Differences Between Inductive and Capacitive Proximity Sensors

Differences Between Inductive and Capacitive Proximity Sensors

Proximity switches contribute to a multitude of industrial applications. They have become vital elements in automation and have made operations significantly more efficient. The devices accomplish these by utilizing sensory technology. Essentially, their primary role is to detect external movement and any nearby presence. Then, they emit electromagnetic signals that alert the system of any changes. By employing this principle, the controllers ensure optimal performance and security in the workplace.

There are several types of proximity technology, but two that are noteworthy are those that are non-contact, namely inductive and capacitive. Compared to other kinds, contactless sensors have a more sizable lifespan. In addition, they are less prone to wear and tear since they are usually not tampered with, physically at least. Finally, they consist of different materials that are sturdier in nature, which helps carry out their function.

Inductive and capacitive sensors share a slew of similarities, and both works to facilitate safety and security. However, they also have considerable differences that prompt a deeper appreciation and understanding of the remarkable technology. Fortunately, the distinctions between the two are elaborated in this article. Read on to learn more about their variance from each other.

First, let’s look at each one extensively.

Inductive Proximity Sensors

Inductive proximity sensors are the more affordable option out of the two. They identify nearby ferrous, metallic objects, regardless of other physical properties outside of their composition. Additionally, the sensors are most effective with items one millimeter and above.

The Principle Behind Inductive Sensors

Inductive sensors run on the principle of inductance by having their specific parts work together to detect metal objects. The mechanism consists of creating an electromagnetic field with the materials of the sensors, resulting in impedance. The changes brought about by this phenomenon also share an inverse relationship with foreign ferrous items, reacting more when the outlier is near.

Inductive Sensors Parts and Functions

Inductive sensors consist of four parts that each contribute a significant function to the device. First, a ferrite core with coils radiates a magnetic field that is integral in playing out the following processes. An oscillating mechanism then carries the symmetrical force at the sensing surface. After that, if a ferrous object penetrates the magnetic field, small electrical currents (eddy currents) interfere with its uniformity, resulting in systematic changes. Next, since there is a deviation in natural frequencies, the amplitude decreases in direct proportion to the amount of material that penetrates the field; it will then collapse. Lastly, the Schmitt trigger notices the disturbance and alters the sensory output in response. Consequently, the procedure resets when the metal body is removed and will repeat when in contact with similar material.

Capacitive Proximity Sensors

On the other hand, capacitive proximity sensors utilize an electrostatic field instead of a magnetic one. Similarly, it functions to detect variations and abnormalities but with capacitance. However, these sensors identify various objects, including non-conductive items and metal. Additionally, liquids and other substances are also covered by this proximity device.

The Principle Behind Capacitive Sensors

In essence, capacitive sensors uncannily resemble the work of inductive ones. It generates an active capacitive field, otherwise known as dielectric, to carry out its functions. As its field changes, the sensory technology within will also emit signals to notify a larger system of interference.

While capacitive sensors do cater to detecting different materials and substances, it is even extensive enough to be sensitive to changes in gas. For example, the regular air in our atmosphere acts as a constant. As a result, the capacitive field changes and switches the sensor when anything with a higher density than gas comes close.

Capacitive Sensors Parts and Functions

The first component of capacitive sensors is their electronic circuit. This part is responsible for the oscillation that creates the electrostatic force. It will activate when an object is in proximity, triggering the desired reaction. Additionally, the device has a threshold function that regulates the changes in oscillation. The response then amplifies the corresponding load operation. Finally, it shares similarities with the inductive sensor in terms of form and control. Depending on the brand and model, capacitive sensors will also have screws and knobs to manage their external adjustments.

Advantages And Disadvantages Of The Two

Proximity sensors and their types share a significant common ground. However, there are several categories for good reason. Each has specialized functions and mechanisms to cater to a specific industry need. Moreover, they also have their own set of advantages and disadvantages, which we will further discuss here.

Inductive Proximity Sensors

The optimal choice for detecting metallic infiltrate are inductive proximity sensors. They are designed to efficiently detect ferrous materials, which are abundant in industrial operations. Additionally, with specialized and singular functions, they are quite easy to maintain and are reliable for constant use. They also withstand diverse environmental conditions.

Differences Between Inductive and Capacitive Proximity Sensors

Inductive sensors also offer numerous industries convenience. They are one of the easiest to install, and the results are predictable. The higher switching rate is also a plus for multiple companies.

Capacitive vs Inductive Sensor: Identifying the Difference - Free Online  PCB CAD Library

While inductive sensors are a great addition to any business operation, they do have a few shortcomings. First, even though they are effective in detecting metal, they are limited to the material, withholding variety. On the same note, their sensing range also depends on a few factors most companies have to consider, such as their coil size and shape.

Capacitive Proximity Sensors

Capacitive proximity sensors definitely have an edge as they are sensitive to a broad range of materials, especially non-metallic targets. For example, they can detect containers, dense items, and liquids with excellent resolution as low as 0.003mm. Not to mention, these devices measure values as well, such as force, humidity, and pressure. In terms of efficiency, they are both cost-effective and operationally optimal. Lastly, they are constructed with simplicity and room for adjustments.

As for the disadvantages of capacitive sensors, there are a few notable ones. First, the overall structure of the device is susceptible to damage from environmental conditions. Undesirable factors such as extreme temperatures or humidity will affect its performance. Also, its measurements are more challenging to attain and are not as accurate as inductive types.

So, choosing the proper proximity sensor takes thorough research and the appropriate resources. By gaining a better understanding of inductive and capacitive sensors, you are guaranteed to make a wiser decision when it comes to acquiring your sensory needs.