Inductive transducers

Inductive transducers are widely used for displacement and thickness measurements. The value of the self inductance of a coil or mutual inductance of a pair of coils changes when the quantity under measurement changes. Ac circuits are a requisite for these types of devices. For this, air cored coils are used. Proper shielding-both magnetic and electric is very much essential in this case. Interference effects can be minimized by the usage of iron-cored coils. We can employ this method in the measurement of the thickness of rolled sheets. Inductive thickness transducers are best suited for this purpose where permeability and resistivity of inductive thickness gauges should remain constant. In variable reluctance-type inductance transducer, a yoke is laminated to limit the eddy currents generated during the excitation of coil by alternating current. An inductive displacement transducer consists of a U-shape laminated ferromagnetic core and an I-shaped armature subjected to input displacements. Self inductance of the coil changes whenever there is a reluctance variation due to a change in air gap. Induction potentiometer is an example of inductive displacement transducer.