Heavy-duty cables for open-cast mining

• What was needed: chainflex cables, specially developed for the application
• Requirements: Extensive requirement profiles for the cables with specifications such as UV resistance, flame resistance, tear resistance, oil, organic oil and alkali resistance, or flexibility
• Industry: Open-cast mining
• Success for the customer: A customised cable solution, specially developed, tested and implemented to meet the customer's requirements

Motorists travelling on the A44 between Düsseldorf and Aachen can watch the gigantic mining equipment of the Garzweiler open-cast lignite mine at work as they drive past. Seven bucket wheel excavators mine 35 to 40 million tonnes of lignite per year on an area currently covering around 3,100 hectares. The mining equipment, and with it the electrical components such as sensors and cables, are subjected to extreme stress during work. The resulting dust has an abrasive effect and is accompanied by moisture, temperature fluctuations and continuous movement. For this reason, RWE Power AG, as the operator, has defined extensive plant standards for technology and purchasing. As technology changes, standards must also be constantly developed and adapted. This applies, for example, to the increasing use of bus technologies. Gunther Busch: "For example, there are many angle encoders installed on the bucket wheel excavators and spreaders that detect the position of equipment parts. We used shielded cables for these and other sensors, but their long-term functional reliability was not up to the task." One of the main reasons for this is the combination of high dust load and, in some cases, the fact that the cables are laid in bundles, which causes them to move against each other. This accelerates abrasion considerably. For each of these cables, requirement profiles were drawn up with exactly 20 criteria such as UV resistance, flame retardancy, tear resistance, resistance to oil, organic oil and lye as well as flexibility.

Since RWE has already had good experience with chainflex cables from igus since 2006, these cables were shortlisted. igus indicated 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 under the highest dynamic loads and smallest bend radii, served as the basis. Tests have confirmed the durability of the cables under the heavy-duty conditions of open-cast mining. Among the modifications made to the cables in the course of customised development is the increased UV resistance of the outer jacket. With the Profibus cable, the special feature worth mentioning is that the supply cores have been integrated. This reduces the effort required in installation because one less cable has to be laid.
After the successful completion of the tests, the chainflex cables were included as special cables in the RWE power plant standards for electrical cables. Four of the five cable types were stored by RWE and a minimum stock quantity was defined.
The wide range of other cables for the energy chain enables a total solution of all cables for this application. Starting from the described bus cables up to medium voltage cables. While the igus employees undertook the harnessing of the cables and the filling, the trough and lining were also installed in the system.