u/InteractionRude2488

How exactly does a Level-to-Flow cascade controller work?

In a level-to-flow cascade arrangement (LC sending SP to FC), I’m trying to understand what the level controller is actually doing.

Does the LC calculate and send a flowrate setpoint to the flow controller?
For example:

  • if level increases slightly → send flow SP = X m³/h
  • if level increases further → send flow SP = X + Δ m³/h

Or is the LC simply increasing/decreasing a 4–20 mA signal to the FC, and the FC interprets that somehow?
Basically, how does the cascade interaction physically and functionally work between the LC and FC in a typical DCS/PLC implementation?

https://preview.redd.it/blo5fjz9y72h1.png?width=382&format=png&auto=webp&s=4115af26d0c5e5b10fcfa4873717464b47121bb1

reddit.com
u/InteractionRude2488 — 3 days ago