Merus® 4DRIVES
Active Harmonic Filter
for VFDs

Merus® 4DRIVES is an optimized active harmonic filter for Variable Frequency Drives (VFD) that is very easy to operate and commission. It is our simple solution to complex power quality problems.

A solution made easy to use

  • User-friendly operation and functionality with easy commissioning
  • Simple to integrate into VFD scope of supply
  • Aimed specifically for volume Original Equipment Manufacturers (OEM) and system integrators
  • Fully designed, manufactured, and tested by Merus Power in Finland
  • Strong industrial background with 15-year experience in power quality solutions

Customer benefits

  • Longer lifetime of electrical and process equipment with reduced maintenance costs
  • Compliance with IEEE 519, G5/4, EN 50160, and other power quality standards and regulations
  • Reduced operational expenditure (OPEX) and increased mean time before failure (MTBF)
  • Compact modular and scalable design
  • Access to professional technical and after-sales support 24/7

Key functions

  • Improves power quality and energy efficiency
  • Enhances sustainability
  • Ensures operational reliability and higher productivity
  • Increases redundancy and reduces maintenance costs
  • Helps comply with demanding power quality standards and regulations


Merus® 4DRIVES active harmonic filter provides an optimized solution for variable frequency drive (VFD) applications. One active harmonic filter can be used for multiple six-pulse drives in a system. The filter selection and dimensioning can be made based on the needed harmonic current distortion. The filter current rating is substantially lower than the combined drive load current, which allows savings in comparison to active front-end (AFE) drives.

Typical segments of Merus® 4DRIVES include water and wastewater treatment plants, buildings and heating, ventilation, and air conditioning (HVAC) applications, data centers, and industry applications.

What Merus® 4DRIVES can do for you?

Active harmonic filtering

Mitigates harmonic current in the measurement point – mitigating current/voltage distortion

Dynamic reactive power compensation

Mitigates reactive power – power factor improvement, voltage sag mitigation

Load current balancing

Balances fundamental cycle current – evens phase imbalance

  • Operation and experience in challenging environments THD(V) <10%
  • Capability to compensate 3rd harmonic in phase unbalance situation
  • Optimized compensation for drive usage and enhances the lifetime of drives

How does Merus® 4DRIVES work?

Merus® 4DRIVES Active Harmonic Filters operate similarly to noise-canceling headphones. They measure the distorted current of VFDs and inject harmonic frequencies, but with an opposite phase angle. Canceling out harmonic currents reduces voltage harmonics and eliminates distortion at the point of common coupling. Alternative connection to Merus Power’s cloud-based platform allows easy remote control and monitoring access.

What product features does Merus® 4DRIVES have?

User-friendly operation and functionality with easy commissioning

Merus™ 4DRIVES active harmonic filter has an easy-to-use 7” touch screen (HMI) for simple commissioning and operation. All essential functions are seen on the home screen. Up to seven active harmonic filter modules can be controlled with one HMI. There are easy-to-use commissioning wizards and both network and load sides can be monitored.


Possibility to integrate into VFD scope of supply

Merus™ 4DRIVES active harmonic filter is designed for easy maintenance. The essential components are easily accessed by service even without removing the module from the enclosure. Remote access to the modules is available with Merus™ remote control concept.


Aimed specifically for volume Original Equipment Manufacturers (OEM)

Merus™ 4DRIVES active harmonic filter is a perfect choice for VFD manufacturers and system integrators. The active harmonic filter design is modular and made for easy installation into drive cabinets with three wire connection parallel with the VFD load busbar. No external power supplies or controllers are needed. The solution is scalable; the current rating is extended by installing several modules side by side. The active harmonic filter is available for all necessary VFD voltage ratings. The modules have CE, CSA, and UL approvals.


Improved redundancy compared to Active Front End (AFE) or Low Harmonic Drives (LHD)

Selecting Merus™ 4DRIVES active harmonic filter solution for drives harmonic mitigation provides improved redundancy in comparison to AFE drives and Low Harmonic Drives (LHD). Drives failure leads to immediate process interruption, whereas an unlikely case of active harmonic filter tripping does not stop the process, only harmonics content is temporarily increased.


Do you have any questions?

Please contact one of our salespeople with questions and inquiries.

Riku Kalliomaa

Head of Sales,
Regions & Channels

Jaakko Poutamo

Sales Manager,
Energy Storage, Europe

Mikko Zavertkin

Sales Manager,
Key Accounts & OEMs

Viktoria Mansikkala

Sales Manager,
Baltics & Eastern and Southern Europe

Juhani Jaatinen

Senior Sales Manager,
DACH, Benelux, France,

Venkatesh Ramachandra

Regional Sales Manager,
Middle East

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