ElectroDrives has completed the commissioning of a 20kV 20,000kVAr Outdoor Harmonics Filter of Riotinto mine. The new filter is intended to compensate the harmonics and reactive power generated by the Cycloconverter that operates the 23MW Wrap Around Motor (or Gearless Motor Drive, GMD) of the new open circuit SAG mill with pebble crushers to process coarsely crushed product and prepare it for the existing ball milling circuit. This SAG mill is part of the 15 Mtpa RioTinto Expansion Project that targets to increase the copper production to approximately 55,000 tonnes per year. The project comprised a new primary crusher, a new SAG Mill, additional flotation cells, concentrate thickening and filtration. The new 23MW SAG mill is currently the largest grinding mill installed in Europe.
ElectroDrives has the scope of design, develop, supply, civil works, installation and commissioning of this passive harmonics filter. The filter was formed by four stages, each one of 5MVAr rated power and 20kV rated voltage, tuned to different frequency ranges to prevent the harmonics of getting into the grid. In total, the harmonics filter is rated 20MVA and it covers an outdoor area of 600 sqm.
The main elements of the passive harmonics filter are power capacitors, air core reactors, power resistors and automatic circuit breakers. It also contain disconnectors to isolate a stage of the filter if necessary, earth disconnectors to ensure that capacitors are fully discharged before accessing for maintenance and surge suppressors to protect from grid disturbances or lighting strike. All elements are protected, monitored and controlled from the control panel, developed also by ElectroDrives, located in the plant substation building.