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What is an inductive sensor?

An inductive sensor detects metal objects contactlessly, using an electromagnetic field. Inductive sensors only detect metal and are not disturbed by dust, dirt, or liquids. It is possible to detect metal through other materials like plastic, glass, and similar. Inductive sensors are used for positioning, end position, counting, speed sensors. They are used in all kinds of automation.

How does an inductive sensor work?

The sensor front consists of a coil and ferrite core, which via an oscillator circuit emits a high-frequency electromagnetic field. When a metal object approaches, the oscillation is dampened so that the output transistor is activated. There are also measuring inductive sensors, with analog output or IO-Link. Smart sensors are available with adjustable sensing distance.

The technology is contactless and lacks moving parts and provides among others:

  • Long service life

  • High repeatability

  • Resistance to vibrations

  • High switching frequency

Important properties of inductive sensors

Sensing Distance (Sn)
Indicates the nominal detection distance against a standard target. The actual distance is affected depending on the type of metal and the shape of the object. A standard target is steel, 1 mm thick, and with a side equal to the sensor diameter.

Shielded or Unshielded
Also referred to as embeddable or non-embeddable design. Refers to whether the sensor can be mounted surrounded by metal or must be mounted more freely. Shielded sensors are electromagnetically shielded and can be mounted with the front flush in metal. An unshielded or non-embeddable sensor generally has a longer sensing distance but also senses more widely around the front.

Enclosure Class
The sensors have IP65, IP67, or IP68/IP69K for more demanding applications.

Inductive sensors are available with:

  • Cylindrical housings from Ø3 mm up to M30, as well as rectangular models

  • Output PNP, NPN, analog 4-20mA or 0-10V, IO-Link, including Smart Sensors Profile

  • Steel front for extremely robust designs

  • Design for food applications

  • Marine approval DNV-GL

  • Design for high pressure