How to Solve Displacement Sensor Failure?
Displacement sensor, also called linear sensor, is a linear unit sensing metal. The function of sensor is to transform the tested physical quantity into electric quantity. The working principle of straight line displacement sensor is same as that of slide rheostat. It is used as voltage divider to present the actual position of tested position through relative output voltage. There are a few requirements for the work at the position:
- If electronic ruler has been used for long, the seal is aging and mixed with impurities, and water and oil mixture can influence the contact resistance of electric brush, the displayed numbers will jump constantly. At the moment, straight line displacement sensor can be considered faulted and need to be replaced.
- The low power capacity will cause many situations, so power supply should have high enough capacity. The low capacity will cause the following situations: the movement of colossal makes the display of closing electronic ruler change and fluctuate or the display of injection electronic ruler fluctuate leading errors. If the drive power of magnetic valve and straight line displacement sensor are in the same position, the above situation is easier to emerge. In a serious case, the fluctuation of voltage can be measured through the voltage profile of multi-meter. If the situation is not caused by high frequency interference, electrostatic interference or poor neutrality, the cause may be low power.
- Frequency-modulation jamming and electrostatic interference may make the electronic ruler of straight line displacement sensor display jumping numbers. The signal line of electronic ruler and strong current line of equipment should be installed in separate wiring ducts. Electronic ruler must use earthling arm and the shell of electronic ruler should be earthed well. Signal line should adopt shielded wire and one segment of signal line should be earthed through shielded wire. If high frequency interference exists, the voltage measurement with multi-meter will display normal, but the displayed numbers are jumping; when electrostatic interference emerges, the situation is same as that of high frequency interference. Electrostatic interference can be proved by connecting cover screw to some metal on machine through one segment of power line which can eliminate electrostatic interference. But the above method can’t eliminate high frequency interference. Frequency conversion power saver and robot arm have frequent high frequency interference, so high frequency interference can be verified by stopping high frequency power saver or mechanical arm.
- If the data at one point jumps regularly or no data emerges when the electronic ruler of straight line displacement sensor is working, check whether the insulating layer of connecting line is damaged and connecting line contacts ground regularly leading to the shell of machine.
- The service voltage must be stable. For example, if the reference voltage is 10V, the fluctuation of ±0.01V is allowable; if it isn’t, that will lead to the fluctuation of displayed trick. The displayed fluctuation range is lower than the fluctuation range of voltage, the electronic ruler is normal.
- Straight line displacement sensor is good for neutral demands, but the errors of ±0.5mm in depth of parallelism and ±12° in angle are allowable. But if the errors of depth of parallelism and angle are too large, the displayed numbers will jump. If that situation emerges, depth of parallelism and angle need to be adjusted.
- In connection, the three lines of electronic ruler can’t be connected wrongly and power line and output line can’t be transposed. The wrong connection will lead to a large linear deviation, which is hard to control, and a jumping display screen.