Chain control
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In DCS control, a high pressure interlock causes a PV valve to close; however, in some PID diagrams it is also denoted as PIC. What is the difference between an interlock valve and an interlock controller? I would appreciate some guidance ? ?
Check the PID diagram. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
PIC refers to the specific actuating unit (valve) in sequential control, which uses sequential control signals to regulate the control system； A interlock controller is a series of operations that force an action to stop when one or more of certain conditions are not met. For example, there are several control conditions in the compressor shutdown interlock; if any one of these conditions is not met, the interlock is triggered, resulting in a shutdown.
This is not contradictory; for DCS systems, PID controllers are used for this purpose, and all PID controllers have an override function. For example, when the pressure here reaches the high-level interlock value, my PIC locks the output at 100% or 0%, which means it causes the PV valve to be fully open or fully closed.
However, the proper approach is to add a PSV solenoid valve to the PV valve circuit.
This is not contradictory; for DCS systems, PID controllers are used for this purpose, and all PID controllers have an override function. For example, when the pressure here reaches the high-level interlock value, my PIC locks the output at 100% or 0%, which means it causes the PV valve to be fully open or fully closed. This is the correct answer
An interlocked valve is used to control a on/off valve (such as a two-position shut-off valve); an interlock controller refers to the activation or deactivation of such a controller, and it can also be used to directly control the output level and closed state of a control valve.
I’m not quite sure. If anyone has detailed information on chains, please share it. Thank you
The biggest difference is that one shuts down the solenoid valve directly, while the other shuts down the controller directly.