Danfoss Drives' VLT® Low Harmonic Drive

The filterportion of VLT Low Harmonic Drives has the same working principle as a set ofnoise cancelling headphones, where the noise or distortion is measured and acomputer phase signal is imposed to compensate for that noise. VLT Low Harmonic Drives don't merely reduceor mask current distortion; they attack it at the source by performing realtime analysis and actively imposing currents, as needed, to restore and ensurethe highest possible quality sine waves from the power supply grid. They are well suited for: meeting thetoughest of harmonics recommendations/standards; installations that aregenerator-powered, or that have generator back-up power; soft power grids; andgrids with limited excess power capacity. VLT Low Harmonic Drives feature amodular design meaning that most elements are produced in large scale for costeffective production - and are individually configured according to thecustomer's specific needs to deliver the value of a highly customized qualitydrive for the price of a mass produced unit. VLT Low Harmonic Drives cause no increasedwinding stress and have no impact on bearing life. They provide the user with a full readout ofthe unit performance towards the grid, including a graphical overview of gridbehavior. Where the performance of otherlow harmonic technologies depend on the stability of the grid and load oraffect the controlled motor, VLT Low Harmonic Drives continuously regulate thenetwork and load conditions without affecting the connected motor. VLT LowHarmonic Drives are the only solution that can cut out the harmonic mitigationduring drive operation and so reduce the energy consumption in cases where thedrives do not need the harmonic reduction (at light loading). The result islower power consumption and higher energy efficiency. A unique design uses a ductedback channel to pass cooling air over heat sinks with minimal air passingthrough the electronics area. This allows 85 percent of the heat losses to beexhausted directly outside of the enclosure, improving reliability andprolonging life by dramatically reducing temperature rise and contamination ofthe electronic components.

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