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Sensor Selection Process: Factors Affecting Cost of Ownership

Linear position sensors have pertinent characteristics that affect durability, robustness, and performance. In selecting the right position sensor, several factors need to be taken in consideration which impacts the installation cost and suitability to the intended use.

Linear position sensing technology is a vital component of industrial machine automation. In general, a linear position sensor measures the displacement of an object along a rectilinear path. Many traditional linear position sensing technologies are still applicable today. Some of the most common examples include potentiometers, LVDTs, and encoders. These linear position sensors vary by cost, resolution, resistance, stroke, and reliability. Thus, having a clear understanding of these differences help with selecting an ideal sensor for a particular application and also impact the ownership cost.


Most common linear position sensors used in industrial applications


Here are the most common types of linear position sensors used for industrial applications today:

Potentiometers. Contacting potentiometers are considered one of the simplest, and cheapest kind of linear position sensors. For applications that are not subject to extreme conditions, potentiometers are an ideal solution. These do not require complex electronics to operate and also offer a relatively fair level of measurement repeatability.

LVDT. Linear Variable Differential Transducers have excellent accuracy and measurement repeatability. As such, it is a favoured type of linear position sensor for applications where the installation will be subject to extreme temperatures, vibration, and other environmental factors. Industries such as mining, manufacturing, and construction benefit from the robustness of LVDTs.

Magnetorestrictive sensors. Magnetorestrictive sensors also provide excellent accuracy, resolution, and measurement repeatability. However, the cost of ownership is relatively high.

Encoders. Encoders are either optical or magnetic. Both types of encoders require complex auxiliary electronic components. Nevertheless, encoders are also excellent concerning resolution, repeatability, and measurement linearity.

LVIT. A linear Variable Inductive Transducer has better performance compared with LVDTs. The improved stroke-to-length ratio of an inductive transducer allows for installation in compact installations such as hydraulic machines. The inductive or non-contact working principle also makes LVITs ideal for applications in extreme conditions.

Making a comparison of the features and cost of each type of sensor helps with the selection process for industrial buyers.


Factors that affect the cost of ownership


In choosing a position sensor, there are a few crucial questions you need to answer to ensure that you find the right device.

What does the position sensor instrument have to accomplish? The purpose of a position sensor should be the first consideration for every buyer. However, there are instances when this is overlooked, resulting in an incompatible installation. It is vital to determine what the sensor needs to accomplish such as whether it is meant to control a particular step during the manufacturing process or control parameters related to quality.

Can you define the nature of the application? Some examples include process monitoring, automation, quality control, and testing. By identifying the nature of the intended use, you can make a list of specific priorities such as whether or not you will need a sensor with higher measurement accuracy or repeatability.

What is the working condition the sensor will be subject to? There are several environmental conditions that you need to take into account when selecting a sensor. For example, you need to precisely determine the correct range of operating temperature because different sensors have varying temperature sensitivity which impacts performance. Another vital factor is the amount of shock or vibration the sensor will run under. Other issues that may affect the sensor's performance are moisture, dust, dirt, and corrosive compounds.

Are auxiliary components required for the sensor to function? Many types of position sensors require electronic components such as an external power supply, signal conditioner, and cables. Some sensors may even require specialised hardware for mounting. These auxiliary requirements can impact the overall cost of ownership; hence needs to be carefully considered.

Will the operator require training or take long to learn the system's operation? A potential overlooked expense is the amount of time it will take for an operator to learn about the intricacies of an installation. To determine the actual cost of ownership, the importance of a trained and knowledgeable operator needs to be taken into account as well.

Apart from identifying the specific parameters and characteristics of the sensor, the questions mentioned above will assist in the correct selection process to find the most suitable linear position sensor for a particular application. By eliminating installation inaccuracies, a method or mechanical engineer can avoid costly adjustments and errors once the machine starts operating.

Article published on: 04/02/2019