As shown on this slide, to maximize PFC in a circuit voltage and current must be in phase. This means the peaks of voltage and current occur at the same point in time. Maximum power occurs when voltage and current are in phase, when power is equal to the voltage multiplied by the current. Such a circuit is said to have a nearly “perfect” Power Factor Correction (PFC). Near “perfect” PFC results in a circuit with no reactive power. Reactive power is the result of circuits with capacitance and/or inductance, which can result in voltage and current being “out of phase”. When voltage and current are “out of phase” PFC is not maximized… not efficient.