Reactive power is a concept in alternating current (AC) electrical systems that represents the portion of power that oscillates back and forth between the source and the load without being consumed by the load itself. It arises due to the presence of reactive components such as inductors and capacitors in the circuit.
In an AC circuit, the power consists of two components: real power (also known as active power) and reactive power. Real power is the actual power consumed by the resistive elements in the circuit and is responsible for performing useful work, such as producing light, heat, or mechanical motion. Reactive power, on the other hand, does not perform any useful work but is necessary for the functioning of certain types of devices and equipment, particularly those with inductive or capacitive components.
Inductive loads, such as electric motors and transformers, consume reactive power because they store energy in their magnetic fields during one-half of the AC cycle and release it during the other half. Capacitive loads, like capacitors used in power factor correction systems, also generate reactive power as they store and release energy in their electric fields.
Reactive power is measured in units called "volt-amperes reactive" (VAR) or "kilovolt-amperes reactive" (kVAR). It doesn't directly contribute to the actual work done by the circuit but plays an essential role in maintaining voltage levels, ensuring proper phase relationships, and overall system stability. It's important to manage reactive power in an AC system to optimize its efficiency and reduce wastage.
The combination of real power and reactive power gives rise to the concept of apparent power, which is the total power flowing in an AC circuit and is measured in units called "volt-amperes" (VA) or "kilovolt-amperes" (kVA). The relationship between real power, reactive power, and apparent power is described by the power factor, which is the ratio of real power to apparent power. Power factor is a crucial factor in power distribution and consumption efficiency.