Heavy-duty cables for open-cast mining

Drivers travelling on the A44 motorway between Düsseldorf and Aachen can watch the gigantic mining machines of the Garzweiler open-cast lignite mine at work as they pass by. Seven bucket wheel excavators are currently extracting 35 to 40 million tonnes of lignite per year from an area of around 3,100 hectares. The mining equipment, and with it the electrical components such as sensors and cables, are subjected to extreme stress during the work. The resulting dust has an abrasive effect, in addition to humidity, temperature changes and constant movement. This is why RWE Power AG, as the operator, has defined extensive plant standards for technology and purchasing. As the technology changes, the standards must also be constantly developed and adapted. This applies, for example, to the increasing use of bus technology. Gunther Busch: "For example, many angle encoders are installed on the bucket wheel excavators and skip loaders to detect the position of equipment parts. We used shielded cables for these and other sensors, but their long-term functional reliability left a lot to be desired." One of the main reasons for this is the combination of high dust exposure and, in some cases, the installation in cable bundles, which causes the cables to move against each other. This accelerates abrasion considerably. Requirement profiles with exactly 20 criteria such as UV resistance, flame resistance, tear resistance, oil, bio-oil and alkali resistance and flexibility were created for each of these cables.

Since RWE had already had good experience with the chainflex® cables from igus® since 2006, these cables were shortlisted. In the process, igus® signalled its willingness to develop special cables for the special requirements of open-cast mining. The bus cables of the CFBUS series, which have proven themselves for years with the highest dynamic load and smallest bend radius, served as the basis. Tests have confirmed the durability of the cables under the heavy-duty conditions of open-cast mining. The modifications made to the cables as part of the customised development include increased UV resistance of the outer sheath. A special feature of the Profibus cable worth mentioning is that the supply wires have been integrated. This reduces the amount of work involved in installation, as one less cable needs to be laid.
Following the successful completion of the tests, the chainflex® cables were included as special cables in the RWE Power works standards for electrical cables. Four of the five cable types were stocked by RWE and a minimum stock quantity was defined.
The wide range of other cables for the energy chain enables a complete solution of all cables for this application. Starting with the bus cables described above through to medium-voltage cables. While the igus® employees took over the harnessing of the cables and the filling, the trough and lining were also installed in the plant.