The selection of sensor level must meet the following two conditions:
1. Meet the requirements of instrument input. The weighing display instrument displays the weighing result after the output signal of the weighing sensor is amplified and processed by A/D conversion. Therefore, the output signal of the load cell must be greater than or equal to the input signal size required by the display instrument, that is, the output sensitivity of the load cell is substituted into the matching formula of the load cell and the instrument, and the calculation result must be greater than or equal to the input sensitivity required by the instrument.
The matching formula of sensor and meter:
Sensor output sensitivity * Excitation power supply voltage * Maximum weighing of the scale
The number of divisions of the scale*The number of sensors*The range of sensors
For example: a quantitative packaging scale weighing 20kg, the maximum number of divisions is 1000 divisions; the scale body adopts CAZF-W130 sensor, the range is 20kg, the sensitivity is 2.0±0.008mV/V, and the power supply is 12V; the scale adopts CAZM10 display instrument . Ask whether the sensor used can match the meter.
Solution: The input sensitivity of the CAZM10 display instrument is 0.6μV/d, so according to the matching formula of the load cell and the display instrument, the actual input signal of the instrument can be obtained as:
Therefore, the load cell used meets the requirements of the input sensitivity of the display instrument and can match the selected instrument.
2. Meet the accuracy requirements of the entire electronic scale. An electronic scale is mainly composed of a scale body, a load cell, and a display instrument. When selecting the accuracy of the load cell, the accuracy of the load cell should be slightly higher than the theoretical calculation value, because the theory is often subject to objective Conditional limitations, such as 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 and other factors directly affect the accuracy requirements of the scale. Therefore, the requirements must be improved from all aspects and economic benefits must be considered. , To ensure that the purpose is achieved.