What is 80 PLUS®  ?

80 PLUS is an innovative, electric utility-funded incentive program to integrate more energy-efficient power supplies into desktop computers and servers.

detailed model list and more information you can find here.

• High efficiency
• Low ripple & Noise
• Output over voltage protection
• Short circuit protection on all output
• 100% burn-in under high ambient temperature (50℃)
• Vacuum-impregnated transformer
• MTBF: 100K hours at 25℃
• 100% Hi-pot tested
• Line input fuse protection

• Active PFC and 80plus
  
• High efficiency
• Low ripple &Noise
• Output over voltage protection
• Short circuit protection on all output
• Reset table power shut down

• ATX Series FSP300-60PL
• 20pin connector
• Monitoroutlet
• full range input 90~264VAC
  

Power factor correction

Power factor correction (PFC) is a technique of counteracting the undesirable effects of electric loads that create a power factor (p.f.) that is less than 1. Power factor correction may be applied either by an electrical power transmission utility to improve the stability and efficiency of the transmission network; or, correction may be installed by individual electrical customers to reduce the costs charged to them by their electricity supplier.

Explanation

When an electric load has a p.f. lower than 1, the apparent power delivered to the load is greater than the real power that the load consumes. Only the real power is capable of doing work, but the apparent power determines the amount of current that flows into the load, for a given load voltage.

Energy losses in transmission lines increase with increasing current. Power companies therefore require that customers, especially those with large loads, maintain the power factors of their respective loads within specified limits or be subject to additional charges. Engineers are often interested in the power factor of a load as one of the factors that affect the efficiency of power transmission.

Power factor correction returns the power factor of an electric AC power transmission system to very near unity by switching in or out banks of capacitors or inductors which act to cancel the inductive or capacitive effects of the load. For example, the inductive effect of motor loads may be offset by locally connected capacitors. It is also possible to affect power factor correction with an unloaded synchronous motor connected across the supply. The power factor of the motor is varied by adjusting the field excitation and can be made to behave like a capacitor when over excited.

It is not possible to cancel out harmonic current using these techniques, so different techniques must be used to correct nonlinear loads.

Switched-mode power supplies: power factor correction of non-linear loads

A typical switched-mode power supply first makes a DC bus, using a bridge rectifier or similar circuit. The output voltage is then derived from this DC bus. The problem with this is that the rectifier is a non-linear device, so the input current is highly non-linear. That means that the input current has energy at harmonics of the frequency of the voltage.

This presents a particular problem for the power companies, because they cannot compensate for the harmonic current by adding capacitors or inductors, as they could for the reactive power drawn by a linear load. Many jurisdictions are beginning to legally require PFC for all power supplies above a certain power level.

The simplest way to control the harmonic current is to use a filter: it is possible to design a filter that passes current only at line frequency (e.g. 50 or 60 Hz). This filter kills the harmonic current, which means that the non-linear device now looks like a linear load. At this point the power factor can be brought to near unity, using capacitors or inductors as required. This filter requires large-value high-current inductors, however, which are bulky and expensive.

It is also possible to perform active PFC. In this case, a boost converter is inserted between the bridge rectifier and the main input capacitors. The boost converter attempts to maintain a constant DC bus voltage on its output while drawing a current that is always in phase with and at the same frequency as the line voltage. Another switchmode converter inside the power supply produces the desired output voltage from the DC bus. This approach requires additional semiconductor switches and control electronics, but permits cheaper and smaller passive components. It is frequently used in practice. Due to their very wide input voltage range, many power supplies with active PFC can automatically adjust to operate on AC power from about 100 V (Japan) to 240 V (UK). That feature is particularly welcome in power supplies for laptops and cell phones.

Active PFC

An Active Power Factor Corrector (active PFC) is a power electronic system that controls the amount of power drawn by a load in order to obtain a Power factor as close as possible to unity. In most applications, the active PFC controls the input current of the load so that the current waveform is proportional to the mains voltage waveform (a sinewave).

Some types of active PFC are

1. Boost
2. Buck
3. Buck-boost

Active power factor correctors can be single-stage or multi-stage.

Active PFC is the most effective. Active PFC can have 99% PFC.

Passive PFC

This is a simple way of correcting the nonlinearity of a load by using capacitor banks. It is not as effective as active PFC. Switching the capacitors into or out of the circuit causes harmonics, which is why active PFC or a synchronous motor is preferred.