| Slip ring or phase wound Induction motor |
Squirrel cage induction motor |
| Construction is complicated due to presence of slip ring and brushes. |
Construction is very simple. |
| The rotor winding is similar to the stator winding. |
The rotor consists of rotor bars which are permanently shorted with the help of end rings. |
| We can easily add rotor resistance by using slip ring and brushes. |
Since the rotor bars are permanently shorted, its not possible to add external resistance. |
| Due to presence of external resistance high starting torque can be obtained. |
Staring torque is low and cannot be improved. |
| Slip ring and brushes are present. |
Slip ring and brushes are absent. |
| Frequent maintenance is required due to presence of brushes. |
Less maintenance is required. |
| The construction is complicated and the presence of brushes and slip ring makes the motor more costly. |
The construction is simple and robust and it is cheap as compared to slip ring induction motor. |
| This motor is rarely used only 10% industry uses slip ring induction motor. |
Due to its simple construction and low cost. The squirrel cage induction motor is widely used. |
| Rotor copper losses are high and hence less efficiency. |
Less rotor copper losses and hence high efficiency. |
| Speed control by rotor resistance method is possible. |
Speed control by rotor resistance method is not possible. |
| Slip ring induction motor are used where high starting torque is required i.e in hoists, cranes, elevator etc. |
Squirrel cage induction motor is used in lathes, drilling machine, fan, blower printing machines etc. |
