Power engineers have introduced the concept of complex power to determine the cumulative effect of parallel loads. This idea plays a crucial role in power analysis because it encompasses all the details related to the power consumed by a specific load.

Complex power is defined as the multiplication of the voltage and the complex conjugate of the current. The magnitude of this power, known as apparent power, is measured in volt-amperes (VA). Notably, the angle of the complex power equates to the power factor angle.

In terms of rms values, complex power is represented by

It can also be expressed in terms of the load impedance, as

Complex power is the product of the rms voltage phasor and the complex conjugate of the rms current phasor. Being a complex quantity, its real portion is referred to as real power P, and its imaginary part is termed reactive power Q. The introduction of complex power allows the direct retrieval of real and reactive powers from voltage and current phasor, demonstrating how complex power encapsulates all pertinent power information in a specific load.

Reactive power represents the energy transfer between the source and the load. For resistive loads, it's zero, for capacitive loads, it's negative, and for inductive loads, it's positive.

One can visualize the complex, real, and reactive power in the form of a triangle, commonly known as the power triangle. This visualization aids in understanding these power concepts.