Four elements of high-precision intelligent weighing system selection

1. The choice of stability

     The ability of a high-precision intelligent weighing system sensor to maintain its performance after a period of use is called stability. In addition to its own structure, the main factor that affects the long-term stability of the sensor is the use environment. Therefore, to make the sensor have good stability, it must have a strong environmental adaptability. Before selecting a sensor, investigate its use environment, and select a suitable sensor according to the specific use environment, or take appropriate measures to reduce the impact of the environment.

The environment will have the following effects on the high-precision intelligent load cell:

   1) The high temperature environment causes the coating material of the sensor to melt, the solder joints are opened, and the stress in the elastomer is structurally changed.

   2) The influence of short-circuit caused by open air dust and humidity on the sensor.

   3) In a highly corrosive environment, such as humidity and acidity, the sensor will damage the elastomer or cause a short circuit.

   4) The influence of electromagnetic field on sensor output disturbance signal.

   5) Special explosion-proof sensors must be used in flammable and explosive environments.

The stability of the high-precision intelligent weighing system has quantitative indicators. After the expiration date, it should be re-calibrated before use to determine whether the performance of the sensor has changed. In some occasions that require the sensor to be used for a long time but cannot be easily replaced or calibrated, the stability of the selected sensor is more stringent and must be able to withstand the test for a long time.

2. The choice of sensitivity

Generally, within the linear range of the sensor, it is desirable that the higher the sensitivity, the better. Because only when the sensitivity is high, the output signal value corresponding to the measured value is relatively large, which is beneficial to signal processing. But when the sensitivity is high, the external noise that has nothing to do with the measurement will also be amplified by the amplification system, which will affect the measurement accuracy. Therefore, it is required that the sensor itself should have a high signal-to-noise ratio and minimize the interference signal introduced from the outside world.

3. Selection of the number and range of sensors

The selection of the number of sensors in the high-precision intelligent weighing system is based on the purpose of the electronic weighing instrument and the number of points that the scale needs to support (the number of support points should be determined according to the principle that the geometric center of gravity of the scale body coincides with the actual center of gravity).

The selection of the sensor range can be determined based on the comprehensive evaluation of factors such as the maximum weighing value of the scale, the number of selected sensors, the self-weight of the scale body, the maximum possible partial load and the dynamic load. According to experience, the sensor should generally work within 30% to 70% of its range, but for weighing instruments with greater impact, when selecting the sensor, the sensor should generally work within 20% to 30% of its range. Ensure the safety and life of the sensor

4. The choice of accuracy

The accuracy of the high-precision intelligent weighing system is an important performance index of the sensor, and it is an important link related to the measurement accuracy of the entire measurement system. The higher the accuracy of the sensor, the more expensive it is. Therefore, the accuracy of the sensor only needs to meet the accuracy requirements of the entire measurement system, and it is not necessary to select too high. In this way, a cheaper and simpler sensor can be selected among many sensors that meet the same measurement purpose. If the measurement purpose is for qualitative analysis, select a sensor with high repeatability accuracy. It is not advisable to use a sensor with high absolute value accuracy; if it is for quantitative analysis and accurate measurement values must be obtained, select a sensor with an accuracy level that can meet the requirements for weighing sensor.

    The accuracy selection satisfies the following two conditions:

      1. Meet the requirements of instrument input. The output signal of the sensor must be greater than or equal to the input signal required by the instrument.

      2. Meet the accuracy requirements of the entire electronic scale. An electronic scale is mainly composed of a scale body, a sensor, and an instrument. When selecting the accuracy of the sensor, the accuracy of the sensor should be slightly higher than the theoretical calculation value.