Merus Active Harmonic Filters

Merus active harmonic filters provide a solution for real-time cancellation of harmonic distortions created by non-linear loads to ensure compliance with IEEE 519, G5/4 and other power quality standards and recommendations. Merus active harmonic filters are a versatile solution, easily tailored to deliver power factor improvement, voltage variation control, flicker mitigation and load balancing functionality.

The Merus A2-series active harmonic filters are built on 3-level topology and are designed for light industrial and commercial buildings with voltage level up to 690V in both 3W and 4W applications. Merus M-series active harmonic filters are customized for demanding applications and are available from 480V up to 1000V. Equipped with state-of-the-art monitoring and reporting functionality, the robust Merus active filters operate in harsh environments and are easily scalable. Merus A2-series active harmonic filter have UL-certificate of compliance.

Functions and customer benefits

Key functions

  • Active harmonic filtering

  • Power factor correction

  • Voltage variation control and flicker mitigation

  • Load balancing in three-phase systems

Customer benefits

  • Energy savings

  • Higher productivity

  • Reliable plant operation at reduced maintenance costs

  • Longer lifetime of electrical and process equipment

  • Additional electric capacity in existing electrical network

  • Compliance with IEEE 519, G5/4, IEC 61000 3-2, 3-4 or any other power quality standards and recommendations

  • Quick return on investment


Merus Active harmonic filtering technology can be applied to wide range of industrial or commercial environments where good power quality is essential. Merus active harmonic filters have been used for the processes that use Variable Speed Drives (VSD), fast fluctuating loads such as welding machines, Uninterrupted Power Supply (UPS) systems and DC load, single phase loads such as lighting and computers as well as electric arc furnaces and rolling mills.

Applications in commercial buildings

  • Data centers & IT

  • Airports

  • Hospitals and laboratories

  • Residential buildings

  • Shopping malls

  • Financial institutions

  • Ski resorts

  • Amusement parks

Applications in infrastructure and renewable energy

  • Water and wastewater treatment plants

  • Heating, ventilation and air conditioning systems (HVAC)

  • Wind and solar farms

  • Traction

  • Metro stations

  • Cranes

  • Lifts

Applications in industry

  • Welding processes in automotive industry

  • Printing industry

  • Chemical Industry

  • Steel industry

  • Cement industry

  • Food and beverage industry

  • Oil and gas industry

  • Pulp and paper industry

  • Textile and clothing industry

  • Pharmaceutical industry

  • Microelectronic manufacturers

  • Package sorting facilities

  • Marine vessels

Modern 3-level topology

Merus A2-series active harmonic filters are built on modern 3-level topology which brings several benefits compared to other active filters built on the conventional 2-level topology. In 3-level topology, the switching frequency and voltage stress are distributed among the two IGBTs. Reduced stress extends the lifetime of the power electronics. The efficiency and lower losses achieved with 3-level topology are excellent. These make the overall cost of ownership much lower compared to conventional solutions.

Product features

Excellent harmonic mitigation with guaranteed compliance

Merus active harmonic filters deliver a real-time response to power quality problems. They sense the harmonic distortions created by the non-linear loads in the network and provide an effective and real-time response to cancel harmonic distortions. Merus A2-series active filters ensure a guaranteed compliance with the harmonic distortion limits specified in IEEE 519, G5/4, IEC 61000 and other power quality standards and recommendations.

Automatic voltage and frequency sensing with smart operation mode

Merus active harmonic filters come with several advanced features. When connected to the network, they automatically sense the voltage and frequency, simplifying the order and delivery processes. A2- series active harmonic filters are also equipped with the built-in smart operation mode. Under low load conditions, the smart operation mode automatically turns off the IGBTs and fans reducing the operational losses and extending the lifetime of the active harmonic filters.

Unlimited scalability

Unlimited scalability can easily be achieved with Merus A2-series active harmonic filters in both; open-loop as well as closed-loop connections. Higher harmonic compensation capacity can be achieved by adding A2-series active harmonic filters modules in parallel without any technical limitations. This gives flexibility to facility engineers when more loads are added in the facilities.

Customizable functionality with several built-in operation modes

Merus active harmonic filters are extremely flexible devices. Merus active harmonic filters functionalities can be customized anytime with a modern touch screen Human Machine Interface (HMI) to meet customer requirements. This allows Merus active harmonic filters to adapt to the changes in the loads. Customer can choose if they want to cancel all the harmonics up to 50th order, or only the selective ones. Furthermore, output capacity of Merus active harmonic filters can be flexibly used to control voltage variations, flicker mitigation, load balancing and power factor improvement.

Compact design and ease of integration

Standard A2-series active harmonic filter is in IP20 protection class module. Extremely compact size allows easy integration into variable speed drives (VFDs) or capacitor bank cubicles. Merus Power can also deliver active harmonic filters in IP42, IP54 or others degrees of protection upon request. Furthermore, A2-series active filters can also be delivered in stand-alone wall-mounted design.

Extremely low noise harmonic filtering solution

Pollution comes in many forms: harmonics pollute the electrical power system, and high audible noise pollutes and disturbs people working in close proximity. Merus A2-series active filters, enabled by 3-level topology, release the lowest possible audible noise among all active filters. Designed with high switching frequency and special inductor core material, Merus A-2 series active filters can be installed into spaces where silence is vital.

Ease of commissioning with modern power quality monitoring and reporting

Merus A2-series active harmonic filters are equipped with sophisticated 7” Human Machine Interface (HMI). Commissioning of the device is simplified and hassle free with the help of the built-in Commissioning Wizard. When connecting the device to the network, the active harmonic filter automatically senses the voltage and the frequency of the system. After acknowledging the voltage and the frequency of the system, Commissioning Wizard guides the user one step at a time to parametrize the device leading to successful commissioning.

Comprehensive monitoring and reporting

Merus A2-series active harmonic filters come with advanced and comprehensive monitoring & reporting features. They not only efficiently filter harmonic distortions from your electrical network but also give you comprehensive power quality report from the last 30 days. It enables before and after analysis by providing you data of harmonic distortions from both supply and load side. The device can be monitored and controlled remotely. SCADA systems can be connected to the device via Modbus TCP. The remote monitoring and controlling services open up possibilities for Internet of Things (IoT) applications.

How Merus active harmonic filter works

Merus active harmonic filters are connected in parallel with the loads to be compensated. They measure the current of the non-linear load and inject the same harmonics, but with opposite phase angle. The current of the active harmonic filter thus cancels out the harmonic currents of the load, and only fundamental frequency current component is left to be supplied from the power system.

In addition to current and voltage profile smoothing by harmonic current mitigation, the active filters also provide fast fundamental frequency reactive power compensation and balance loads in three-phase systems. Reactive power compensation stabilizes voltage, mitigates flicker, releases additional capacity for transferring more active power in the existing electrical network and improves the power factor. Fast response to reactive power changes is important, for example, in electric arc furnaces. A typical case where load balancing is needed is a phase-to-phase connected welding equipment that burdens only two of the three lines and can thus create voltage unbalance between the phases. Merus active harmonic filters can be installed to cancel harmonics of the individual large load or group of loads.

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Power System Solutions | 250 Hogan Lane | Conway, AR 72034