Proportional Valve LVDT Feedback

An LVDT reports where a valve spool is, allowing the electronics to compare its actual position with the commanded position. In this proportional valve model, the moving core follows the spool while the winding assembly remains fixed. The sensor measures displacement; it does not move the spool itself.

The primary winding receives AC excitation. Movement of the core changes how strongly it couples the magnetic field into the two secondary windings. Their differential output gives the position information. TE Connectivity's LVDT tutorial explains the null position, changing output magnitude, and phase relationship used to distinguish the direction of displacement.

An important interface distinction is AC-operated versus DC-operated LVDTs. The former require suitable external excitation and signal conditioning; the latter package those functions with the sensor. A raw secondary-winding signal is therefore not automatically the same thing as a ready-to-use DC position output. The servo amplifier electronics must match the selected sensor arrangement.

BOMwiki also places this valve within a hydraulic test bench, where that feedback relationship helps explain the control system. The four-line component breakdown is illustrative, not calibration data. Stroke range, excitation, output scaling, wiring, and mechanical coupling must be taken from the actual valve and sensor documentation. No universal voltage or frequency should be inferred from the generic winding entries.