The contractor who won the project installed 26 variable speed drives to control the movement of air and approached Fuseco for engineering and product solutions for the expected power quality issues, harmonics being the primary concern, placed back on the grid and the protection of the electric motors.

Fuseco supplied 2 x 60A Sinexcel Active Harmonic Filters for the mitigation of harmonics that the variable speed drives were releasing back onto the supply and the electrical reticulation system of the site. Fuseco also supplied MTE Line Reactors for each variable speed drive for harmonic mitigation and to aid in the protection of the variable speed drives rectifier by reducing powerline disturbances. Line reactors aid the performance of the AHF by reducing the THDI and reducing the possibility of resonance. Fuseco supplied Schaffner Sine Wave Filters for motor protection due to the long distance between the variable speed drives and the motor, the Schaffner Sine Wave Filter reduces motor noise, vibration, heat, eddy and bearing currents and protects the motor from pulse pattern stress.

The results were immediate and the performance of the solutions implemented were above and beyond expectations. The Sinexcel AHF provided a reduction of THDI from around 55% to around 7% (please refer to the screen shot) and there was also a reduction in the grid current. The THDV was reduced to less than 2% thus providing an impressive result and eliminating the risk of random MCCB and RCD tripping, interference to SCADA or BMS systems and complying to local harmonic limits.