Tagged: Harmonic

New Generation Passive Harmonic Filters – Ecosine Evo

Modular Passive Harmonic Filters from Schaffner – Ecosine Evo – the New Generation

The new PHF generation “ecosine evo” is designed for the most demanding harmonic mitigation tasks with front-end 6-pulse rectifiers.

Even partial load situations causing harmonic currents can be effectively mitigated. The introduction of a modular system allows the Ecosine Evo passive harmonic filter to deliver optimally tailored solutions for your particular installation. The solution is easily adapted by simply plugging in the suitable module where needed. For more information, watch this:

Active Harmonic Filter Application in Ba Na Hills, Vietnam

Here is a great showcase of the effects of applying active harmonic filters on a cable car installation made by Power More in Vietnam. Ba Na Hills Mountain Resort are holders of three Guiness Records – Longest single rope cable car system, Longest distance between stations and Heaviest cable roll. For Ba Na Hills, power quality is a question of safety and service quality. With total harmonic distortion 5 times higher than the national regulated level, Ba Na Hills were facing several problems.

  • Station to station communcation was interrupted
  • Power factor penalties
  • Damaged PFC capacitor units
  • Inerference with PFC controller
  • Reduced motor effeciency in generator mode to 50%

Applying ADF Power Tuning active filters from Comsys to battle both power factor correction and harmonic filtering resulted in:

  • Eliminated risk of PFC failures
  • Eliminated power factor penalties
  • Increased motor efficiency to 100%
  • Improved cable speed

Applications of Active Filter Technology

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Wind Energy (Photo credit: Wikipedia)

Active Harmonic Filter Technology have many potential applications where its use can offer plenty of benefits. Active Filters have been proven to provide lowered disturbances, lower carbon dioxide emissions through improved energy efficiency, lower current consumption and increased production stability to name a few. Just as other technology has evolved, so have various production technologies. Today’s semiconductor loads require far more sophisticated solutions than was necessary in the past – a need met by modern Active Filtering technology.

Some of the most common applications for Active Harmonic Filters are:

Variable Speed Drives

The most common application for Active Filters is the compensation of harmonics generated by variable speed drives, often referred to as VFDs or Frequency Converters. Drive systems have the benefits of lower losses and increased production flexibility at the cost of higher harmonics emissions. Harmonics emissions make passive compensation unsuitable. Active harmonic filtering, especially with a modular approach, allows successive installation and mitigation of selected harmonics.

Welding Plants

Electrical welding systems place uneven demands with extremely high peaks in current demand during short periods. The resulting highly fluctuating voltage levels cause flicker. Flicker emissions can cause disturbances with other electrical consumers such as neighboring industries or residential areas and can cause reliability issues with nearby equipment. Active Filters can mitigate Flicker.


Furnaces and casting processes are known to give rise to both flicker and harmonics. This is largely due to being some of the most energy intensive production processes today. Active Filtering technology is ideal to combat both of these issues to increase production stability and reduce effects on the grid.

Wind and Solar Power Systems

A major problem inherent in many renewable energy sources today is the inconstant load delivered to the grid. Both wind and solar energy is delivered as wind and sun is available, causing surges of energy that the existing grid is usually not built for. The remote location of these energy plants also means that grid connections are suboptimal.

Wind power systems cause flicker, harmonics or interharmonics as well as other problems. Solar power plants cause harmonics and interharmonics. In some cases, especially in weaker networks, resonances may be excited by the harmonic output of the solar inverters. Modern Active Filtering technology is very effective in combatting these problems; reducing the stress placed on the grid and making these renewable energy sources more effective and widely viable.


Light systems can cause harmonics that heat neutral conductors and disturb nearby equipment. This can mean production disturbances and unnecessary maintenance costs. Modern energy saving lamps may be more likely to cause disturbances depending on type. Active Filters are well suited to combat these problems.

UPS Systems

UPS or Uniterruptible Power Suplies can save lives as well as data and financial loss. A UPS system connected to a network polluted with harmonics can malfunction and has a shortened life span. Connecting an Active Filter to secure uninterrupted power supply will ensure production uptime.

Active Harmonic Filters In Printing Applications

Harmonics causes problems in printing plant

Harmonic Filter Restores Power Quality and Reduces Downtime Caused by Harmonics

Problems with power quality often become apparent through problems in production and surrounding equipment such as lighting.

This is what happened at one of the largest printers in Holland.


Line to line voltage with Active Harmonic Filter

Line to line voltage without Active Harmonic Filter

The printing company consists of two printing plants located in Amsterdam. The plant employs 170 people, producing six daily newspapers and several other free local papers and magazines. The plant prints up to 1 million papers every day with printing presses running almost nonstop.

Poor Power Quality – the Challenge

The printers had been struggling with power quality problems for many years. Flourescent lighting had to be changed continuously as the tubes kept failing. The electrical ballast had to be changed every six months instead of every 5 years. This kept one employee busy 2-3 days a week. In 2011 just the lighting problems and other broken components cost the printers about

300 000 €. In addition to these losses, the plant had power quality related problems during startup of the presses, which resulted in additional losses through production downtime.

Active Harmonic Filters – the Solution

Line to line voltage with Active Harmonic Filter

Line to line voltage with Active Harmonic Filter

The printing group decided on an investment in power quality and quite literally, a brighter future. Six harmonic filters with a total compensation current of 1800 A were installed to optimize the power grid and reduce harmonics.

Harmonic Filtering Gave Quick Results

Following installation and commisioning of the active harmonic filters all previous problems disappeared. The printing plant can nowuse their printing presses without disturbances from poor power quality. Due to the continuous stops in production and equipment failure, which had been a daily occurrance, the return on investment for the harmonic filtering system was very short.

Harmonics and Notches in Dynamic Test Load

Active Harmonic Filters Improve Dynamic Test-Bed

A major pioneer in the manufacturing industry caused problems on the power supply network with their dynamic test bed. Here, an installation of the right combination of active harmonic filters now compensates harmonics up to the 100th order with great results. Both harmonics and voltage notches are reduced to enable top performance of the equipment.

Case Background

Dynamic test load before harmonics compensation

Before Compensation:
– Very high distortion on current
– Note the severe voltage notches

The test benches, owned by the development department of a major European production plant, are used to test components in the development phase. Varying test conditions can be programmed, which gives the test bench very dynamic properties.

Harmonics Compensation Challenge

The same transformer is connected to two parts of the test bench. With a very dynamic load whose load current amplitude can change from zero to maximum in approximately 100 ms, it was impossible to run both parts of the test bench simultaneously. The voltage notches of up to 25% in combination with very high harmonic disturbances prevented this. This caused serious delay in the testing facility as well as exceeding the limits in EN61000-2-4.

Active Harmonic Filters – the Solution

To solve the power quality issues, several active harmonic filters were installed to compensate the disturbances. Two 200/480V filters were installed together with one 100/480V filter that in combination compensate all frequencies up to the 100th harmonic order. The first two filters can be used to compensate lower harmonics while the third compensates for higher order harmonics and interharmonics. The three units were configured to share the

load with the 100/480V filter working on higher orders only. This resulted in extremely short response times and considerably lowered load disturbances.

Dynamic load after harmonics compensation

After Compensation:
– Very low distortion on both voltage and current
– Note the reduced notches

Harmonics Compensation – the Result

Thanks to the active harmonic filter installation, voltage notches could be reduced to 10%. In addition, harmonics were lowered to the required level stipulated in EN61000-2-4. Now, both test benches can be run simultaneously without any of the problems caused by poor power quality.

Flicker Compensation Case Study

  AHF Flicker compensation welding

AHF Reduces Flicker from Radiator Production

Today’s industry constantly faces new challenges. As the local community grows, large businesses with energy intensive production processes are faced with the challenge of reducing their effects on the grid. High flicker emission levels can potentially disturb other industries on the public grid.


Flicker levels before AHF compensation

Flicker Level Before Compensation

The plant is a 55000 square meter radiator factory in Belgium, It consists of six production lines that in total can produce about 5000 radiators a day. The production process consists of presses, seam welding and spot welding. The process is inherently very energy demanding and so puts great demands on the power grid. These processes combined to create large voltage drops in the feeding substation with the result of too high Pst values. The problems at the plant caused flashing lights when the local utility company would connect other consumers to the same transformer.

Flicker level after AHF compensation

Flicker Level After Compensation


The local utility company demanded that the Pst 95% value could not exceed 0,7. Measured values during 2009 showed tops in the Pst equivalent to 1,6. Achieving this goal was no small feat due to the rapidly fluctuating load, and the many different load patterns that could occur with such a high number of welding machines.

Active Harmonic Filters – the Solution

The market leading response time for the active harmonic filter was a necessity for the customer to reach the values that the utility company demanded. The system consists of six units, making it a total of 2,1 MVAr continous power to compensate for the voltage drops.

Installation of Active Harmonic Filters Creates Results

After installing the active harmonic filters, the plant has managed to keep their Pst value below 0,63, regardless of how many welding lines are run simultaneously. The reference values have been measured by external consultants and approved by the local utility. As a side effect of the lowered flicker value, the plant now also enjoys stabilized production environment.

Harmonics Mitigation on VFD – Case Study

Harmonics mitigation of variable frequency drives

Harmonics Mitigation Increases Output with 30%

The water treatment process involves a large number of variable-speed pumps to process large amounts of fluids. By using Active Harmonic Filtering technology to optimize the electrical behaviour of their variable frequency drives, a major water processing plant in Sweden managed to increase the maximum output capacity of their systems by 30%.

Thanks to Active Harmonic Filtering we can now process 30% more fluids during periods of peak demand. We also save energy.
– Project Manager


The treatment plant is part of the sewage works in Gothenburg. It is one of the largest in all of Scandinavia and central to saving the environment from pollution. With heavy demands, the two basic requirements on this critical regional infrastructure are constant operation and sufficient treatment capacity. UPS power backup systems are crucial to ensure a secure and stable power supply.

Harmonics mitigation

To increase plant capacity, 17 new VFD-controlled pumps were installed at the processing plant. This increased harmonic distortion on the electrical system significantly and the resulting overcurrents caused the UPS fuses to melt. To avoid this, the pumps were run at reduced speed. This was however a temporary solution as it reduced treatment capacity below demand. Frequency converters are a well-known source of potentially damaging harmonics.

Harmonics Elimination – the Challenge

After consulting a premier Swedish consulting firm, the processing plant announced a public procurement process seeking the implementation of active harmonic elimination technology. The target was to retrieve full treatment capacity by eliminating the harmonics.

Solution – Active Filter Units

The result was the installation of two 600 kVA Active Harmonic Filter units to manage two transformers supplying 2160 kVA. There were a number of characteristics of the specific harmonic filter solution that led to the plant’s choice:

  • Flexible connection and system dimensioning
  • Reduced maintenance costs to other connected equipment
  • Disturbance free electrical environment
  • Reduced energy consumption through decreased transformer losses

Harmonics Eliminated – the Result

Eliminating the harmonics in the system resulted in an increased max output capacity of 30%.
In addition, the processing plant now manages to operate below the threshold value for harmonic distortion (SS 421 1811). The plant now enjoys further benefits with a reduced energy consumption and improved environmental performance.

Harmonics Case Study

food processing harmonics

Harmonics Case Study:
Secure Food Production by Mitigating Harmonics

Highly automized processes often contain VFDs, which cause harmonics in the power supply. This can affect machinery and can cause downtime in production lines. This was the case at a major food processing plant in Dortmund, Germany.


Harmonics profile before AHF

High harmonic current distortion
Large disturbance of production

The food processing plant is part of a federation of over 300 independent retail dealers and suppliers to approximately 540 grocery stores. The center is a 100.000 m² warehouse and distribution center with affiliated butcher. After the butcher was destroyed in a fire in 2009, it had been rebuilt and expanded in 2011 into an 18.000 m² large butcher shop. Since completion at the end of 2011, the new processing plant produces 250 tons of meat for the grocery stores and up to 25 tons of sausages every day. The new butcher shop contains state of the art logistics and meat processing systems.


The VFDs connected to the new meat cutter created typical current harmonics of a six-pulse-converter (5th, 7th, 11th, 13th, etc). These harmonics resulted in commutation notches in the voltage, which influenced the whole production process. The harmonics caused blackouts and disturbances to the lighting. It also influenced the sausage stuffing and caused long production stops disturbing the process flow. Occasionally up to half of the employees had to be sent home for the day due to disturbances in the process.

Harmonics profile after AHF

Low harmonic current distortion
No disturbance of production

Solution – Active Harmonic Filter with Harmonics Compensation

The food processing plant decided to use an Active Harmonic Filter to eliminate the problems in the power supply. The installed system consists of one filter with a capacity of 300 A harmonics compensation to provide the needed harmonic power for the meat cutter.


After the installation and a short commissioning, all disturbing harmonics were cancelled and the commutation notches disappeared. All meat cutters could now, for the first time, be started at the same time, without any effect on lighting or the sausage stuffing process.

Trusted Suppliers

Train in tunnel

Trusted suppliers of Active Harmonic Filters

There are plenty of suppliers of Active Harmonic Filters on the market. Their capabilities vary and the innovations within the field have been numerous. While some filters really only compensate for harmonics, other Active Harmonic Filters have the ability to compensate for just about any power quality problems with a few sofware adjustments to fit your specific problem profile.

Investing in Active Harmonic Filters

Make sure to always start by getting proper measurements to ensure you know what issues are the real cause of your power quality problems. Harmonics is only one of many potential concerns with regards to power quality – transients, oscillations and flicker are just a few of the additional problems you could be facing.

There are many potential solutions within the power quality field. Keeping an open mind is the best way to ensure you get the most effective solution and best ROI on your investment. It may also be that a combination of technologies is the most effective way to protect your production.

Trusted Suppliers of Active Harmonic Filters

  • Schaffner (www.schaffner.com)
  • ABB (www.abb.com)
  • Comsys (www.comsys.se)
  • Danfoss (www.danfoss.com)
  • Schneider (www.schneider.com)
  • Siemens (www.siemens.com)
  • Vacon (www.vacon.com)