APFC (Automatic Power Factor Controllers) is used for centralized reactive power compensation of electrical distribution system composed of varying loads. APFC has a capacitor bank sub-divided into one or more number of step(s), which can be switched on & off automatically by using the APFC Controller. The controller continuously senses the instantaneous magnitude and direction of the reactive power demand through line Current Transformer (CT) and Potential Transformer (PT). It generates a signal for switching and turns the capacitor bank on & off to provide the necessary reactive power (kVAr). This achieves the pre-determined value of Power Factor (PF).