The castle mill in Rochlitz/Saxony has been producing electricity since 1994. For reasons of fish protection, the operator has now invested in the conversion of the inlet to the turbine house and had a new screen installed at the same time. The screen is a cleaning system that removes the floating debris that collects in front of the screen and ensures the water supply to the turbine. After obtaining various offers, the decision was made in favour of a screen system from Erhard Muhr GmbH.
Muhr offers the hydropower plant operator a comprehensive programme of screen cleaners in various types (vertical, horizontal, with different arms ...). The systems are used all over the world and are customised for each individual case. For the project in Rochlitz, Muhr proposed a horizontal rake system from the H-series. The cleaning arm moves horizontally past the screen and pushes the floating debris, which is deliberately left in the river, into the drainage channel. The cleaning arm is attached to a travelling carriage, which is moved by a rack and pinion drive. Propulsion is provided by a direct drive with a 3-kilowatt low-speed motor, which, like the other components, is suitable for underwater operation.
Parallel to the project discussions in Rochlitz, the Muhr engineers developed a new solution for the power supply of the cleaning arm in the H-series. The reason for this was the high installation effort and the festooning system with flat cable that had previously been used. Two power cables and three sensor cables had to be routed to the motor, which is mounted on the cleaning arm. As all standard connection components such as seals and feed-throughs were designed for round cables, connecting the flat cables required a great deal of effort. In addition, the free-hanging cables could become entangled and the resulting cable station required around two metres of space. This prompted the planners to look for an alternative.