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Electric Circuits, 9th Edition P46. Designed for use in a one or two-semester Introductory Circuit Analysis or Circuit Theory Course taught in Electrical or Computer Engineering Departments. Electric Circuits 9/e is the most widely used introductory circuits textbook of the past 25 years. As this book has evolved over the years to meet the changing learning styles of students, importantly, the underlying teaching approaches and philosophies remain unchanged. | 426 Balanced Three-Phase Circuits 11.48 a Calculate the reading of each wattmeter in the circuit shown in Fig. Pl 1.48 when Z 13.44 46.08 il. b Check that the sum of the two wattmeter readings equals the total power delivered to the load. c Check that V3 Wi W2 equals the total magnetizing vars delivered to the load. Figure Pl 1.48 11.49 a Calculate the complex power associated with each phase of the balanced load in Problem 11.17. b If the two-wattmeter method is used to measure the average power delivered to the load specify the reading of each meter. 11.50 a Find the reading of each wattmeter in the circuit shown in Fig. Pl 1.50 if ZA 20 30 O ZB 60 0 O and Zc 40 -30 il. b Show that the sum of the wattmeter readings equals the total average power delivered to the unbalanced three-phase load. Figure P11.50 11.51 The balanced three-phase load shown in Fig. Pl 1.51 is fed from a balanced positive-sequence three-phase Y-connected source. The impedance of the line connecting the source to the load is negligible. The line-to-neutral voltage of the source is 7200 V. a Find the reading of the wattmeter in watts. b Explain how you would connect a second wattmeter in the circuit so that the two wattmeters would measure the total power. c Calculate the reading of the second wattmeter. d Verify that the sum of the two wattmeter readings equals the total average power delivered to the load. Figure P11.51 a Source b c A 432 kVA - B 0.96 pf lead c Sections 11.1-11.6 11.52 Refer to the Practical Perspective example PERSPECTIVE a Construct a power triangle for the substation load before the capacitors are connected to the bus. b Repeat a after the capacitors are connected to the bus. c Using the line-to-neutral voltage at the substation as a reference construct a phasor diagram that depicts the relationship between VAN and van before the capacitors are added. d Assume a positive phase sequence and construct a phasor diagram that depicts the relationship between VAB and vab. 11.53
