I want to learn **some basic knowledge**

Interlocking and control are two distinct concepts in the field of automatic control. Interlocking is primarily a safety protection mechanism; when certain conditions in the system are met or not met, it automatically carries out certain operations based on logical relationships to ensure the safe operation of the system. Control, on the other hand, is achieved by adjusting the operating conditions of the equipment to bring it to the preset working conditions. Control valves can be interlocked; for example, in situations where it is necessary to keep fluid parameters within safe limits, the opening of the control valve can be controlled through interlock conditions. Isolation valves can also be controlled and are typically used to switch processes or to cut off the flow of fluid in case of an emergency shutdown. Your understanding makes some sense, but in practical applications, control valves and isolation valves are not limited to use for control and interlocking; they can be configured flexibly according to needs. .

As long as it doesn’t violate the standards, whatever the process says goes: lol

My understanding is that interlocking is control with additional logic added

The scope of control concepts is quite broad! Manual, single-loop, cascade, split-range, feedforward, coupling, sequential control, batch control, interlock – all of these are forms of control. Interlocking means performing certain operations under specific conditions.

This post was last edited by Hao Liang Zhi Le on 2024-10-31 at 22:08. Control: In a narrow sense, it refers to making the controlled variable change according to predetermined rules; in a broader sense, it means making the state of the controlled process change according to such rules. In the process industries (petrochemicals, pesticides, food fermentation, etc.), there is an older term called \"Regulate\"; its original meaning is to maintain the controlled variable at a preset value (setpoint) within a certain range through regulation. The adjustment is continuous ； Interlock: It is a mechanism that enables emergency intervention in the production process when an emergency occurs (the interlock condition is met), in order to prevent hazards from arising. Typically, interlocking is logical control (extreme valve positions of on or off) ； Control or regulation refers to the adjustments made under normal production conditions; it is the task of the Basic Process Control System (BPCS). Interlocking, on the other hand, is the function of the Safety Interlock System within the Safety Instrumented System (SIS). In the petrochemical industry, the vast majority of basic process control systems are implemented using DCS systems. There are several options for safety instrument systems; for small-scale production or situations with low risk levels, they can be implemented within a DCS system. Most production processes now use separate SIS systems ； Some safety measures are implemented in the DCS, while most are implemented in a separate SIS; this represents a hybrid safety interlock approach.

Isn’t a chain nothing but automatic control with logic added to it? It’s that simple; there’s nothing to get confused about. Anything automatic is a chain. Everything manual is controlled!

Interlocking is a logical control relationship. Close the feed cut-off valve when the liquid level is high, stop the pump when the level is low, and so on. It is divided into DCS and SIS; SIS has a higher level than DCS. DCS is used for control and regulation, while SIS is used for safe shutdown. Put simply, DCS is used to keep the process parameters within an appropriate range, while SIS is a safety device that ensures the safety of people and equipment when those parameters exceed acceptable limits. Important and dangerous processes should be equipped with SIS.