Fault in FUJI differential pressure transmitter
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This is the malfunction I encountered recently; the process was a bit tricky and unlucky. I’ll only mention the symptoms and the conclusions. In the conclusion, I need the experts to clarify one point of confusion. Observation: The 275 communicator shows a current of 4 mA and a differential pressure of 0 kPa (the range setting has not been changed; it remains at 0–1000 kPa, and the gauge also displays 0%). Everything is normal. However, the loop current was measured at 6 mA, which resulted in an additional 125 kPa corresponding to 2 mA being displayed in the DCS. A LOOP TEST was conducted using 275; for currents of 4mA, 8mA, 12mA, 16mA, and 20mA, the measured circuit current was about 2mA higher than the corresponding value. This increase decreased as the current increased, with values of approximately 4+2.8mA, 8+2.5mA, 12+2.1mA, 16+1.9mA, and 20+1.6mA respectively. Solution: By sending a signal using a signal generator on-site, it was confirmed that the issue lay with the gauge on site. I originally planned to replace the watch, but since there were no spare parts available, I replaced some of the circuit modules instead. Eventually, after replacing the black module where the terminals were located, the current output became normal. Therefore, it is determined to be a fault in this module. Question: 1. Is this module a D/A module? I searched online but couldn’t find any information on the internal modules of that table. 2. For the situation of “drift” in the output of this type of current, can it be corrected using a dedicated Fuji communicator? 3. Such an issue has never occurred when using instruments from Rosemount, EJA, etc., but it has happened several times with Fuji’s instruments. Is it a problem with a certain batch? Otherwise, I really wouldn’t dare to use such tables for future interlocking systems. 4. I would be grateful if experts could share any more detailed technical documents. There are many documents related to product selection, but none of them provide even the slightest introduction to the few modules listed in the tables. I’m sorry, I didn’t take any pictures.
If the process is rather complicated, wouldn’t it be better to use a multimeter to measure the current from the start, thereby avoiding some steps? The current is still good; it should be determined by actual measurement with a meter. Can’t trust Hart
It is presumed that the issue mentioned by the poster arose because the control system and the process team noticed a discrepancy between the readings on-site and those displayed on the control system, which led to requests for repairs. . For this type of fault, by using the displayed differential pressure value and percentage, the multimeter becomes fully functional. It allows for quick detection of faults caused by abnormally high current levels.
The central control system mainly detects that the indicated values are too high; during instrument checks, it is found that there is a mismatch. Which module is it that causes the mismatch in the current? What feature? D/A? Thank you!
You’re right; by relying on the multimeter, it’s possible to confirm that the current is incorrect. But unfortunately, when I switched to another watch (the old one), I ran into the same problem, which made me doubt that it was actually a problem with the watch. . . . . . Who would have thought that LZ would be so unlucky as to run into two watches with the same problem in a row. Finally, the only option is to use a signal generator to provide standard signals on-site. . .
To be honest, when I was buying a car, a friend asked me which brands I was considering, and I said I definitely wouldn’t buy a Japanese car. The kind of resistance that can be exercised is mainly by buying things oneself; there’s nothing else that can be done. Moreover, it’s a fact that they are more advanced than us; all we can do is endure humiliation and patience, as one day we will be able to surpass them. Also, we conducted an experiment today; the current issue can be corrected, so there’s no need to replace the module.