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Unformatted text preview: G. Rizzoni, Principles and Applications of Electrical Engineering Problem solutions, Chapter 7 7.1 Chapter 7 Instructor Notes Chapter 7 surveys all important aspects of electric power. Coverage of Chapter 7 can take place immediately following Chapter 4, or as part of a later course on energy systems or electric machines. The material in this chapter will be of particular importance to Aerospace, Civil, Industrial, and Mechanical engineers, who are concerned with the utilization of electric power. The chapter permits very flexible coverage, with sections 7.1 and 7.2 describing basic single-phase AC power ideas. The 11 examples contained in these two sections and the boxes Focus on Methodology: Complex Power Calculations for a Single Load (p. 338), Focus on Methodology: Complex Power Calculation for Power Factor Correction (p. 345), Focus on Measurements: The Wattmeter (pp. 315-353), and Focus on Measurements: Power Factor (p. 354), will help the students master this basic material. A survey course might only use this introductory material. The next two sections discuss transformers and three-phase power. Sixexamples illustrate these ideas in detail. Two descriptive sections, 7.5 and 7.6 are also provided to introduce the ideas of residential wiring, grounding and safety, and the generation and distribution of AC power. These sections can be covered independent of the transformer and three-phase material. The homework problems present a few simple applications in addition to the usual exercises meant to reinforce the understanding of the fundamentals. Problems 7.19 and 7.21-24 present a variety of power factor correction problems. Problem 7.20 illustrates the billing penalties incurred when electric loads have insufficient power factors (this problem is based on actual data supplied by Detroit Edison). .Two advanced problems (7.40, 7.41) discuss transformer test methods, and problems 7.42 and 7.58 describe additional advanced applications; these problems may be suitable in a second course in energy systems. Those instructors who plan to integrate the three-phase material into a course on power systems and electric machines, will find that some of the three-phase circuit problems (7.45-7.59) can be assigned in conjunction with the material covered in Chapter 17, as part of a more in-depth look at three-phase machines. Learning Objectives 1. Understand the meaning of instantaneous and average power, master AC power notation, and compute average power for AC circuits. Compute the power factor of a complex load. 2. Learn complex power notation, compute apparent, real and reactive power for complex loads. Draw the power triangle, and compute the capacitor size required to perform power factor correction on a load....
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This note was uploaded on 01/28/2009 for the course GENENG 2930 taught by Professor Almquist during the Spring '08 term at Wisc Platteville.
- Spring '08