What type of control mechanisms are these?
Thread Content
As shown in the figure, which category do these control methods belong to? The control process is clear to see; there are many different types of control methods. What kind of control methods are shown in the figure, and what are their respective characteristics? The diagram was drawn casually; please forgive its simplicity···
1. Uniform； 2. Segmented distance ； 3. Cascade
These control schemes are somewhat ambiguous; classic control schemes are not drawn this way.
The control valves in (1) and (3) receive signals from two controllers; which signal does the control valve act on? ?
I see the signal lines are drawn that way on the PID diagram; how is it controlled?
As indicated in the picture, 1 represents selective control, 2 represents proportional control, and 3 can also be used for selective control
In (1) and (3), if there is a switching or selection option (manual or automatic) above the control valve, it is possible to choose a certain controller signal to be sent to the control valve, thereby enabling manual switching or automatic selection control； (2) Diagram: It seems to be a proportional control system based on the diagram; in other words, the outflow (or inflow) flow rate is used first to control the liquid level, and when the liquid level is high (or low), inflow (or outflow) is used for control ； (2) If the controller output allows for switching or selection (manual or automatic), it is possible to choose to send the controller signal to a certain control valve based on the operating conditions, thereby enabling manual switching or automatic selection control.
1 Agree, 2 should be the flow level cascade control loop, 3 should be the temperature and pressure selection control loop!
1 There should also be a selection switch; with the high-selection switch, it’s high-selection control, with the low-selection switch it’s low-selection control, and with the manual switch it’s selective control. 2 refers to proportional control: changes in the output value cause the two control valves to open to different degrees. Generally, between 0-50, one valve gradually opens or closes, while between 50-100, the other valve gradually closes or opens, depending on the process requirements. 3 is also a selection switch, used to choose the control method depending on the process.