What is the function of a Reactor?

A reactor is a device that introduces reactance into a circuit.

It is classified into 2 types of reactors:

  • Inductive reactors and
  • Capacitive reactors.

Inductive Reactor

An inductive reactor, also known as an inductor, is a coil of wire wound over a core material like iron or ferrite. When alternating current (AC) travels through a coil, it creates a magnetic field surrounding it. This magnetic field stores energy while opposing changes in current flowing through coil, resulting in inductive reactance. Inductive reactors are utilized for a variety of applications, including filtering, impedance matching, & power factor correction.

Capacitive Reactor

A capacitive reactor, also called a capacitor, is a device which stores electrical energy in an electric field formed by 2 conducting plates separated by a dielectric material. When attached to an AC circuit, a capacitive reactor enables alternating current to flow through it while opposing voltage changes across it, resulting in capacitive reactance. Capacitive reactors are used for power factor adjustment, energy storage, & filtering.

Different Types of Reactors

It is categorized into different types

• Series reactors and

• Shunt reactors.

Series Reactors

This type of reactor is linked in series to the transmission line (or) load. Its primary application is to restrict short-circuit currents, improve voltage regulation, & reduce power system oscillations. Series reactors increase the system’s impedance, lowering the flow of current.

Working Principle

Increases the impedance of the line, which impedes the flow of current. When a problem develops, the series reactor restricts the fault current, lowering stress on the equipment and enhancing system reliability. It also helps to keep voltage levels stable by adjusting for voltage decreases.


A series reactor is one that is connected in series to a transmission line (or) load.


Increased impedance reduces short-circuit currents, improves voltage regulation, & dampens power system oscillations.

Shunt Reactors

Shunt reactors are linked in parallel to the transmission line (or) load. They are primarily used to compensate for capacitive reactive power, regulate voltage levels, and increase power factor. Shunt reactors absorb reactive power while the system voltage is high & release it when the voltage drops, helping to maintain voltage stability.

Working Principle

Reactive power is absorbed or released depending on the system voltage. When the voltage is high, the shunt reactor absorb reactive power, preventing over-voltages. When the voltage drops, the shunt reactor releases reactive power to maintain the system voltage.


The shunt reactor is connected in parallel with the transmission line (or) load.


Capacitive reactive power is compensated, voltage levels are stabilized, and the power factor is improved by absorbing (or) releasing reactive power as needed.