A high-pressure LVDT displacement sensor used in a chemical reaction kettle converts mechanical movement into an electrical signal through electromagnetic induction. The sensor contains one primary coil and two secondary coils wound around an insulated bore. An AC excitation voltage drives the primary coil. A magnetic core attached to the measured part, such as a stirrer shaft, valve stem, or internal component, moves inside the bore. The core induces different voltages in the two secondary coils. When the core is centered, the differential output is near zero. When it shifts, the output changes linearly with displacement, and the phase indicates direction.

For chemical reaction kettle service, the LVDT must withstand high pressure, temperature, and corrosive media. The coil assembly is usually sealed in a pressure-rated stainless or alloy housing. A pressure feedthrough carries the cable, while the core and bore are isolated by a non-magnetic pressure barrier or designed as part of the reactor pressure boundary. This protects windings from process fluid without blocking magnetic coupling. Temperature compensation and stable excitation improve accuracy. During operation, the sensor measures axial or radial displacement, enabling monitoring of shaft position, valve travel, or deformation. Regular calibration ensures reliable performance in demanding high-pressure processes. Signal conditioning converts the AC output into a stable DC or digital reading for a PLC control system.