West Control Solutions KS 92-1 Programmer manual - Manual (Page 18)

3.5.6 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.SP¹ OFF), the set-point
gradient is started from the process value and there isn't a sufficient set-point
reserve.
Optimization-at-the-set-point procedure:
The controller uses its instantaneous parameters for control to the set-point. In
lined out condition, the controller makes a pulse attempt. This pulse reduces the
correcting variable by max. 20% 1, to generate a slight process value under-
shoot. The changing process is analyzed and the parameters thus calculated are
recorded in the controller. The optimized parameters are used for line-out to the
set-point.
With a 3-point controller, optimization for the “heating“ or “cooling” parameters
occurs dependent of the instantaneous condition.
These two optimizations must be started separately.
1 If the correcting variable is too low for reduction in lined out condition it is
increased by max. 20%.
Operation
Self-tuning 18 KS 90-1
p / KS 92-1 p
set-point
process value
correcting
variable
Optimization at the set-point