, X«=0.2 pu Tị: 25 MVA, 220 Y:13.8 AkV, X = 10% T;: single-phase units, each rated 10 MVA, 127 Y:18 A kV, X = 10% T;: 35 MVA, 220 Y:22 Y kV, X= 10% a. Draw the impedance diagram with all reactances marked in per uint with letters to indicate points corresponding to the single line diagram. Choose a base of 50 MVA, 13.8 kV in the circuit of generator 1. b. Suppose that the system is unloaded and that the voltage throughout the system is I per unit on bases chosen in part a. If a three-phase short circuit occurs from bus C to ground, find the phasor value of the short circuit current (in amperes) if each generator is represented by its subtransient reactance. j 80 Q -머

Introductory Circuit Analysis (13th Edition)

13th Edition

ISBN:9780133923605

Author:Robert L. Boylestad

Publisher:Robert L. Boylestad

Chapter1: Introduction

Section: Chapter Questions

Problem 1P: Visit your local library (at school or home) and describe the extent to which it provides literature...

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Z1 = 10 ohms Z2 = 25 ohms Z3 = 50 ohms Z4 = 75 ohms Z5 = 100 ohms Z6 = 75 ohms Voltage = 12 V
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As an Engineer you have been contracted by a power distribution company to investigate the causes of frequent transformer failures in its network. In the course of your investigation you came across the following: The Transformer installed in urban area failed within the warrant period of 3 years; the diagnostic results showed failure of one phase of the High Voltage (HV), It was further observed that this failure was causes by Overheating and overloading of that phase which caused burning of both HV and Low Voltage (LV). Explain what could be the cause(s) of this overload and the implications it could have on other equipment in the Transformer
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