I have a problem with PID diagrams; I need help from experts.
Thread Content
What does this internal connection wire refer to, and what signals are transmitted? Also, what does GS mean in terms of interlocking? Please help, thanks!
Flow ratio cascade control: stop the grinder after closing the GS valve
Take a closer look at the legend; once you examine the control logic, you’ll understand
GS refers to input safety interlock (as opposed to the fail-safe interlock of SIS; SIS has a higher level of safety). In normal conditions, it is in an open state (0), while in interlock mode it is in a closed state (1). The GS on the left side represents a signal indicating low flow rate of grinding water, which is sent to the interlock system; the resulting interlock action is usually to stop the pump and close the outlet valve. The GS on the right side is an interlock signal from the interlock system – once this signal is received, the solenoid valve is activated, allowing the instrument air inside the diaphragm cover to be released through the solenoid valve, thereby closing valve FV1001 (since it is an FC valve). The complex control system shown is a proportional control that adjusts the ratio of grinding water based on the feed rate.
This should be ratio control with a dual closed loop, without any cascade relationship. The grinding water serves as the passive momentum, while another signal represents the active momentum. With flow low interlock, FV1001 is shut down; simultaneously, other equipment may also be stopped.