One of the most commonly used types of displacement sensor is a potentiometer. This type of position sensor is also resistive because the working principle relies on the wire’s resistance change in relation to its length. Since the wire’s resistance is directly proportional to its length, any change in the wire’s resistance equates to the change in length.
How do potentiometers work?
When measuring the displacement of a body, a potentiometer’s side element is connected to the moving object. The movement of the body changes the slider position which results in a change in resistance between the slider and the fixed point of reference. Consequently, the voltage produced from this movement also changes. Potentiometers as a position sensor can measure both linear and rotational movement.
Parameters measuring potentiometer performance
The performance of potentiometers depends on a variety of parameters. These parameters determine the suitability of a potentiometer for various applications.
- The measurement resolution of a potentiometer refers to the smallest measurement increment of the slider’s movement across its length. The smaller the recorded number, the higher the potentiometer’s resolution. High-resolution potentiometers may be necessary for some applications, while it may not be essential for others.
- This parameter refers to the maximum allowed change in deviation between the potentiometer’s resistance change and the slider’s linear position.
- High sensitivity is achieved when a potentiometer has a high output voltage. This is a contrasting parameter to linearity where it requires low resistance.
Potentiometers or resistive transducers are well-suited for many applications but still have a few limitations making them incompatible with some industrial uses. Some of these limitations include:
- A potentiometer uses contact technology through its slider. This movement causes wear and tear and decreases the lifespan of the sensor.
- Potentiometers have limited bandwidth.
- Potentiometers have inertial loading.
In selecting a potentiometer, you need to consider the following factors:
- Presence of contaminants
- Hermetic sealing
- Presence of vibration and shock
- Operating temperatures
- Humidity and moisture
- Required lifecycle
Potentiometers are used often for measuring linear displacement. Aside from this, common applications of potentiometers also include the following:
- Measuring liquid levels
- Measuring rotational displacement
- Controlling brightness
- Controlling volume
In spite of the inherent limitations of a potentiometer, there are still some advantages to using it as opposed to other types of transducers.
- Potentiometers are cheaper which makes them quite suitable for a variety of industrial application, and mass-produced consumer products.
- In applications not subject to extreme conditions, potentiometers are simple and easy to use.
- Potentiometers produce sufficient measurement output without requiring additional amplification.
- These devices are suitable for measuring large displacements.
Resistive transducers like potentiometers remain one of the most popular position sensors used today. While advanced sensor technology is now available, the uncomplicated working principle behind a potentiometer makes it a preferred device in some engineering set-ups. When finding a supplier, always take into consideration the years of experience and the expertise of the manufacturer in producing the best sensors used in industrial and commercial applications.