reactivepower

Reactive power is a component of electrical power in alternating-current systems that alternates between the source and reactive elements, such as inductors and capacitors, storing energy temporarily in magnetic and electric fields. It does not perform net work on a load over a cycle, but it is essential for the operation of many electrical devices and for maintaining voltage levels in a power system.

In AC circuits, reactive power is denoted by Q and is measured in volt-amps reactive (VAR). The apparent power S, measured in volt-amperes (VA), combines real power P (watts, W) and reactive power: S^2 = P^2 + Q^2. For sinusoidal voltages and currents, P = VI cos φ and Q = VI sin φ, where V and I are RMS values and φ is the phase angle between voltage and current. The sign of Q indicates the type of reactance: Q > 0 for inductive loads (current lags voltage, lagging power factor) and Q < 0 for capacitive loads (current leads voltage, leading power factor).

Power systems manage reactive power to maintain stable voltage and reliable operation. It can be supplied or absorbed by equipment such as capacitor banks, reactors, synchronous condensers, or certain power-electronic devices. Correcting the power factor by adjusting reactive power reduces current, lowers losses, and improves voltage regulation, contributing to overall system efficiency and stability.