Tempco TEC-2500, Инструкция по эксплуатации, Страница: 54 / 108

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3–19 Self Tuning
Self-tuning, which was designed using an innovative algorithm, provides an
alternate option for tuning the controller. It is activated when YES is selected for
SELF. When self-tuning is working, the controller will change its working PID
values and compare the process behavior to previous cycles. If the new PID
values achieve better control, then it changes the next PID values in the same
direction. Otherwise, it changes the next PID values in the reverse direction.
When an optimal condition is obtained, the optimal PID values will be stored in
PB1, TI1, and TD1, or PB2, TI2, and TD2, as determined by the event input
conditions. See section 4-1. When self-tuning is completed, the value of SELF
will change from YES to NONE to disable the self-tuning function.
When self-tuning is enabled, the control variables are tuned slowly so that the
disturbance to the process is less than auto-tuning. Usually, self-tuning will
perform successfully with no need to apply additional auto-tuning.
Exceptions: Self-tuning will be disabled as soon as one of the following
conditions occurs:
1. NONE is selected for SELF.
2. The controller is used for on-off control, that is PB=0.
3. The controller is used for manual reset, that is TI=0.
4. The controller is in a loop break condition.
5. The controller is in failure mode (e.g., sensor break).
6. The controller is in manual control mode.
7. The controller is in sleep mode.
8. The controller is being calibrated.
If self-tuning is enabled, auto-tuning can still be used any time. Self-tuning will
use the auto-tuning results for its initial values.
Benefits of self-tuning:
1. Unlike auto-tuning, self-tuning will produce less disturbance to the process.
2. Unlike auto-tuning, self-tuning doesn't change the control mode during the
tuning period. It always performs PID control.
3. Changing the set point during self-tuning is allowable. Therefore, self-tuning
can be used for ramping set point control as well as remote set point control
where the set point is changed from time to time.
Operation:
The parameter SELF is contained in the setup menu. Refer to section 1-5 to
find SELF for initiating self-tuning.
Benefits of self-tuning:
1. Less disturbance to the process.
2. Perform PID control during tuning
period.
3. Available for ramping set point
control and remote set point control.