Why single phase induction motor has low power factor?

    When an induction motor is operating with no load, its power factor is relatively low, typically between 0.1 and 0.3. The no load current, also known as the no load loss component current, has two parts: the magnetizing current and the working current . 

    In order to create a magnetic field in the air gap, the motor uses magnetizing current. If the voltage and frequency are constant, the magnetizing current remains constant. The magnetizing current lags the stator voltage by 90°. The magnetizing current is watt-less current.

Why power factor of single phase induction motor is low?

➤ The low power factor of a single phase induction motor at no load is mainly due to the large magnetizing current (60% - 70%) of full-load current.

➤ When the load on the motor is increased, the current supplied to the motor increases having same magnetizing component. 

➤ Consequently, even at no load, these motors reach temperature close to full-load temperature.

    On no load, the phase angle between the rotor current and the rotor induced voltage is more hence the power factor of the rotor circuit is low.  The stator side reflects the rotor current's equivalent magnitude. The total stator current of the motor is equal to the vector sum of the rotor reflected current and the no load current.

    At no load, the phase angle between the stator current and the stator applied voltage is larger. Therefore, the power factor of the motor is very low about 0.1 to 0.3.