35
EN
5.12. PI CONTROL IN CONS TANT PRESSURE/AIRFLOW SYSTEMS WITH EXTERNAL
SENSOR WITH 0-10V SIGNAL
With this confi guration, both a constant fl ow mode (CAV) and a constant pressure type (COP) can
be obtained.
Constant airfl ow (CAV)
The VSD is used to guarantee a certain airfl ow in a duct network, regardless of fi lters closing.
Constant pressure (COP)
The drive is used in variable air volume systems to guarantee specifi c air pressure in the duct sys-
tems regardless of whether the dampers are open or closed.
In both cases, the pressure must be constant in the duct system. The value of this pressure must be
determined by experimenting during the system start-up process. For this adjustment, it is essen-
tial to have a differential pressure sensor with display (S&P,
5416731400 TDP-D
model).
First, an attempt will be made to make the adjustment by modifying sensor range. Examples:
Sensor range
“rPI” value introduced
Pressure set point to maintain by VFTM320
0-100
500
50 Pa
0-300
333
100 Pa
0-300
400
120 Pa
0-300
600
180 Pa
0-300
666
200 Pa
0-500
600
300 Pa
0-500
700
350 Pa
0-500
800
400 Pa
5.12.1. Installation diagram
TDP-D
PRESSURE
SENSOR
FREQUENCY
DRIVE
FAN
FILTER
Constant airfl ow (CAV) diagram
