How is reactive power (Q) measured?

Reactive power (Q) is measured in volt-amperes reactive (VAR). This measurement is essential in alternating current (AC) systems, where not all power contributes to useful work. While active power (measured in watts) represents the actual power consumed by electrical devices, reactive power accounts for energy oscillating between the source and the load, which does not perform work but is necessary for maintaining electric and magnetic fields in the system.

In AC circuits, reactive power is crucial for devices with inductance or capacitance, such as motors and transformers, where energy is stored temporarily before being returned to the system. This reactive power is represented separately from active power to ensure proper system design, efficiency, and to manage power factor correction.

The measurement in VAR highlights the power factor and the role of reactive components, which is vital for understanding and optimizing the performance of AC power systems. Other units like watts, volt-amperes, or amperes do not specifically quantify this aspect of power in AC circuits, making volt-amperes reactive the appropriate unit.