Temperature transmitter
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The integrated temperature transmitter (thermistor, four-wire type) shows a temperature of around minus three degrees on the DCS screen. The safety barrier also functions even when there is a power outage at the site; it returns to normal operation after the power is restored. What could be the cause of this?
There is no data from on-site measurements, such as the output signal of the temperature transmitter at that time, the input and output currents of the safety barrier, or whether the integrated temperature sensor is intelligent or a standard analog type; it’s difficult to conduct an analysis. It is likely a problem with temperature changes or the safety barrier; power needs to be turned off and then reactivated to restore normal operation.
Measure the voltage, current, etc., and try using a different power supply
On-site temperature variation fault. Just like phones and computers sometimes need to be restarted, there’s no real reason for it. If it happens frequently, it has to be replaced.
What is the current at the site? If it’s the same as that in the DCS system, I agree with the view from the 4th floor: it’s a temperature variation fault. Smart meters exhibit this phenomenon.
Possible reasons are: on-site temperature changes, safety barriers. If it appears again next time, we need to obtain the data in order to analyze it and determine further.
Connect an ammeter in series with the temperature sensor and the safety barrier to measure the output and check whether it is correct; then connect it in series between the safety barrier and the DCS, and finally determine whether the problem lies with the safety barrier or the output from the temperature sensor