
PID for process control
The following is an example of a process controller
used in a ventilation system.
In a ventilation system, the temperature is to be setta-
ble from - 5 - 35°C with a potentiometer of 0-10 Volt.
The set temperature must be kept constant, for which
purpose the integrated process controller 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 temperature drops, the speed is reduced.
The transmitter used is a temperature sensor with a
working range of -10-40°C, 4-20 mA.
Min./Max. speed 10/50 Hz.
NB!
The example shows a two-wire transmit-
ter.
1.
Start/Stop
2.
Temperature reference -5-35°C, 0-10 V (set-
point)
3.
Temperature transmitter -10-40°C, 4-20 mA
(feedback).
The following must be programmed in order shown - see explanation of settings in the Operating Instructions:
Function:
Parameter no.
Setting
Data value no.
Activation of process controller
100
Process control, closed loop
[3]
Feedback signal
314
Feedback signal
[2]
Terminal 60, min. scale
315
4 mA
Terminal 60, max. scale
316
20 mA (factory setting)
Minimum feedback
414
-10°C
Maximum feedback
415
40°C
Process units
416
°C
[10]
Reference
308
Reference
(factory setting)
[1]
Terminal 53, min. scale
309
0 Volt (factory setting)
Terminal 53, max. scale
310
10 Volt (factory setting)
Minimum reference
204
-5°C
Maximum reference
205
35°C
Inverse control
437
Inverse
[1]
Min. frequency
201
10 Hz
Max. frequency
202
50 Hz
Proportional gain
440
Application-dependent (e.g. 1.0)
Integration time
441
Application-dependent (e.g. 5 sec.)
VLT
®
5000 Design Guide
106
MG.52.B2.02 - VLT
®
is a registered Danfoss trademark