The product of the voltage and the current in phase with the voltage gives the real power or active power.
The power which flows from the source to load and load to source is called the reactive energy. The reactive energy flows in both the direction. The reactive power is measured in kilo volts ampere reactive(kVAR) or MVAR.
The active power in case of purely inductive and capacitive circuit is VICosΦ= VI Cos90=0. The reactive power in case of purely inductive and capacitive circuit VISinΦ= VI Sin90=VI.
Active Component of the Current :
The current which is in phase with the applied voltage is called active component of the current. The active or real power consuption of the load depends on the active current component of the circuit.
Reactive Component of the Current :
Let an electrical inductive load draws current I and phase displacement between voltage and current is Φ.
Active Power of Single phase Load
Active Power of Three Phase Load
The apparent power is the vector sum of the active and the reactive power.
For single phase supply system apparent power drawn cam be expressed by the following mathematical expression.