Regarding the emergency stop button
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Dear teachers: According to the \"Specifications for the Design of Signal Alarm and Safety Interlock Systems\" (HG_T20511-2014), the emergency stop buttons for non-safety interlock systems can be implemented as software buttons on the BPCS operator station, while the emergency stop buttons for safety interlock systems should be implemented as hardware buttons on the auxiliary operation panel. How can an emergency stop from a non-safety interlock system be distinguished from one from a safety interlock system? After all, isn’t every emergency stop a form of safety interlock?
The difference between the emergency stop of the non-safety interlock system and that of the safety interlock system lies mainly in their respective functions and scope of operation. The emergency stop of non-safety interlock systems mainly refers to the emergency stop function implemented through software buttons in ordinary operating systems. It is achieved through the Basic Process Control System (BPCS) of the control system, and is primarily used to handle some non-critical emergencies such as equipment failures; shutdown can be carried out quickly using the software buttons on the operator station. The emergency stop of a safety interlock system refers to the emergency stop function that is implemented through hardware buttons within a specific safety system. This emergency stop button is located on the auxiliary control panel and is part of the Safety Instrumented System (SIS); it is used to handle emergency situations that could pose a risk to personnel safety or equipment safety. Compared to the emergency shutdowns in non-safety interlock systems, this type of emergency shutdown places greater emphasis on safety issues; it is typically used in more serious or dangerous situations, and is implemented through hardware buttons to ensure that hazardous sources can be quickly and effectively shut down in emergency situations. Overall, the main differences between the two lie in the nature of the emergencies they handle, the way in which they are activated (software buttons or hardware buttons), and the systems to which they belong (BPCS or SIS). The emergency stop function of the safety interlock system is geared more toward dealing with emergencies that require a higher level of safety. .
In simple terms, the safety interlocks specified in this standard are of the SIS type, while those that are not related to safety are of the DCS type, which makes it easier to understand. The wording used in some standards is closely tied to the preferences of the standards’ compilers; some of them prefer to include their own preferences in the standards