Power is the key energy for many processes at the quarry. Today 400 V is the standard voltage level. That was not always the case. In the past, numerous motors and systems ran on 500 V. Alpiq adapted and converted the entire power supply system to 400 V at the Mellikon quarry in the Canton of Aargau. Alpiq managed the complex project as the general contractor and supplied the customer with a turnkey package including planning, engineering, sub-contractor coordination and implementation. The planning process took place in the fall of 2018 and the project was realised in January 2019.
Several components had to be replaced as a result of the power supply conversion: A four-tonne transformer, the low-voltage main distribution board, cabling, the 200-kW and 1.7-tonne electric motor for the crusher, conveyors and hydraulic systems. The earthing system was also improved in order to achieve higher grid safety. The installation of state-of-the-art components has increased the energy efficiency of the new systems. A key factor here is the Xamax energy management system. This system monitors equipment, provides transparency in the area of energy flows and reduces grid utilisation costs. An important project component was the temporary emergency power supply system during the two-week conversion. "The conversion took place without any problems and on a tight schedule," says André Schärer, the quarry manager. The Mellikon quarry is located in the Canton of Aargau east of Bad Zurzach on the Rhine River. Steinbruch Mellikon AG has been operating the limestone mining facility since 1988 and excavates about 350,000 tonnes annually.