INFRATHERM
pyrometers IS 5 · IS 5-LO · IGA 5 · IGA 5-LO
50
10.8.1 The PID controller
The IS 5-C, IS5-LO-C, IGA 5-C and IGA 5-LO-C are equipped with an integrated PID controller. This enables
automatic controlling and monitoring of processes. The controller compares the current measuring tempera-
ture with the target temperature value, calculates the control signal and gives a controller output signal of 0
or 4 ... 20 mA (instead of the temperature signal output). The controller is very fast and updates the signal
with the pyrometer's response time (
≤
2 ms). The built-in self-tuning algorithm determines automatically and
a very good approximation of the controlling parameters P, I and D.
Activating and deactivating of the controller as well as setting the parameters can be done via interface and
software
A click on the PID button in the
pyrometer parameter
window opens the setting window:
•
Analog output:
Click on
controller output
(controlling
ON) to activate the controller. With
temperature
(controlling OFF) the con-
troller is switched off.
•
Desired temperature:
The
desired temperature
can be se-
lected within the selected temperature
range.
•
Proportional band Xp (0.0 - 1000%)
A difference between the “desired tem-
perature” and the measuring tempera-
ture generates a proportional signal to
the pyrometer output. This signal can
be amplified (Xp < 100% alternatively
Kp > 1) or attenuated (Xp > 100% al-
ternatively Kp < 1), the amplification is
Kp = 100% / Xp.
If the proportional band is set to 0%
(amplification =
∞
), the controller operates as a two-state point controller.
•
Integral time T
i
:
As the temperature deviates from the “desired temperature”, a corresponding signal which changes over
the time is transmitted to the analog output until the deviation reaches zero.
The integral time can be set in two different formats: “min:s” for the range of 0.00 s to 99.99 s;
”s” for the range of 0:01 min to 99:99 min. In the first case, an update of the integral error will occur every
10 ms, in the second case, every second.
With a set of T
i
= 0 no integral proportion will be calculated.
•
Rate time T
d
:
The rate time enables the initial amplitude to be jump-started. The rate time can be set in two formats:
In the range from 0.00 s to 99.99 s or from 0:01 min to 99:99 min. The rate time will be recalculated in the
interval of the entered time. With a set of T
d
= 0 no rate time proportion will be calculated.
•
Output delimitation Y
max
(
±
0.1 ...
±
100%)
:
The output delimitation Y
s
can be limited to a maximum value of < 100%. A negative setting of the output
delimitation follows a reversal of the direction of action.
In case of a two-state controller this means for example:
Y
max
= +80%: (actual value > desired value)
Î
output Y
s
= 0%
(actual value < desired value)
Î
output Y
s
= 80%
Y
max
= -80%: (actual value > desired value)
Î
output Y
s
= 80%
(actual value < desired value)
Î
output Y
s
= 0%
•
Apply:
Click the
apply
button to set the entered values (under “New”) into the pyrometer.
•
Apply + Self Tune:
Click the
Apply + Self Tune
button to set the entered values (under “New”) into the pyrometer and simul-
taneously start the automatic self-tuning algorithm.
•
Stop:
If the temperature is getting out of control, the whole process can be stopped by pressing the stop button.
•
Output Y:
If the output Y is set to “manu.”, the analog output signal can be controlled directly. In this case the bar
graph on the right side has the function as a sliding controller and the temperature adaptation can be ob-
served directly.
