Case Study – Iowa WWTP


The electrical engineering firm was in the process of renovating a WWTP in Iowa which required several small to medium horsepower VFDs. They wanted a design that met IEEE-519 and was simple for their customer. With VFDs on several pieces of OEM equipment, from small pumps to larger aeration systems with blowers, it was going to be difficult to specify larger, more complicated, and expensive 18 pulse or active front end VFDs that were uniform on all of the different pieces of equipment. OEM suppliers often do not offer the option of specifying the type or brand of VFD that comes with their equipment.


Adding just one TCI HGA active harmonic filter, with a few inexpensive line reactors placed at certain loads, gave the plant a single, cost-effective harmonic solution that worked effectively with the variety of OEM equipment. The active filter was placed at the service entrance, filtering the entire plant, and resulting in a large cost and space saving package. The active filter was also sized for power factor correction due to local utility demands. While operating in “dual mode,” the filter lowered harmonics down to 5% ITHD and kept power factor at a .95 lagging.