English (GB)
19
8.5.3 Control mode (2.1.2)
Fig. 19
Control mode
Description
There are two control modes, namely closed and open loop.
Closed loop
The typical control mode is closed loop where the built-in PI
controller ensures that the system reaches and maintains the
selected setpoint. The performance is based on the setpoint set
for closed loop. See figures
.
Fig. 20
Booster system controlled by built-in PI controller
(closed loop)
Fig. 21
Regulation curve for closed loop
Setting via control panel
• Operation > Further settings > Control mode > Closed loop.
Set the setpoint. See sections
and
.
Open loop
In open-loop control, the pumps run at a fixed speed.
The pump speed is calculated from the performance set by the
user (0-100 %). The pump performance in percentage is
proportional with the flow rate.
Open-loop control is usually used when the system is controlled
by an external controller which controls the performance via an
external signal. The external controller could for instance be a
building management system connected to the MPC system. In
such cases the MPC is like an actuator. See figures
and
.
Fig. 22
Booster system with external controller (open loop)
Fig. 23
Regulation curve for open loop
Fig. 24
Regulation curve for MPC-E system in open loop
TM
03 223
1 390
5
TM
03
23
90
41
05
P [bar]
Time [sec]
Setpoint
TM
03
22
32
39
05
TM0
3
239
1
3
6
0
7
TM
0
3
9
977
4
807
0
5
Input [%] from
external controller
Flow rate [m
3
/h]
100
50
70.7
5
25
50
75
100
86.6
Flow rate [m
3
/h]
Input [%] from
external controller
Pump 1
Pump 4
Pump 3
Flow rate
Pump 2
