Electrical Engineering ⇒ Topic : Phasor Diagram of Sine Waves of Same Frequency

Phasor Diagram of Sine Waves of Same Frequency

Consider a sinusoidal voltage wave y and sinusoidal current wave i of the same frequency.Suppose the current lags behind the voltage by Φ. The two alternating quantities can be represented on the same phasor diagram because the phasors V_m and I_m [See Fig. a (i)] rotate at the same angular velocity co** and hence phase difference 4) between them remains the same at all times.

When each phasor completes one revolution, it generates the corresponding cycle [See Fig. a (ii)]. The equations of the two waves can be  represented as

                                                                              figure (a)

The following points may be noted carefully

• The wave diagram and the phasor diagram convey the same information. However, it is more difficult to draw the waves than to sketch the phasor diagram.
• Since the two phasors have the same angular velocity (ω) and there is no relative motion between them, they can be displayed in a stationary diagram, the common angular rotation (ωt) being disregarded.