Todd Shudarek, Principle Engineer – The proliferation of variable frequency drives (VFDs) has brought increased attention to harmonic effects created by drives. A standard 6-pulse drive with no harmonic mitigation technology may interfere with neighboring equipment, reduce equipment life, and negatively impact the utility power quality. Under some circumstances the total harmonic current distortion (THID) may approach the level of the fundamental current. Drvie manufacturers offer a low harmonic, 18-pulse drive to combat these effects. An alternative solution is the use of a traditional 6-pulse drive equipped with a passive harmonic filter; however, typical passive harmonic filteres experience reduced effectiveness at loads less than 100%. With the introduction of adaptive passive technology, the Matrix AP harmonic filter maintains strong harmonic filtering performance across a wide range of loads. This paper compares the performance of a 100 HP 18-pulse drive with the performance of a standard 100 HP 6-pulse drive equipped with a 128 amp Matrix AP harmonic filter.