Operation
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 set-point.
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 set-point. After successfull determination of
the "cooling parameters", line-out to the set-point is using the optimized
parameters.
Pulse attempt after start-up
Condition: - tunE = 1 and sufficient set-point reserve provided.
The controller outputs 0% correcting variable or Y. L o and waits, until the process
is at rest (see start conditions page 16)
Subsequently, a short pulse of 100% is output (Y=100%) and reset.
The controller attempts to determine the optimum control parameters from the
process response. If this is completed successfully, these optimized parameters
are taken over and used for line-out to the set-point.
With a 3-point controller, this is followed by "cooling".
After completing the 1st step as described and line-out to the set-point, correcting
variable "heating" remains unchanged and a cooling pulse (100% cooling energy)
is output additionally. After successful determination of the "cooling
parameters", the optimized parameters are used for line-out to the set-point.
Optimization at the set-point
Conditions:
w A sufficient set-point reserve is not provided at self-tuning start (see page 17).
w tunE is 0 or 1
w With Strt = 1 configured and detection of a process value oscillation by
more than ± 0,5% of (rnG. H - rnG. L ) by the controller, the control
parameters are preset for process stabilization and the controller realizes an
optimization at the set-point (see figure "Optimization at the set-point").
w when the step attempt after power-on has failed
w with active gradient function ( PArA/ SETP/ r. S P≠ OFF), the set-point
gradient is started from the process value and there isn't a sufficient set-point
reserve.
Self-tuning
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8800 process controller