Unitraf JSC

Knowledge Base

Reactor (Inductor)

An electromagnetic component used to limit current, smooth waveforms, filter harmonics, or store energy in a magnetic field.

A reactor, also known as an inductor or choke, is an electromagnetic device consisting of a coil wound around a magnetic core. Unlike a transformer, a reactor has a single winding and is designed to introduce controlled impedance into an electrical circuit.

How Reactors Work

When current flows through a reactor's coil, it generates a magnetic field that stores energy. The reactor opposes changes in current (due to self-inductance), which makes it effective at smoothing current waveforms, limiting fault currents, and filtering out harmonic distortion.

Types of Reactors

  • Line reactors — connected in series with the supply to limit inrush current and reduce harmonics from variable frequency drives (VFDs)
  • DC link reactors (DC chokes) — placed in the DC bus of a VFD to smooth the rectified voltage
  • Filter reactors — used in LC/LCL filters for power quality improvement
  • Current-limiting reactors — protect equipment by limiting short-circuit current
  • Smoothing reactors — reduce ripple in DC power supplies

Industrial Applications

Reactors are critical components in modern power electronics and motor drive systems. They protect sensitive equipment from voltage spikes, reduce total harmonic distortion (THD), and improve the power factor of industrial installations.

Unitraf JSC manufactures a full range of reactors for industrial applications, designed to work with variable frequency drives, power converters, and renewable energy systems.

Frequently Asked Questions

Why do I need a line reactor with my VFD?

A line reactor protects your variable frequency drive from voltage spikes on the supply, reduces harmonic currents flowing back to the grid, and limits inrush current during switching. It extends the life of the VFD and improves power quality for other equipment on the same bus.

What is the difference between an AC reactor and a DC reactor?

An AC reactor operates on alternating current and is typically placed on the input or output of a power converter. A DC reactor (DC choke) operates in the DC link of a converter, smoothing the rectified voltage. They have different core designs — DC reactors need air gaps to prevent core saturation.

Related Terms

TransformerMagnetic CoreHarmonic DistortionVariable Frequency Drive (VFD)

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