A load cell is a device that converts one form of energy into the other, and is primarily used to generate an electrical signal whose magnitude is directly related to the amount of force being measured. Simply put, load cells are one of the simplest and most accurate tools for measuring force.
Many industries utilize load cells for high precision weight management because they offer non-intrusive, highly accurate load measurement data. Properly installed load cells can easily achieve measurements as accurate as 0.03 to 1%, and custom load cells can be designed for virtually any application.
There are two primary forms of load cells, analog and digital. Here is a simple breakdown of both.
Analog load cells
The most popular form of load cell is an analog cell that measures stress and weight strain. These strain gauging sensors are attached to the spring element of the load, and this will bend when weight is placed upon it. The strain gauge then causes resistors to stretch, and their resistance is changed. This resistance is then converted into voltage, which is sent via wire to the scale to give an accurate, real-time measurement to the engineer.
Digital load cells
In simple terms, the difference between analog and digital load cells is how their signal is processed. They differ in three major ways:
- Their signal strength. Strain gauge signals begin with analog electrical voltages, but in this type of cell they are automatically converted to digital signals. In general, these signals use between two to six volts of energy, meaning the digital signal is quite stronger than analog.
- Signal content. A digital load cell transmits data from each load cell, compared to analog systems that use only one cell's electrical voltage. This information uses a binary language, similar to computers, and because this binary information is safe from interference from radio signals, electromagnetism, and temperature, it is much more stable than analog.
- Data sample rate. This measures how fast a cell can read its information. Instead of analog cells providing information continuously in real time, digital load cells take bits of information at a time, multiple times per second.
This means that digital load cells can accurately record hundreds of measurements, from hundreds of individual load cells, in mere seconds. When custom load cells are needed for complex applications, digital is usually the first choice.