Cleaning the air conditioner in the DCS control cabinet room caused parameter fluctuations
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What is the reason for this? These fluctuating instruments are not all in one card slot, nor even in the same cabinet. How could there be fluctuations? Is the electrical grounding of this room poor? Is it still the air conditioner that’s leaking electricity? Or some other reason?
About a dozen or so temperature gauges fluctuated at the same time. The range of fluctuations is not large. Fluctuations have occurred before as well, and they happened when the instrument operators were in the DCS room. It’s like an unsolved mystery within this department
If there are fluctuations, it might be due to an issue with grounding; it is recommended to test the grounding resistance of each cabinet. Also, check whether the air conditioners are leaking electricity – if the air conditioners and the DCS share the same grounding system, leakage from the air conditioners could be the cause. It is suggested to use a multimeter to measure the voltage between the neutral and ground wires. Air conditioners are high-power electrical appliances, but they should not interfere with the temperature signals transmitted via shielded cables. Once the cabinet door is closed, they should also not cause any interference with the cabinet itself……
It’s hard to say; wait and observe for a while.
Find an opportunity to conduct a test to determine whether the fluctuations are related to the air conditioner.
Is the power supply for the air conditioner connected from the cabinet? Is there any voltage interference? Then there’s also the cold-junction compensation for the thermocouples; changes in the environment at the cold junction can cause quite strange behavior: lol:lol
First, determine whether the temperature sensor is a thermal resistor or a thermocouple. If it is a thermocouple, check whether those thermocouples subject to fluctuations are equipped with a cold-junction compensation module When considering whether there might be a leakage in the air conditioner or unstable voltage, the air conditioner and the DCS power supply should be completely separated; they must not share the same ground, neutral, or phase. Because the live and neutral wires in the electrical system might be connected to each other, and if the DCS does not have an independent ground connection, it can have a significant impact. It is recommended to measure the grounding resistance of the ground wire, then use a multimeter to check the voltage between the neutral and live wires. Finally, it is necessary to determine whether the interference occurs when the air conditioner is turned on or as a result of someone cleaning the air conditioner. If it is the latter, then there must be a common connection between the air conditioner and the DCS system (neutral wire, live wire, ground wire), and cleaning the air conditioner causes fluctuations in its internal load, which in turn affects the DCS system. As for other reasons, they are nothing more than interference issues; people entering the cabinet room can cause certain types of interference, such as from mobile phones or strong magnetic devices. However, with the cabinet doors closed and shielded cables being used, such interference problems generally do not occur. It is also necessary to consider whether the grounding of the other cabinets is proper, and whether rodenticides have been placed under those cabinets... That’s why it was said upstairs that this issue is complex; indeed, it is quite complex……
There are thermal resistors as well as thermocouples. . . . And it’s very far away. The card components are not together, nor are the instrument locations in the same place
Well, it’s very likely a voltage change. I’m not in charge of the instruments, and I can’t check them either. . Sigh
The basic assumption is that changes in room temperature cause changes in the thermocouple output, leading to fluctuations in the system
It has nothing to do with the instrument location or the card; it’s still an electrical issue~