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Size Matters!

Designing a sensor for wireless condition monitoring is a complex balancing act between meeting performance requirements whilst adding the most value for the end user.


The choice of technology becomes very critical when trying to optimise certain aspects of the design. Form over function, or vice versa is just one of the design directions that needs to be established very early in development. Thus, choosing an appropriate power source is one of the earliest decisions that needs to be made.


Here, we will focus on the implementation of the battery. Batteries are available in all shapes and sizes, different chemistries, non-chargeable, re-chargeable, etc. However, the form factor of the power source will largely dictate the overall dimensions of the sensor. Many wireless sensors coming to market have very large batteries to meet the longevity requirements that are needed by customers to trend their equipment performance over many maintenance cycles. If a more power-hungry technology is used to perform measurements and serve wireless communications, then the battery consumption will be substantial. However, a larger battery can have many knock-on effects. A larger battery adds additional weight and influences the centre of gravity, which most likely increases the size of the magnet or mounting bracket needed to fasten or secure the sensor. It is difficult to describe how important and impactful this component selection is on the outcome of the product design.


Vibration analysts are calling out for smaller, compact sensors which means a tight balancing act between battery size and battery life. Most customers and product users are happy to concede a replaceable battery design, as a way of lengthening product service. However, this can often make ingress protection more challenging, as the design must allow easy access to change the battery but still maintain a high level of robustness. Having a small, lightweight, low centre of gravity sensor with a compressed mounting footprint, will allow the sensor to fit into tighter and more “ideal” surface mounting locations. This is very important when measuring vibration and temperature close to the source of the vibration.


Kappa X uses a ½ AA battery, which is one the smallest power cells on the market, yet it boasts a 4-year battery life (standard configuration). The battery cell is also replaceable, which often makes ingress protection more challenging, however, Kappa X is fully waterproof (validated IP69K). The in-house knowledge and expertise of true low-power electronics at Sensoteq enables Kappa X to have a small 25mm diameter mounting footprint and overall compact size. Having this small, lightweight, low centre of gravity sensor with a compressed mounting footprint, allows for Kappa X to fit into tighter and more “ideal” surface mounting locations. This is very important when measuring vibration and temperature close to the source of the vibration. To summarise, a high-performing sensor, that you cannot mount correctly, has diminishing benefits in terms of machine health analysis. Ultimately, measurement performance and determination of early failure are very closely tied when it comes to adding the most value for the end user.


Kappa X makes no compromises when it comes to the designed, developed and implemented technologies. It uses a unique communications protocol capable of providing a reliable transmission over long-range in complex and challenging industrial environments. The sensing technology within Kappa X has been researched in collaboration with industry experts to deliver a market-leading product.


Diagram of Kappa X sensor with dimensions
Kappa X

By David Procter

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