Displacement sensors help measure displacement distances, and many interesting applications can be created based on them. To enhance everyone's understanding of displacement sensors, this article will introduce the working requirements of linear displacement sensors. If you are interested in linear displacement sensors, please continue reading.
The working principle of a linear displacement sensor is the same as that of a sliding rheostat; it functions as a voltage divider, using a relative output voltage to represent the actual position of the measured location. The following requirements apply to the operation of this device:
1. If the linear displacement sensor's ruler has been used for a long time, and the seal has aged, containing many impurities, and the mixture of water and oil severely affects the contact resistance of the brushes, causing the displayed numbers to fluctuate continuously, then the linear displacement sensor's ruler is likely damaged and needs to be replaced.
2. If the power supply capacity is too small, many problems will arise. Therefore, the power supply needs to have sufficient capacity. Insufficient capacity will cause the following issues: the movement of the molten plastic will cause fluctuations in the display of the mold closing electronic ruler, or the movement of the mold closing will cause fluctuations in the display of the injection electronic ruler, resulting in large measurement errors. These problems are more likely to occur if the solenoid valve's drive power supply and the linear displacement sensor's power supply are connected simultaneously. In severe cases, voltage fluctuations can even be measured with a multimeter in voltage mode. If the problem is not caused by high-frequency interference, electrostatic interference, or insufficient neutralization, then it is likely due to insufficient power supply capacity.
3. Both frequency modulation interference and electrostatic discharge (ESD) interference can cause the digital display of the linear displacement sensor's electronic ruler to fluctuate. The signal cable of the electronic ruler must be kept in a separate cable tray from the equipment's power lines. The electronic ruler must be equipped with a grounded bracket, and the ruler's casing must have good contact with the ground. Shielded cables must be used for the signal cable, and one end of the cable in the electrical box should be grounded to the shield.
When there is high-frequency interference, a multimeter voltage measurement will usually show normal readings, but the displayed numbers will fluctuate continuously. The same situation occurs with electrostatic interference. To verify if it's electrostatic interference, you can short-circuit the cover screw of the electronic ruler with some metal parts on the machine using a power cord. The electrostatic interference will immediately disappear upon short-circuiting. However, eliminating high-frequency interference is difficult using the above method. Variable frequency drives and robotic arms frequently experience high-frequency interference, so you can try stopping the high-frequency drive or robotic arm to verify if it's high-frequency interference.
4. If the linear displacement sensor's electronic ruler displays data that jumps regularly at a certain point during operation, or if no data is displayed, it is necessary to check whether the insulation of the connecting wire is damaged and whether it is making regular contact with the machine's casing, resulting in a short circuit to ground.
5. The power supply voltage must be stable. Industrial voltages need to meet a stability requirement of ±0.1%. For example, if the reference voltage is 10V, a fluctuation of ±0.01V is permissible. Otherwise, it will cause fluctuations in the display. However, if the amplitude of the display fluctuation does not exceed the amplitude of the voltage fluctuation, then the electronic ruler is normal.
6. The alignment of the linear displacement sensor needs to be excellent, but a parallelism error of ±0.5mm and an angle error of ±12° are permissible. However, if both the parallelism and angle errors are too large, the displayed numbers will fluctuate. In such cases, the parallelism and angle must be adjusted.
7. During the connection process, extra care must be taken. The three wires of the electronic ruler must not be connected incorrectly, and the power wire and output wire cannot be interchanged. If the above wires are connected incorrectly, a large linear error will occur, which will be difficult to control, the control accuracy will become very poor, and the display will easily exhibit fluctuations, etc.
