Capacitor Start and Run Induction Motor

 Capacitor Start and Run Motor
  • It consists of starting winding and running winding. 
  • The starting winding is connected is in series with capacitor and there is no centrifugal switch it means that the capacitor is permanently connected in the circuit. 
  • As the capacitor is permanently connected it is also called as Permanent split capacitor run motor. 
  • As the capacitor is used during starting and running condition neither optimum starting nor running performance is achieved. 
  • The rating of the capacitor is in the range of 2 to 20 µF and it is oil or paper foil type continuous duty type capacitor. 
  • If the rating of the capacitor is selected in the low range, very low starting torque is achieved.  
  • It is practically behaves like unbalance two phase motor.

capacitor start and capacitor run motor

Function of the capacitor
  • Improve power factor
  • Improved efficiency
  • Quieter operation
  • Improved overload capacity

torque speed characteristic of the capacitor start and capacitor run motor

As the starting torque is very low it is used in the
  • Fans
  • Blowers
  • Voltage regulator circuit
  • Oil burners

Forward – Reverse rotation

  • If the starting and running winding is identical, the forward and reverse rotation of the motor is possible by connecting external forward – reverse switch.


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