Help: Problem with remote transmission of magnetic flap level gauge
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This post was last edited by gewensheng1987 on 2012-3-7 at 11:28. The 1700mm long magnetic flap level gauge is showing normal readings at the site; if the on-site indication is 1500mm, however, the remote DCS displays only around 300mm, with a signal strength of just over 5mA. What could be the reason for this? It was working fine in the first two months, but then for some reason it stopped working
In the first two months after it was installed, the magnetic flip-level gauge worked normally, but then for some reason it stopped functioning
1 Does it need to be cleaned? Is there a problem with the 2-level gauge conversion section? This is my way of thinking when I encounter this problem
Does the transmitter need to have its range recalibrated?
The on-site reading is correct, but the DCS reading is incorrect, which indicates that there was a problem during transmission. It was working fine before, which indicates that the DCS configuration is correct; the problem might lie in the header output or the grounding shielding
For remote transmission of magnetic flap switches, reed switches are usually used; based on what you’ve described, it’s possible that one of these components is faulty. If there is an identical transmitter, it is recommended to try swapping them.
Typically, dry reed switches are used in magnetic flap level gauge transmitters. You can remove the transmitter module and measure the resistance of the two wires coming from the dry reed switch. Then, use a magnet to attract it at any position between 300–1700 mm, and also at positions between 0–300 mm, to see if the resistance value changes. If the resistance remains unchanged between 300–1700 mm but changes within the 0–300 mm range, it’s possible that the dry reed switch at 300 mm has broken and caused a short circuit
If there was no problem originally, it proves that it’s not an issue related to the range or zero point. If the liquid level is 1300 but the output is only 5 mA, then there must be a problem in the process of converting the liquid level into an electrical current. In most cases like this, the problem lies with some moving parts; I guess the same is true in your case as well!
This post was last edited by Ah Hai on 2012-3-7 at 21:55. First, it’s necessary to check which part is having the problem and locate where the float is. Then use a multimeter to measure the resistance; the resistance between two wires is generally 1000 ohms per meter. For the transmitter unit: (300/1700)×16+4 = 6.8 MA; (5-4)/16×1700 = 106 MM. The indication on-site does not necessarily mean that the liquid level is exactly there – it’s possible that the magnetic flip switch isn’t moving or isn’t responding properly, or that the float lacks sufficient magnetism, preventing the ball from moving. The level gauge operates based on the principles of buoyancy and magnetic coupling. As the liquid level in the container under test rises or falls, the float in the main tube of the level gauge moves up or down accordingly. The permanent magnet inside the float transmits a magnetic signal to the on-site indicator, causing the red and white flip columns to rotate 180°. When the liquid level rises, the flip columns change from white to red; when the liquid level drops, they change from red to white. The boundary between red and white on the indicator represents the actual height of the liquid level in the container, thereby enabling the indication of the liquid level.
It’s possible that there is a problem with the transducer element.