Rosemount temperature transmitter
Thread Content
I noticed something strange with my device. The temperature reading showed 79 degrees normally, but suddenly it rose to 110 degrees. The measurement range is from -50 to 300. Our technicians went over, separated the measuring unit from the protective tube, and checked it; the reading was normal, around 25 degrees, with a resistance of about 108, which is within the normal range. After reinstalling it, the readings became normal again, so process-related issues were ruled out. I’m not sure what caused the problem; it might have been due to loose wires (4-20MA)
Has any other professional encountered this situation? Let’s analyze it and exchange ideas
The most likely cause is poor wire contact；
Sometimes, dust and other debris on the terminal blocks cause a decrease in their insulation, which can also lead to the aforementioned situation. As long as it is not an instantaneous temperature, the curve of the measured temperature is generally continuous, with few jumps, and such jumps are usually due to instrument failures.
We have encountered this phenomenon; it is caused by issues with the wiring at the measurement site, where poor contact leads to changes in the resistance value. Personnel went to the site for inspection; that is, the wiring had to be reconnected before normal operation could be restored.
If the displayed temperature is higher than the actual one, it indicates that the sensor input resistance of the transmitter is higher than it should be. If the sensor resistance is normal, then the problem may lie in the wiring connecting the sensor to the transmitter; check for any loose connections or poor contacts.
Measure the actual temperature at the top of the sleeve; I’ve encountered situations where water droplets were inside, causing a continuous cycle of vaporization and condensation that led to temperature fluctuations
Insufficient regular maintenance can lead to very complex problems, yet the solutions to those complex problems are quite simple.