11.5 Complex Power (2)

S  =      P             +   j               Q

P: is the average power in watts delivered to a load and it is     the only useful power. Q: is the reactive power exchange between the source and     the reactive part of the load. It is measured in VAR. • Q = 0 for resistive loads (unity pf). • Q < 0 for capacitive loads (leading pf). • Q > 0 for inductive loads (lagging pf).