Справочник Пользователя для Marathon Computer AACC 2000

AACC 2000 Carbon                                                                       Nov.  1, 1997

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If for any reason automatic tuning gives unsatisfactory results, you can tune the controller
manually.  There are a number of standard methods for manual tuning.  The one
described here is the Ziegler-Nichols method.

With the process at its normal running process variable:

1. Set the Integral Time ‘

ti’ and the Derivative Time ‘td’ to OFF.

 

2. Set High Cutback and Low Cutback, ‘

Hcb’ and ‘Lcb’, to ‘Auto’.

 

3. Ignore the fact that the process variable may not settle precisely at the setpoint.

 

4. If the process variable is stable, reduce the proportional band ‘

Pb’ so that the process

variable just starts to oscillate.  If the process variable is already oscillating, increase
the proportional band until it just stops oscillating.  Allow enough time between each
adjustment for the loop to stabilise.  Make a note of the proportional band value ‘B’
and the period of oscillation ‘T’.

 

5. Set the Pb, ti, td parameter values according to the calculations given in Table 4-2.

Proportional only

2xB

OFF

OFF

P + I control

2.2xB

0.8xT

OFF

P + I + D control

1.7xB

0.5xT

0.12xT

Table 4-2 Tuning values