Active vs Reactive vs Apparent Power: Learn the Differences

In this article, we will give you the definitions of active, reactive, and apparent power. Also, we will check their differences from each other.

What is active power?

The active power is the power that is used by the load to meet the functional output. The active power performs useful work and it is the usable portion of the energy that is present in the grid. It is also called true power or real power. It is measured in watts and represented by “P”.

The following formulas can be used to calculate active power.

In DC circuits

P = V x I

In Single-phase AC Circuits

P = V x I x Cosθ

In Three Phase AC Circuits

P = √3 x V x I x Cosθ

What is reactive power?

Reactive power is the power that is supplied to the load and returned to the source, rather than being dissipated in the load. This is caused by the reactive elements in an AC circuit, specifically inductors, and capacitors which charge and discharge during normal operation. Reactive power is measured as Volt-Amps-reactive (VAr) and represented by “Q”.

The following formulas can be used to calculate reactive power.

In Single-phase AC Circuits

Q = V x I x Sinθ

In Three Phase AC Circuits

Q = √3 x V x I x Sinθ

Reactive Power= √ (Apparent Power²– True Power²)

VAR =√ (VA² – P²)

What is apparent power?

Apparent power is the total power in a circuit at any one time. It includes both dissipated (active) and returned (reactive) power. Apparent power is measured in Volt-Amps (VA) and represented by “S”.

The following formulas can be used to calculate apparent power?

In Single-phase AC Circuits

S = V x I

In Three Phase AC Circuits

S = √3 x V x I

Apparent Power = √ (True power² + Reactive Power²)

VA = √ (W² + VAR²)

The relation between true active power, reactive power, and apparent power

The relationship between these three types of power can be described using the power triangle. Active, reactive, and apparent power are trigonometrically related to each other. Each power type can be described as follows:

P (active power) is the adjacent length

Q (reactive power) is the opposite length

S (apparent power) is the hypotenuse