An Active Harmonic Filter as a solution for harmonic pollution

Reducing risks and ensuring safety

An Active Harmonic Filter can be introduced as a solution for several different kinds of Power Quality problem. The most common application is reducing harmonic pollution within electrical installations. An Active Harmonic Filter helps ensure ‘clean’ current.

Active harmonic filer module close-up

Benefits of installing an Active Harmonic Filter:

  • Prevention of breakdown and equipment failure
  • Maximum utilization of installation capacity
  • Improvement of energy efficiency
  • Securement of reliability and continuity
  • Reduction of service and maintenance costs
  • Prevention/reduction of unnecessary energy losses
  • Increased safety by reducing fire risk

Benefits of Cos Phi compensation with a capacitor bank


Owing to the rise and growth of non-linear loads, such as power electronics, demand for Active Harmonic Filters has increased in most networks. In addition, an Active Harmonic Filter remains an excellent solution for very specific situations. These include large power installations, such as installations with electric arc furnaces, induction furnaces and/or welding equipment.

Usage of Active Harmonic Filter

What causes harmonic pollution?

Harmonic pollution is the result of harmonics in electricity. These harmonics are caused by non-linear loads in the network. One example of a non-linear load would be a LED lamp. Depending on the strength of the network (network impedance) and the magnitude of the harmonic currents, the voltage will distort and voltage quality will deteriorate. As a result connected equipment may malfunction or fail. In addition, the harmonic currents may overload the equipment and cables, resulting in (energy) losses and unnecessary heating of cables and components. A worst-case scenario could be temperature buildup resulting in a fire.
The Active Harmonic Filter reduces risks by reducing harmonics.

A maximum of 5% harmonic pollution

Harmonic pollution is a threat to operational reliability, energy efficiency and safety of electrical installations. Therefore, it is important to ensure the total harmonic pollution does not exceed a level of 8%, as prescribed by the Netcode (NEN-EN 50160). In specific situations HyTEPS recommends a maximum of 5%. In weak networks such as offshore installations, for example, or in critical sectors such as data centers and hospitals.

By installing a correctly dimensioned Active Harmonic Filter, you can reduce harmonic pollution and all associated risks.

Illustration Harmonic Pollution THDU

The functioning of an Active Harmonic Filter

An Active Harmonic Filter is used to improve Power Quality through autonomous detection and dynamic filtering of harmonic currents present in the installation. The Active Harmonic Filter can detect any harmonic current flowing through the installation and counteract these. Detection of harmonic currents can take place on the power supply to a single harmonics- inducing load, or it can detect harmonic currents in the power supply of the total electrical installation.

On the power supply of a single load, the filter can focus all its capacity on this particular load and make sure that the harmonics induced by this device are countered before they can access other parts of the installation. This is very useful in situations where a large part of the harmonic pollution is created by a single device or device group on a sub-distribution board.

If a filter is placed on the main power supply, it can counteract all harmonic currents present before they can reach the transformer or generator. In this case, however, any harmonic currents present will be able to flow through a bigger part of the electrical installation. Filtering on the main power supply is a very useful solution when a large number of small harmonic-inducing devices are collectively causing large amounts of harmonic pollution.

Two typical characteristics

Fast response time
Our harmonic filters have a very fast response time, so that harmonic pollution and malfunctions are almost immediately detected and eliminated before they cause any damage or problems.

Adjustable and dynamic
The type of pollution the filter set to focus on can be chosen by setting parameters correctly. It is also possible to set the degree to which this pollution must be eliminated. The Active Harmonic Filter is dynamic and continuously adjusts to changing circumstances. Parameters of the Active Harmonic Filter can also be adjusted at a later time. This makes the filter future-proof and effective throughout its lifetime.

Reduction of the harmonic currents and pollution considerably lowers the chance of malfunctions and problems occurring. An additional advantage is the fact that an Active Harmonic Filter reduces the absorption of reactive power and equipment wear and tear. This results in further cost savings.

Parameters instellen Actief Harmonisch Filter

Result of filtering harmonic currents

A transformer or generator has relatively high impedance, compared to the rest of an installation, especially for the higher frequencies harmonics consist of. If these harmonic currents flow through any impedance, they will introduce harmonic voltages. The higher the impedance, the higher the harmonic voltages. Especially when induced on the main power supply, these harmonic voltages can access the total installation and cause major problems. These are explained under ‘Harmonic pollution’.

When harmonic currents are counteracted by the Active Harmonic Filter, they can no longer flow through certain parts of the electrical installation – the transformer or generator in particular. When the harmonic currents no longer flow through these specific high impedance areas of the electrical installation, harmonic voltages will no longer be induced and Power Quality will greatly improve. For the best filtering results, filtering should take place as close to the source of pollution as possible.

Chart power and voltage WITHOUT	Active Harmonic Filter

Chart power and voltage WITHOUT Active Harmonic Filter

Chart power and voltage WITH Active Harmonic Filter

Chart power and voltage WITH Active Harmonic Filter

Why a HyTEPS Active Harmonic Filter?

Harmonic pollution is a key characteristic of poor Power Quality. Over the years, HyTEPS - a specialist in the field of Power Quality - has gained a considerable amount of knowledge and experience in this field. This is the result of measuring, analyzing and solving the most complex Power Quality problems in a wide range of installations and sectors. We have the knowledge, experience and products to tackle harmonic pollution within each installation.

Advantages HyTEPS offers:

  • We have many years of experience and can, therefore, rapidly respond to potential problems
  • Through measurements, analyses and calculations we create the most suitable Active Harmonic Filter for your specific installation and situation
  • If required, we can offer your installer support during installation
  • Commissioning and reports are provided exclusively by our own engineers
  • We offer inspections, service and maintenance to ensure proper functioning of the Active Harmonic Filter
  • Harmonic compensation can be adjusted from the 2ndto the 50thharmonic with our filters
  • Each specific harmonic can be compensated to a desired level
  • An Active Harmonic Filter from HyTEPS can be read remotely via MODBUS communication over Ethernet
  • The response speed of our filters is <300μs, allowing rapid harmonic variations to be resolved without any problems
  • Due to the reaction speed, harmonic variations are solved quickly without problems
  • Settings on the Active Harmonic Filter are easy to change and monitor
  • The filter easily can adapt to changing loads
  • The Active Harmonic Filter can also be set to compensate for current unbalance between phases, reducing the voltage unbalance to a minimum.

HyTEPS provides you with the best fitting solution


We have the knowledge and experience to advise, implement and maintain the right solution. Through measurements and analyses we gain insight into the installation, load(s) and harmonic pollution. We use this information to advise you on the best fitting solution; an Active Harmonic Filter or Passive Harmonic Filter. All of the Harmonic Filters we supply are from respected manufacturers with their own R&D and engineering departments. In this way, the high-quality filters remain continuously aligned with changes in society and are developed in accordance with the latest scientific insights.