PV = Process Value/Controlled Variable SV = Setpoint/Desired Value MV = Manipulated Value/Controller Output Error = Deviation Objective : To bring PV = SV by manipulating FCE(Final Control Element) via MV
Upset / Disturbance Setpoint change : at the SV Load Variables : all other variables that cause upset and affect control (e.g: input fow rate, output flow rate, environment, heater power variation Control is easier( unnecessary) if there is no UPSET Control is more difficult if UPSET is due to LOAD upset than setpoint upset.
Laboratory Experiment 1: Gas Pressure Control Experiment 2: Level Flow Control Experiment 3: Flow Control Experiment 4: On Off & Temperature Control Experiment 5: pH Control using Open Loop Method Experiment 6: pH Control using Closed Loop Method
What is expected from you ? 1.Understand the feedback control loop system 2. Able to illustrate control system instrumentation (transducer,transmitter, FCE etc.) 3.Able to analyze responses at different value of PID 4.Tuning- Find the best PID for the process 5.Find PID using open loop method (Ziegler and Nichols Formula)
What you will see in the lab? PID, where: PB = 100/Kc ; TI= time integral ; TD = time derivative P-control only PI control PID
System Behavior Underdamped An underdamped response is one that oscillates within a decaying envelope. The more underdamped the system, the more oscillations and longer it takes to reach steady-state. Here Damping Ratio is always < 1envelope Critically damped A critically damped response is the response that reaches the steady-state value the fastest without being underdamped. It is related to critical points in the sense that it straddles the boundary of underdamped and overdamped responses. Here, damping ratio is always less than or equal to one (≤1). There should be no oscillation about the steady state value in the ideal case.critical points Overdamped An overdamped response is the response that does not oscillate about the steady-state value but takes longer to reach than the critically damped case. Here Damping Ratio is >1
Ziegler and Nichols formula Please refer to the handout given.
Laboratory Report Introduction/Theory of the experiment Procedure: -summarize the procedure - PFD is shown Discuss the responses form the chart graph.