Working Principle of Inductive Proximity Switch

Inductive proximity switches are basically used for detection of metallic objects.

The Figure shows the construction of inductive proximity switch. An inductive proximity sensor has four components; the coil, oscillator, detection circuit and output circuit.

Inductive proximity switches

An alternating current is supplied to the coil which generates a magnetic field. When, a metal object comes closer to the end of the coil, inductance of the coil changes. This is continuously monitored by a circuit which triggers a switch when a preset value of inductance change is occurred.

Applications of inductive proximity switches

• Industrial automation: counting of products during production or transfer
• Security: detection of metal objects, arms, land mines