The world’s longest energy chain, which was manufactured by Igus, recently completed a decade of uninterrupted service at a coal power station in the Czech Republic.

The chain, which measures 615 meters, conveys coal to a stacker from the periphery of a power station operated by the CEZ Group in the city of Tušimice. The coal is stockpiled in a long heap, and the long e-chain supplies the stacker with energy, data, and media. igus, the Germany-based manufacturer of motion plastics, runs its North American operations out of Providence, R.I.

The application in Tušimice was awarded the golden vector award in 2010. Every two years, igus initiates the competition to recognize the most innovative energy chain applications. Ten years later, this system continues to work reliably and displays plenty of life, and sometimes even runs on a 24/7 production schedule.

Energy Chain Includes Rollers
The Tušimice power station project was managed by Hennlich, a stocking distributor for igus based in the Czech Republic. A 5050RHD energy chain is used in the system, and the 'R' in the name stands for “rollers.”

"By using a roller, the coefficient of friction on long travels drops dramatically, when the upper run of the chain runs on the lower run," said Frank Schlögel, head of engineering projects, sales and marketing at Igus. "Because of the lower friction, up to 57 percent of the required drive energy can be saved. Which, of course, is all the more worthwhile on record-breaking travels like this one."

With his project engineering team, Schlögel supervises special projects around the globe and accompanies customers closely in every step, from the first design and detailed planning stages up to assembly and even maintenance.

Problems are a Thing of the Past
A cable drum served as the conveyance source before the igus energy chain system was installed at Tušimice. During cold Czech winters, the cables froze frequently, resulting in failures and unplanned shutdowns.

Work stoppages related to those issues have discontinued since the installation of the igus e-chain. Working with Hennlich, igus developed a complete package for the application. Since then, regular visual inspections have been implemented and just 10 crossbars have been replaced.

Two more systems in the plant also feature roller energy chains from igus. One chain travels 400 meters, and the other traverses 150 meters. The two systems supply the “reclaimer,”  which removes the coal from the pile and transfers it to the conveyor belt that runs to the power plant.

Reliable routing and safe overall concept
Inside the energy chains are chainflex cables from igus, which have been developed specifically for use in energy chains. In addition to the chainflex motor and control cables, a fiber optic cable is used for data transmission.

"Bus cables are out of the question for these long travels, as the signal strength would be insufficient," Schlögel said. A water hose is also routed in the chain together with a heating cable that prevents the water from freezing inside the hose. The water hose works in conjunction with a sprayer at the end of the stacker. When the coal is mined and piled up onto the heap, there is significant dust, which is counteracted by continuous spraying.

The energy chains have been electronically monitored since their installation. Monitoring measures the push/pull forces of the chains and can switch off the system if the forces become too high. This can happen when debris enters the system. In recent years, igus has further developed this form of “condition monitoring.” isense, as it is known today, offers machine builders modules for monitoring and predictive maintenance as an additional safeguard.

Under the 'smart plastics” umbrella, this includes break (isense EC.B) and push/pull (isense EC.P) monitoring modules. In the event of a chain break, the system can be switched off, so that further damage is avoided. To complement this the abrasion monitoring module (isense EC.W) continuously measures the wear of the energy chain to provide a reliable indication of the remaining service life of the system. This enables a planned replacement of the system without sudden failures.

Continuous operation as proof of quality
The stacker moves at a moderate speed. About 20 minutes are needed to cover the 600 meters. Every now and then the system is idle for an entire month. But when the coal needs to be conveyed to the heap, the operator can trust that the system will work reliably with the igus energy chains. Even in harsh conditions and after more than 10 years, the energy chains continue to prove reliable, durable, and up to the challenge of a strenuous application.