The weighing sensor is a part of the automatic weighing mechanism key, and its function is no less than the "heart of the human body". It is a key component for judging whether the product weighing meets the standard. If the weighing sensor malfunctions, it is difficult for us to estimate how much loss it will cause to the production line. Therefore, users must regularly test this key component in order to reduce losses. Today, let's learn about the detection steps for faults in the weighing sensor of an automatic weighing scale. We hope that users of automatic weighing scales can easily understand and apply them.

1. Test sensor output

Connect the sensor separately to a regulated power supply and use an excitation voltage of 10-15VDC. Connect the output terminal of the sensor to a millivolt meter (or set the multimeter to DC millivolt mode), load on the loading terminal of the sensor according to its installation and usage status, and observe the output changes of the sensor.

2. Zero point output check

Zero point output refers to the output value of a sensor when there is no load, and when all loads (including static loads such as scales and force transmission components) must be removed, the output of the sensor is tested. The zero point of the sensor should be the value obtained from testing under the requirements of the sensor design, installation, and use, in order to prevent erroneous effects caused by the sensor's own weight.

3. Test the impedance of the bridge circuit

Testing the bridge impedance is to check the integrity of the sensor bridge. During the testing, the sensor should be disconnected from the junction box and other testing equipment. The input and output impedance testing involves using a digital multimeter probe to sequentially measure the impedance values at the input and output terminals of the sensor, and comparing the test values with the values on the product's certificate of conformity; The confirmation of bridge symmetry refers to using a digital multimeter to measure the impedance between an input terminal and an output terminal. Four sets of impedance values can be obtained by measuring them sequentially. In sensors with symmetrical compensation, the range of these four impedance values should not exceed 1 Ω (for low precision multimeters, this value should not exceed 2 Ω).

4. Test insulation impedance

Generally, we require testing the impedance between the sensor's lead wire and the sensor body (elastic body, housing, etc.). Attention, disconnect the sensor, junction box, and instrument. Debug the insulation test box (meter) and connect one end of the probe to the sensor's cable (output, input, shielded wire, etc.) and the other end to the sensor's body (elastic body, housing, etc.). Generally, the impedance should be ≥ 5000M Ω.