ESD instrument configuration settings
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Today I encountered a temperature transmitter that uses HART communication to receive thermocouple signals. It is necessary to configure the sensors of the ESD instrument to determine how it behaves under fault conditions, and what are the various output methods available? At an open circuit, the output is at the maximum, minimum, or a given value (MA value) ； The output is maximum, minimum, or a given value (MA value) during a short circuit ； If I want to set the values to remain the same in case of a short circuit or an open circuit, how should I do that? Should I turn off this feature directly? Do the instruments in the DCS system need to be set up in the same way?
ESD Emergency Shutdown System. The thermocouple signal goes to the transmitter and then to the system; it are two signals, two circuits. You mentioned temperature transmitters at the beginning; are you asking whether such transmitters have the aforementioned functions? It seems that temperature changes don’t work right now; my knowledge is limited, as I’ve never encountered this issue before. If you ask whether the system side has the aforementioned functions, then your question itself is flawed – how can a signal be transmitted when all paths are open? What happens to signal transmission after a short circuit?
This temperature transmitter is equipped with a HART bus; I configured the transmitter on-site, and that’s where this function I mentioned comes into play
If that temperature signal is used for a high-temperature interlock, then in cases such as an open circuit in the signal or temperature variation faults that do not result in an interlocked shutdown, the output should be set to a minimum; the opposite is true as well
Hart has the features you requested.
It should be like this: if it is a high-interlock condition (which is the case in most situations), the signal line from the sensing element to the temperature sensor should be configured to show a value below the lower limit of the range, whether there is an open circuit or a short circuit. In this way, the ESD system can detect such conditions, issue an alarm, without causing the system to stop operating. If the signal line experiences a short circuit or an open circuit due to temperature changes, ESD can be detected; in such cases as well, the machine should not be stopped.
The temperature-dependent output is a digital signal; I’ve really never used this before. Our unit is still at the 4-20ma stage!
This is a HART instrument that also outputs a 4–20 milliampere signal; its functionality is slightly better than that of ordinary transmitters. It is the FF instrument that outputs digital signals
Systems that support HART should have such a function. But I’ve never used it. Many of the instruments in our factory support Hart, and the DCS system also supports Hart, yet we haven’t used it at all; it’s embarrassing to admit!
When determining requirements such as open circuit of the temperature signal or temperature variation faults based on the interlock values of ESD, minimum or maximum values are set to avoid shutdown. It seems that only temperature works; other levels or pressures don’t work.
Instruments in DCS can also be set up in this way.