Power factor (PF) is one of the most important but often misunderstood quantities of AC power. It is sometimes incorrectly referred to as a characteristic of power quality. In reality, PF is a property of the load downstream of the electric source, rather than a property of the source itself. There is another common misconception that PF is just cosφ, where φ is the phase angle between the voltage and current. This is true only in an ideal case of a linear circuit with sinusoidal input. In general, power factor is much more than cosφ, as you can learn from our tutorial.

How does PF have to be taken into account by design engineers and when should it be corrected? There are three main scenarios:

This site is designed as a quick educational reference source for all information related to power factor correction techniques. Here you will find tutorials and calculators intended for newbie engineers, students and hobbyists. We will also discuss the question of whether or not homeowners and consumers should worry about PF of their appliances.