In this topic, you study the Difference between squirrel cage and slip ring induction motor.
The comparison between squirrel cage and slip-ring induction motors in a tabular form given below will be helpful in understanding the suitability of these motors for different applications as given in Table 1:
Table 1
| Points for Comparison | Squirrel cage Induction Motor | Slip-Ring Induction Motor |
| Construction | Simple and robust construction | Less simple construction |
| Cost | Cheaper | Costlier. |
| Starting | The motor can be started by
(i) Star-delta starter (ii) Stator-resistance starter (iii) Auto-transformer starter. |
The motor requires rotor-resistance starter. |
| Starting torque | Low starting torque. It cannot be increased in an ordinary way | High starting torque. It can be increased by the insertion of external resistance in each
phase of the rotor. |
| Pull-out torque | Pull-out torque greater.
|
Pull -out torque less. |
| Efficiency | More efficiency.
|
Comparatively less efficiency. |
| Power factor | Better power factor on full load.
|
Poor power factor on full load. |
| Speed control | Speed control difficult.
|
Speed control easier.
|
| Maintenance | Requires less maintenance. | Requires more maintenance. |
| Fire hazards | Safe from the point of view of fire hazards as there are no rubbing contacts. | Risk of fire hazards due to sparking at the brushes. |