Basic Concepts of Alternating Current - CED （交流电的基本概念清洁能源）.pdf

Basic Concepts of Alternating Current Course No: E03-003 Credit: 3 PDH A. Bhatia Continuing Education and Development, Inc. 9 Greyridge Farm Court Stony Point, NY 10980 P: (877) 322-5800 F: (877) 322-4774 info@ CHAPTER 1 CONCEPTS OF ALTERNATING CURRENT LEARNING OBJECTIVES CONCEPTS OF ALTERNATING CURRENT AC AND DC Q1. Define direct current. Q2. Define alternating current. DISADVANTAGES OF DC COMPARED TO AC Q3. What is a disadvantage of a direct-current system with respect to supply voltage? Q4. What disadvantage of a direct current is due to the resistance of the transmission wires? Q5. What kind of electrical current is used in most modern power distribution systems? VOLTAGE WAVEFORMS Figure 1-1.—Voltage waveforms: (A) Direct voltage; (B) Alternating voltage. ELECTROMAGNETISM • • • MAGNETIC FIELDS MAGNETIC FIELD AROUND A CURRENT-CARRYING CONDUCTOR Figure 1-2.—Magnetic field around a current-carrying conductor. − Figure 1-3.—Magnetic field around a current-carrying conductor, detailed view. Figure 1-4.—Magne