Functional Schematic of the Waldeck II Pump Turbine
Turbine
Francis turbines are used several times a day, during which they are often switched from minimum to full load mode to balance out the grid or generate peak-load power. After decades of operation, the turbine regulating devices and shaft bearings that have been subjected to the most wear and tear and all of the other turbine components will be inspected by their manufacturers, who will do all necessary repair work, eliminating damage and the effects of wear and tear as well as corrosion. Maximum output, which was limited due to machine vibration, is to be increased by up to 20 MW to 240 MW by installing a newly designed 18 ton runner with a diameter of 3.1 meters and improved fluid dynamics.
Turbine and Pump Head Water and Underwater Ball Sliders
The four main shut-off devices are responsible for cutting off the flow of water to the pump when the turbine is in operation and, conversely, to the turbine when the pump is in operation. In addition to the intake gates at the upper and lower basins, the shut-off devices handle important safety tasks in the event of machine malfunction and during servicing work. When doing their job, they are subjected to operating pressures of 36 to 38 bar. The ball sliders, each of which weighs between 90 and 160 metric tons, will be removed, disassembled and sent off to their manufacturers on heavy duty trucks for servicing. Once they arrive, the rotating member bearings, which block off the pipe cross-sections, will be serviced, and the shut-off actuators and elements will be overhauled or replaced. The remainder of the parts will be inspected and re-coated with an anti-corrosive layer.
Generator
The generator runner weighs in at some 375 metric tons and is about 5.1 meters in diameter. Once they have been subjected to intensive cleaning, all of the major components will be inspected and necessary repair work carried out. In need of replacement is the pole support, for example.
The generator support weighs about 240 metric tons and has a diameter of approximately 5.2 meters. It consists of a casing, a sheetmetal package and a winding and will be manufactured from scratch. The exciter unit has to be replaced as well. The generator support will be assembled at the designated site in the cavern. After the support has been installed, the generator runner will be put back in place and connected to both the turbine and the pump.
Pump
The pump has sophisticated movable runner labyrinth seals that retract to ensure that the pump runs efficiently. In turbine mode, the pump runner rotates with the machine shaft, during which the labyrinth rings are deployed to avoid losses that would be caused by the narrow runner gaps. Components that have been subjected to significant wear and tear will be inspected and serviced in the manufacturers' plants, along with the other parts. Extensive corrosion damage will be remedied.
