Danfoss VLT AutomationDrive FC 300 Design Manual page 36

3. Introduction to FC 300
3.3.4. Example of Process PID Control
The following is an example of a Process PID Control used in a ventilation system:
3
In a ventilation system, the temperature is to
be settable from - 5 - 35°C with a potentiom-
eter of 0-10 Volt. The set temperature must
be kept constant, for which purpose the Proc-
ess 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 -10-40°C, 4-20 mA. Min. /
Max. speed 300 / 1500 RPM.
1.
2.
3.
Example of Process PID Control set-up
36
NB!
The example shows a two-wire
transmitter.
Start/Stop via switch connected to terminal 18.
Temperature reference via potentiometer (-5-35°C, 0-10 VDC) connected to terminal 53.
Temperature feedback via transmitter (-10-40°C, 4-20 mA) connected to terminal 54.
Switch S202 set to ON (current input).
MG.33.B9.02 - VLT ® is a registered Danfoss trademark
FC 300 Design Guide