ABSTRACT
Motors and transformers are the key components for industrial, commercial, and residential equipment and appliances. The objective of this chapter is to present a simple but comprehensive discussion of the operation of electric machines. Electric motors use about 60% of all electricity; they are present almost everywhere in industrial equipment, systems, and appliances. Major types are the induction, synchronous, and DC machines. A transformer can change the system voltage from one level to another, making them critical power system components, found in many installations and appliances. DC machines, thought at one time to be a dying breed, have found extended applications in transportation, electric drives, cars, actuators, and low-power systems due to their versatility, easy control, and operation. Robust construction, relatively low manufacturing cost, and ease of control resulted in induction motors being the horsepower of modern industry. They are in single-phase or three-phase versions (the most popular electric motors) and in a very broad range of power, construction, and shapes. Almost all electricity is generated by three-phase synchronous generators, usually very large, robust, easy-to-control, and efficient machines. A given synchronous machine can operate as a generator or as a motor, being used as motors in drives, fixed- and constant-speed applications, condensers (running above their synchronous speed) to improve power factors, or in consumer electronics. The chapter contains enough materials for students and readers to get a good understanding of electric machine principles, operation, and characteristics. However, interested readers are directed to the end-of-chapter references or elsewhere in the literature.
