How do Load Cells Work?

by | Oct 6, 2016 | Construction and Maintenance

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A load cell is a sensor – and like all sensors, the way it functions depends on an input generating an electrical signal that makes its way to an indicator.
All sensors work either by indicating a level or measure of some sort, or by telling you whether or not something has happened. That’s the difference between a barometer and a doorbell – a barometer will tell you what the exact atmospheric pressure is of wherever you currently are, indicating a specific level or measurement, while a doorbell will ring if someone pushes its button, indicating a yes or no.
Load cells measure, just like barometers, although instead of measuring atmospheric pressure they measure the pressure exerted on them by physical objects, acting as a major component in industrial scales.

How a Load Cell Works

Load cells come in different shapes and sizes – there are load shackles, load links, a tension load cell and beam load cells alike, from reputable vendors like Hardy Solutions – but they all function similarly. A load cell is basically a single unit of flexible and deflective material, outfitted with a few strain gauges, strain being as per NI the potential deformation caused by pressure.
Typically, you’ll have four – two on the surface of both the bottom and top of the load cell. As the load cell is bent through the force exerted onto it, the strain gauges measure the stress of the material they’re placed onto, either as compression or tension. They transmit an electrical signal to a measurement device through the Wheatstone bridge, and thus, a measurement is made.

What is the Wheatstone Bridge?

The Wheatstone bridge is a simple electrical circuit designed to measure an unknown resistance by balancing the two legs of a regular bridge circuit, one of which details the unknown resistance. As per Electrical4U, it’s used to make extremely accurate measurements.

That’s the gist of how a load cell functions, and how it is integral to the function and usage of a basic industrial weighting system.