Regarding the issue with the safety barrier, I hope the seniors can provide some guidance.
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Question 1: If the safety barrier does not supply power to the field instruments, how should it be wired or programmed? For example, P+F safety barriers. Question 2: The safety barrier sends a 4-20mA signal to the card; is this signal circuit powered by the card or by the safety barrier? (Is the situation the same if active or passive signals are transmitted to the site?) Question 3: What capabilities do typical DCS maintenance personnel need to have? Or what needs to be mastered? (For example, adding or removing elements, basic configuration, etc.)
Actually, for this question, as long as you determine the model of the safety barrier and find the relevant instructions, you can obtain the corresponding answer
The safety barrier transmits the 4-20mA signal to the card; this signal circuit can be powered either by the card or by the safety barrier, with the safety barrier being the common choice for power supply. The card should be wired in such a way that it operates on passive power supply (i.e., without being powered by itself).
Question 1: If the safety barrier does not supply power to the field instruments, how should it be wired or programmed? For example, P+F safety barriers. Answer: Check the manual or the configuration instructions; this issue shouldn’t arise. Question 2: The safety barrier sends a 4-20mA signal to the card; is this signal circuit powered by the card or by the safety barrier? (Is the situation the same if the signal coming from the field is active or passive?) Answer: In this case, the signal circuit is powered by the safety gate. Whether the signal coming from the field is active or passive makes a difference; if it is passive, a safety gate or card is required to supply power, whereas if it is active, no power supply is needed. Question 3: What skills are required of a typical DCS maintenance technician? Or what needs to be mastered? (For example, adding or removing elements, basic configuration, etc.) Answer: Generally, DCS maintenance personnel must know how to perform basic configuration; they should be able to configure DCS, SIS, PLCs, etc., as well as understand the configuration of DCS systems from different manufacturers. In addition, they need to have a thorough understanding of the instruments and equipment on site. We are able to set up loop control; our organization currently uses at least 5 different brands of DCS and SIS systems, and we have some knowledge of each of them. Although we don’t reach a level of mastery, it’s still necessary to know how to use the most common ones. Typically, what can be used include adding and subtracting values, setting up interlocks, configuring alarms, printing reports, dismissing ordinary alarms, replacing hardware and carrying out configuration tasks after such replacements. It is also necessary to have some knowledge of networking – these are the basic aspects.
The first two aren’t really questions; just give them a try and you’ll see. Third question: All DCS engineers should be able to do this; it’s no different from what instrument engineers can do.
Question 2: The signal circuit is powered by a safety barrier. If there are no passive components on site, then a safety barrier or a card is required to supply power; if there are active components, then no power supply is needed.