What is an inductive proximity sensor?
Automation is the future, no doubt. Among the various components of automation, sensors make up an important part. Take a look around, and you will see how sensors surround us. Detecting fire or smoke, turning on lights by detecting your presence, opening garage doors as soon as the car is in front of the gate, and adjusting room temperature, have all become common parts of our lives, and all these take place with the help of sensors.
But what is a sensor? Let’s find out.
There is a simple definition of a sensor. It is a device that helps in detecting and responding to some kind of input and provides an output. The output is practically a signal which converts to a human-readable display at the display location. It is also possible to transmit it electronically via some network for further processing.
There are varieties of sensors working on different principles, and discussing all is out of scope for this article. In this article, we aim to discuss the inductive proximity sensor in detail.
What do you mean by induction proximity sensor?
An inductive proximity sensor helps detect metallic objects – both with ferrous and non-ferrous characteristics. The sensing range of this non-contact type sensor is up to 100 mm. The operation of this sensor depends on the principle of inductance. Here a fluctuating current induces an electromotive force into the target object.
Only metallic objects exhibit inductive attributes. Therefore, if you want the sensor to sense and detect non-metallic substances such as cardboard or plastic, it will not show any results.
Inductive properties vary from one metal to another. The sensing distance will depend on the kind of metal you are using for the testing. If you are using ferromagnetic objects, you will have a very long sensing distance. For non-ferrous metals like copper or aluminium, the sensing distance will be shorter. Generally, for an inductive proximity sensor, short-range applications are good as inductive effects wane with increasing distance between the object and the sensor.
How does it work?
The working of the inductive proximity sensor is quite simple. The coil in the sensor helps in generating an electromagnetic field. When the target object, most usually a metallic object, enters the magnetic field, an eddy current starts circulating around the target. This leads to added load on the sensor. As a result, the oscillator’s amplitude decreases. The more the target gets close to the sensor, the oscillator’s amplitude decreases further.
The best thing about an inductive proximity sensor is that non-metallic substances don’t interfere with the detection. Dirt and liquid substances do not affect the detection process. Hence the sensor works excellently in dirty as well as wet conditions. There is no need for the sensor to come in direct contact with the target object.
Tips for selecting inductive proximity sensors
There are many variables impacting the selection of an inductive proximity sensor. Hence make sure you consider these main factors while purchasing this sensor:
- Application of the sensor
- Type of installation (flush or non-flush)
- Switching frequency
- If the sensor is shielded, unshielded, or partially shielded
- Type of the target (what it senses)
- Switching output type (PNP proximity sensor or NPN proximity sensor)
- Response time
- Body style
- Sensing range
Components of inductive proximity sensors
Here are the main components of an inductive proximity sensor:
- Coil – The coil is among the most important components of this sensor as it generates the electromagnetic field that helps detect the target. The coil is held inside by a ferrite magnetic core. The cup-shaped core helps in concentrating the magnetic field of the coil on the sensor’s front area.
- Oscillator – There is usually an LC oscillator producing a radio frequency of 100 kHz to 1 MHz. The main purpose of the oscillator is to create an electromagnetic field for sensing the target object.
- Trigger Circuit – It is the function of the trigger circuit to sense the alteration in the amplitude of oscillation. It then provides the necessary signal to solid-state output.
- Output Circuit – There is a transistor NPN or PNP in the output circuit. On receiving the gate signal, the transistor switches ON, and you get an output.
Where to buy the best quality inductive proximity sensor?
Now that you know about the components and the working of the inductive proximity sensor, you must also know that there are various applications for these sensors. You can use the sensors to detect metal parts in extremely harsh conditions. You can also use them in the assembly line, high-speed moving parts, toll machines, and in the automotive industry. You can purchase these sensors with various operating voltages as per your needs and convenience.
If you are looking to buy the best quality electronic sensors, the place to go to is the Schneider Electric eShop. The online store is a treasure house for all things electrical. You will find a solution for all your electrical requirements when you visit the Schneider Electric eShop. Browse the website and buy high-quality inductive proximity sensors and also other sensors at affordable prices.