Sensor Functions Explained


Inductive proximity sensors are suitable for the detection of metallic elements. The operating princicle is based on a high frequency oscillator able to create an electromagnetic field in the close surroundings of the sensor. The presence of a matallic object (actuator) in the operating area causes a decrease of the oscillation amplitude. This happens when part of the electromagnetic energy that is transferred from the sensor to the actuator is dissipated by the effect of the Focault Parasitic currents. By using a threshold circuit a digital signal is produced.

Operating distance derating as a function of actuator material

The magnetic effect electronic sensors uses a physical property called Hall effect. When a thin sheet of a semiconductor material (Hall element) is placed in a magnetic field and a perpendicular current is passed through it, a voltage is generated between thee opposite borders of the semiconductor sheet. The sensor is housed in a three branch slot case. The Hall element with all the electronics is in one branch and a magnet is in another branch. The third slot containes a ferromagnetic vane (actuator) that blocks the influence of the magnetic field of the Hall element, determining an output change of the state.


The distance between the switching “ON” point of the actuator approach and the switching “OFF” point of the actuator retreat. This distance reduces false triggering. Its value is given as a percent of the operating distance or as a distance.


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