Define what is active power, reactive power, apparent power & power factor

Active, Reactive and Apparent Power

Consider a series R-L circuit connected across voltage of value V draws an current I. Let the current I lags behind the applied voltage by an angle ϕ. In this case there are three types of power drawn by circuit.

Active Power (p)

It is the power which is actually dissipated by resistance in the circuit.

Reactive Power (Q)

It is the power developed in the inductive reactance of the circuit

Apparent Power (S)

It is given by the product of rms value of voltage and value of circuit current.

Therefor, S = VI = (IZ)I = I2Z in volt amp (VA) of kVA Fig. shows a power triangle in which

Power Factor (P.F.)

Power factor is defined as (a) Cosine of an angle of lead or lag P.F. = cos ϕ (b) The ratio of resistance value to impedance value,PF=R/Z .(c) the ratio of true power to the Apparent power value .


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