Watertight AUMA actuators for underwater hydro turbine control

An AUMA electric actuation solution ensures high-precision guide vane adjustment for a fully-submersible hydro turbine from Natel Energy at the Sauerbrunn hydropower plant near Graz, Austria, thus helping to boost green energy.


California-based turbine manufacturer Natel Energy required an actuator that could operate continuously underwater, provide accurate positioning to optimally control the water supply to the turbine, and send feedback signals to the higher-level PLC. Previously, their only option was a hydraulic actuator.


AUMA suggested an electric actuation solution that provides better control and feedback at a much lower total cost. The AUMA SARV-UW actuator for continuous underwater use proved to be ideal for this application. It provides high positioning accuracy (≤0.2 %) with continuous feedback to the higher-level PLC. The actuator controls is mounted above the shaft and separately from the actuator separately is an extra bonus that allows the end user to operate the actuator locally should the PLC fail. The low power consumption of the SARV also allows the end user to utilise an uninterruptible power supply (UPS) as a backup in case the main power is lost.


The AUMA solution has been successfully in operation in Sauerbrunn since autumn 2022. The small hydropower plant was integrated into the Muehlgang, an existing bypass channel to the River Mur. With the 15 kW RHT turbine supplied by Natel Energy, the operator, Energie Steiermark, aims to generate environmentally friendly electricity for the municipality of Großsulz.