3 Steps for Multimeter Testing Load Cells
1. The sensor manufacturer provides the sensor output sensitivity and power supply voltage before leaving the factory. We detect the sensor output signal according to these two parameters. The strain gauge load cell outputs an analog signal millivolt voltage. For example, the sensor output sensitivity is 2.0mV/V, and the power supply voltage is DC10V. The two parameters can provide us with the sensor excitation voltage that requires DC10V, and the sensor output signal corresponds to a linear relationship of 2.0mV per 1V excitation voltage. For example, the full scale of the sensor is 50KG, then the full scale output of DC10V voltage to the sensor is 20mV. According to this relationship, we use the multimeter mV gear to measure the output signal of the sensor. It is normal for the no-load output of the sensor to be 0mV, which is greater than this value, but close to this value, and the value change means that the sensor has zero drift. If the value is large, it means that the sensor is damaged or the internal bridge is a circuit, and the resistance of the bridge arm is asymmetrical.
2. According to the sensor parameters, input resistance and output resistance provided by the sensor, judge whether the sensor strain gauge is damaged. Sensor input and output resistance values vary from manufacturer to manufacturer. So this should be tested according to the manufacturer's label. Use a multimeter to detect the ohm position, the resistance of the power supply and the power ground, and the resistance of the signal line and the signal ground. If it is larger than the factory resistance value, it means that the sensor has been overloaded and the strain gauge is deformed. If the resistance value is infinite, the sensor strain gauge is seriously damaged and cannot be repaired.
3. Because the lead wire is often broken during the use of the sensor, but the outer layer of the sheath wire is intact, so the sensor wire is intact by visual inspection. We use the ohm gear of the multimeter to detect the continuity of the sensor wire. If the resistance is infinite determine a break, if the resistance changes bad contact.
