Questions about selective control systems?

Why isn’t anyone here to explain? I’ll take on one myself

Bro, I’m waiting online. . . . Please also provide an explanation

I haven’t seen these three concepts anywhere; it seems they’re not mentioned in either basic control theory or advanced control theory

Reply to 4# wang5924: It’s not that complicated, bro. I just saw it in the test questions collection for instrument technicians

A switch-type selective control system includes a level transmitter and a solenoid three-way valve in addition to a simple control system. Under normal operating conditions, the three-way valve sends the control signal P from the temperature regulator to the pneumatic regulator chamber; the system operates in the same way as a simple control system. When the liquid level rises to a certain position, the upper limit terminal of the level transmitter is activated, the solenoid valve is powered on, thereby cutting off the path of the control signal P; air from the atmosphere (i.e., with a gauge pressure of 0) is allowed to enter the air chamber, and the valve closes. The control valve in a switch-type selective control system is either fully open or fully closed when switching from normal operating conditions to abnormal ones. A continuous selective control system is one that switches to another continuous control system. Using both switch-mode and continuous-mode selective control within a single control system is known as a hybrid selective control system.

Reply to 6# windsorwin1: There are so many experts in Haichuan