What Does An Active Harmonic Filter Do?

An active harmonic filter is a device used to mitigate or reduce harmonic distortion in electrical systems. Harmonic distortion refers to the presence of frequencies that are multiples of the fundamental frequency in an electrical system. These harmonics can cause a range of issues, including equipment malfunction, power quality problems, and increased energy consumption.

How Does an Active Harmonic Filter Work?

An active harmonic filter works by continuously monitoring the electrical system for harmonic currents or voltages. When it detects harmonics, it generates and injects equal but opposite harmonic currents or voltages to cancel out the harmonics. This process is known as active cancellation.

The active harmonic filter is connected in parallel to the load or equipment generating the harmonics. It constantly measures the harmonic content of the electrical system and adjusts its output to ensure that the harmonics are effectively canceled out.

Benefits of Using an Active Harmonic Filter

Using an active harmonic filter offers several benefits:

  1. Improved Power Quality: Harmonic distortion can cause voltage fluctuations, flickering lights, and overheating of equipment. An active harmonic filter helps to maintain a stable and clean power supply, resulting in improved power quality.
  2. Reduced Equipment Downtime: Harmonic distortion can lead to equipment malfunctions and premature failure. By mitigating harmonics, an active harmonic filter helps to extend the lifespan of electrical equipment and reduce downtime.
  3. Energy Savings: Harmonic distortion causes additional energy losses in electrical systems. By reducing harmonics, an active harmonic filter can help to optimize energy consumption and reduce electricity costs.
  4. Compliance with Standards: Many countries have regulations and standards in place to limit the amount of harmonic distortion allowed in electrical systems. By using an active harmonic filter, businesses can ensure compliance with these standards.
  5. Compatibility with Renewable Energy Sources: Renewable energy sources such as solar and wind power can introduce harmonics into the electrical grid. An active harmonic filter can help to mitigate these harmonics and ensure the smooth integration of renewable energy sources.

Applications of Active Harmonic Filters

Active harmonic filters are used in a variety of applications, including:

  • Industrial Facilities: Active harmonic filters are commonly used in industrial facilities with non-linear loads such as variable frequency drives, rectifiers, and arc furnaces. These loads can generate significant harmonic distortion, which can be mitigated by active harmonic filters.
  • Commercial Buildings: Commercial buildings with sensitive equipment, such as data centers, hospitals, and laboratories, can benefit from the use of active harmonic filters to maintain power quality and protect equipment.
  • Renewable Energy Systems: Active harmonic filters are essential in renewable energy systems to mitigate the harmonics introduced by inverters and other power conversion equipment.
  • Power Distribution Networks: Active harmonic filters can be installed at various points in the power distribution network to mitigate harmonics and maintain power quality for all connected consumers.


An active harmonic filter is a valuable device for mitigating harmonic distortion in electrical systems. By actively canceling out harmonics, it improves power quality, reduces equipment downtime, saves energy, ensures compliance with standards, and supports the integration of renewable energy sources. Active harmonic filters find applications in various industries and are essential for maintaining a stable and efficient electrical system.

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