AC Machines:

In the previous units we have learned the basic fundamentals of the AC and DC circuits. We have got familiar with electro-magnetism also. In this unit we will study the transformer and AC machines. In the AC machines we shall target on the basic principles and construction of the transformer, induction motor and single-phase motors. The transformer is one of the most significant components of a variety of electrical circuits ranging from low power, low current electronic and control circuits to ultra high-voltage power systems. The induction machine determines wide applicability as a motor in industry and in its single-phase form in several domestic applications. More than 85% of industrial motors in use today are actually induction motors.

Objectives

After learning this unit, you should be able to

• explain the transformer and its basic working,
• describe the testing of the transformer,
• describe the fundamental construction of three phase induction machine,
• describe the working principle and speed-torque characteristics of a three phase induction motor,
• understand the variety of single phase induction motors, and
• Describe the servomotors and permanent magnet DC motor.