There are many things to consider when choosing a load cell, one of which is how to choose the most accurate load cell for your application. Some items listed in the data sheet of the load cell include: combined error, hysteresis, non-linearity, repeatability (non-repeatability), creep and temperature effects. The accuracy is generally also stated in the specifications section of the data sheet. Most load cell data sheets will indicate accuracy-related specifications in percentage of full-scale output (FSO); also known as rated output (RO). These professional terms may be very unfamiliar to consumers, but as long as they read this article, they will have a preliminary understanding of the accuracy of a load cell.
Regarding the overall accuracy under ideal conditions, the most important indicators are non-linearity, hysteresis and combined errors. Non-linearity determines the error range of the load cell in the working range from zero load to maximum capacity. This difference is shown on the curve as a curve that deviates from the theoretical ideal straight line. Hysteresis is the difference between the output readings under the same load; one is to increase the load from zero, and the other is to decrease it from the load cell's rated capacity. The combined error is a combination of non-linearity and hysteresis.
Application notes
In addition to the accuracy of the baseline, the accuracy of the digital load cell also needs to consider three important specifications that depend on the application. These specifications are for repeatability, creep and temperature effects.
1. Repeatability. Repeatability is especially important for weighing applications. It refers to the ability of the load cell to maintain a consistent output when the same load is repeatedly applied. If the rated output of the load cell is 3.00 mV/V and the repeatability is listed as 0.01%, then for repeated loads of the same weight, the output of a 1,000-pound load cell may change to 0.0003 mv/V (3.3 lbs).
2. Creep error: When a load is applied to the load cell for a long time, as time passes, the output value will gradually change in proportion to the elapsed time. This change is called a creep error. In applications that require the load to be left on the scale for a longer period of time, load cells with very low creep errors are most needed.
3. Temperature fluctuations or too high will also affect the accuracy of the load cell. These effects on the output are listed as "the effect of temperature on zero", and the "effect of temperature on the output" is listed as the change in the sensitivity of the load cell, which causes the entire output range to shift, and the compensation temperature range means that it will maintain the temperature range of the load cell accuracy. When working outside this range, the temperature effects listed above need to be considered. In environments with large temperature fluctuations, such as outdoors or when working in an overheated or overcooled indoor environment, it is important to consider temperature errors. In a controlled or naturally stable environment where the temperature is kept within the compensation temperature range, the temperature effect is negligible.
These are the three most typical factors that affect the accuracy of the load cell, and there are many other factors, including the impact during the installation process.
