What is the power factor?  Eq PF = TP/AP AP= Apparent Power TP= True Power or Real Power A number that represents the portion of the apparent power dissipated as true power. (Number represented as a decimal fraction or percentage.)

In an electric power system, a load with a low power factor draws more current than a load with a high power factor for the same amount of useful power transferred. The higher currents increase the energy lost in the distribution system, and require larger wires and other equipment. Because of the costs of larger equipment and wasted energy, electrical utilities will usually charge a higher cost to industrial or commercial customers where there is a low power factor. An automatic power factor correction unit consists of a number of capacitor that are switched by means of contactors. These contactors are controlled by a regulator that measures power factor in an electrical network.

 Substituting the equations for TP and AP in the Power Factor equation will yield: I R 2 R / I T 2 Z = PF

For Series Circuits Only!! In series circuits, the current is the same, and I R equals I T. Therefore this power factor equation becomes: Eq I R 2 R / I T 2 Z R / Z = PF

Eq is modified as: Eq I R / I Z = PF (Note: I Z = I T )

Eq PF = Cos θ S= Apparent Power P= True Power Q= Reactive Power

 Find the power factor of a series circuit when R=5kΩ, Z=7.07kΩ, θ= 45°, V S = 20V, and I T = 2.82mA

PF = (2.82mA) 2 *5kΩ/(2.82mA) 2 *7.07k Ω =.707 PF = 5kΩ/7.07kΩ =.707 PF = Cos 45° =.707 Find the power factor of a series circuit when R=5kΩ, Z=7.07kΩ, θ= 45°, V S = 20V, and I T = 2.82mA

Last equation to know EEq ▪T▪TP = I T V S Cos θ Combining the previous equations gives us an equation for true power that is universal. Can be used for any type of circuit.

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