How to use a multimeter to measure the quality of a weighing sensor

How to use a multimeter to measure the quality of a weighing sensor

1. The sensor manufacturer provides the sensor output sensitivity and power supply voltage at the factory, and we detect the sensor output signal based on these two parameters. The strain gauge weighing force sensor outputs an analog signal in millivolts. For example, the sensor output sensitivity is 2.0mV/V, and the power supply voltage is DC10V. These two parameters can provide us with a linear relationship between the sensor excitation working voltage requiring DC10V and the sensor output signal corresponding to a 2.0mV excitation voltage output for every 1V. For example, if the full range of the sensor is 50KG, then give the sensor a DC10V voltage and output 20mV at full range. Based on this relationship, we use a multimeter mV to measure the sensor output signal. The no-load output of the sensor is 0mV, which is normal. If it is greater than this value, but close to this value, the numerical change indicates that the sensor has zero drift. If the value is large, it indicates that the sensor is damaged or the internal bridge is a circuit with asymmetric bridge arm resistance.

2. Determine whether the sensor strain gauge is damaged based on the sensor parameters provided by the factory, input resistance, and output resistance. The input and output resistance values of sensors vary from manufacturer to manufacturer. So this needs to be tested according to the manufacturer's labeling. Use a multimeter to measure the resistance of the power supply and power ground, as well as the resistance of the signal line and signal ground. If the resistance value is greater than the factory resistance value, it indicates that the sensor has been overloaded and the strain gauge has deformed. If the resistance value is infinite, the sensor strain gauge is severely damaged and cannot be repaired.

3. Due to frequent wire breakage during the use of the sensor, while the outer layer of the protective wire is intact, we visually inspected the integrity of the sensor wire. We used the ohm range of a multimeter to detect the continuity of the sensor wire. If the resistance is infinite, it is certain to break, and if the resistance changes, the contact is poor.  

The weighing sensor is known as the heart component of electronic scales. With the rapid development of science and technology, electronic scales made from weighing sensors have been widely used in various industries, achieving fast and accurate weighing of materials. Especially with the emergence of microprocessors and the continuous improvement of automation in industrial production processes, weighing sensors have become a necessary device in process control. From the weight measurement of large tanks, hoppers, and other scales that could not be weighed before, as well as the measurement and control systems of crane scales, car scales, etc., to the batching system for mixing and distributing multiple raw materials, automatic detection in production processes, and powder feeding control, weighing sensors have been applied. At present, weighing sensors are almost used in all weighing fields. Here, I will take the example of a faulty weighing sensor to discuss its on-site use and debugging. For fully electronic truck scales, the troubleshooting of various sensor faults should follow these steps; Observation (fault observation) - Analysis (fault cause) - Detection (providing a basis for fault diagnosis or verifying the judgment results) - Repair (repair or replacement) - Calibration (testing its metrological performance after system debugging). According to the actual situation, the following methods can be selected for judgment: visual method, substitution method, comparison method, insertion and extraction method, and code diagnosis method. Let's talk about using a multimeter for detection.