Steps to Follow to Adjust the Model Loop Controller
(Original Document)
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Procedure
The steps in this table describe the action to be taken in order to adjust a model loop controller.
Step
Action
1
Use a graphic method based on an indexed response, such as the Broida method. This directly provides the parameters for a first order model with pure delay, in order to identify the process model.
2
Enhance the adjustment by running the IMC loop controller in automatic mode.
3
To check whether the model is adapted to the process, set CL_PERF to 1.0 (time constant of closed loop = time constant of open loop).
4
Proceed to the point of operation and run the loop controller in automatic mode.
5
Carry out a setpoint step function C.
Result: If the model parameters are correct, the measurement should rejoin the setpoint without overflow and the OUT_MAN command signal should be almost one division. If this is not the case, a correction must be made, which means:
  • adapting the static gain
  • adapting the dead time
  • adapting the time constant