Which type of single phase induction motor is having the highest power factor at full load ?
A. Shaded pole type.
B. Split phase type.
C. Capacitor start.
D. Capacitor run type.
Answer: D
Share your understanding of this question with the correct explanation.
The answer is D. Capacitor run type.
A capacitor run motor has a permanently connected capacitor in parallel with the auxiliary winding. This capacitor helps to improve the power factor of the motor by shifting the current waveform ahead of the voltage waveform. This results in a more efficient motor that draws less current from the power line.
Shaded pole motors have a shaded pole on one or more poles of the stator. This shaded pole creates a rotating magnetic field that helps to start the motor. However, shaded pole motors have a low power factor and are not very efficient.
Split phase motors have two windings, a main winding and an auxiliary winding. The auxiliary winding is connected to the power line through a capacitor. This capacitor creates a phase shift between the currents in the two windings. This phase shift helps to start the motor and also improves the power factor of the motor.
Capacitor start motors have the same construction as split phase motors. However, the capacitor is only connected to the auxiliary winding during the starting period. Once the motor is up to speed, the capacitor is disconnected. This type of motor has a lower power factor than a capacitor run motor.