Automatic electric manufactures power factor controllers to measure system power factor. These controllers automatically switch capacitor banks on/off as required by the plant load to maintain desired power factor. The power factor controllers are available with the facility of programmable target power factor range from 0.8 lag to unity and dead band setting to avoid over-correction and hunting. The capacitor switching of the power factor controllers is first in last out sequential method applicable for equal value capacitor banks and can be changed to ascending or descending order when needed. The power factor controllers are also useful for eliminating power factor penalty fees from power utility bills by automatic maintaining system power factor within set range. Power factor controllers come with salient features like 4-digit, 7-segment led display; display of power factor and set power factor; display of dead band setting in degrees; auto/manual operation; power factor setting range of 0.8 lag to unity; dead band setting range of 4 degrees to 14 degrees; status of all capacitor banks displayed by leds; and status of system power factor with reference to setting displayed on front panel.