# Why a Reactor is used with a Capacitor Bank?

**URL:** <https://forumautomation.com/t/why-a-reactor-is-used-with-a-capacitor-bank/14590>\
**Category:** Electrical\
**Tags:** capacitance\
**Created:** [November 11, 2026, 3:07pm UTC](https://forumautomation.com/t/why-a-reactor-is-used-with-a-capacitor-bank/14590 "2026-11-11T15:07:54Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![Rabert](https://forumautomation.com/user_avatar/forumautomation.com/rabert/32/6784_2.png) [@Rabert](https://forumautomation.com/u/Rabert)\
**Post date:** [November 11, 2026, 3:07pm UTC](https://forumautomation.com/t/why-a-reactor-is-used-with-a-capacitor-bank/14590/1 "2026-11-11T15:07:54Z")

</div>

# Why a Reactor is used with a Capacitor Bank?

When a reactor is connected in series with a **[capacitor bank,](https://forumelectrical.com/capacitor-bank-factory-acceptance-test-fat-checklist/)** it is called a Detuned Reactor. It serves two critical protection purposes:

1. Harmonics Mitigation
2. Limiting Inrush Current

## Harmonics Mitigation

Modern industries use non-linear loads like VFDs, UPS systems, and LED lighting, which inject harmonics (distortions) into the power grid.

Capacitors naturally attract these high-frequency harmonic currents, which can cause them to overheat, swell, or explode.

The reactor acts as a barrier, blocking or absorbing these harmonics to protect the capacitor.

 ![1](https://cdn.forumautomation.com/original/2X/1/16f1fb7b0786763c927892266d46d6ff3b55fc5d.jpeg)

## Limiting Inrush Current

When a capacitor bank is switched on, it acts like a temporary short circuit, drawing a massive spike of current known as inrush current.

This spike can weld contactor contacts and trip circuit breakers.

The **[reactor](https://forumelectrical.com/reactor-switching-voltage-drop-calculator/)** introduces inductive impedance that chokes and dampens this initial current spike.