Inductive sensors

Inductive sensors

Inductive sensors detect objects made of metal or electrically conductive objects that move into their measuring field without any contact. They provide the user with a binary signal that provides information about whether an object has been detected or not. Inductive sensors are also called proximity switches or position sensors.

Structure and mode of operation

Inductive sensors consist of three functional units: an oscillator, an evaluation unit and an output stage. As part of the oscillator, a coil has the task of using an oscillating circuit to generate an alternating magnetic field that emerges from the active surface of the inductive sensor. Eddy currents are generated in the metallic object approaching from the front, which draw energy from the oscillator. The amplitude and frequency of the oscillating circuit change and the output stage is switched via a Schmitt trigger or the amplitude is converted into a distance. If several coils are used, this increases the measuring accuracy of the inductive sensor.

Advantages of inductive sensors

Due to the non-contact function, inductive sensors have numerous advantages:

  • Long service life due to hardly any mechanical wear
  • No downtime due to dirty or damaged contacts
  • No contact bounce and therefore no switching errors
  • High switching frequencies
  • Vibration resistance
  • High degree of protection due to fully encapsulated housing
  • Any mounting position

Inductive sensors from Festo

Festo inductive proximity sensors are almost wear-free, easy to use and of the highest quality. We offer inductive sensors in numerous designs for a wide variety of applications.

The proximity switches SIED and SIEN with a normal switching distance are suitable either for use with direct voltage or for use in applications with alternating voltage. The metric thread and the round design are characteristic of SIED and SIEN.

Our inductive proximity sensor SIEH -...-CR is particularly robust due to the all-round closed stainless steel housing, which, in contrast to conventional sensors, offers rugged resistance to almost all gases and media. Other features include the increased switching distance, the flush installation, the LED switching status display and the metric thread.

The Festo proximity switch SIEF is particularly easy and safe to use. It is weld-field-proof, has a spatter-resistant housing, an LED status display and can be installed flush, partially flush or non-flush.

Our inductive sensor SIES-8M is particularly suitable for position detection on electric axes and grippers with a T-slot. SIES-8M has a switching status indication with two LEDs for better visibility regardless of the direction from which it is approached. The fastening technology helps to position the proximity switch quickly and to fasten it easily.

The inductive proximity sensor SIES-Q is extremely space-saving thanks to its cuboid shape. It allows flush installation and also has an LED switching status display.