When an intelligent transmitter fails, for production safety and to facilitate fault diagnosis, it is generally necessary to fix the transmitter’s output...
Thread Content
When an intelligent transmitter fails, for the sake of production safety and ease in fault diagnosis, it is generally necessary to fix the transmitter’s output at a certain value; however, the set value is usually not fixed at ( ). A. The value before the fault occurred; B. Above the scale line (21.6 mA); C. 12 mA; D. Below the scale line (3.8 mA). The correct answer is C. What is the reason for choosing this? Why can’t it be set at 12mA?
If the output is 12mA in case of a fault, the DCS shows normal, but the operator cannot tell whether it is normal or not.
If the output is 12mA in case of a fault, the DCS shows normal, but the operator cannot tell whether it is normal or not.
If the output is 12mA in the event of a fault, the DCS shows \"normal\", but the operator cannot tell whether it is normal or not
Set it below 3.8 mA and above 21.6 mA; in this way, faults can be detected when the DCS or SIS system operates at its maximum or minimum levels. The current value is incorrect, and this alerts the operators that there is a problem with this circuit； Or, by using maximum and minimum values, the interlock circuit or control circuit can be brought to a safe position to ensure safety. Setting it to the value before the failure, that is, maintaining it at that level during a fault, ensures continuous production. This approach helps to maintain stability in the manufacturing process; it prevents any interlocks or abnormal adjustments caused by transmitter failures, which could otherwise lead to fluctuations or shutdowns in production. In short, either safety is not ensured, or production is not ensured, or it’s just an unimportant display indicating a fault. But C is meaningless; what’s the point of using 12mA? The answer is nonsensical, so it’s not chosen.
The value is around 12 mA; the surface appears normal, and the operator cannot determine whether there is a fault with the instrument. Factors such as pressure, temperature, and liquid level are typically also monitored at the surface level. If there is a discrepancy when comparing these values with those from remote sensors, it indicates that there is a problem with one of them (with some exceptions, such as discrepancies in liquid level before a boiler is started up)