Pi Controller (4.1 - Grundfos CONTROL MPC Installation And Operating Instructions Manual

11.7.2 PI controller (4.1.1)

Fig. 33 PI controller
Description
Control MPC includes a standard PI controller which ensures that
the pressure is stable and corresponds to the setpoint.
It is possible to adjust the PI controller if a faster or slower
reaction to changes of consumption is required.
A faster reaction is obtained if K
A slower reaction is obtained if K
Setting range
• Gain K : –30 to 30.
p
Note: For inverse control, set K
• Integral time T : 0.1 to 3600 seconds.
i
Setting via control panel
1. Mark the Settings menu with
2. Mark Primary controller with
3. Mark PI controller with
4. Select the gain (K ) with
p
or , and save with
Note: Usually it is not necessary to adjust K
5. Select the integral time (T
or , and press
Factory setting
The setting of K and T depends on the system and application.
p i
PI controller settings for pressure boosting
If the application has been set to pressure boosting in the start-up
wizard, the following values of K
• K : 0.5
p
• T : 1 second.
i
26
is increased and T is reduced.
p i
is reduced and T is increased.
p i
to a negative value.
p
.
or , and press
or , and press .
or . Set the value with
.
.
p
) with or . Set the time with
i
.
and T will be set automatically:
p i
PI controller settings for heating and cooling
If another application than pressure boosting has been selected
in the start-up wizard, the values of K
automatically according to the table below. As Control MPC does
not know the pipe length, the default parameters will be set
according to the table to a pipe length (L
System/application
L [m]
1
Q
t
L [m]
.
L [m]
L [m]
t
1)
Heating systems are systems in which an increase in pump
performance will result in a temperature rise at the sensor.
2)
Cooling systems are systems in which an increase in pump
performance will result in a temperature drop at the sensor.
L : Distance [m] between pump and sensor.
1
L : Distance [m] between heat exchanger and sensor.
2
ΔP: Measurement of differential pressure.
Q: Measurement of flow rate.
t: Measurement of temperature.
Δ t:
Measurement of differential temperature.
and T will be set
p i
or L ) of 5 metres.
1 2
K
p
Heating Cooling
[Seconds]
1) 2)
system system
0.5
L
L
0.5
L
1
0.5
-0.5
0.5
0.5
0.5 -0.5
T
i
1
< 5 m: 1
1
> 5 m: 3
1
> 10 m: 5
1
10 + 5L
2
10 + 5L
2
30 + 5L
2