Introduction of detection methods for common faults of load cells

First of all, before removing the load cell from the weighing system, you should carefully judge whether the structure of the system and the sensor have the following problems:

(1) Check whether the limit device of the system is working and whether the gap meets the requirements;

(2) Check whether the system has damage, rust or obvious wear on the force transmission part; in winter, pay attention to whether the sensor force transmission part has icing, which affects the force transmission and reset of the system;

(3) Check whether it is a system transmission failure, which may be due to dust, misalignment of mechanical parts, delayed component transmission, etc., rather than sensor failure; whether the sensor is installed in the correct direction.

(4) Check whether the connection between the sensor cable and the junction box and the display instrument is correct,

Whether there is any disconnection and poor contact of the connecting wire;

(5) Check whether the junction box and meter are faulty, especially the potentiometer in the junction box.

(6) Check whether the sensor is corroded (especially the patch hole area); the integrity of the sensor cable; the environment at the entrance of the sensor cable, etc.

 

Excluding the problems of the system structure and the appearance of the sensor, the following methods can be used for step-by-step testing.

(1) Rough line inspection

The power supply line, signal line and shielding line of the sensor are coaxial cables, which can be tested with a multimeter (i.e. power line-signal line, power line-shielding line, signal line-shielding line), if there is a short circuit, open circuit or Phenomenon such as insulation performance degradation indicates that the sensor may be damaged.

(2) Check the impedance of the load cell

When checking, it is necessary to cut off the power of the electronic scale, open the junction box, and disconnect the signal wires of each sensor. When there is no special testing equipment, the input impedance Zi and output impedance Zo of the sensor can be measured with the ohm file of a 4-digit digital multimeter, and the measured value can be compared with the nominal value on the product qualification certificate provided by the manufacturer. When the side value exceeds the allowable range, it indicates that the sensor may be damaged (Note: the value of the multimeter used should be accurate, and it should be used after measurement verification/calibration)