Active vs Reactive Power: Difference and Comparison

In physics, power is a very important concept for students.

Power is the result of the voltage and current. This concept is equally important in all engineering branches, from mechanical to electrical to electronics engineering branches.

Key Takeaways

  1. Active power is the real power electrical devices consume to perform useful work.
  2. Reactive power is the imaginary power that helps maintain the voltage in the electrical system.
  3. Both active and reactive power are essential for proper functioning electrical systems, but only active power contributes to energy consumption.

Active vs Reactive Power

The difference between active and reactive power is that in the case of active power, the power is used in the circuit, and in reactive power, the power is imaginary and is thought to be used in the circuit for subsidiary purposes. The active power is unidirectional, and on the other hand, the reactive power is bidirectional.

Active vs Reactive Power

The active power is the power that is used in the circuit. The active power exists in both AC and DC circuits. This power exists when the current is in phase with the voltage.

This power is seen flowing and can be measured, so it is called real power.

Reactive power travels from the emergency source towards the load and back from the load to the emerging power. The reactive power is the imaginary power in a circuit.

This power is imaginary as it is not known to be flowing. This power flows due to the reactive components in the circuit.

Comparison Table

Parameters of ComparisonActive PowerReactive Power
DefinitionIt is the power that travels from the source of emergence towards the load.It is the power that travels from the emergence source towards the load and the returns back towards the source.
DirectionIt is unidirectional that is travels in one direction.It is bidirectional that is travels in both direction.
Circuits used inIt is used in both AC and DC circuits.It is used only in SC circuits.
UseThis is used to convert the electrical energy into other forms of energy.This does not convert but produces electric flux in the circuit.
ExamplesActive power is used in toaster, heater, coffee machine, etc.Reactive power is used in refrigerators, air condition, etc.

What is Active Power?

In electrical and electronics, active power is a very important concept for basic knowledge. The active power is the power that is used in the circuit. The active power exists in both AC and DC circuits.

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This power exists when the current is in phase with the voltage. This power is seen flowing and can be measured, so it is called real power.

When the term power is used, it is termed for the active power only. The unit of active power is the same as that of power, which is ‘Watt.’

In the practical field of electrical power work, Kilowatts (kW) and Megawatts (mW) are used. The active power is measured in all circuits to understand the dissipated power from the circuit.

The symbol for the active power used is ‘P.’ The formula for active power is P=V I cos ø, ‘ø’ is the angle between the phase between the current and voltage.

The active power is seen when the current is in phase with the voltage that is the ø is 0 degrees or 180 degrees. Active power is used to convert electrical energy into other forms of energy.

For example, electrical energy to luminance like in a bulb, or electrical energy to optical, etc. Some devices that work in this principle are a toaster, heater, coffee machine, etc.

What is Reactive Power?

In the concept of power, reactive power is a power that is invisible but exists with that of real power.

Reactive power travels from the emergency source towards the load and back from the load to the emerging power.

The reactive power is the imaginary power in a circuit. This power is imaginary as it is not known to be flowing. This power flows due to the reactive components in the circuit.

The reactive power is the resultant power in the case of an AC circuit when the current is out of phase with that of voltage. This is mainly observed when the current is 90 degrees out of phase with the voltage.

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This reactive power is bi-directional. That is, it flows from the emerging source towards the load and the load towards the emergency source.

Reactive power is a form of power, but the unit of this power is not expressed in watts. It is mainly expressed in ‘var’ in AC power systems.

The reactive power is expressed as ‘Q.’ The formula of the reactive power is Q= V I sin ø. Here ‘ø’ is the phase angle between current and voltage, normally 90 degrees.

Main Differences Between Active and Reactive Power

  1. Active power is the power that travels from the source of emergence toward the load. In contrast to that, reactive power is the power that travels from the emergence source towards the load and then returns back towards the source. It is the power that travels from the emergence source towards the load and returns back towards the source.
  2. Active power is unidirectional that is travels in one direction. On the other hand, the reactive power is bidirectional that is travels in both directions.
  3. Active power is used in both AC and DC circuits, whereas reactive power is used only in AC circuits.
  4. Active power is used to convert electrical energy into other forms of energy in comparison to that reactive power does not convert but produces electric flux in the circuit.
  5. Active power is used in toasters, heaters, coffee machines, etc. On the other hand, reactive power is used in refrigerators, air conditioning, etc.
References
  1. https://ieeexplore.ieee.org/abstract/document/57998/
  2. https://ieeexplore.ieee.org/abstract/document/317674/

Last Updated : 11 June, 2023

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10 thoughts on “Active vs Reactive Power: Difference and Comparison”

  1. Active power is the real power consumed by electrical devices to perform useful work, whereas reactive power helps maintain the voltage in the electrical system.

    Reply
  2. It’s interesting to learn about the practical applications of active power in converting electrical energy into other forms of energy, such as in toasters and coffee machines.

    Reply
  3. Reactive power is expressed in ‘var’ in AC power systems and does not convert energy, but produces electric flux in the circuit.

    Reply
  4. The comparison table provides a clear understanding of the differences between active and reactive power, such as direction of travel and circuits used in.

    Reply
  5. It’s fascinating to understand how active power exists in both AC and DC circuits and its application in converting electrical energy into other forms of energy.

    Reply
  6. The information on reactive power and its uni/bidirectional flow, as well as its application in AC circuits, is a valuable addition to understanding power concepts.

    Reply
    • The explanation of the differences between active and reactive power in terms of direction of travel and conversion of energy is very informative.

      Reply
    • It’s interesting to note that reactive power is bi-directional and flows from the emerging source towards the load and the load towards the emerging source.

      Reply
  7. The formula provided for active power (P=V I cos ø) offers a clear definition of the calculation of active power based on the phase angle between the current and voltage.

    Reply
  8. It is important for students to understand the concept of power and its applications across different engineering branches.

    Reply

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