Page 35 - Basics of Electrical, Electronic and Communication
P. 35
Chapter 8
Three phase induction motor
8.1 Introduction
Three phase induction motor is extensively used for various kinds of
industrial drives. The three phase induction motor has a three phase
wound stator to which the three phase supply is connected. The power
transfer to the rotor is by ’induction’ and that is why these motors are
called induction motors. Three phase induction motors possess many
advantages such as simple design, low cost, rugged construction and
reliable operation. They have good speed regulation and high starting
torque.
8.2 Construction
The main parts of a three phase induction motor are (i) Stator and (ii)
Rotor. The stator is the stationary part and the rotor is the rotating
part. The rotor is separated from the stator by a small air gap whose
thickness(length) depends on the power rating of the motor. There are
two types of three phase induction motors based on the construction of
rotor
1. Squirrel cage induction motor
2. Slip ring induction motor
159
