What is the general process of instrument control loops in refineries?
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Today, instrument circuit calibration was carried out. In the cabinet room, I saw safety barrier cabinets, power supply cabinets, digital signal cabinets, analog signal cabinets, etc. I would like to understand what the process is like for instrument signals between the field site and the control room Those who know please explain: lol
It depends on what protocol the DCS in your control system uses. If it’s the FF bus protocol, then the signals are transmitted over the field bus; whereas if it’s ordinary AI/AO cards, then essentially one signal is transmitted per wire
I want to understand the entire process of signal transmission, including the various conversions and devices used in it. In other words, I’d like an explanation that someone who isn’t familiar with this field can understand (I’m not trained in instrumentation): lol
For example: The field transmitter converts the process parameters into 4–20 mA current signals, which are sent to the safety barrier cabinet and then to the analog input card (analog input panel), from where they are fed into the DCS for various calculations, displays, and controls.
Thank you, what I’m trying to understand is exactly what you mentioned: lol. But I have a question – are all the calculations carried out inside the system cabinet?
Instrument signals are generally divided into four categories: AI, which refers to the 4-20mA or PT100 resistance signals coming from the field, or the MV signals from thermocouples; AO, which is 4-20mA and is used for controlling valves on-site; DI, which represents digital signals from the field, or operational signals from electrical systems; and DO, which is used to control the switching on or off of pumps or solenoid valves, either in electrical systems or on-site.