Server Case UK - Order Online Quality Rackmount & Server Cases, SATA/SAS Backplanes, RAID Cards and LCD KVM - Chenbro, PCI Case, Chieftec, 3ware, LSI - Call NOW 0800 652 1649

Live Sales - Click Here
 
Home > FAQ's > View
What is PFC on a Power Supply?

PFC is short for Power Factor Correction.
The PFC is a number between 0 and 1, it is stated as £f ( greek letter Lambda ) which is the ratio of the real power consumed and the RMS power consumed.
There are two forms of PFC, passive PFC (mostly just called PFC) and active PFC.
Passive PFC is done by a choke and active PFC is done by an electronics circuit.
Active PFC is more expensive because it takes more components to build.
The typical figure of passive PFC is 0.65 whilst the typical figure of active PFC is 0.98.
Example calculations ( an efficiency of 85%, AC line voltage of 230V and a power of 300W are used in these calculations ):
Passive PFC: 300W / (230V x 0.65 x 0.85) = 2.36 A (RMS current)
Active PFC: 300W / (230V x 0.98 x 0.85) = 1.57 A (RMS current).
Conclusion: The higher the PFC, the lower the RMS current drawn from the AC line.

Return to FAQ's Listing