What are the differences between SIS systems, DCS systems, and ESD systems?

Regarding the SIS system and ESD system: http://bbs.hcbbs.com/thread-840398-1-1.html

SIS is a safety instrumented system, and ESD is an emergency shutdown system; ESD is part of SIS. A SIS consists of field instruments, logic processors, and actuators, all of which must be designed with safety in mind. A conventional ESD system is merely the logic processor part of a SIS, which, of course, also needs to be designed safely. Its characteristic remains PID control; thanks to its robust communication capabilities, it serves as a system for integrating all automated devices in a factory. SIS requires higher levels of reliability and availability compared to DCS, and standards such as IEC61508 and IEC61511 stipulate that SIS and DCS hardware should be installed separately. The DCS system is a process control system that is dynamic and requires frequent manual intervention, which may lead to human-induced errors ； Meanwhile, SIS (ESD) is static and does not require human intervention; this setup helps to avoid accidental actions by humans. It is usually used as a control scheme for complete sets of equipment, such as systems that form their own integrated units for vacuum, wastewater, containerization, compressors, and so on. Their characteristic is that they require little analog control; they are extremely effective, convenient, reliable, and economical for digital control. It is usually used as a sub-site of the DCS to facilitate monitoring. It is clear that from the diagram below, we can see that SIS includes ESD, ITCC, etc., while under DCS are PLC, FCS, etc. ESD emergency shutdown system: emergency stop system. SIS safety interlocking system (safety instrument system). Safety interlock system – in my opinion, different manufacturers use various terms to refer to safety systems; some call it a safety manager. Such systems are often used in high-risk industries such as the petrochemical sector. Generally, there aren’t many points involved, as once an action is taken, the entire operation comes to a halt; this is the lowest line of defense to sacrifice production efficiency in order to ensure safety. SM requires SIS certification, with the level in the petrochemical industry typically being 3.

I learned it again! If anyone asks again what the difference is between it and SCADA,? ! Another question: what’s the difference between it and PLC? !

According to current perspectives, process control systems are divided into two categories: one is the Basic Process Control System (BPCS) and the Safe Instrument System (SIS) or Safe Interlock System (SIS). The function of a basic process control system is to ensure the smooth and continuous operation of the production process, while the function of a safety instrumented system is to maintain production safety in case of abnormalities; their purposes are different. The Emergency Shutdown System (ESD: Emergency Shutdown Device) is also a type of system designed to ensure production safety; conceptually, it belongs to the category of safety interlock systems. In addition, there is another category of dedicated control systems, such as the Integrated Turbine Compressor Control System (ITCC) and the Motor Control Center (MCC). As for the structure of these systems, it varies among different manufacturers, though their functions are largely similar.