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ADF in Dynamic Test load

ADF Improves dynamic test-bed

Within a major leading edge manufacturing company, a test bed put extreme demands on the power supply network. In this case study, an ADF installation compensates harmonics up to the 100th order resulting in significant reduction of notching.


The development department within a major european plant owns several test benches to test certain components in their products during the development phase. Different test conditions can be programmed, giving the test bench extremely dynamic properties.


Two parts of the test bench are connected to the same transformer. The load is very dynamic and the amplitude of the load current can change from zero to its maximum in approximately 100 ms. Both parts of the test bench could not be run at the same time, because of the high harmonic disturbances and voltage notches up to 25 %. Apart from exceeding the limits in EN61000-2-4, this also caused serious delay in the testing facility.

Solution – ADF Active Filters from Comsys

The owner of the facility installed equipment from Comsys AB to compensate the disturbances. Two ADF P300W-200/480 and one ADF P200W-100/480 were installed to compensate all frequencies up to the 100th harmonic order. The ADF P300 series can be used to compensate lower harmonics and the ADF P200 series can compensate the higher order harmonics and interharmonics. The ADF Active Filter units were configured to share the load, the P200 working on higher orders only. The result was extremely short response times and much lowered disturbances of the load. 


Voltage notches could be reduced to 10 % and all harmonics could be lowered to the requested level with regard to EN61000-2-4. The usage of both test benches is now possible and surrounding problems that had been linked to the poor power quality where solved.


  • Very high distortion on current
  • Note the severe voltage notches

dynamic before


  • Very low distortion on both voltage and current
  • Note the reduced notches

dynamic after

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