Advantages and disadvantages of rotor resistance control


  • Absence of in-rush starting current
  • Availability of full rated torque at starting
  • High line power factor
  • Absence of line current harmonics
  • Smooth and wide range of speed control


  • Reduced efficiency because of the slip energy is wasted in the rotor circuit resistance
  • Speed changes very widely with load variation
  • Unbalance in voltages and current of rotor circuit resistances are not equal.