Exam Question
Differentiate between squirrel cage and wound rotor motors, of the three phase a.c. induction type, in respect of the following: (16)
(a) Rotor construction
(b) Torque characteristics
(c) Speed variation
Class 4 (4th Engineer)
MET
📅 May 2024
Reference Answer
### Introduction
Three-phase A.C. induction motors are the most common type of motor used for marine applications. They operate on the principle of a rotating magnetic field produced by the stator winding inducing a current and subsequent magnetic field in the rotor, resulting in torque. The two primary types are the Squirrel Cage Induction Motor (SCIM) and the Wound Rotor Induction Motor (WRIM), also known as the Slip-Ring Motor. Their fundamental difference lies in the rotor construction, which in turn dictates their performance characteristics regarding torque and speed control.
### (a) Rotor Construction
**1. Squirrel Cage Motor:**
Three-phase A.C. induction motors are the most common type of motor used for marine applications. They operate on the principle of a rotating magnetic field produced by the stator winding inducing a current and subsequent magnetic field in the rotor, resulting in torque. The two primary types are the Squirrel Cage Induction Motor (SCIM) and the Wound Rotor Induction Motor (WRIM), also known as the Slip-Ring Motor. Their fundamental difference lies in the rotor construction, which in turn dictates their performance characteristics regarding torque and speed control.
### (a) Rotor Construction
**1. Squirrel Cage Motor:**
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