What is Phasor Diagram for AC Series Motor?

What is Phasor Diagram for AC Series Motor?

Phasor diagram definition

The phasor diagram illustrates the phase relationship between different electrical quantities in AC series motors.

Characteristics of AC series motor

• Power factor characteristic

• Velocity current characteristic

• Torque current characteristics

• Torque speed characteristics

• Power output characteristic

Power factor

A high power factor requires low reactance and back electromotive force, which decreases when overloaded.

Velocity and back electromotive force

The speed of the motor is proportional to the back electromotive force, and the AC motor has a lower speed due to the higher voltage drop.

Torque and current

Ignoring the small phase Angle (the Angle between the magnetic flux and the current) and the saturation effect, torque is proportional to the square of the current.

Torque speed characteristics

The relationship between torque and speed can be derived from the torque current and speed current characteristics. The torque speed characteristics are shown in the figure.

Power output characteristic

The mechanical output power of an AC series motor is calculated by multiplying the back electromotive force and current. The mechanical power is proportional to the current, if we ignore the slight decrease in the back electromotive force as the current increases.