Reactive Power

Mr. PowerMan has two water drums, A and B. Both are connected by a hose. A drum has a special arrangement, there is fixed a tap to pour water to drink. Mr. PowerMan has a tendency to shake the two drums often, not for any particular reason, but as a habit. While he shakes, water creates turbulence, and does flow from one drum to another, and the direction of flow depends on the instantaneous state of water energy created by the shakes.

Can we relate this simple case with our reactive power concept?

Yes! somehow, we can.

Let us consider two scenarios.

Mr. PowerMan has not touched the drums, they are kept on a table, valve to the glass is closed. In this condition, there will be no change in water quantity and no water flow between the two drums.

In the second scenario, Mr. PowerMan starts agitating the drums. Due to the turbulence, water flows between drums. The direction of water flow depends on the energy of the water. Until the valve is open to pour water into the glass, the water quantity is not changed.

In the second case, water is moving from one drum to another drum. The flow tries to balance energy inequality between the two drums. But total water remains the same. if we pour water in both cases, we can get the same amount of water.

In an electrical system, energy is stored in two fields - magnetic and electric. they can be interchanged between them, as the water flows from A to B or vice versa. The flow of energy between magnetic and electric fields is the result of some agitating action (hence we can tell it is reactive in nature). The flows of energy between fields do not change the amount of energy contained. This energy is reactive energy.

But if we drain some energy from the electric or magnetic field, similar to pouring water into the glass, we are converting the energy to our favorable working format (light, heat, force etc.). This working format of energy can not be restored again into the field energy, its flow is restricted to one direction. This is active energy.

Active energy and reactive energy are not actually different. Both are real. Reactive energy can be turned into active energy if it is liberated from the contained field. Capacitors and inductors are two field-creating devices.