Load Cell Systems and Scale Systems

February 17, 2020

By Dara Trent, Technical Content Director

In industrial weighing, a standard scale is often not sufficient for the job at hand. In many cases, aspects of the application require specialized components to accommodate extreme size or weight, space limitations, location/distance, data processing needs, safety requirements, integration of data into a larger and more complex process, and much more.

In these cases, a multi-part load cell system can be created to meet the requirements of your application. Individual components can be selected and combined together creating a customized solution to what would otherwise be a suboptimal, or complicated, process issue.

Components of a Weighing System

Load cell – A load cell is the heart of a scale system, the part that does the actual weighing. A basic definition would be that it is a solid metal body on which strain gauges are attached. When force is applied to the load cell body it causes a change in resistance in the strain gauge. The amount of force can be calculated using the change in resistance. For more information on strain gauge load cells and how they work, click here.

Junction box – In a multi-cell weighing system, because each load cell naturally exhibits a slightly different mV/V output, the signals are run through a junction box. When the system is calibrated, each signal is “trimmed” within the junction box to return the same mV/V output when a known force is applied. This process ensures that the same load will read the same regardless of load placement or orientation. Junction boxes also perform a summing function that combines the outputs of the individual load cells in such a way as to appear to the digital indicator to be one load cell bearing the load.

Indicator – At its most basic level a digital indicator is a device that amplifies and digitizes the signal from the load cell and communicates the force being applied to a load cell to an operator, via digital display. This data can also be communicated to another machine or a PC, triggering an action as part of a larger process. These basic actions include simple batching, checkweighing, and emergency shutoff. At a higher level are programmable indicators that can control more complex processes that involve custom programming, numerous data points, and auxiliary internal signal conditioning.

Load cell mount – Load cell mounts and mounting assemblies provide structure to ensure the load cell is held firmly in the correct orientation and loaded properly, which is essential for accuracy in weighing.

Amplifier/signal conditioner – A signal conditioner can be a separate device or, in some cases, an internal component of the digital display. A signal conditioner converts the signal from the load cell into another form of signal that can be used by the indicator, display, PC, or other device. Load cell signal conditioning may include amplification, attenuation, excitation, filtering and isolation. For more information on signal conditioners, click here.

Wireless – A wireless system is often necessary for logistics and safety. Components such as handheld indicators, wireless base stations, printers, relays, displays, and more can be combined with wireless-enabled load cells to create a system to suit your needs.

For further explanation on how load cell systems work, read Load Cell System Basics.

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