Large fluctuations in the ultrasonic level gauge? Solve
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In the wastewater treatment plant, there are three top-mounted ultrasonic level gauges, and two of them show particularly large fluctuations in the data displayed on the PLC interface. The liquid level display fluctuates by about 1M. However, the level gauge on site showed no fluctuations, which matched the actual situation on site. Solve? How should this problem be solved?
Add a shielding barrier, or check whether the shielding is properly connected
What brand of ultrasonic device? Is there foam on the surface of the liquid? What wiring type?
1. Radar: Mad man; Ultrasonic waves: Mad woman. Using a mad woman for a project – your troubles are likely just beginning. :Lol 2. You need to disconnect the PLC and use a multimeter to check whether the output signal is fluctuating; in other words, you must first determine whether it’s the instrument’s signal itself that is unstable. 3. The following 10,000 words are omitted.............. For more exciting content, subscribe for access, hehehe :P
The liquid level is reduced to the lowest level acceptable for the process, and suppression is applied above the liquid surface
Is the medium in that container producing vapor? Check if there’s any spiderwebbing on the table header. It’s not about checking the power supply voltage, cable insulation, and shielding.
It’s very likely to be an interference issue; it’s possible that you won’t be able to detect it using a multimeter. A simple solution is to add an optoelectronic isolation barrier and check again to see if there’s any fluctuation. If not, then it’s indeed an interference problem
If the value displayed on the instrument does not fluctuate, check whether there is electromagnetic interference at the site, and confirm whether shielded wires are being used to transmit the 4-20mA signal； If that still doesn’t work, remove the meter and position it vertically at a distance of 1-2 meters from the wall to check whether the readings are accurate and whether there are any fluctuations in the current
Ultrasonic level gauges have weaker interference resistance compared to other type of level gauges
It’s the usual thing to say – check each item one by one; that’s how ultrasound works.
The level gauge is from Beijing Jingbo; there is foam on the water surface, about 5 cm thick. The final issue was identified: the terminals of the PLC module had burned down for some unknown reason; after replacing those terminals, the liquid level display worked properly.