
Steady State Analysis of AC Circuits 101
3.5 APPARENT POWER, REAL POWER AND REACTIVE POWER
Apparent power S = rms value of voltage × rms value of current
or S = VI
The apparent power is expressed in volt-ampere, that is, VA or in kilo-volt ampere is kVA.
Real power or active power P or W = Apparent power × Power factor
or P = VI cos f. Watts or kilo-Watts
Reactive power Q = VI sin f VAR or kilo-VAR.
These three types of powers are related as given in the following:
or
SPQ
SPQ
222
22
=+
=+
or
KVA KW KVAR()
3.6 POWER IN R–L SERIES CIRCUIT
Let us now develop a general expression for power in an AC circuit by considering ...