Inductive proximity switches

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

Inductive sensors from Festo

Festo inductive proximity sensors are virtually wear-free, easy to operate and of very high quality. We offer inductive sensors in numerous designs for a wide range of applications.

For example, the proximity switches SIED and SIEN with standard switching distance are suitable for use in applications with either DC or AC voltage. They are characterised by their round design and metric thread.

Our inductive proximity sensor SIEH -...-CR is particularly sturdy thanks to its fully enclosed stainless steel housing. Unlike conventional sensors, it offers high resistance to almost all gases and media. Other features include the increased switching distance, flush mounting, LED switching status display and metric thread.

The Festo proximity switch SIEF is extremely easy and reliable to use. It is welding field-resistant, has a weld spatter-resistant housing, LED status indicator and can be installed flush, partially flush or not flush.

Our inductive sensor SIES-8M is especially suitable for position detection on electric axes and grippers with T-slot. The SIES-8M has 2 LEDs for indicating the switching status and better visibility regardless of the direction from which it is approached. The mounting technology helps to position and fit the proximity switch quickly and easily.

The inductive proximity sensor SIES-Q is extremely space-saving thanks to its cuboid-shaped design. It can be flush mounted and also has an LED for indicating the switching status.