What's PFC? (Power Factor Correction)
Power factor is the relationship between working (active) power and total power consumed (apparent power). The ratio of true ac input power to the apparent ac input power. Essentially, power factor is a measurement of how effectively electrical power is being used. A higher power factor represents a more effective use of electrical power. Power Factor Correction on a switching power supply controls the timing and wave shape of the input current drawn to maintain the current waveform approximately in phase with and of the same shape as the line voltage. This results in a power factor of approximately 1.0. This is important when electronic equipment consumes a significant amount of power, since otherwise the facility power system could exceed its current ratings for the power consumed and potentially impact other equipment on the same power system.
In normal , electronic equipment without PFC function , the PF is around 50% only.
Why we need PFC?
The benefits of Power Factor Correction include:
- Reduced electric utility bills ( a typical payback period is less than six months to a year)
- Increased system capacity
- Improved voltage
- Protects your invenstment in Model Railroad Trains and Equipment
Low power factor means poor electrical efficiency. The lower the power factor, the higher the apparent power drawn from the distribution network. When low power factor is not corrected, the utility must provide the nonworking reactive power in addition to the working active power. This results in the use of larger generators, transformers, bus bars, wires, and other distribution system devices that otherwise would not be necessary. Electronic equipment with PFC could promote it-self energy utilization to help cut consumer bill in percentage , also PFC is a environment friendly technology, reducing the harmonics that creat electrical polluation to benefits the society as a whole
How can a PFC power supply save energy?
By reducing the volt-amperes your electric utility has to deliver in order to provide a gene power level demanded by the power supply. Much less power is lost in generating useless “harmonics” that unnecessarily load down the AC electrical delivery system.
What is harmonics?
Harmonics are a form of noise, produced in frequencies which are a multiple of the basic 60 cycle sine wave. They are caused by switching power supplies and in other sophisticated machines, including computers and variable frequency drivers. Harmonics can distort the basic sine wave, as well as cause high currents on the neutral and ground wires in a system.
What countries are adopting the PFC requirement for electronic equipment?
January 2001, European Union have adopted the requirement for new electronic equipment that consumes more than 75 watts to meet the EN 61000-3-2 specification for harmonic content. In
, since May 1 , 2002, all electrical products used in governmental institutions must be with PFC ,
is now developing a new project for power saving , and in the foreseeable future, the US
as well , will adopt power management regulations.