Technical Parameters of Load Cells for Electronic Belt Scales

Electronic belt scales are continuous dynamic weighing instruments, primarily consisting of load cells, speed sensors, instruments, and scale frames. As belt scales measure the weight of materials, load cells are crucial components. The quality of load cells determines the accuracy and reliability of the scale, making them the heart of the entire electronic belt scale weighing system.

When purchasing an electronic belt scale, it is essential to ensure the performance of the load cell, which is directly reflected in its technical parameters. While load cells have numerous technical parameters, some of which are specialized, it is necessary for users to understand the basic ones.

1. Rated Load: The maximum load that the sensor can measure within specified technical indicators. However, in practical use, only 2/3 to 1/3 of the rated range is typically used.

2. Allowable Load (or Safe Overload): The maximum load that the load cell can withstand, allowing for some overload operation, usually within 120% to 150%.

3. Limit Load (or Ultimate Overload): The maximum load that the load cell can bear without losing functionality. Exceeding this value will damage the sensor. It must not be exceeded during operation.

4. Sensitivity: The ratio of output increment to applied load increment, typically measured in mV of rated output per 1V of input voltage.

5. Non-linearity: A parameter indicating the precision of the relationship between the sensor's output voltage signal and the load.

6. Repeatability: The consistency of multiple output values when the same load is applied repeatedly under the same conditions. It is crucial and reflects the sensor's quality. The national standard defines repeatability error as the maximum difference (mV) between three actual output signal values measured at the same test point.

7. Hysteresis: The degree of inconsistency when loads are applied step-by-step and then removed, with ideal readings expected to be the same but often differing. This inconsistency is quantified as hysteresis error.

8. Creep and Creep Recovery: Creep is tested by applying the rated load without shock over 5-10 seconds, taking readings, and recording output values at intervals over 30 minutes. Creep recovery is tested by quickly removing the load and recording values similarly.

9. Allowable Operating Temperature: The ambient temperature range within which the load cell can operate, e.g., -20℃ to +70℃ for standard sensors.

10. Temperature Compensation Range: The range within which the sensor is compensated for temperature changes to reduce their impact, e.g., -10℃ to +55℃ for standard sensors.

11. Zero Temperature Effect (Zero Drift): The stability of the sensor's zero point with changes in ambient temperature, measured as drift per 10℃.

12. Temperature Effect on Output Sensitivity Coefficient (Coefficient Drift): The stability of the sensor's output sensitivity with changes in ambient temperature, measured as drift per 10℃.

13. Output Impedance: The resistance value of the sensor's output under rated conditions. High output impedance sensors feature low noise, low drift, and strong anti-interference ability, while low output impedance sensors prioritize stability and anti-interference.

14. Input Impedance: The resistance value at the sensor's excitation terminals. A lower input impedance reduces the load on the current source.

15. Insulation Impedance: The insulation resistance between the sensor's circuit and elastic beam, which should be as high as possible. Low insulation impedance can affect sensor performance, and below a certain value, the bridge may not function properly.

16. Recommended Excitation Voltage: Typically 5-12V, matching the stabilized DC power supply in most weighing instruments.

17. Maximum Allowable Excitation Voltage: The highest voltage the sensor can withstand, though using the maximum is not recommended.

18. Cable Length: The standard cable length provided by the manufacturer, which should not be altered.

19. Seal Protection Level: The dust and waterproof performance rating of the load cell, e.g., IP65, where the first digit indicates dust protection and the second indicates moisture (or water) protection.

Understanding these basic parameters is important for both purchasing and practical use, considering the varied operating environments and requirements for load cells, which impact their service life, functionality, and the accuracy and stability of the entire weighing system.