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[C] If there is a large difference between the SV and PV as the temperature is falling
When AT bias is set to 20 , the AT process will fluctuate at the temperature 20
higher than the SV.
(1) Calculating PID constants
(2) PID constants calculated
(3) Controlled by the PID constants
set by AT.
(4) AT bias value (Factory default: 20 )
(Fig. 8.5-3)
(2) AT on Startup
When usual AT cannot be performed normally due to temperature interference, P, I, D and ARW
values can be calculated only when temperature is rising.
As the selected [AT on startup Perform] is internally memorized, ‘AT on startup’ is performed
whenever the power is turned ON.
To stop ‘AT on startup’, select ‘AT/AT on startup/Auto-reset Cancel’ in [AT/Auto-reset Perform/Cancel].
(1) Calculating AT (from startup, until PV is stabilized at SV)
(2) PID constants calculated
(3) Controls with PID constants set by ‘AT on startup’
(Fig. 8.5-4)
[Conditions of Performing ‘AT on startup’]
• When starting ‘AT on startup’, if deviation between PV and SV exceeds the proportional band by
2 times or more, ‘AT on startup’ will perform.
When power is turned ON
(*)
, or when the unit reverts to RUN mode after canceling control output
OFF, ‘AT on startup’ performs.
Even after ‘AT on startup’ is successfully finished, ‘AT on startup’ has been still selected in
[AT/Auto-reset Perform/Cancel].
When power is turned ON again, or when the unit reverts to RUN mode by cancelling Control output
OFF, ‘AT on startup’ performs again under the above performance conditions.
To stop ‘AT on startup’, select ‘AT/AT on startup/Auto-reset Cancel’ in [AT/Auto-reset Perform/Cancel].
(*) For Fixed value control, ‘AT on startup’ can be performed when power is turned ON. It cannot be performed for
Program control.
AT starting point
(1)
(2)
(3)
(4)
SV
Time
Temperature
Temperature 20
higher than the SV
(1)
(2)
(3)
AT
SV
PV
Elapsed time
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