Power factor controller

Claim 1

For use in conjunction with an alternating current power distribution system having a voltage signal and a current signal, a power factor controller comprising: a plurality of capacitors, wherein the number of capacitors can be varied, means for generating a first signal representative of the number of said capacitors, switch means comprising a plurality of switches, one switch being electrically connected with each capacitor and operable, upon activation, to electrically connect its associated capacitor to the power distribution system, and operable, upon deactivation, to electrically disconnect its associated capacitor to the power distribution system, means for determining the direction and magnitude of a phase shift between the voltage signal and the current signal in the power distribution system and for generating a magnitude output signal and a LEAD/LAG representative thereof, means for comparing said magnitude output signal with a preset phase shift signal, and switch control means responsive to said first signal and to said comparing means for selectively activating one of said switches in said switch means to electrically connect the capacitor in said plurality of capacitors which has been disconnected from the power distribution system for the longest period of time when the magnitude output signal exceeds said preset signal and when said LEAD/LAG is in a first direction and for selectively deactivating one of said switches in said switch means to electrically disconnect the capacitor of said plurality of capacitors which has been electrically connected to said power distribution system for the longest period of time when either said preset signal exceeds said magnitude output signal or said LEAD/LAG signal is in the opposite direction.