Dimensions and Weight

This parameter is very helpful to identify the application this sensor can be used for. If a sensor is of larger size and is very heavy, it cannot be used in smaller applications. Dimension is usually measured in millimeter (mm) whereas weight in grams (g).Life

These sensors are all contact type sensors where mechanical wear and tear hamper deteriorates their working capability and thus their life. The life of a pod is expressed in number of movements.

Measurement Range

It provides the range of operation of the sensor within which it can provides an accurate value. It may be calculated either in degrees or in mm depending upon the type of potentiometric position sensor being used.Repeatability

It is the variations in measurements by a single person or sensor on the same device under same conditions.

Independent Linearity

It is the maximum deviation of the actual function from the straight line that acts as a reference with the slope and the position that has been chosen in order to minimize any deviations. It is expressed as a percent of the total applied voltage.

Operating Temperature

It defines the range of temperature within which this sensor can operate without being affected by the environment. It is expressed usually in degree Celsius.
Vibration

It is the frequency of oscillation of the sensor about an equilibrium position. It is expressed in hertz (Hz).

Shock/ Noise

It is a disturbance in the function of the sensor due to an unexpected impact. It is a form of vibration that may be described in terms of acceleration, force, velocity or displacement.

Output

A potentiometer may give either a digital or an analog output which makes it an important parameter that should be considered for the application we would use it for.

Click here to view Table to help select Potentiometric Position Sensor

Pros & Cons

Every product in this world has some positive as well as negative features and so do the Potentiometric position sensors. The disadvantages, although few in number, are with respect to the contact type sensors.

  • Inertial loading: These types of sensors are affected highly by the environment, at times. Dust gets easily accumulated between the resistive surface and the slider thus increasing the resistance than the actual value. This results in incorrect output voltage or in some cases loss of total voltage.
  • Limited Bandwidth: Precautions need to be taken so that the working of these types of sensors is very smooth and slow, so that they can measure the accurate and continuous voltage. Now if the slider is moved very fast, chances are there that the contact would bounce, which would result in an intermittent output voltage.
  • Wear and Tear: At times the frictional forces between the slider and the resistive surface increases so much so that the actual movement of the body is also limited. Again the more the frictional forces, the more is the wear and tear of the sensor. This also limits the number of operating cycles.

The negative points are just not enough because if we want to select a sensor for the different applications, we should also be able to identify it’s advantages for the right selection.

  • Ease of implementation: Due to their mechanism, they are easy to use and do not require any additional implementation assistance
  • Low price: They have quite low price so are widely used.
  • Analog output: They provide high amplitude, analog output thus no signal processing is required and the output can be accessed easily.
  • Proven technology
  • Ease to add additional channels to increase reliability
  • Easy Availability

Sneha Ambastha is a technical journalist at EFY Gurgaon

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