Inductive sensors

Inductive sensors detect metal or electrically conductive objects, which move into their sensing range, without any contact. They provide the user with a binary signal that indicates whether an object has been detected or not. Inductive sensors are also called proximity switches or position sensors.

Design and operation

Inductive sensors consist of three functional units: an oscillator, an evaluation unit and an output stage. As part of the oscillator, the coil uses the oscillating circuit to generate an alternating magnetic field that then radiates from the active surface of the inductive sensor. When a metallic object enters the magnetic field, eddy currents develop that reduce the energy from the oscillator. The amplitude and frequency of the oscillating circuit change and the output stage is adjusted by a Schmitt trigger or the amplitude is converted into a distance. If several coils are used, the sensing accuracy of the inductive sensor is increased.

Advantages of inductive sensors

Thanks to their contactless operating mode, inductive sensors have numerous advantages:

• Long service life thanks to hardly any mechanical wear
• No downtime caused by dirty or damaged contacts
• No contact bounce and thus no switching errors
• High switching frequency
• Vibration resistance
• High degree of protection thanks to a fully encapsulated housing
• Any mounting position possible