Process Control, 2-4 Cascade Control of a Level/Flow Process

The different measureable variables in a process are often interrelated to the extent that knowledge of an intermediate variable could be used beneficially to control a primary process variable. One example is a flow of water entering a tank in which the level is to be controlled. Controlling the incoming flow with a control valve certainly has a direct effect on the level of water in the tank. This is because the two variables, incoming flow and tank level, are interacting. Cascade control takes advantage of this inherent interaction between variables to improve the overall control on a process variable.