ITCC is neither useful nor useful at all
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For continuous control, there is a DCS; for safety interlocks, an SIS system is used. So why is an ITCC needed? At least it left me completely confused. I searched online and got a general idea of it. Let’s talk about it; it’s not necessarily correct, so let’s discuss among everyone. The concept of ITCC was introduced and put into use in the 1990s. It includes the main process control and safety control of the unit. Everyone thought it was good. Since it includes certain safety controls, some people consider it to be part of SIS; in fact, SIS had not yet been fully defined at that time. Later on, SIS was fully specified (in the 1998 IEC standard), and institutional verification was required. This puts ITCC in an awkward position. But everyone is already familiar with it and thinks it’s good; most importantly, the suppliers like it as well, which provides an excuse for selling it. So no one wants to replace it. In fact, with SIS and DCS, ITCC is completely unnecessary. It’s not useless, but it is still useless.
Another important feature of ITCC is the algorithm for unit control; DCS and SIS are not integrated, so programming is required manually
ITCC is a term used in commercial promotions; strictly speaking, it should be CCS (Unit Control System), and it differs to some extent from conventional DCS and SIS in terms of control and functionality. It has control, but it requires a faster response speed than conventional DCS ； The typical scanning cycle is less than 100ms ； SIS is generally less than 300 ms, while DCS is 1 second. It has specialized algorithms for anti-surge control, which are more complex than conventional PID control ； Its unit protection is similar to the safety requirements of SIS ；
What was said on floors 2 and 3 is correct; this is exactly how suppliers try to create confusion, otherwise there would be no selling points at all. Whether it is integrated or not, or regardless of the scanning time, assigning it to DCS and SIS is not a problem at all.
You're wrong. I’m not necessarily forced to allocate a part of the ITCC to the DCS; moreover, even if the control part is moved to the DCS, it’s entirely possible to speed up the scanning. Why isn’t it allocated to DCS? It’s not a scanning issue; it’s because the safety integrity level of DCS is below 0.1. SIS includes control functions and protection functions, and ITCC can be fully classified under SIS. According to IEC61508, all functions that utilize electrical, electronic, or programming elements fall under PES; in IEC61511, this is referred to as SIS. ITCC is no exception; scanning is a performance issue related to electronic products, and it cannot determine ownership.