Control block diagrams are used to analyze the dynamic effect of feedback control loops. All dynamic elements in a control loop are combined, using their Laplace transfer function representation. In this section we use the control strategy from Figure 5-1 (where the inlet flow rate is manipulated) for illustration. Block diagrams are based on Laplace domain signals, which are assumed to be in deviation variable (perturbations from steady state) form. The block diagram for Figure 5-1 has the following components:
Level controller (relates error to controller output)
Valve (relates controller output signal to flow-through valve)
Process (relates manipulated input to process output)
Disturbance (relates the ...