Owner manual

7.3 Self-tuning
For determination of optimum process parameters, self-tuning is possible.
After starting by the operator, the controller makes an adaptation attempt, whereby the process characteristics are
used to calculate the parameters for fast line-out to the setpoint without overshoot.
The following parameters are optimized when self-tuning:
Pb1 - Proportional band 1 (heating) in engineering units [e.g. °C]
ti1 - Integral time 1 (heating) in [s] r only, unless set to OFF
td1 - Derivative time 1 (heating) in [s] r only, unless set to OFF
t1 - Minimum cycle time 1 (heating) in [s] r only, unless Adt0 was set to
“no self-tuning” during configuration by means of BlueControl
®.
Pb2 - Proportional band 2 (cooling) in engineering units [e.g. °C]
ti2 - Integral time 2 (cooling) in [s] r only, unless set to OFF
td2 - Derivative time 2 (cooling) in [s] r only, unless set to OFF
t2 - Minimum cycle time 2 (cooling) in [s] r only, unless Adt0 was set to
“no self-tuning” during configuration by means of BlueControl
®
7.3.1 Preparation for self-tuning
•
Adjust the controller measuring range as control range limits. Set values rnG.L and rnG.H to the
limits of subsequent control. (ConfigurationrControllerrlower and upper control range limits)
ConFrCntrr rnG.L and rnG.H
•
Determine which parameter set shall be optimized (see tables above).
7.3.2 Self-tuning sequence
The controller outputs 0% correcting variable or Y.Lo and waits, until the process is at rest (see start-conditions
below).
Subsequently, a correcting variable step change to 100% is output.
The controller attempts to calculate the optimum control parameters from the process response. If this is done
successfully, the optimized parameters are taken over and used for line-out to the setpoint.
With a 3-point controller, this is followed by “cooling”.
After completing the 1st step as described, a correcting variable of -100% (100% cooling energy) is output from the
setpoint.
After successfull determination of the “cooling parameters”, line-out to the setpoint is using the optimized parameters.
Start condition:
w
Rest condition
For process evaluation, a stable condition is required. Therefore, the controller waits until the process has
reached a stable condition after self-tuning start. The rest condition is considered being reached, when the
process value oscillation is smaller than ± 0,5% of (rnG.H - rnG.L).
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setpoint reserve
After having come to rest with 0% correcting variable or with Y.Lo, the controller requires a sufficient
setpoint reserve for its self-tuning attempt, in order to avoid overshoot.
w
Sufficient setpoint reserve:
inverse controller:(with process value <setpoint-(10% of SP.Hi - SP.LO)
direct controller: (with process value >setpoint+ (10% of SP.Hi - SP.LO)
Controlling
KS 45 43 Self-tuning