Problem

A Wastewater Treatment Plant in Hawaii needed to move flows across long and elevated distances. They added 7 large Horsepower pumps to meet their needs. These pumps are controlled by large non-linear load variable frequency drives (VFDs). These VFDs created an environment with substantial harmonic distortion, which resulted in high voltage distortion for the transformer. The Wastewater Treatment facility reached out to Allient | TCI to find a solution to mitigate the harmonics from the VFDs that were wreaking havoc on their facility.

Solution

The solution could be handled a multitude of ways, including addressing the harmonics on three or four of the large pumps at once, or all of the pumps running together. Allient Milwaukee recommended and installed two 300A active harmonic filters across all of the pumps, allowing for the most flexibility and reducing the Total Demand Distortion (TDD) to less than 5%, which enabled the transformer to function properly. The filters were installed in Type 1 enclosures to allow the best fit in the new pump station. Now the Wastewater Treatment plant is able to run all 7 large pumps without disrupting their equipment or putting harmonics back onto the grid.