Page 314 - Basic Electrical Engineering
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Power is, P = VI cos ϕ
or, Power = Volt-Ampere × Power factor
3.2.3 Apparent Power, Real Power, and Reactive Power
Apparent power (S)
It is defined as the product of the RMS value of voltage (V) and current (I). It
is denoted by S
Apparent power,
S = VI = Voltage × Current
Unit of apparent power is VA or kVA. (3.12)
Real or true power or active power (P or W)
It is the power which is actually dissipated in the circuit resistance. (watt-full
power)
Active power, P = Apparent power × power factor (3.13)
or, P = VI cos ϕ Watts or kW
Reactive power (Q)
It is the power developed in the inductive reactance of the circuit. (watt-less
power)
