How to use a multimeter to test a load cell
Load cells are widely used in industrial weighing (e.g. belt scales, weighing scales, electronic scales, body scales, etc.), force detection, and tensile force measurement. Field use in the process of load cell failure is generally as follows.
1. Sensor overload, the user and the manufacturer did not communicate clearly, the sensor range and the actual force value, weight size mismatch, resulting in sensor overload, so that the sensor bridge arm resistance deformation caused by circuit imbalance. Sensor can not work properly, the output signal fluctuations, resistance infinity and other phenomena.
2. Sensor lead pull off, the user does not do the process of protection measures sensor lead pull off, generally in the sensor lead interface fracture affects the sensor to use the non-responsive or sudden changes in the measured value. 3. Improper use of sensors, static sensors in the use of impact, shear, torque and other serious damage to the sensor to be unable to repair.
So how do we effectively use a multimeter on-site detection of common faults in the load cell?
1, the sensor manufacturer factory to provide sensor output sensitivity and supply voltage, we detect the sensing output signal according to these two parameters. Strain gauge load cell output analogue signal millivolt voltage. For example, the sensor output sensitivity is 2.0mV/V, the supply voltage is DC10V, the two parameters can provide us with a sensor to stimulate the operating voltage is the need for DC10V, the sensor output signal corresponds to the output of every 1V excitation voltage 2.0mV linear relationship. For example, the sensor full scale is 50KG, then give the sensor DC10V voltage full scale output 20mV. according to this relationship we use the multimeter mV gear to measure the sensor output signal. Sensor no-load output is 0mV normal, greater than this value, but close to this value, the value of the change is that the sensor has zero drift. If the value is very large that the sensor is damaged or internal bridge is the circuit, the bridge arm resistance asymmetry.
2, according to the sensor factory to provide sensor parameters, input resistance and output resistance to determine whether the sensor strain gauge damage. Sensor input and output resistance value of each manufacturer is not the same specifications. So this should be tested in accordance with the manufacturer's label. With a multimeter ohm gear detection, power supply and power ground resistance, signal line and signal ground resistance. If the resistance value is larger than the factory suggests that the sensor has been overloaded strain gage deformation, if the resistance value is infinite sensor strain gage serious damage can not be repaired.
3. Because the sensor is often used in the process of lead breakage, and the outer layer of the sheath line is intact, so the visual sensor wire is intact, we use the multimeter ohm gear detection sensor wire through the break. If the resistance is infinite to determine the fracture, if the resistance changes poor contact.
