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