The PFC is the abbreviations of Power Factor Correction, using for improving the ratio value between the efficient power of the power input terminal and the apparent power. Generally for the machine type without the PFC circuits, the power factor of its input terminal, when the rated power is over 80%, is only 0.4~0.65; moreover; however the power factor of the active PFC circuit is over 0.95; the relational expression is detailed as follows:

Apparent power = input voltage x input current (VA)

Efficient power = input voltage x input current x power factor (W)

Note: The power generation plant must generate the electric energy larger than the apparent power, if so a stable electric energy can be supplied; however what the electric energy is used actually is the effective power. If the power factor is 0.5, it means the power generation plant generates the electric energy of 2VA power, which can then offer 1W power safely; so the energy operation efficiency is very poor; contrarily, if the power fact is 0.95, as long as the power generation plant generates the electric energy of 1.06VA, it shall be no problem to offer the electric energy of 1W; if so the energy operation efficiency is sound better.