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8.5.2 AT Action
In order to set each value of P, I, D and ARW automatically, the AT process should be made to fluctuate
to obtain an optimal value.
For DC voltage, current inputs, the AT process will fluctuate around the SV for conditions of [A], [B] and
[C] below.
One of 3 types of fluctuation below is automatically selected depending on the deviation between SV
and PV.
[A] If there is a large difference between the SV and PV as the temperature is rising
When AT bias is set to 20 , AT process will fluctuate at the temperature 20
lower than the SV.
(Fig. 8.5.2-1)
[B] When the control is stable
The AT process will fluctuate around the SV.
(Fig. 8.5.2-2)
[C] If there is a large difference between the SV and PV as the temperature is falling
When AT bias is set to 20 , AT process will fluctuate at the temperature 20
higher than the SV.
(Fig. 8.5.2-3)
(1) Calculates PID constants.
(2) PID constants calculated
(3) Controlled by the PID constants
set by AT
(4) AT bias value (Factory default: 20 )
SV
(1)
Time
(2)
Temperature
(4)
AT starting point
(3)
Temperature 20
lower than the SV
(1) Calculates PID constants.
(2) PID constants calculated
(3) Controlled by the PID constants
set by AT
SV
Time
AT starting point
(1)
(2)
(3)
Temperature
(1) Calculates PID constants.
(2) PID constants calculated
(3) Controlled by the PID constants
set by AT
(4) AT bias value (Factory default: 20 )
SV
Temperature
Time
(4)
Temperature 20
higher than the SV
AT starting point
(1)
(2)
(3)
