This book describes the design and development of a power factor compensator via STATIC VAR. This involves measuring the power factor value from the load using 8051 micro-controller and proper algorithm to determine and trigger TRIAC to select capacitor value in order to compensate excessive reactive components, thus bringing power factor near to unity. This book also describes the application of static power factor compensator in Flexible Alternating Current Transmission Systems (FACTS). FACTS devices are used for the dynamic control of voltage, impedance and phase angle of high voltage AC lines. FACTS devices provides strategic benefits for improved transmission system management through: increased transmission system reliability and availability; better utilization of existing transmission assets; increased transmission system reliability and availability; increased dynamic and transient grid stability; increased quality of supply for sensitive industries and enabling environmental benefits.