Embankment dams help to store large water quantities. They have to withstand considerable water pressure, while allowing a certain water flow. The “Three Gorges Dam” in the Yangtze River in China is a good example for this. It is located near the town of Sandouping approx. 40 km upriver in the province of Hubei. The hydroelectric power station in the dam is the largest in the world and generates 22.5 GW.
The monitoring of the floodgates is essential for the save operation of the dam. The floodgates are opened and closed by hydraulic cylinders, that have to withstand the considerable water pressure. Draw wire transducers like the SX300 are used to measure the stroke of these hydraulic cylinders. Draw wire sensors can control and monitor the traverse speed directly inside the cylinder. Due to the pressure-tight case of the SX300, the transducer can be mounted on the front side of the cylinder. The draw wire is extended with the piston of the cylinder. The draw wire is coiled single-layered, which allows the conversion from a linear movement into a rotary movement. This rotation is directed into the pressure-free area and detected by an encoder.