Danfoss FC 300 Design Manual page 38

3. Introduction to FC 300
3.3.4. Example of Process PID Control
The following is an example of process PID control used in a ventilation system:
3
In a ventilation system, the temperature is to
be able to be set from 23°-95° F ( -5°-35° C)
with a potentiometer of 0-10 Volt. The set
temperature must be kept constant, for which
purpose the process control is to be used.
The control is of the inverse type, which
means that when the temperature increases,
the ventilation speed is increased as well, so
as to generate more air. When the tempera-
ture drops, the speed is reduced. The trans-
mitter used is a temperature sensor with a
working range of 14°-104 °F (-10°- +40°C),
4-20 mA. Min. / Max. speed 300 /1,500 RPM.
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2.
3.
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NOTE
The example shows a two-wire
transmitter.
Start/Stop via switch connected to terminal 18.
Temperature reference via potentiometer (23°-95° F (-5°- +35° C), 0-10 VDC) connec-
ted to terminal 53.
Temperature feedback via transmitter (14°-104° F (-10°- +40° C), 4-20 mA) connected
to terminal 54. Switch S202 set to ON (current input).
MG.33.B9.22 - VLT ® is a registered Danfoss trademark.
FC 300 Design Guide