Introduction:
Single-phase induction motors are widely used in various applications due to their simplicity, low cost, and robust construction. However, these motors typically have a lower power factor compared to three-phase induction motors. The power factor is a measure of the efficiency of power utilization in an electrical system. A higher power factor indicates better utilization of electrical power and reduces the overall power consumption. In single-phase induction motors, the type of motor that exhibits the highest power factor at full load is the capacitor-run type.

Explanation:

1. Shaded Pole Type:
The shaded pole type single-phase induction motor is the simplest and most cost-effective motor. It consists of a main winding and a shaded pole winding. The shaded pole winding creates a rotating magnetic field that starts the motor. However, this type of motor has a low power factor due to the phase difference between the magnetic field and the applied voltage.

2. Split-Phase Type:
The split-phase type single-phase induction motor is commonly used in household appliances and light-duty applications. It has a main winding and a starting winding with a centrifugal switch. The starting winding is disconnected once the motor reaches a certain speed. This type of motor also has a low power factor due to the phase difference between the windings.

3. Capacitor-Start Type:
The capacitor-start type single-phase induction motor is designed to provide higher starting torque. It has a main winding, a starting winding, and a capacitor. The capacitor creates a phase shift between the windings, which helps in starting the motor. However, the power factor of this type of motor is still relatively low.

4. Capacitor-Run Type:
The capacitor-run type single-phase induction motor is specifically designed to improve the power factor. It has a main winding, a starting winding, and a capacitor that remains connected during operation. The capacitor creates a phase shift and helps in improving the power factor. This type of motor has the highest power factor among the single-phase induction motors at full load.

Conclusion:
In summary, the capacitor-run type single-phase induction motor has the highest power factor at full load. The presence of a capacitor in the motor circuit helps in improving the power factor by creating a phase shift. This type of motor is commonly used in applications where a higher power factor is desired to improve energy efficiency.

1-phase induction motor is not self starting, so it is used to start with a different method at full load condition. Capacitor-run type motors have higher power factor. In this type, the capacitor is connected in running condition.