The accuracy level of the load cell includes the sensor's non-linearity, creep, repeatability, hysteresis, sensitivity and other technical indicators. When selecting a high-level sensor, the accuracy level and cost of the electronic scale should not be blindly pursued.
Load cell accuracy grade test method
1) In order to simplify the expression method of load cell accuracy in engineering technology, the concept of accuracy level is cited. The accuracy level of the load cell is expressed in a series of standard percentage values, such as the accuracy levels of the load cell are 0.05, 0.1, 0.2, 0.5, 1.0, 1.5, 2.5, etc. During the load cell design and factory inspection, the error represented by its accuracy grade refers to the maximum allowable error of the load cell measurement. A solid molecule has a certain steady-state microstructure. When it is subjected to an external force, it will deviate from the original structure and produce a certain deformation. When the external force is removed, it will instinctively return to the original structure, but this recovery process It should be attenuated by oscillation, just like playing a swing. After the external force of the push is removed, it takes N times of oscillation attenuation to reach the lowest point of stability. Therefore, we assume that the stress release process is fluctuating, but the amplitude of the fluctuations will gradually become smaller.
2) Everyone knows that the aluminum profile will produce a lot of stress during the extrusion process. The best way to eliminate the accuracy of the load cell is to put it in the open air and let it be naturally eliminated in the sun and rain for a long time. Stress will also be generated during the sawing and iron processing of aluminum elastomer, and there must be a release process. Celtron load cell has a gradual release process due to sandblasting, pressure after patching, high-temperature baking and stress after gluing, according to many previous test experiences, so the process from patching to gluing is just finished The parameters of the accuracy level test of the load cell can only be used for reference, and no absolute conclusion can be made.
3) Generally, the accuracy level of the load cell is composed of a single sensitive element and a single transmitter, and its output-input characteristics are poor. If a differential, symmetrical structure and a differential circuit (such as a bridge) are used, it will be poor Dynamic technology can achieve the effects of eliminating zero value, reducing non-linearity, improving sensitivity, realizing temperature compensation and offsetting common mode error interference, and improving the technical performance of the sensor to increase the accuracy of the load cell. The accuracy grade of the load cell is expressed by the percentage of the ratio of the maximum basic error within its range to the full range. The basic error is composed of two parts: systematic error and random error. The error represented by hysteresis and linearity is the systematic error of the load cell, and the error represented by the repeatability is a random error.
How to determine the accuracy level of the load cell
The accuracy level of the load cell includes the sensor's non-linearity, creep, repeatability, hysteresis, sensitivity and other technical indicators. When selecting the sensor, you should not blindly pursue a high-level sensor, and should consider the accuracy level and cost of the electronic scale.
In general, the total accuracy of the selected sensor is the sum of the three indicators of non-linearity, non-repeatability and hysteresis. The root mean square value is slightly higher than the accuracy of the scale.
The accuracy level of the load cell refers to the reliability of the measurement result. It represents the ability to repeat a certain reading with a given accuracy. The smaller the error, the higher the accuracy of the sensor. Sensors and meters have an accuracy of generally 1/3000. Generally, domestic load cells are of the C3 level. C3 means 3000 divisions, and the accuracy is 1/3000. Imported load cells have relatively high accuracy some.
First, it must meet the input requirements of the weighing display instrument. The output signal of the load cell is amplified, and the A/D conversion process displays the indicator of the weighing result. In view of this, the output signal of the sensor should not be less than the size of the input signal of the required instrument, that is, the output sensitivity of the sensor is substituted into the matching formula of the sensor and the instrument, and the result is greater than or equal to the input sensitivity of the instrument Claim.
Department size*Sensor*Number range of sensors
Set quantitative packaging scale, weighing 25KG, the maximum number of indexed sectors is 1000, three L-BE-25 sensors, the range is 25 kg ± 2.00.008mV/V, 12V arch bridge voltage and force sensitivity and body scale, scale AD4325 instrument meter. When asked about the matching between the selected sensor and the instrument.
Check the input sensitivity of the AD4325 instrument to 0.6μV/D. The Yading sensor and the instrument match the instrument with the current input signal: 2×12×25/1000×3×25=8μV/D》0.6μV/D. Satisfaction can be simplified in that the output signal of the sensor should not be smaller than the size of the input signal required by the instrument, so that they match.
In addition to the input requirements of the weighing display, the load cell level also needs to meet the accuracy requirements of the entire electronic scale. Normally, the electronic human body scale consists of scales, sensors, and meters, which are slightly larger than the theoretical value. When selecting the load cell with the accuracy of the load cell, the accuracy of the load cell is usually restricted due to the theory. For example, the scale body is almost the instrument Whether the performance of the load cell is very strong, the large-scale working environment is directly affected by the relative poverty, the accuracy of the scale, and therefore the requirements of all aspects are improved. When choosing the accuracy of the load cell, the load cell should be The accuracy is slightly higher than the theoretical calculation value, but because the theory is generally restricted by objective conditions, for example, the strength of the scale body is a little bit weak, the performance of the instrument is not very good, the working environment of the scale is relatively bad, etc., which directly affect The accuracy of the scale is required, so the requirements must be improved from all aspects, not only must consider the economic benefits, but also ensure that the purpose of weighing is achieved.
We choose to load cells instead of indulging in its pursuit of high quality and satisfying our own needs is the best load cell level. Under normal circumstances, the higher the level, the more expensive the price as a comprehensive consideration.
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