A load cell is a transducer that converts a force into a measurable electrical output. The strain gage based load cells are the ones that are most commonly used. They are used for individual weighing applications.

 

The conversion takes place in two stages. When the force is sensed through the mechanical arrangement, it is deformed into a strain gauge. In the second stage, the strain gauge converts the strain into an electrical signal.

 

A load cell is made up of four strain gauges, but there are one strain gauges, called quarter bridge, and two strain gauges, called half bridge. It can only be used when it is amplified with an instrumentation amplifier and the electrical signal output is measured in millivolts. They are distinguished according to the type of output signal they generate.

 

Other kinds of load cells include hydraulic and piezoelectric load cells. The hydraulic kind is found in outdoor devices as it is immune to lightening. The piezoelectric kind is used in geomechanical applications as it is low in drift.

 

Strain-gage load cell convert loads into electrical signals. The gauges are bonded on a beamer and as soon as the weight is applied, it deforms. Four strain gauges are needed for maximum temperature compensation and sensitivity. Two gauges are in tension and the other two are in compression.

 

When there is a load sound in the vicinity of the load cell, it causes a ringing as they are spring-like in behavior. It must have this behavior to perform its natural frequency. To suppress the ringing, a control system is used to damp out the ringing of the cell.

 

Load cells are applied in the fields such as force measurement, impact measurement, batch weighing, feedback control, onboard weighing, platform scales, electronic weight bridges for truck weighing, tank weighing, railcar weighing, impact measurement and to monitor inventory.

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