Inductive Level Measurement Principle

If primary & secondary coils are wounded on non magnetic side-tube of the tank, which contains liquid having good magnetic permeability (e.g. liquid metals) the arrangement resembles LVDT.

Consequently by feeding sinusoidal voltage to primary and through phase sensitive detection of voltage across secondary coil connected in series opposition.

The arrangement works like LVDT, offering accurate measurement.


a) High range
b) No frictional loss
c) High output & low sensitivity
d) Low hysteresis
e) Low power consumption
f) Direct conversion of electric signal


a) Sensitive to stray magnetic field requires shield.
b) Effected by vibrations & temperature.