Asking the experts for advice on the causes of instrument failures
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I would like to ask the experts here: if the field pressure transmitter is a device with a range of 0–60 MPa, and it shows 30 MPa at the field site, but 40 MPa on the host computer (the range of the transmitter is the same as that of the host computer). At this time, the current value measured on the pressure transmitter gauge is around 12 mA. I would like to know what is causing the discrepancy between the value at the site and the value displayed on the host computer. (If a new gauge is used, the on-site value will match that of the host computer…)
I still think that the range of the transmitter changed before it was replaced
If there is no error in the current value, then the problem lies in the set limits of the DCS range; if the range is set to 0–80 MPa, then 12 mA should correspond to a reading of 40 MPa. This is the range of the meter; it does not match the signal range set for this station during DCS configuration.
The possible reasons are as follows: 1. Fault in the gauge itself: There may be problems with the internal components of the gauge, which prevents accurate pressure measurement, or there could be issues with the signal conversion circuit. After replacing the gauge, it was determined that the problem was caused by a fault in the gauge itself. 2. Signal transmission issues: The signal may become distorted due to interference or losses in the signal transmission lines, or the signal may be lost as a result of poor connections such as at the connectors. Check whether the signal lines and connectors are functioning properly; you can try replacing the signal cables and connectors to resolve the issue. 3. Host computer setting issue: It may be that the parameter settings displayed on the host computer are incorrect, resulting in discrepancies between the displayed values and the actual values. Check whether the parameter settings on the host computer are correct, including the measurement range and units. 4. Influence of other environmental factors: Environmental factors such as temperature and humidity can affect the measurement accuracy of the instrument. Check whether the environmental conditions meet the requirements of the instrument; if there are any abnormalities, try to adjust the environmental conditions. It is necessary to take all the above factors into consideration and examine each possible issue one by one in order to determine the specific cause. If the problem persists and affects the normal operation of the system, it is recommended to have professional technicians conduct on-site debugging and fault resolution. .
It’s a bit abstract; it’s necessary to check some data on-site to be sure
(If a new meter is installed, the on-site value will match that of the host computer…) Measure the positive and negative current values separately; if there are issues with different circuits or meters, then check inside the building
There are options for output linearization and other methods during DCS configuration; checking these will resolve the issue.
When measuring the current on the DCS side, if it is 12mA, 400 is displayed. If the channel is set to 4-20mA, then the range must be set to 0-800. This has nothing to do with the transmitter; as long as the transmitter can output 12mA as normal, there is no problem.
The transmitter has been squared, and the DCS has also been squared. The replaced transmitter does not apply the square root function.