Initiating The Autotuner Function - Fisher DPR900 User Manual

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Configuration 5-45
Autotuning begins at
A.
The process noise level is evaluated and the
first output signal is transmitted. When three acceptable (equal) peaks
have been obtained, autotuning is complete. Autotuning can stop at
any time, but no new PID parameters will be installed.
The Autotuner incorporates a form of intelligence. In situations where
the D element should not be used, for example in level control, the
Autotuner automatically identifies the process and eliminates the D
element.
If the process has a long deadtime (at lease twice as long as the
dominant time constant in the process), the normal configuration rules
for PID controllers do not apply. The DPRSOO has a special set-up
method for dead time processes. The method involves a PI controller
with relatively low gain and a short integration time.
510.2
It is never necessary to define the length of
deadtime.
Most processes
Deadtime >2 times the dominant time constant. This
provides a PI controller with low gain and a relatively
short l-time. This design method is specially developed
and must not be used with integrating processes.
Noisy processes which cannot be filtered
Enabled, break
Initiating the Autotuner Function
Press the TUNE button in either the auto or manual mode. The button
flashes to indicate that autotuning is in progress.
May 1991
UM6.1:DPR900:9102