Debmarine Namibia, a joint venture between the Namibian government and diamond giant De Beers, operates five offshore mining vessels, which mines diamonds from the ocean off the west coast of southern Africa.
One of these vessels, Debmar Pacific, was experiencing problems with its electrical system. Debmar Pacific is one of the oldest vessels, having been built in 1977, and the vessel was having problems with a lighting circuit, in which several transformers were malfunctioning because of poor power quality supply. This is a classic symptom of an electrical circuit experiencing harmonic noise-related problems.
Actom Energy, electrical engineering specialist in South Africa, was chosen to design, manufacture, and install an active harmonic filter control panel to the vessel to alleviate this problem. Actom needed to source a harmonic filter fast, and based on a recommendation from De Beers, called upon CP Automation. Using the information supplied by Actom and De Beers, CP Automation advised the use of an ADF P100 active dynamic filter by Comsys.
Harmonics becomes a problem because of the use of variable-frequency drives (VFDs) and other non-linear loads. A load is considered non-linear if its impedance changes with the applied voltage. This change means that the current drawn by the non-linear load will not be sinusoidal, even when it is connected to a sinusoidal voltage.
Non-sinusoidal loads contain harmonic currents that interact with the impedance of the power distribution system to create voltage distortion and power quality problems, which heat the transformer. This explains why the previous transformers malfunctioned in the lighting circuit on the Debmar Pacific.
Harmonic filters — as the name suggests — remove harmonics. However, they also correct the phase of the fundamental currents, converting non-linear loads into linear ones. They cancel out the noise and keep the transformers cool and working efficiently.
“We cannot stress enough how much of a positive impact the right harmonic filter can have on a company’s environmental performance, lowering energy consumption and improving productivity,” says John Mitchell, business development manager at CP Automation. “With this in mind, we were confident that the ADF P100 was a perfect match for Actom’s project, and that it would put an end to the previous transformer issues,” he adds.