Burkert Type 1150 - Manual (Page 88)

86 - 1150
O
PTIMIZATION
Self-optimization
Oscillation method
Self-optimization SO establishes the optimum controller parameters for PID or PI controllers.
Depending on the controller type, the following controller parameters can be defined:
Reset time (Tn), derivative time (Tv), proportional band (Xp), cycle time (Cy), filter time constant (dF)
The controller selects one of two procedures (a or b), depending on the size of the control deviation:
a) SO in start-up phase b) SO at setpoint
Step response method
This type of optimization involves determining the control parameters through an output step that is
applied to the process. First a steady output is produced until the process value is “steady” (constant).
Afterwards, an output step (step size - user defined), which can be defined by the user, is automatically
applied to the process. The resulting response of the process value is used to calculate the control
parameters.
Self-optimization establishes the optimum control parameters for PID or PI controllers, in accordance with
the selected control structure.
Depending on the controller type, the following control parameters can be defined:
Reset time (Tn), derivative time (Tv), proportional band (Xp), cycle time (Cy), filter time constant (dF)
Optimization can be started from any system status and can be repeated as often as is required.
The controller outputs (analog, relay, solid-state), the steady output and the step size (min. 10%) have to
be defined.
Principal applications of the step response method
Optimization instantly after “power on”, during the start-up phase considerable time savings, setting:
steady output = 0 %.
The process does not readily permit oscillations (e.g. highly insulated furnaces with small losses, long
oscillation period)
Process value must not exceed setpoint. If the output (with stabilized setpoint) is known, an overshoot
can be avoided through the following adjustment:
steady output + step size <= output in stabilized condition
Start of SO Start of SO
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