What is an Inductive Proximity Sensor? Why it is important?

What is an Inductive Proximity Sensor?

Proximity sensors are used in many industries to detect the presence of a metallic object without being physical contact with it. They are commonly referred to as non-contact sensors. Common proximity sensor types include photoelectric, capacitive, and inductive.

Operation of Inductive Proximity Sensor

The inductive proximity sensor is completely self-contained and houses an oscillator, amplifier, and other necessary circuits to accomplish electronic switching.

image reference from motioncontroltips.com

Inductive proximity sensor works on the principle of Faraday’s Law. A high-frequency magnetic field is generated by the oscillation circuit inside the sensor. When a metal object approaches this magnetic field, an induction current will start flowing from the object due to magnetic induction.

As the object approaches the magnetic field, more induction current will start flowing from the object. This load on the oscillator and oscillator attenuates or stops. This sensor detects this reduction of oscillation and will give an output signal.

Only metallic objects have induction properties, therefore inductive proximity sensors are mainly used to detect metallic objects only. It can’t be used to detect plastic, rubber, or other non-metallic objects.

However different metals have different induction properties which will affect the distance of being measured by the inductive proximity sensor.

Inductive proximity sensor works well in dusty environments. They are resistant to dirt, dust, and smoke in the environment between the object and the sensor. However, contaminants like metallic chips or any other metallic dust will surely impact on the sensing.

The below figures shows the example of the inductive proximity sensor used to detect the motion of the rotating object.