Corrosion-resistant linear displacement sensors are essential for monitoring gate opening and hoist stroke in water conservancy projects. Most use magnetostrictive technology. A position magnet is fixed to the moving hoist component, while the sensor rod is mounted along the travel path. The sensor electronics emit a short current pulse through a magnetostrictive waveguide. When the pulse magnetic field meets the permanent magnet field, a torsional strain wave is generated at the magnet position. This wave travels along the waveguide to a pickup coil and is converted into an electrical signal. The time between pulse emission and wave reception is proportional to the magnet position, so the sensor calculates linear displacement precisely.

For wet, humid, and corrosive environments, the sensor uses a 316L stainless steel tube, anti-corrosion coating, IP67/IP68 sealing, and a sealed connector. Temperature compensation and surge protection improve stability. The output, such as 4–20 mA, RS485, or SSI, is sent to the hoist PLC. It provides real-time gate position feedback for start/stop control, over-travel protection, and synchronization. Regular calibration and cable inspection keep measurement reliable.