3 February 2018

Compare Squirrel Cage Induction Motor and Slip Ring Induction Motor

Squirrel Cage Induction Motor

Rotor
  • Copper bars are slotted in the rotor and these bars are short circuited from both ends by end rings
End rings
  • Two end rings are used on both side of rotor
External Resistance
  • As the rotor is short circuited by end rings, extra resistances are not connected.
  • Not used
Starting torque
Speed control
  • Speed control from rotor side is not possible because the rotor itself a closed by end rings.
Copper losses
  • Better space factor for rotor slots, shorted over hang and smaller copper loss
Cooling condition
  • Cooling condition is better because it has bare end rings thus large space available for fan
Overload capacity
  • Better overload capacity
Power factor
  • Better power factor due to smaller rotor overhang
Pull out torque
  • High
Maintenance
  • Less
Construction
  • Simple and robust
Cost
  • Low
Efficiency
  • High
Application
  • Fan, printing machine, lathes, drill machine, blower etc 

Slip ring Induction Motor

Rotor
  • Three phase winding is slotted in the rotor similar to stator winding
End rings
  • End rings are not used
External Resistance
  • External resistance can be added from rotor side
  • Three slip rings and brushes are used as per current capacity at rotor side
Starting torque
  • High starting torque is achieved by adding external resistances to rotor side.
Speed control
  • Speed control is possible by rotor resistance starter
Copper losses
Cooling condition
  • Cooling condition is affected by some times sparking between slip rings and brushes.
Overload capacity
  • Low overload capacity as compared to squirrel cage induction motor
Power factor
  • Comparatively high power factor
Pull out torque
  • Low
Maintenance
  • High
Construction
  • Complicated
Cost
  • High
Efficiency
  • Low as compared to Squirrel cage Induction Motor
Application
  • Lift, compressor, crane, hoist etc.

 You may also like :