Problems with radar level gauge 5300

Given your situation, the radar and the card channels have both been replaced, and the level gauge itself has an LCD display. After this issue occurred, check whether the indications on site match those from the DCS, look for any nearby sources of interference, and verify that the grounding is proper. Since you have already replaced the hardware yet the problem still persists, hardware issues can basically be ruled out

Some details need to be verified; please let me know. First, whether it is a waveguide installation and what the size of the waveguide is. Second, what is the height of the tank, that is, the distance from the instrument mounting flange to the bottom of the tank. Third, what is the length of the cable? Has it been cut by a cable manufacturer, and is its length less than the height of the tank?

The radar probe is installed near the liquid inlet, where there are significant fluctuations; it is recommended to change its installation location

Analyze based on the DCS historical curves, related operations, and process media as a whole

The waveguide is DN100; the tank height is 11.3 meters, and the cable length is 11 meters. The bottom of the waveguide is 30 cm above the bottom of the tank. The weight at the bottom of the cable has a positioning ring, and both are located inside the waveguide.

It is preliminarily determined that the issue lies with the waveguide; how long has this radar been in use? If a long period of time has passed, it is recommended to flush and clean the waveguide

As mentioned above, check if the waveguide or cables are dirty; also examine the shielding grounding of the cables and check their insulation condition.

It has only been in use for half a year. The waveguide is welded inside the tank, so it cannot be cleaned. The medium being measured is qualified ethylbenzene product, which is very clean; ethylbenzene is a solvent, so there is no possibility of the waveguide being dirty. The cable shielding is also good; by connecting another functional radar cable to this radar, the same fault symptoms persist.

It’s no problem if the cables and waveguides are dirty; the waveguides are a bit thin, but it’s still acceptable. Has it always been like this, or did it start suddenly? The tank is too tall and the cable is too long; I think it’s very likely that the middle part of the cable is touching the wall of the waveguide, or at least quite close to it. Although there is a centering ring at the bottom, the cable being too long means that its middle part might still touch the wall. If it hits a barrier, the metal signal becomes very strong; it will stay stuck in this position when the liquid level is low. Once the liquid level rises above that point, it might function normally again. In this case, it is recommended to use PTFE material to create centering rings with a diameter slightly less than 100, which should be installed on the cables; it is suggested to use one such ring every two meters and fix them to the cables. Non-metallic materials should be used to avoid any reaction with the medium. If the radar can be disassembled, you can give it a try. For example, if it’s currently stuck at 7 meters, turn the radar flange by an angle; if the liquid level is no longer 7 meters, then that indicates this is the problem. If you have Emerson’s handheld device, you can check what the strength of the level echo signal is at the level where jamming occurs. A high value can indicate this issue as well; the echo signal strength is indicated as XXXX mV, and a value over 3000 is considered high. I guess 80% of the time it’s this issue; you can give it a try. Even if it’s not that, adding a fixed center ring can’t hurt, as this problem will arise sooner or later. It should work normally. If it still doesn’t work after that, it’s necessary to examine the waveform in detail; a professional needs to handle it. The claw machine guys, they’re killing me