Power Factor

In the equation P =(VmIm/2)cosθ, the factor that has significant control over the delivered power level is the cosθ. No matter how large the voltage or current, if cosθ= 0, the power is zero; if cosθ=1,the power delivered is a maximum.Thus the power factor is defined by,

power factor= cosθ

For situations where the load is a combination of resistive and reactive elements, the power factor will vary between 0 and 1. The more resistive the total impedance, the closer the power factor is to 1; the more reactive the total impedance, the closer the power factor is to 0.

Power factor=True power/ Apparent power