22 ATR 421 - User manual
8.3 Manual tuning
Manual tuning procedure allows user a greater exibilty on decidingto upda-
te PID parameters. To enable this function set
MAN. on parameter 11 tune.
To start manual tuning procedure, follow the table below:
Press Display
1
Press until red display shows tune.
2
Green display shows on, led TUN turns on and procedure
starts.
Controller activates output increasing (or decreasing - if cooling regulation)
the process value entered on parameter 12 S.D.TU. Than it turns o the ou-
tput and calculates the new PID parameters depending from overshoot/un-
dershoot oscillations.
It is possible to end manual tuning procedure any time, following the points
below:
Press Display
1
Press until red display shows tune.
2
Green display shows oFF, led TUN turns o and procedure
ends. PID parameters will not be modi ed.
8.4 Recovery of interrupted cycle
Recovery function is particulary useful for kilns temperature regulation. After
a power failure, at restarting, ATR421 can resume the interrupted cycle. There
are two recovery modes:
8.4.1 Recovery with automatic gradient
To enable cycle recovery with automatic gradient, set 1 parameter 38 as
R. i . c Y . This mode does not operate for cooling regulations. At restart, after a
power failure, controller will operate like this:
1. If a power failure occurs during a rising step, the gradient will be those of
the operating step with the setpoint temperature equal to the temperatu-
re read by the sensor.
2. If a power failure occurs during a holding step, two options are possible.
If gap between process and setpoint is limited (not exceeding the value
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