2. Inductive proximity switch
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Figure 2.3.2 Schematic of Inductive Proximity Switch |
Inductive proximity switches are basically used for detection of metallic objects. Figure 2.3.2 shows the construction of inductive proximity switch. An inductive proximity sensor has four components; the coil, oscillator, detection circuit and output circuit. 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