3.6 Setting the Configuration Chapter 3: Configuration
152 493-0736-11 (6-2)
When the Reset parameter is set to OK the internal parameters for the Adapt
function are reset.
Table 110 Adapt Block Parameters.
The controller start value is determined by carrying out the Autotune procedure.
Warning – Large Parameter Changes: Adaptive PID control continuously
adjusts itself to the process by changing the PID parameters, but for safety reasons
the parameters should not be altered in an unlimited way. Gain, for example,
might increase due to a clogged valve (the controller interprets this fault as
reduced process gain). The controller thus provides a warning by means of a
warning message on the display once the parameters have changed sufficiently to
exceed the permitted value (maximum four times the change in gain).
Notes:
• In a few cases (about 1% of the total controller applications) the Autotuner may
not work very well, e.g. in extremely noisy processes. In these cases the
controller should be given a start value by inserting the CriticalPeriod and the
CriticalGain. Analyse the process to determine these values. See the section
Critical Gain and Critical Period below.
• If the process has a long deadtime, or a noisy measuring signal, select deadtime
or PI design. The adaptive controller then automatically selects the PID
parameters which are particularly suited to this type of process.
• If Three State Pulse output is used actuator feedback must be employed.
• Adaptive functions cannot be configured if the controller is set for tracking in
Auto since the adaptive function would receive false information.
Parameters
Name Setting Unit
Mode Off, On None
CriticalGain 0.0 < CriticalGain ≤ 100.0 None
CriticalPeriod 0.0 ≤ CriticalPeriod < 10000.0 seconds
Reset OK None
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