When it comes to switched power supplies, is the power supply efficiency affected by the presence of a power factor correction circuit? In my understanding power supply efficiency is estimated by measuring the ratio of power drawn from the electrical outlet when the power supply works under several loads, for instance 20,50 and 100% loads are analyzed in computer PSUs to give the 80 plus certificate, but is the presence of a power factor correction (PFC) circuit improving the efficiency? Do they take under account the reactive power drawn from the outlet to estimate the ratio to compute the efficiency or just real part and then the PFC circuit has no influence?
In the field of engineering, efficiency means thermodynamic efficiency, real output power divided by real input power. A power factor correction circuit reduces the efficiency of the equipment that contains the circuit but improves the overall system efficiency by reducing the RMS current required to transmit a given amount of real power.
In the case of switched power supplies, the power factor correction circuit improves the total power factor by reducing the harmonic distortion of the input power waveform. The benefit is partly reducing the current required, but perhaps more importantly, preventing the power supply from contributing to distortion of the voltage of the source power system.