Photo: The cranes at the Bleiloch power plant were modernized and are now controlled by Emotron VFX variable speed drives.
Cranes modernized after 75 years
The Bleiloch Dam is the largest artificial area of water in Germany. The upper reaches of the Saale in Thüringen were dammed back in 1932.
Since then, power has been generated here in a pumped storage power plant. The peak output of the two pumped storage units is 80 megawatts. The plant is run by the Swedish power company Vattenfall.
The plant’s cranes have now undergone a comprehensive modernization after 75 years of operation. The project, carried out by the crane manufacturer Saalfelder Hebezeugbau GmbH and Emotron, also involved the complete renewal of the electrical equipment in the crane units and the creation of a user-friendly and easily maintained electrical control system.
A number of objectives were set for the modernization. One of them was increased functional and operational reliability.
Another objective was improvement in the tracking controls for the crane gears. Low-maintenance operation for at least another 25 years was one request, as was of course the compliance with safety regulations.
Bridge and portal cranes transport 100 tonnes
The pumped storage power plant has two 100/25-tonne bridge cranes and a 25-tonne portal crane used to move machines and equipment in the engine room and on the neighbouring throttle valve forecourt.
The local conditions are almost Alpine: the plant can only be reached by means of a funicular railway or on foot. The funicular railway, which connects the forecourt with the access road to the power plant, can transport loads of up to 45 tonnes.
The bride cranes of the engine room can be mechanically connected with the portal crane. The travelling winch can then be passed over from the bridge crane on to the winch rail of the portal crane on a piece of rail attached to the building. To do this, gaps in the rails of 20 millimetres must be overcome. The solution enables loads weighing up to 100 tonnes to be transported.
Variable speed drives optimize operation
The modernization process was based on a standard developed by Saalfelder Hebezeugbau GmbH for the flexible replacement of hosting equipment in wind power stations. This made it possible to plan and deliver quickly.
The electrical equipment for the internal crane units and the portal crane was installed separately. In order for the portal crane to also be fully functional in winter, a temperature-based rail heating system was installed.
Emotron VFX variable speed drives are used to control the hoisting gears of the cranes. The result is optimized operation and high efficiency thanks to direct speed and torque control. With the application of a nominal load of 110 per cent it was possible to achieve a ratio of almost 1:1 between current and torque.
Photo: The IP54 enclosure allowed the variable speed drives to be installed on the crane bridges and the winch. This reduced installation costs.
Low installation cost with IP54
As the Emotron VFX variable speed drives have a high protection class (IP54), they are protected against dust and spray water. They could therefore be installed outside the equipment cabinets on the crane bridges and the winch. This electrical crane equipment design is not common in special crane design, but it brings significant savings potential.
“Costs are reduced since smaller equipment cabinets can be installed for the crane control,” says Lothar Sendzik, crane manager of Emotron and the one to develop the solution together with Uwe Bergmann, project engineer at Saalfelder Hebezeugbau. “In addition, it eliminates the need for traditional solutions that demand the design and cabling of numerous coupling relays, or a PLC.”
Functions such as riding, lifting, deviation monitoring and speed are controlled via a crane I/O option board in the variable speed drive, one for each gear group.
Operators benefit from easier handling
The modernization also brought improved user-friendliness in handling the cranes.
A HBC radio-controlled system was installed for remote control. A transmitter in the engine room remote control can be used to operate the two bridge cranes, either separately or in tandem. If a winch moves from the overhead crane to the portal crane, technical control is taken over by the portal crane’s remote control. To assist the operator, the selection or release of the transmitter is indicated on an illuminated panel.
Complicated transport procedures by the engine room cranes can be controlled from the crane cockpit. A user-friendly and easily maintained electrical control unit was designed to facilitate the operators’ work.
Photo: The unique electronic tracking system ensures fully synchronized travelling. The auto tune function of the crane control system means no PC is needed. Parameters and settings are clearly displayed.
Reduced wear on wheels and rails
The Emotron electronic tracking system was installed for the control of the crane gears in the engine room cranes. The previous control through mechanical flange contact led to a high level of wear and high maintenance costs.
“Thanks to the Emotron electronic tracking system, the wheels are fully synchronized and the crane travels on the running rails without any sideways contact of the flanges,” says Lothar Sendzik. “The mechanical stress is minimized and maintenance costs are reduced. The ready-to-install system meant it was not necessary to replace the crane wheels and the crane rails.”
An Emotron crane control system is used for the configuration. An auto tune function senses the system and automatically sets the required values. No PC is needed and the system is easy to install and use. Parameters and settings are clearly displayed in the process units of the operator’s choice.