Power Factor in Power Supplies

You may think that the impact of omitting the power factor will result in only a slight error and/or that the power factor of an external adapter cannot be that bad. In fact, without power factor correction, the power factor of an external adapter could easily be as low as 0.5 at a rated load. An adapter with a power factor of 0.5 will have an apparent power twice that of the real power, thus leading to incorrect results. Even if the Power Supply had a real efficiency of 100%, this measurement would only show 50%.

In addition to the general inclusion of power factor in efficiency calculations, it is important to note that the power factor is line and load dependent. Efficiency requirements, such as DoE Level VI, require the efficiency to be measured at several points (25%, 50%, 75%, and 100% load) at both high and low line voltages. If power factor is used in the calculation of real power, then it must be re-measured for each of these conditions.

Shenzhenshi Zhenhuan Electronic Co.,Ltd was founded in 2008, specialize in external power adaptor, ac dc adapter, Outdoor Waterproof power supply, led driver, Power Transformer, switching power supply, dimmable or non-dimmable LED Drivers and Battery Charger in Shenzhen, China.