Regarding the calculation method for load cells
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Dear experts: I would like to ask some questions regarding the calculation methods for load cells. The rated load of the load cell is 635 Kg; the excitation voltage is 10 VDC, and its sensitivity is 2 mV/V. It can be calculated that at a rated load of 635 Kg, the output signal of the sensor is 10 V * 2 mV/V = 20 mV. It is not possible to determine that the signal increase per additional 1 Kg is 20 mV / 635 Kg = 0.031496 mV/Kg; therefore, at a load of 500 Kg, the output signal would be 500 * 0.031496 = 15.748 mV. So if there are four sensors, will the output signal also be 15.748 mV? I would appreciate it if experts could help verify whether the above calculation method is correct. Please provide some guidance. Thank you
1, 2 mV/V is the sensitivity; therefore, what is calculated is only the change amount, not the absolute value of the output. In other words, it’s not necessarily 0–20 mV; it could also be 1–21 mV ； 2. 2mV/V is just a figure; there will be actual errors ； 3. It is necessary to consider the method used to indicate the sensor’s accuracy; if percentages are used, there will be corresponding differences for 2mV/V, while if absolute values are used, there will be corresponding differences at the zero point ； 4. Multiple sensors are usually used in parallel. The output value is its arithmetic mean. In other words, if the weight distribution inside the hopper is even, it’s still possible to use it normally even after removing 1 to 3 of them.
Firstly, the zero point of the sensor is not necessarily 0.0 mv, so 15.748 is also not necessarily correct. By using this calculation, it is possible to estimate the load capacity roughly; however, it is uncertain whether the actual weight will be exactly that much. Reference can be made to the theoretical calibration of the instrument; generally, it is calculated automatically by the instrument, but slight adjustments are still needed to achieve relative accuracy. Secondly, sensors with a range of 635 kg, such as the HBM PW16A, are typically single-point sensors; if their sensitivity has not been adjusted, they are not suitable for use in parallel with four others.