User Manual

83
[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, PID parameters 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].
(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.
Even when power is turned ON (*), or when the unit reverts to the RUN mode after canceling control
output OFF, ‘AT on startup’ performs.
However, if PV slope and delay time cannot be measured normally for P, I, D calculation, the error
code below will be indicated in the PV display, and automatically ‘AT on startup’ will stop.
To release the error code, press the key.
Error Code
Error Contents
PV slope and delay time cannot be measured normally for P, I, D calculation.
(*) When power is turned ON, ‘AT on startup’ can be performed for Fixed value control. It cannot be performed for Program control.
[Conditions of Cancelling ‘AT on startup’]
• When Control output is turned OFF
• When input is burnt out
AT starting point
(1)
(2) (3)
(4)
SV
Time
Temperature
Temperature 20 higher than the SV
(1)
(2)
(3)
AT
SV
PV
Elapsed time