Electrical Engineering ⇒ Topic : Power Factor

Samual
 
Power Factor The power factor (i. e. cos (Φ) of a circuit can be defined in one of the following ways For example, in a resistor, the current and voltage are in phase i.e. (Φ) = 00. Therefore, power factor of a pure resistive circuit is cos 0^{0} = 1. Similarly, phase difference between voltage and current in a pure inductance or capacitance is 90°. Hence power factor of pure L or C is zero. This is the reason that power consumed by pure L or C is *zero. For a circuit having R, L and C in varying proportions, the value of power factor will lie between 0 and 1. It may be noted that power factor can never have a value greater than 1. (1) It is a usual practice to attach the word 'lagging' or 'leading' with the numerical value of power factor to signify whether the cunent lags or leads the voltage. Thus if a circuit has a p.f. of 0.5 and the current lags the voltage, we generally write p.f. as 0.5 lagging. (2) Sometimes power factor is expressed as a percentage. Thus 0.8 lagging power factor may be expressed as 80% lagging.  
 
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