Reactive power is defined as power flow that does not perform work. It is created by a non-resistive load, either inductive or capacitive. Usually the typical load in an electrical distribution system is inductive. In an inductive load, the power transferred down the distribution system to the inductor, is briefly stored in a magnetic field and then returned back to the utility a short time later. This back-and-forth transfer causes more current flow in the system. In a load that is capacitive, the power is briefly stored in an electrostatic field before being returned back into the system.
In either inductive or capacitive system, reactive power is sent through the entire distribution system down to the inductance or capacitance, briefly held in magnetic or electric fields, and then returned back to the system every 60Hz cycle. Although a considerable amount of power can move back and forth, the net real power from this is zero, because no useful work is done with reactive power. The current flowing to move reactive power back and forth is real and causes higher losses in a power transmission system.