If voltage is applied to the coil (1) of an inductive proximity sensor, it will generate an electromagnetic field (2) around the sensor surface. If a metallic object (3) moves into the field, eddy currents will occur in the metal [4] that weaken the magnetic field. If this happens, the metal will be detected.
Advantages and applications:
A direct current flows through the sensor coil and generates an electromagnetic field there. This coil current is switched on and off (pulsed) at a high frequency, so that the electromagnetic field builds up and decays in a predictable way. If a metallic object approaches the sensor, the decay behaviour changes, and the sensor output switches.
(1) Sensor output
(2) Induced voltage
(3) Metallic object
(4) Decay behaviour
(5) Time window for evaluation
Advantages and applications: