13 February 2018

Compare Squirrel Cage Induction Motor and Synchronous Motor

Three Phase Induction Motor

  • It requires only three phase alternating supply. It is single excited motor.
  • The speed of the Three phase induction motor decreases as the load on the motor increases.
  • The induction motor runs at lagging power factor.
  • The rotor of the induction may be wound or squirrel cage type.
  • The induction motor is used for driving mechanical loads.
  • The efficiency of induction motor is higher than that of synchronous motor for same voltage rating.
  • The induction motor is known as asynchronous motor because it runs less than synchronous speed.
  • The induction motor is used in industrial drives, textile industries, centrifugal pump, compressor etc. 

Synchronous Motor

  • It requires alternating supply for armature winding and DC supply for field winding. It is doubly excited motor. 
  • The speed of the synchronous motor remains constant. If the load increases beyond its specific rating, the motor becomes out of synchronous.
  • The synchronous motor may runs at lagging, leading or unity power factor.
  • The rotor of the synchronous motor may be cylindrical or projecting ( Salient ) type.
  • It can be used for power factor correcting device. It is called as synchronous condenser when it is operated at leading power factor.
  • The efficiency of synchronous motor is lower than that of induction motor for same voltage rating.
  • The synchronous motor is cheaper than induction motor of low speed high power applications.
  • The damper winding is used in the pole face of rotor in order to dampen oscillations.
  • The application of synchronous machines for constant speed drives for compressors, blowers, fan and low head pumps.
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