West Control Solutions N8840 - Manual (Page 19)

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
undershoot. 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
8840 profiler 19 Self-tuning
set-point
process value
correcting
variable
Optimization at the set-point