The measurement of the load cell adopts the principle of strain gauge. The strain gauge is fixed on the elastic body. The action of external force causes the elastic body to deform, and the strain gauge on the elastic body deforms accordingly. Due to the change of the external shape of the strain gauge, its resistance The value will change accordingly.
For each load cell, at least 4 strain gauges are connected together to form a Wheatstone bridge. When the load on the sensor causes the strain gauge resistance to change, the bridge is unbalanced. Under the condition that the excitation voltage remains unchanged, the output signal is The size is proportional to the force on the sensor.
Four-wire and six-wire load cells
The four-wire load cell has a set of signal wires and a set of excitation power supply. For the six-wire load cell, there is an extra set of feedback compared to before. If the six-wire sensor is connected to the four-wire junction box, you only need to short-circuit the feedback positive and the excitation positive, and the feedback negative and the excitation negative to meet the wiring requirements.
What should I do if there is a weighing display error or instability during use?
- Check whether the connection is secure and whether there is moisture leakage.
- Measure the input and output impedance. Normally, the input impedance is greater than the output impedance, the input impedance is about 400Ω (measure the excitation power line), and the output impedance is about 350Ω (the signal test line).
- Power on and measure the zero point voltage value, which is normal within the signal measuring range of the instrument, otherwise replace it.
- Single test to find out the abnormal sensor.
- Measure input and output impedance
- Power-on test signal terminal zero voltage, compare with theoretical value
- Test a single sensor in turn
- Check whether the connection line is correct and reliable